src/libFLAC/encoder.c

   1 /* libFLAC - Free Lossless Audio Coder library
   2  * Copyright (C) 2000  Josh Coalson
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA  02111-1307, USA.
  18  */
  19
  20 #include <assert.h>
  21 #include <stdio.h>
  22 #include <stdlib.h> /* for malloc() */
  23 #include <string.h> /* for memcpy() */
  24 #include "FLAC/encoder.h"
  25 #include "private/bitbuffer.h"
  26 #include "private/encoder_framing.h"
  27 #include "private/fixed.h"
  28 #include "private/lpc.h"
  29
  30 #ifdef min
  31 #undef min
  32 #endif
  33 #define min(x,y) ((x)<(y)?(x):(y))
  34
  35 #ifdef max
  36 #undef max
  37 #endif
  38 #define max(x,y) ((x)>(y)?(x):(y))
  39
  40 #ifdef RICE_BITS
  41 #undef RICE_BITS
  42 #endif
  43 #define RICE_BITS(value, parameter) (2 + (parameter) + (((unsigned)((value) < 0? -(value) : (value))) >> (parameter)))
  44
  45 typedef struct FLAC__EncoderPrivate {
  46         unsigned input_capacity;                    /* current size (in samples) of the signal and residual buffers */
  47         int32 *integer_signal[FLAC__MAX_CHANNELS];  /* the integer version of the input signal */
  48         int32 *integer_signal_mid_side[2];          /* the integer version of the mid-side input signal (stereo only) */
  49         real *real_signal[FLAC__MAX_CHANNELS];      /* the floating-point version of the input signal */
  50         real *real_signal_mid_side[2];              /* the floating-point version of the mid-side input signal (stereo only) */
  51         int32 *residual[2];                         /* where the candidate and best subframe residual signals will be stored */
  52         unsigned best_residual;                     /* index into the above */
  53         FLAC__BitBuffer frame;                      /* the current frame being worked on */
  54         FLAC__BitBuffer frame_mid_side;             /* special parallel workspace for the mid-side coded version of the current frame */
  55         FLAC__BitBuffer frame_left_side;            /* special parallel workspace for the left-side coded version of the current frame */
  56         FLAC__BitBuffer frame_right_side;           /* special parallel workspace for the right-side coded version of the current frame */
  57         FLAC__SubframeHeader best_subframe, candidate_subframe;
  58         bool current_frame_can_do_mid_side;         /* encoder sets this false when any given sample of a frame's side channel exceeds 16 bits */
  59         FLAC__StreamMetaData metadata;
  60         unsigned current_sample_number;
  61         unsigned current_frame_number;
  62         FLAC__EncoderWriteStatus (*write_callback)(const FLAC__Encoder *encoder, const byte buffer[], unsigned bytes, unsigned samples, unsigned current_frame, void *client_data);
  63         void (*metadata_callback)(const FLAC__Encoder *encoder, const FLAC__StreamMetaData *metadata, void *client_data);
  64         void *client_data;
  65 } FLAC__EncoderPrivate;
  66
  67 static bool encoder_resize_buffers_(FLAC__Encoder *encoder, unsigned new_size);
  68 static bool encoder_process_frame_(FLAC__Encoder *encoder, bool is_last_frame);
  69 static bool encoder_process_subframes_(FLAC__Encoder *encoder, bool is_last_frame, const FLAC__FrameHeader *frame_header, unsigned channels, const int32 *integer_signal[], const real *real_signal[], FLAC__BitBuffer *bitbuffer);
  70 static unsigned encoder_evaluate_constant_subframe_(const int32 signal, unsigned bits_per_sample, FLAC__SubframeHeader *subframe);
  71 static unsigned encoder_evaluate_fixed_subframe_(const int32 signal[], int32 residual[], unsigned blocksize, unsigned bits_per_sample, unsigned order, unsigned rice_parameter, unsigned max_partition_order, FLAC__SubframeHeader *subframe);
  72 static unsigned encoder_evaluate_lpc_subframe_(const int32 signal[], int32 residual[], const real lp_coeff[], unsigned blocksize, unsigned bits_per_sample, unsigned order, unsigned qlp_coeff_precision, unsigned rice_parameter, unsigned max_partition_order, FLAC__SubframeHeader *subframe);
  73 static unsigned encoder_evaluate_verbatim_subframe_(unsigned blocksize, unsigned bits_per_sample, FLAC__SubframeHeader *subframe);
  74 static unsigned encoder_find_best_partition_order_(int32 residual[], unsigned residual_samples, unsigned predictor_order, unsigned rice_parameter, unsigned max_partition_order, unsigned *best_partition_order, unsigned best_parameters[]);
  75 static bool encoder_generate_constant_subframe_(const FLAC__SubframeHeader *header, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer);
  76 static bool encoder_generate_fixed_subframe_(const FLAC__SubframeHeader *header, int32 residual[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer);
  77 static bool encoder_generate_lpc_subframe_(const FLAC__SubframeHeader *header, int32 residual[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer);
  78 static bool encoder_generate_verbatim_subframe_(const FLAC__SubframeHeader *header, const int32 signal[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer);
  79 static void encoder_promote_candidate_subframe_(FLAC__Encoder *encoder);
  80 static bool encoder_set_partitioned_rice_(const int32 residual[], const unsigned residual_samples, const unsigned predictor_order, const unsigned rice_parameter, const unsigned partition_order, unsigned parameters[], unsigned *bits);
  81
  82 const char *FLAC__EncoderWriteStatusString[] = {
  83         "FLAC__ENCODER_WRITE_OK",
  84         "FLAC__ENCODER_WRITE_FATAL_ERROR"
  85 };
  86
  87 const char *FLAC__EncoderStateString[] = {
  88         "FLAC__ENCODER_OK",
  89         "FLAC__ENCODER_UNINITIALIZED",
  90         "FLAC__ENCODER_INVALID_NUMBER_OF_CHANNELS",
  91         "FLAC__ENCODER_INVALID_BITS_PER_SAMPLE",
  92         "FLAC__ENCODER_INVALID_SAMPLE_RATE",
  93         "FLAC__ENCODER_INVALID_BLOCK_SIZE",
  94         "FLAC__ENCODER_INVALID_QLP_COEFF_PRECISION",
  95         "FLAC__ENCODER_MID_SIDE_CHANNELS_MISMATCH",
  96         "FLAC__ENCODER_MID_SIDE_SAMPLE_SIZE_MISMATCH",
  97         "FLAC__ENCODER_BLOCK_SIZE_TOO_SMALL_FOR_LPC_ORDER",
  98         "FLAC__ENCODER_NOT_STREAMABLE",
  99         "FLAC__ENCODER_FRAMING_ERROR",
 100         "FLAC__ENCODER_FATAL_ERROR_WHILE_ENCODING",
 101         "FLAC__ENCODER_FATAL_ERROR_WHILE_WRITING",
 102         "FLAC__ENCODER_MEMORY_ALLOCATION_ERROR"
 103 };
 104
 105
 106 bool encoder_resize_buffers_(FLAC__Encoder *encoder, unsigned new_size)
 107 {
 108         bool ok;
 109         unsigned i;
 110         int32 *previous_is, *current_is;
 111         real *previous_rs, *current_rs;
 112         int32 *residual;
 113
 114         assert(new_size > 0);
 115         assert(encoder->state == FLAC__ENCODER_OK);
 116         assert(encoder->guts->current_sample_number == 0);
 117
 118         /* To avoid excessive malloc'ing, we only grow the buffer; no shrinking. */
 119         if(new_size <= encoder->guts->input_capacity)
 120                 return true;
 121
 122         ok = 1;
 123         if(ok) {
 124                 for(i = 0; ok && i < encoder->channels; i++) {
 125                         /* integer version of the signal */
 126                         previous_is = encoder->guts->integer_signal[i];
 127                         current_is = (int32*)malloc(sizeof(int32) * new_size);
 128                         if(0 == current_is) {
 129                                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 130                                 ok = 0;
 131                         }
 132                         else {
 133                                 encoder->guts->integer_signal[i] = current_is;
 134                                 if(previous_is != 0)
 135                                         free(previous_is);
 136                         }
 137                         /* real version of the signal */
 138                         previous_rs = encoder->guts->real_signal[i];
 139                         current_rs = (real*)malloc(sizeof(real) * new_size);
 140                         if(0 == current_rs) {
 141                                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 142                                 ok = 0;
 143                         }
 144                         else {
 145                                 encoder->guts->real_signal[i] = current_rs;
 146                                 if(previous_rs != 0)
 147                                         free(previous_rs);
 148                         }
 149                 }
 150         }
 151         if(ok) {
 152                 for(i = 0; ok && i < 2; i++) {
 153                         /* integer version of the signal */
 154                         previous_is = encoder->guts->integer_signal_mid_side[i];
 155                         current_is = (int32*)malloc(sizeof(int32) * new_size);
 156                         if(0 == current_is) {
 157                                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 158                                 ok = 0;
 159                         }
 160                         else {
 161                                 encoder->guts->integer_signal_mid_side[i] = current_is;
 162                                 if(previous_is != 0)
 163                                         free(previous_is);
 164                         }
 165                         /* real version of the signal */
 166                         previous_rs = encoder->guts->real_signal_mid_side[i];
 167                         current_rs = (real*)malloc(sizeof(real) * new_size);
 168                         if(0 == current_rs) {
 169                                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 170                                 ok = 0;
 171                         }
 172                         else {
 173                                 encoder->guts->real_signal_mid_side[i] = current_rs;
 174                                 if(previous_rs != 0)
 175                                         free(previous_rs);
 176                         }
 177                 }
 178         }
 179         if(ok) {
 180                 for(i = 0; i < 2; i++) {
 181                         residual = (int32*)malloc(sizeof(int32) * new_size);
 182                         if(0 == residual) {
 183                                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 184                                 ok = 0;
 185                         }
 186                         else {
 187                                 if(encoder->guts->residual[i] != 0)
 188                                         free(encoder->guts->residual[i]);
 189                                 encoder->guts->residual[i] = residual;
 190                         }
 191                 }
 192         }
 193         if(ok)
 194                 encoder->guts->input_capacity = new_size;
 195
 196         return ok;
 197 }
 198
 199 FLAC__Encoder *FLAC__encoder_get_new_instance()
 200 {
 201         FLAC__Encoder *encoder = (FLAC__Encoder*)malloc(sizeof(FLAC__Encoder));
 202         if(encoder != 0) {
 203                 encoder->state = FLAC__ENCODER_UNINITIALIZED;
 204                 encoder->guts = 0;
 205         }
 206         return encoder;
 207 }
 208
 209 void FLAC__encoder_free_instance(FLAC__Encoder *encoder)
 210 {
 211         assert(encoder != 0);
 212         free(encoder);
 213 }
 214
 215 FLAC__EncoderState FLAC__encoder_init(FLAC__Encoder *encoder, FLAC__EncoderWriteStatus (*write_callback)(const FLAC__Encoder *encoder, const byte buffer[], unsigned bytes, unsigned samples, unsigned current_frame, void *client_data), void (*metadata_callback)(const FLAC__Encoder *encoder, const FLAC__StreamMetaData *metadata, void *client_data), void *client_data)
 216 {
 217         unsigned i;
 218
 219         assert(sizeof(int) >= 4); /* we want to die right away if this is not true */
 220         assert(encoder != 0);
 221         assert(write_callback != 0);
 222         assert(metadata_callback != 0);
 223         assert(encoder->state == FLAC__ENCODER_UNINITIALIZED);
 224         assert(encoder->guts == 0);
 225
 226         encoder->state = FLAC__ENCODER_OK;
 227
 228         if(encoder->channels == 0 || encoder->channels > FLAC__MAX_CHANNELS)
 229                 return encoder->state = FLAC__ENCODER_INVALID_NUMBER_OF_CHANNELS;
 230
 231         if(encoder->do_mid_side_stereo && encoder->channels != 2)
 232                 return encoder->state = FLAC__ENCODER_MID_SIDE_CHANNELS_MISMATCH;
 233
 234         if(encoder->do_mid_side_stereo && encoder->bits_per_sample > 16)
 235                 return encoder->state = FLAC__ENCODER_MID_SIDE_SAMPLE_SIZE_MISMATCH;
 236
 237         if(encoder->bits_per_sample == 0 || encoder->bits_per_sample > FLAC__MAX_BITS_PER_SAMPLE)
 238                 return encoder->state = FLAC__ENCODER_INVALID_BITS_PER_SAMPLE;
 239
 240         if(encoder->sample_rate == 0 || encoder->sample_rate > FLAC__MAX_SAMPLE_RATE)
 241                 return encoder->state = FLAC__ENCODER_INVALID_SAMPLE_RATE;
 242
 243         if(encoder->blocksize < FLAC__MIN_BLOCK_SIZE || encoder->blocksize > FLAC__MAX_BLOCK_SIZE)
 244                 return encoder->state = FLAC__ENCODER_INVALID_BLOCK_SIZE;
 245
 246         if(encoder->blocksize < encoder->max_lpc_order)
 247                 return encoder->state = FLAC__ENCODER_BLOCK_SIZE_TOO_SMALL_FOR_LPC_ORDER;
 248
 249         if(encoder->qlp_coeff_precision == 0) {
 250                 if(encoder->bits_per_sample < 16) {
 251                         /* @@@ need some data about how to set this here w.r.t. blocksize and sample rate */
 252                         /* @@@ until then we'll make a guess */
 253                         encoder->qlp_coeff_precision = max(5, 2 + encoder->bits_per_sample / 2);
 254                 }
 255                 else if(encoder->bits_per_sample == 16) {
 256                         if(encoder->blocksize <= 192)
 257                                 encoder->qlp_coeff_precision = 7;
 258                         else if(encoder->blocksize <= 384)
 259                                 encoder->qlp_coeff_precision = 8;
 260                         else if(encoder->blocksize <= 576)
 261                                 encoder->qlp_coeff_precision = 9;
 262                         else if(encoder->blocksize <= 1152)
 263                                 encoder->qlp_coeff_precision = 10;
 264                         else if(encoder->blocksize <= 2304)
 265                                 encoder->qlp_coeff_precision = 11;
 266                         else if(encoder->blocksize <= 4608)
 267                                 encoder->qlp_coeff_precision = 12;
 268                         else
 269                                 encoder->qlp_coeff_precision = 13;
 270                 }
 271                 else {
 272                         encoder->qlp_coeff_precision = min(13, 8*sizeof(int32) - encoder->bits_per_sample - 1);
 273                 }
 274         }
 275         else if(encoder->qlp_coeff_precision < FLAC__MIN_QLP_COEFF_PRECISION || encoder->qlp_coeff_precision + encoder->bits_per_sample >= 8*sizeof(uint32))
 276                 return encoder->state = FLAC__ENCODER_INVALID_QLP_COEFF_PRECISION;
 277
 278         if(encoder->streamable_subset) {
 279                 if(encoder->bits_per_sample != 8 && encoder->bits_per_sample != 12 && encoder->bits_per_sample != 16 && encoder->bits_per_sample != 20 && encoder->bits_per_sample != 24)
 280                         return encoder->state = FLAC__ENCODER_NOT_STREAMABLE;
 281                 if(encoder->sample_rate > 655350)
 282                         return encoder->state = FLAC__ENCODER_NOT_STREAMABLE;
 283         }
 284
 285         if(encoder->rice_optimization_level >= (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ORDER_LEN))
 286                 encoder->rice_optimization_level = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ORDER_LEN) - 1;
 287
 288         encoder->guts = (FLAC__EncoderPrivate*)malloc(sizeof(FLAC__EncoderPrivate));
 289         if(encoder->guts == 0)
 290                 return encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 291
 292         encoder->guts->input_capacity = 0;
 293         for(i = 0; i < encoder->channels; i++) {
 294                 encoder->guts->integer_signal[i] = 0;
 295                 encoder->guts->real_signal[i] = 0;
 296         }
 297         for(i = 0; i < 2; i++) {
 298                 encoder->guts->integer_signal_mid_side[i] = 0;
 299                 encoder->guts->real_signal_mid_side[i] = 0;
 300         }
 301         encoder->guts->residual[0] = 0;
 302         encoder->guts->residual[1] = 0;
 303         encoder->guts->best_residual = 0;
 304         encoder->guts->current_frame_can_do_mid_side = true;
 305         encoder->guts->current_sample_number = 0;
 306         encoder->guts->current_frame_number = 0;
 307
 308         if(!encoder_resize_buffers_(encoder, encoder->blocksize)) {
 309                 /* the above function sets the state for us in case of an error */
 310                 return encoder->state;
 311         }
 312         FLAC__bitbuffer_init(&encoder->guts->frame);
 313         encoder->guts->write_callback = write_callback;
 314         encoder->guts->metadata_callback = metadata_callback;
 315         encoder->guts->client_data = client_data;
 316
 317         /*
 318          * write the stream header
 319          */
 320         if(!FLAC__bitbuffer_clear(&encoder->guts->frame))
 321                 return encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 322
 323         if(!FLAC__bitbuffer_write_raw_uint32(&encoder->guts->frame, FLAC__STREAM_SYNC, FLAC__STREAM_SYNC_LEN))
 324                 return encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 325
 326         encoder->guts->metadata.type = FLAC__METADATA_TYPE_ENCODING;
 327         encoder->guts->metadata.is_last = true;
 328         encoder->guts->metadata.length = FLAC__STREAM_METADATA_ENCODING_LENGTH;
 329         encoder->guts->metadata.data.encoding.min_blocksize = encoder->blocksize; /* this encoder uses the same blocksize for the whole stream */
 330         encoder->guts->metadata.data.encoding.max_blocksize = encoder->blocksize;
 331         encoder->guts->metadata.data.encoding.min_framesize = 0; /* we don't know this yet; have to fill it in later */
 332         encoder->guts->metadata.data.encoding.max_framesize = 0; /* we don't know this yet; have to fill it in later */
 333         encoder->guts->metadata.data.encoding.sample_rate = encoder->sample_rate;
 334         encoder->guts->metadata.data.encoding.channels = encoder->channels;
 335         encoder->guts->metadata.data.encoding.bits_per_sample = encoder->bits_per_sample;
 336         encoder->guts->metadata.data.encoding.total_samples = 0; /* we don't know this yet; have to fill it in later */
 337         if(!FLAC__add_metadata_block(&encoder->guts->metadata, &encoder->guts->frame))
 338                 return encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 339
 340         assert(encoder->guts->frame.bits == 0); /* assert that we're byte-aligned before writing */
 341         assert(encoder->guts->frame.total_consumed_bits == 0); /* assert that no reading of the buffer was done */
 342         if(encoder->guts->write_callback(encoder, encoder->guts->frame.buffer, encoder->guts->frame.bytes, 0, encoder->guts->current_frame_number, encoder->guts->client_data) != FLAC__ENCODER_WRITE_OK)
 343                 return encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_WRITING;
 344
 345         /* now that the metadata block is written, we can init this to an absurdly-high value */
 346         encoder->guts->metadata.data.encoding.min_framesize = (1u << FLAC__STREAM_METADATA_ENCODING_MIN_FRAME_SIZE_LEN) - 1;
 347
 348         return encoder->state;
 349 }
 350
 351 void FLAC__encoder_finish(FLAC__Encoder *encoder)
 352 {
 353         unsigned i;
 354
 355         assert(encoder != 0);
 356         if(encoder->state == FLAC__ENCODER_UNINITIALIZED)
 357                 return;
 358         if(encoder->guts->current_sample_number != 0) {
 359                 encoder->blocksize = encoder->guts->current_sample_number;
 360                 encoder_process_frame_(encoder, true); /* true => is last frame */
 361         }
 362         encoder->guts->metadata_callback(encoder, &encoder->guts->metadata, encoder->guts->client_data);
 363         if(encoder->guts != 0) {
 364                 for(i = 0; i < encoder->channels; i++) {
 365                         if(encoder->guts->integer_signal[i] != 0) {
 366                                 free(encoder->guts->integer_signal[i]);
 367                                 encoder->guts->integer_signal[i] = 0;
 368                         }
 369                         if(encoder->guts->real_signal[i] != 0) {
 370                                 free(encoder->guts->real_signal[i]);
 371                                 encoder->guts->real_signal[i] = 0;
 372                         }
 373                 }
 374                 for(i = 0; i < 2; i++) {
 375                         if(encoder->guts->integer_signal_mid_side[i] != 0) {
 376                                 free(encoder->guts->integer_signal_mid_side[i]);
 377                                 encoder->guts->integer_signal_mid_side[i] = 0;
 378                         }
 379                         if(encoder->guts->real_signal_mid_side[i] != 0) {
 380                                 free(encoder->guts->real_signal_mid_side[i]);
 381                                 encoder->guts->real_signal_mid_side[i] = 0;
 382                         }
 383                 }
 384                 for(i = 0; i < 2; i++) {
 385                         if(encoder->guts->residual[i] != 0) {
 386                                 free(encoder->guts->residual[i]);
 387                                 encoder->guts->residual[i] = 0;
 388                         }
 389                 }
 390                 FLAC__bitbuffer_free(&encoder->guts->frame);
 391                 free(encoder->guts);
 392                 encoder->guts = 0;
 393         }
 394         encoder->state = FLAC__ENCODER_UNINITIALIZED;
 395 }
 396
 397 bool FLAC__encoder_process(FLAC__Encoder *encoder, const int32 *buf[], unsigned samples)
 398 {
 399         unsigned i, j, channel;
 400         int32 x, mid, side;
 401         const bool ms = encoder->do_mid_side_stereo && encoder->channels == 2;
 402         const int32 min_side = -((int64)1 << (encoder->bits_per_sample-1));
 403         const int32 max_side =  ((int64)1 << (encoder->bits_per_sample-1)) - 1;
 404
 405         assert(encoder != 0);
 406         assert(encoder->state == FLAC__ENCODER_OK);
 407
 408         j = 0;
 409         do {
 410                 for(i = encoder->guts->current_sample_number; i < encoder->blocksize && j < samples; i++, j++) {
 411                         for(channel = 0; channel < encoder->channels; channel++) {
 412                                 x = buf[channel][j];
 413                                 encoder->guts->integer_signal[channel][i] = x;
 414                                 encoder->guts->real_signal[channel][i] = (real)x;
 415                         }
 416                         if(ms && encoder->guts->current_frame_can_do_mid_side) {
 417                                 side = buf[0][j] - buf[1][j];
 418                                 if(side < min_side || side > max_side) {
 419                                         encoder->guts->current_frame_can_do_mid_side = false;
 420                                 }
 421                                 else {
 422                                         mid = (buf[0][j] + buf[1][j]) >> 1; /* NOTE: not the same as divide-by-two ! */
 423                                         encoder->guts->integer_signal_mid_side[0][i] = mid;
 424                                         encoder->guts->integer_signal_mid_side[1][i] = side;
 425                                         encoder->guts->real_signal_mid_side[0][i] = (real)mid;
 426                                         encoder->guts->real_signal_mid_side[1][i] = (real)side;
 427                                 }
 428                         }
 429                         encoder->guts->current_sample_number++;
 430                 }
 431                 if(i == encoder->blocksize) {
 432                         if(!encoder_process_frame_(encoder, false)) /* false => not last frame */
 433                                 return false;
 434                 }
 435         } while(j < samples);
 436
 437         return true;
 438 }
 439
 440 /* 'samples' is channel-wide samples, e.g. for 1 second at 44100Hz, 'samples' = 44100 regardless of the number of channels */
 441 bool FLAC__encoder_process_interleaved(FLAC__Encoder *encoder, const int32 buf[], unsigned samples)
 442 {
 443         unsigned i, j, k, channel;
 444         int32 x, left = 0, mid, side;
 445         const bool ms = encoder->do_mid_side_stereo && encoder->channels == 2;
 446         const int32 min_side = -((int64)1 << (encoder->bits_per_sample-1));
 447         const int32 max_side =  ((int64)1 << (encoder->bits_per_sample-1)) - 1;
 448
 449         assert(encoder != 0);
 450         assert(encoder->state == FLAC__ENCODER_OK);
 451
 452         j = k = 0;
 453         do {
 454                 for(i = encoder->guts->current_sample_number; i < encoder->blocksize && j < samples; i++, j++, k++) {
 455                         for(channel = 0; channel < encoder->channels; channel++, k++) {
 456                                 x = buf[k];
 457                                 encoder->guts->integer_signal[channel][i] = x;
 458                                 encoder->guts->real_signal[channel][i] = (real)x;
 459                                 if(ms && encoder->guts->current_frame_can_do_mid_side) {
 460                                         if(channel == 0) {
 461                                                 left = x;
 462                                         }
 463                                         else {
 464                                                 side = left - x;
 465                                                 if(side < min_side || side > max_side) {
 466                                                         encoder->guts->current_frame_can_do_mid_side = false;
 467                                                 }
 468                                                 else {
 469                                                         mid = (left + x) >> 1; /* NOTE: not the same as divide-by-two ! */
 470                                                         encoder->guts->integer_signal_mid_side[0][i] = mid;
 471                                                         encoder->guts->integer_signal_mid_side[1][i] = side;
 472                                                         encoder->guts->real_signal_mid_side[0][i] = (real)mid;
 473                                                         encoder->guts->real_signal_mid_side[1][i] = (real)side;
 474                                                 }
 475                                         }
 476                                 }
 477                         }
 478                         encoder->guts->current_sample_number++;
 479                 }
 480                 if(i == encoder->blocksize) {
 481                         if(!encoder_process_frame_(encoder, false)) /* false => not last frame */
 482                                 return false;
 483                 }
 484         } while(j < samples);
 485
 486         return true;
 487 }
 488
 489 bool encoder_process_frame_(FLAC__Encoder *encoder, bool is_last_frame)
 490 {
 491         FLAC__FrameHeader frame_header;
 492         FLAC__BitBuffer *smallest_frame;
 493
 494         assert(encoder->state == FLAC__ENCODER_OK);
 495
 496         /*
 497          * First do a normal encoding pass
 498          */
 499         frame_header.blocksize = encoder->blocksize;
 500         frame_header.sample_rate = encoder->sample_rate;
 501         frame_header.channels = encoder->channels;
 502         frame_header.channel_assignment = FLAC__CHANNEL_ASSIGNMENT_INDEPENDENT; /* the default unless the encoder determines otherwise */
 503         frame_header.bits_per_sample = encoder->bits_per_sample;
 504         frame_header.number.frame_number = encoder->guts->current_frame_number;
 505
 506         if(!FLAC__bitbuffer_clear(&encoder->guts->frame)) {
 507                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 508                 return false;
 509         }
 510         if(!FLAC__frame_add_header(&frame_header, encoder->streamable_subset, is_last_frame, &encoder->guts->frame)) {
 511                 encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 512                 return false;
 513         }
 514
 515         if(!encoder_process_subframes_(encoder, is_last_frame, &frame_header, encoder->channels, encoder->guts->integer_signal, encoder->guts->real_signal, &encoder->guts->frame))
 516                 return false;
 517
 518         smallest_frame = &encoder->guts->frame;
 519
 520         /*
 521          * Now try a mid-side version if necessary; otherwise, just use the previous step's frame
 522          */
 523         if(encoder->do_mid_side_stereo && encoder->guts->current_frame_can_do_mid_side) {
 524                 int32 *integer_signal[2];
 525                 real *real_signal[2];
 526
 527                 assert(encoder->channels == 2);
 528
 529                 /* mid-side */
 530                 frame_header.channel_assignment = FLAC__CHANNEL_ASSIGNMENT_MID_SIDE;
 531                 if(!FLAC__bitbuffer_clear(&encoder->guts->frame_mid_side)) {
 532                         encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 533                         return false;
 534                 }
 535                 if(!FLAC__frame_add_header(&frame_header, encoder->streamable_subset, is_last_frame, &encoder->guts->frame_mid_side)) {
 536                         encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 537                         return false;
 538                 }
 539                 integer_signal[0] = encoder->guts->integer_signal_mid_side[0]; /* mid channel */
 540                 integer_signal[1] = encoder->guts->integer_signal_mid_side[1]; /* side channel */
 541                 real_signal[0] = encoder->guts->real_signal_mid_side[0]; /* mid channel */
 542                 real_signal[1] = encoder->guts->real_signal_mid_side[1]; /* side channel */
 543                 if(!encoder_process_subframes_(encoder, is_last_frame, &frame_header, encoder->channels, integer_signal, real_signal, &encoder->guts->frame_mid_side))
 544                         return false;
 545                 if(encoder->guts->frame_mid_side.total_bits < smallest_frame->total_bits)
 546                         smallest_frame = &encoder->guts->frame_mid_side;
 547
 548                 /* left-side */
 549                 frame_header.channel_assignment = FLAC__CHANNEL_ASSIGNMENT_LEFT_SIDE;
 550                 if(!FLAC__bitbuffer_clear(&encoder->guts->frame_left_side)) {
 551                         encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 552                         return false;
 553                 }
 554                 if(!FLAC__frame_add_header(&frame_header, encoder->streamable_subset, is_last_frame, &encoder->guts->frame_left_side)) {
 555                         encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 556                         return false;
 557                 }
 558                 integer_signal[0] = encoder->guts->integer_signal[0]; /* left channel */
 559                 integer_signal[1] = encoder->guts->integer_signal_mid_side[1]; /* side channel */
 560                 real_signal[0] = encoder->guts->real_signal[0]; /* left channel */
 561                 real_signal[1] = encoder->guts->real_signal_mid_side[1]; /* side channel */
 562                 if(!encoder_process_subframes_(encoder, is_last_frame, &frame_header, encoder->channels, integer_signal, real_signal, &encoder->guts->frame_left_side))
 563                         return false;
 564                 if(encoder->guts->frame_left_side.total_bits < smallest_frame->total_bits)
 565                         smallest_frame = &encoder->guts->frame_left_side;
 566
 567                 /* right-side */
 568                 frame_header.channel_assignment = FLAC__CHANNEL_ASSIGNMENT_RIGHT_SIDE;
 569                 if(!FLAC__bitbuffer_clear(&encoder->guts->frame_right_side)) {
 570                         encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 571                         return false;
 572                 }
 573                 if(!FLAC__frame_add_header(&frame_header, encoder->streamable_subset, is_last_frame, &encoder->guts->frame_right_side)) {
 574                         encoder->state = FLAC__ENCODER_FRAMING_ERROR;
 575                         return false;
 576                 }
 577                 integer_signal[0] = encoder->guts->integer_signal_mid_side[1]; /* side channel */
 578                 integer_signal[1] = encoder->guts->integer_signal[1]; /* right channel */
 579                 real_signal[0] = encoder->guts->real_signal_mid_side[1]; /* side channel */
 580                 real_signal[1] = encoder->guts->real_signal[1]; /* right channel */
 581                 if(!encoder_process_subframes_(encoder, is_last_frame, &frame_header, encoder->channels, integer_signal, real_signal, &encoder->guts->frame_right_side))
 582                         return false;
 583                 if(encoder->guts->frame_right_side.total_bits < smallest_frame->total_bits)
 584                         smallest_frame = &encoder->guts->frame_right_side;
 585         }
 586
 587         /*
 588          * Zero-pad the frame to a byte_boundary
 589          */
 590         if(!FLAC__bitbuffer_zero_pad_to_byte_boundary(smallest_frame)) {
 591                 encoder->state = FLAC__ENCODER_MEMORY_ALLOCATION_ERROR;
 592                 return false;
 593         }
 594
 595         /*
 596          * Write it
 597          */
 598         assert(smallest_frame->bits == 0); /* assert that we're byte-aligned before writing */
 599         assert(smallest_frame->total_consumed_bits == 0); /* assert that no reading of the buffer was done */
 600         if(encoder->guts->write_callback(encoder, smallest_frame->buffer, smallest_frame->bytes, encoder->blocksize, encoder->guts->current_frame_number, encoder->guts->client_data) != FLAC__ENCODER_WRITE_OK) {
 601                 encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_WRITING;
 602                 return false;
 603         }
 604
 605         /*
 606          * Get ready for the next frame
 607          */
 608         encoder->guts->current_frame_can_do_mid_side = true;
 609         encoder->guts->current_sample_number = 0;
 610         encoder->guts->current_frame_number++;
 611         encoder->guts->metadata.data.encoding.total_samples += (uint64)encoder->blocksize;
 612         encoder->guts->metadata.data.encoding.min_framesize = min(smallest_frame->bytes, encoder->guts->metadata.data.encoding.min_framesize);
 613         encoder->guts->metadata.data.encoding.max_framesize = max(smallest_frame->bytes, encoder->guts->metadata.data.encoding.max_framesize);
 614
 615         return true;
 616 }
 617
 618 bool encoder_process_subframes_(FLAC__Encoder *encoder, bool is_last_frame, const FLAC__FrameHeader *frame_header, unsigned channels, const int32 *integer_signal[], const real *real_signal[], FLAC__BitBuffer *frame)
 619 {
 620         real fixed_residual_bits_per_sample[FLAC__MAX_FIXED_ORDER+1];
 621         real lpc_residual_bits_per_sample;
 622         real autoc[FLAC__MAX_LPC_ORDER+1];
 623         real lp_coeff[FLAC__MAX_LPC_ORDER][FLAC__MAX_LPC_ORDER];
 624         real lpc_error[FLAC__MAX_LPC_ORDER];
 625         unsigned channel;
 626         unsigned min_lpc_order, max_lpc_order, lpc_order;
 627         unsigned min_fixed_order, max_fixed_order, guess_fixed_order, fixed_order;
 628         unsigned max_partition_order;
 629         unsigned min_qlp_coeff_precision, max_qlp_coeff_precision, qlp_coeff_precision;
 630         unsigned rice_parameter;
 631         unsigned candidate_bits, best_bits;
 632
 633         if(is_last_frame) {
 634                 max_partition_order = 0;
 635         }
 636         else {
 637                 unsigned limit = 0, b = encoder->blocksize;
 638                 while(!(b & 1)) {
 639                         limit++;
 640                         b >>= 1;
 641                 }
 642                 max_partition_order = min(encoder->rice_optimization_level, limit);
 643         }
 644
 645         for(channel = 0; channel < channels; channel++) {
 646                 /* verbatim subframe is the baseline against which we measure other compressed subframes */
 647                 best_bits = encoder_evaluate_verbatim_subframe_(frame_header->blocksize, frame_header->bits_per_sample, &(encoder->guts->best_subframe));
 648
 649                 if(frame_header->blocksize >= FLAC__MAX_FIXED_ORDER) {
 650                         /* check for constant subframe */
 651                         guess_fixed_order = FLAC__fixed_compute_best_predictor(integer_signal[channel]+FLAC__MAX_FIXED_ORDER, frame_header->blocksize-FLAC__MAX_FIXED_ORDER, fixed_residual_bits_per_sample);
 652                         if(fixed_residual_bits_per_sample[1] == 0.0) {
 653                                 /* the above means integer_signal[channel]+FLAC__MAX_FIXED_ORDER is constant, now we just have to check the warmup samples */
 654                                 unsigned i, signal_is_constant = true;
 655                                 for(i = 1; i <= FLAC__MAX_FIXED_ORDER; i++) {
 656                                         if(integer_signal[channel][0] != integer_signal[channel][i]) {
 657                                                 signal_is_constant = false;
 658                                                 break;
 659                                         }
 660                                 }
 661                                 if(signal_is_constant) {
 662                                         candidate_bits = encoder_evaluate_constant_subframe_(integer_signal[channel][0], frame_header->bits_per_sample, &(encoder->guts->candidate_subframe));
 663                                         if(candidate_bits < best_bits) {
 664                                                 encoder_promote_candidate_subframe_(encoder);
 665                                                 best_bits = candidate_bits;
 666                                         }
 667                                 }
 668                         }
 669                         else {
 670                                 /* encode fixed */
 671                                 if(encoder->do_exhaustive_model_search) {
 672                                         min_fixed_order = 0;
 673                                         max_fixed_order = FLAC__MAX_FIXED_ORDER;
 674                                 }
 675                                 else {
 676                                         min_fixed_order = max_fixed_order = guess_fixed_order;
 677                                 }
 678                                 for(fixed_order = min_fixed_order; fixed_order <= max_fixed_order; fixed_order++) {
 679                                         if(fixed_residual_bits_per_sample[fixed_order] >= (real)frame_header->bits_per_sample)
 680                                                 continue; /* don't even try */
 681                                         rice_parameter = (fixed_residual_bits_per_sample[fixed_order] > 0.0)? (unsigned)(fixed_residual_bits_per_sample[fixed_order]+0.5) : 0;
 682                                         if(rice_parameter >= (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN))
 683                                                 rice_parameter = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN) - 1;
 684                                         candidate_bits = encoder_evaluate_fixed_subframe_(integer_signal[channel], encoder->guts->residual[!encoder->guts->best_residual], frame_header->blocksize, frame_header->bits_per_sample, fixed_order, rice_parameter, max_partition_order, &(encoder->guts->candidate_subframe));
 685                                         if(candidate_bits < best_bits) {
 686                                                 encoder_promote_candidate_subframe_(encoder);
 687                                                 best_bits = candidate_bits;
 688                                         }
 689                                 }
 690
 691                                 /* encode lpc */
 692                                 if(encoder->max_lpc_order > 0) {
 693                                         if(encoder->max_lpc_order >= frame_header->blocksize)
 694                                                 max_lpc_order = frame_header->blocksize-1;
 695                                         else
 696                                                 max_lpc_order = encoder->max_lpc_order;
 697                                         if(max_lpc_order > 0) {
 698                                                 FLAC__lpc_compute_autocorrelation(real_signal[channel], frame_header->blocksize, max_lpc_order+1, autoc);
 699                                                 FLAC__lpc_compute_lp_coefficients(autoc, max_lpc_order, lp_coeff, lpc_error);
 700                                                 if(encoder->do_exhaustive_model_search) {
 701                                                         min_lpc_order = 1;
 702                                                 }
 703                                                 else {
 704                                                         unsigned guess_lpc_order = FLAC__lpc_compute_best_order(lpc_error, max_lpc_order, frame_header->blocksize, frame_header->bits_per_sample);
 705                                                         min_lpc_order = max_lpc_order = guess_lpc_order;
 706                                                 }
 707                                                 if(encoder->do_qlp_coeff_prec_search) {
 708                                                         min_qlp_coeff_precision = FLAC__MIN_QLP_COEFF_PRECISION;
 709                                                         max_qlp_coeff_precision = 32 - frame_header->bits_per_sample - 1;
 710                                                 }
 711                                                 else {
 712                                                         min_qlp_coeff_precision = max_qlp_coeff_precision = encoder->qlp_coeff_precision;
 713                                                 }
 714                                                 for(lpc_order = min_lpc_order; lpc_order <= max_lpc_order; lpc_order++) {
 715                                                         lpc_residual_bits_per_sample = FLAC__lpc_compute_expected_bits_per_residual_sample(lpc_error[lpc_order-1], frame_header->blocksize);
 716                                                         if(lpc_residual_bits_per_sample >= (real)frame_header->bits_per_sample)
 717                                                                 continue; /* don't even try */
 718                                                         rice_parameter = (lpc_residual_bits_per_sample > 0.0)? (unsigned)(lpc_residual_bits_per_sample+0.5) : 0;
 719                                                         if(rice_parameter >= (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN))
 720                                                                 rice_parameter = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN) - 1;
 721                                                         for(qlp_coeff_precision = min_qlp_coeff_precision; qlp_coeff_precision <= max_qlp_coeff_precision; qlp_coeff_precision++) {
 722                                                                 candidate_bits = encoder_evaluate_lpc_subframe_(integer_signal[channel], encoder->guts->residual[!encoder->guts->best_residual], lp_coeff[lpc_order-1], frame_header->blocksize, frame_header->bits_per_sample, lpc_order, qlp_coeff_precision, rice_parameter, max_partition_order, &(encoder->guts->candidate_subframe));
 723                                                                 if(candidate_bits > 0) { /* if == 0, there was a problem quantizing the lpcoeffs */
 724                                                                         if(candidate_bits < best_bits) {
 725                                                                                 encoder_promote_candidate_subframe_(encoder);
 726                                                                                 best_bits = candidate_bits;
 727                                                                         }
 728                                                                 }
 729                                                         }
 730                                                 }
 731                                         }
 732                                 }
 733                         }
 734                 }
 735
 736                 /* add the best subframe */
 737                 switch(encoder->guts->best_subframe.type) {
 738                         case FLAC__SUBFRAME_TYPE_CONSTANT:
 739                                 if(!encoder_generate_constant_subframe_(&(encoder->guts->best_subframe), frame_header->bits_per_sample, frame)) {
 740                                         encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_ENCODING;
 741                                         return false;
 742                                 }
 743                                 break;
 744                         case FLAC__SUBFRAME_TYPE_FIXED:
 745                                 if(!encoder_generate_fixed_subframe_(&(encoder->guts->best_subframe), encoder->guts->residual[encoder->guts->best_residual], frame_header->blocksize, frame_header->bits_per_sample, frame)) {
 746                                         encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_ENCODING;
 747                                         return false;
 748                                 }
 749                                 break;
 750                         case FLAC__SUBFRAME_TYPE_LPC:
 751                                 if(!encoder_generate_lpc_subframe_(&(encoder->guts->best_subframe), encoder->guts->residual[encoder->guts->best_residual], frame_header->blocksize, frame_header->bits_per_sample, frame)) {
 752                                         encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_ENCODING;
 753                                         return false;
 754                                 }
 755                                 break;
 756                         case FLAC__SUBFRAME_TYPE_VERBATIM:
 757                                 if(!encoder_generate_verbatim_subframe_(&(encoder->guts->best_subframe), integer_signal[channel], frame_header->blocksize, frame_header->bits_per_sample, frame)) {
 758                                         encoder->state = FLAC__ENCODER_FATAL_ERROR_WHILE_ENCODING;
 759                                         return false;
 760                                 }
 761                                 break;
 762                 }
 763         }
 764
 765         return true;
 766 }
 767
 768 unsigned encoder_evaluate_constant_subframe_(const int32 signal, unsigned bits_per_sample, FLAC__SubframeHeader *subframe)
 769 {
 770         subframe->type = FLAC__SUBFRAME_TYPE_CONSTANT;
 771         subframe->data.constant.value = signal;
 772
 773         return 8 + bits_per_sample;
 774 }
 775
 776 unsigned encoder_evaluate_fixed_subframe_(const int32 signal[], int32 residual[], unsigned blocksize, unsigned bits_per_sample, unsigned order, unsigned rice_parameter, unsigned max_partition_order, FLAC__SubframeHeader *subframe)
 777 {
 778         unsigned i, residual_bits;
 779         const unsigned residual_samples = blocksize - order;
 780
 781         FLAC__fixed_compute_residual(signal+order, residual_samples, order, residual);
 782
 783         subframe->type = FLAC__SUBFRAME_TYPE_FIXED;
 784
 785         subframe->data.fixed.entropy_coding_method.type = FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE;
 786
 787         residual_bits = encoder_find_best_partition_order_(residual, residual_samples, order, rice_parameter, max_partition_order, &subframe->data.fixed.entropy_coding_method.data.partitioned_rice.order, subframe->data.fixed.entropy_coding_method.data.partitioned_rice.parameters);
 788
 789         subframe->data.fixed.order = order;
 790         for(i = 0; i < order; i++)
 791                 subframe->data.fixed.warmup[i] = signal[i];
 792
 793         return 8 + (order * bits_per_sample) + residual_bits;
 794 }
 795
 796 unsigned encoder_evaluate_lpc_subframe_(const int32 signal[], int32 residual[], const real lp_coeff[], unsigned blocksize, unsigned bits_per_sample, unsigned order, unsigned qlp_coeff_precision, unsigned rice_parameter, unsigned max_partition_order, FLAC__SubframeHeader *subframe)
 797 {
 798         int32 qlp_coeff[FLAC__MAX_LPC_ORDER];
 799         unsigned i, residual_bits;
 800         int quantization, ret;
 801         const unsigned residual_samples = blocksize - order;
 802
 803         ret = FLAC__lpc_quantize_coefficients(lp_coeff, order, qlp_coeff_precision, bits_per_sample, qlp_coeff, &quantization);
 804         if(ret != 0)
 805                 return 0; /* this is a hack to indicate to the caller that we can't do lp at this order on this subframe */
 806
 807         FLAC__lpc_compute_residual_from_qlp_coefficients(signal+order, residual_samples, qlp_coeff, order, quantization, residual);
 808
 809         subframe->type = FLAC__SUBFRAME_TYPE_LPC;
 810
 811         subframe->data.lpc.entropy_coding_method.type = FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE;
 812
 813         residual_bits = encoder_find_best_partition_order_(residual, residual_samples, order, rice_parameter, max_partition_order, &subframe->data.lpc.entropy_coding_method.data.partitioned_rice.order, subframe->data.lpc.entropy_coding_method.data.partitioned_rice.parameters);
 814
 815         subframe->data.lpc.order = order;
 816         subframe->data.lpc.qlp_coeff_precision = qlp_coeff_precision;
 817         subframe->data.lpc.quantization_level = quantization;
 818         memcpy(subframe->data.lpc.qlp_coeff, qlp_coeff, sizeof(int32)*FLAC__MAX_LPC_ORDER);
 819         for(i = 0; i < order; i++)
 820                 subframe->data.lpc.warmup[i] = signal[i];
 821
 822         return 8 + 9 + (order * (qlp_coeff_precision + bits_per_sample)) + residual_bits;
 823 }
 824
 825 unsigned encoder_evaluate_verbatim_subframe_(unsigned blocksize, unsigned bits_per_sample, FLAC__SubframeHeader *subframe)
 826 {
 827         subframe->type = FLAC__SUBFRAME_TYPE_VERBATIM;
 828
 829         return 8 + (blocksize * bits_per_sample);
 830 }
 831
 832 unsigned encoder_find_best_partition_order_(int32 residual[], unsigned residual_samples, unsigned predictor_order, unsigned rice_parameter, unsigned max_partition_order, unsigned *best_partition_order, unsigned best_parameters[])
 833 {
 834         unsigned residual_bits, best_residual_bits = 0;
 835         unsigned partition_order;
 836         unsigned best_parameters_index = 0, parameters[2][1 << FLAC__MAX_RICE_PARTITION_ORDER];
 837
 838         for(partition_order = 0; partition_order <= max_partition_order; partition_order++) {
 839                 if(!encoder_set_partitioned_rice_(residual, residual_samples, predictor_order, rice_parameter, partition_order, parameters[!best_parameters_index], &residual_bits)) {
 840                         assert(best_residual_bits != 0);
 841                         break;
 842                 }
 843                 if(best_residual_bits == 0 || residual_bits < best_residual_bits) {
 844                         best_residual_bits = residual_bits;
 845                         *best_partition_order = partition_order;
 846                         best_parameters_index = !best_parameters_index;
 847                 }
 848         }
 849         memcpy(best_parameters, parameters[best_parameters_index], sizeof(unsigned)*(1<<(*best_partition_order)));
 850
 851         return best_residual_bits;
 852 }
 853
 854 bool encoder_generate_constant_subframe_(const FLAC__SubframeHeader *header, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer)
 855 {
 856         assert(header->type == FLAC__SUBFRAME_TYPE_CONSTANT);
 857         return FLAC__subframe_add_constant(bits_per_sample, header, bitbuffer);
 858 }
 859
 860 bool encoder_generate_fixed_subframe_(const FLAC__SubframeHeader *header, int32 residual[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer)
 861 {
 862         assert(header->type == FLAC__SUBFRAME_TYPE_FIXED);
 863         return FLAC__subframe_add_fixed(residual, blocksize - header->data.fixed.order, bits_per_sample, header, bitbuffer);
 864 }
 865
 866 bool encoder_generate_lpc_subframe_(const FLAC__SubframeHeader *header, int32 residual[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer)
 867 {
 868         assert(header->type == FLAC__SUBFRAME_TYPE_LPC);
 869         return FLAC__subframe_add_lpc(residual, blocksize - header->data.lpc.order, bits_per_sample, header, bitbuffer);
 870 }
 871
 872 bool encoder_generate_verbatim_subframe_(const FLAC__SubframeHeader *header, const int32 signal[], unsigned blocksize, unsigned bits_per_sample, FLAC__BitBuffer *bitbuffer)
 873 {
 874         assert(header->type == FLAC__SUBFRAME_TYPE_VERBATIM);
 875 #ifdef NDEBUG
 876         (void)header; /* silence compiler warning about unused parameter */
 877 #endif
 878         return FLAC__subframe_add_verbatim(signal, blocksize, bits_per_sample, bitbuffer);
 879 }
 880
 881 void encoder_promote_candidate_subframe_(FLAC__Encoder *encoder)
 882 {
 883         assert(encoder->state == FLAC__ENCODER_OK);
 884         encoder->guts->best_subframe = encoder->guts->candidate_subframe;
 885         encoder->guts->best_residual = !encoder->guts->best_residual;
 886 }
 887
 888 bool encoder_set_partitioned_rice_(const int32 residual[], const unsigned residual_samples, const unsigned predictor_order, const unsigned rice_parameter, const unsigned partition_order, unsigned parameters[], unsigned *bits)
 889 {
 890         unsigned bits_ = 2 + 3;
 891
 892         if(partition_order == 0) {
 893                 unsigned i;
 894                 parameters[0] = rice_parameter;
 895                 bits_ += FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN;
 896                 for(i = 0; i < residual_samples; i++)
 897                         bits_ += RICE_BITS(residual[i], rice_parameter);
 898         }
 899         else {
 900                 unsigned i, j, k = 0, k_last = 0, z;
 901                 unsigned mean;
 902                 unsigned parameter, partition_samples;
 903                 const unsigned max_parameter = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN) - 1;
 904                 for(i = 0; i < (1u<<partition_order); i++) {
 905                         partition_samples = (residual_samples+predictor_order) >> partition_order;
 906                         if(i == 0) {
 907                                 if(partition_samples <= predictor_order)
 908                                         return false;
 909                                 else
 910                                         partition_samples -= predictor_order;
 911                         }
 912                         mean = partition_samples >> 1;
 913                         for(j = 0; j < partition_samples; j++, k++)
 914                                 mean += ((residual[k] < 0)? (unsigned)(-residual[k]) : (unsigned)residual[k]);
 915                         mean /= partition_samples;
 916                         z = 0x80000000;
 917                         for(j = 0; j < 32; j++, z >>= 1)
 918                                 if(mean & z)
 919                                         break;
 920                         parameter = j > 31? 0 : 32 - j - 1;
 921                         if(parameter > max_parameter)
 922                                 parameter = max_parameter;
 923                         parameters[i] = parameter;
 924                         bits_ += FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN;
 925                         for(j = k_last; j < k; j++)
 926                                 bits_ += RICE_BITS(residual[j], parameter);
 927                         k_last = k;
 928                 }
 929         }
 930
 931         *bits = bits_;
 932         return true;
 933 }