/*
- * MPEG1/2 decoder
+ * MPEG-1/2 decoder
* Copyright (c) 2000,2001 Fabrice Bellard.
* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
*
/**
* @file mpeg12.c
- * MPEG1/2 decoder
+ * MPEG-1/2 decoder
*/
//#define DEBUG
}
}
-/* motion type (for mpeg2) */
+/* motion type (for MPEG-2) */
#define MT_FIELD 1
#define MT_FRAME 2
#define MT_16X8 2
if(s->mb_x)
mb_type= s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride - 1];
else
- mb_type= s->current_picture.mb_type[ s->mb_width + (s->mb_y-1)*s->mb_stride - 1]; // FIXME not sure if this is allowed in mpeg at all,
+ mb_type= s->current_picture.mb_type[ s->mb_width + (s->mb_y-1)*s->mb_stride - 1]; // FIXME not sure if this is allowed in MPEG at all
if(IS_INTRA(mb_type))
return -1;
s->dsp.clear_blocks(s->block[6]);
}
- /* compute dct type */
- if (s->picture_structure == PICT_FRAME && //FIXME add a interlaced_dct coded var?
+ /* compute DCT type */
+ if (s->picture_structure == PICT_FRAME && //FIXME add an interlaced_dct coded var?
!s->frame_pred_frame_dct) {
s->interlaced_dct = get_bits1(&s->gb);
}
memset(s->last_mv, 0, sizeof(s->last_mv)); /* reset mv prediction */
s->mb_intra = 1;
#ifdef HAVE_XVMC
- //one 1 we memcpy blocks in xvmcvideo
+ //if 1, we memcpy blocks in xvmcvideo
if(s->avctx->xvmc_acceleration > 1){
XVMC_pack_pblocks(s,-1);//inter are always full blocks
if(s->swap_uv){
mpeg_decode_motion(s, s->mpeg_f_code[i][0], s->last_mv[i][0][0]);
s->mv[i][0][1]= s->last_mv[i][0][1]= s->last_mv[i][1][1] =
mpeg_decode_motion(s, s->mpeg_f_code[i][1], s->last_mv[i][0][1]);
- /* full_pel: only for mpeg1 */
+ /* full_pel: only for MPEG-1 */
if (s->full_pel[i]){
s->mv[i][0][0] <<= 1;
s->mv[i][0][1] <<= 1;
}
#ifdef HAVE_XVMC
- //on 1 we memcpy blocks in xvmcvideo
+ //if 1, we memcpy blocks in xvmcvideo
if(s->avctx->xvmc_acceleration > 1){
XVMC_pack_pblocks(s,cbp);
if(s->swap_uv){
return 0;
}
-/* as h263, but only 17 codes */
+/* as H.263, but only 17 codes */
static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
{
int code, sign, val, l, shift;
const uint16_t *quant_matrix= s->intra_matrix;
const int qscale= s->qscale;
- /* DC coef */
+ /* DC coefficient */
component = (n <= 3 ? 0 : n - 4 + 1);
diff = decode_dc(&s->gb, component);
if (diff >= 0xffff)
i = 0;
{
OPEN_READER(re, &s->gb);
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
UPDATE_CACHE(re, &s->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
{
OPEN_READER(re, &s->gb);
i = -1;
- /* special case for the first coef. no need to add a second vlc table */
+ // special case for first coefficient, no need to add second VLC table
UPDATE_CACHE(re, &s->gb);
if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
level= (3*qscale*quant_matrix[0])>>5;
#if MIN_CACHE_BITS < 19
UPDATE_CACHE(re, &s->gb);
#endif
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
{
OPEN_READER(re, &s->gb);
i = -1;
- /* special case for the first coef. no need to add a second vlc table */
+ // special case for first coefficient, no need to add second VLC table
UPDATE_CACHE(re, &s->gb);
if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
level= (3*qscale)>>1;
UPDATE_CACHE(re, &s->gb);
#endif
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
else
quant_matrix = s->chroma_inter_matrix;
- /* special case for the first coef. no need to add a second vlc table */
+ // special case for first coefficient, no need to add second VLC table
UPDATE_CACHE(re, &s->gb);
if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
level= (3*qscale*quant_matrix[0])>>5;
UPDATE_CACHE(re, &s->gb);
#endif
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
OPEN_READER(re, &s->gb);
i = -1;
- /* special case for the first coef. no need to add a second vlc table */
+ // special case for first coefficient, no need to add second VLC table
UPDATE_CACHE(re, &s->gb);
if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {
level= (3*qscale)>>1;
UPDATE_CACHE(re, &s->gb);
#endif
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
const int qscale= s->qscale;
int mismatch;
- /* DC coef */
+ /* DC coefficient */
if (n < 4){
quant_matrix = s->intra_matrix;
component = 0;
{
OPEN_READER(re, &s->gb);
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
UPDATE_CACHE(re, &s->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
const uint16_t *quant_matrix;
const int qscale= s->qscale;
- /* DC coef */
+ /* DC coefficient */
if (n < 4){
quant_matrix = s->intra_matrix;
component = 0;
{
OPEN_READER(re, &s->gb);
- /* now quantify & encode AC coefs */
+ /* now quantify & encode AC coefficients */
for(;;) {
UPDATE_CACHE(re, &s->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
MpegEncContext *s2 = &s->mpeg_enc_ctx;
int i;
- //we need some parmutation to store
- //matrixes, until MPV_common_init()
- //set the real permutatuon
+ /* we need some permutation to store matrices,
+ * until MPV_common_init() sets the real permutation. */
for(i=0;i<64;i++)
s2->dsp.idct_permutation[i]=i;
}
}
-//Call this function when we know all parameters
-//it may be called in different places for mpeg1 and mpeg2
+/* Call this function when we know all parameters.
+ * It may be called in different places for MPEG-1 and MPEG-2. */
static int mpeg_decode_postinit(AVCodecContext *avctx){
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
s1->save_width = s->width;
s1->save_height = s->height;
- //low_delay may be forced, in this case we will have B frames
- //that behave like P frames
+ /* low_delay may be forced, in this case we will have B-frames
+ * that behave like P-frames. */
avctx->has_b_frames = !(s->low_delay);
if(avctx->sub_id==1){//s->codec_id==avctx->codec_id==CODEC_ID
- //mpeg1 fps
+ //MPEG-1 fps
avctx->time_base.den= ff_frame_rate_tab[s->frame_rate_index].num;
avctx->time_base.num= ff_frame_rate_tab[s->frame_rate_index].den;
- //mpeg1 aspect
+ //MPEG-1 aspect
avctx->sample_aspect_ratio= av_d2q(
1.0/ff_mpeg1_aspect[s->aspect_ratio_info], 255);
- }else{//mpeg2
- //mpeg2 fps
+ }else{//MPEG-2
+ //MPEG-2 fps
av_reduce(
&s->avctx->time_base.den,
&s->avctx->time_base.num,
ff_frame_rate_tab[s->frame_rate_index].num * s1->frame_rate_ext.num,
ff_frame_rate_tab[s->frame_rate_index].den * s1->frame_rate_ext.den,
1<<30);
- //mpeg2 aspect
+ //MPEG-2 aspect
if(s->aspect_ratio_info > 1){
if( (s1->pan_scan.width == 0 )||(s1->pan_scan.height == 0) ){
s->avctx->sample_aspect_ratio=
s->avctx->sample_aspect_ratio=
ff_mpeg2_aspect[s->aspect_ratio_info];
}
- }//mpeg2
+ }//MPEG-2
if(avctx->xvmc_acceleration){
avctx->pix_fmt = avctx->get_format(avctx,pixfmt_xvmc_mpg2_420);
if( avctx->idct_algo == FF_IDCT_AUTO )
avctx->idct_algo = FF_IDCT_SIMPLE;
- //quantization matrixes may need reordering
- //if dct permutation is changed
+ /* Quantization matrices may need reordering
+ * if DCT permutation is changed. */
memcpy(old_permutation,s->dsp.idct_permutation,64*sizeof(uint8_t));
if (MPV_common_init(s) < 0)
int horiz_size_ext, vert_size_ext;
int bit_rate_ext;
- skip_bits(&s->gb, 1); /* profil and level esc*/
+ skip_bits(&s->gb, 1); /* profile and level esc*/
s->avctx->profile= get_bits(&s->gb, 3);
s->avctx->level= get_bits(&s->gb, 4);
s->progressive_sequence = get_bits1(&s->gb); /* progressive_sequence */
dprintf(s->avctx, "sequence extension\n");
s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG2VIDEO;
- s->avctx->sub_id = 2; /* indicates mpeg2 found */
+ s->avctx->sub_id = 2; /* indicates MPEG-2 found */
if(s->avctx->debug & FF_DEBUG_PICT_INFO)
av_log(s->avctx, AV_LOG_DEBUG, "profile: %d, level: %d vbv buffer: %d, bitrate:%d\n",
for(;;) {
#ifdef HAVE_XVMC
- //one 1 we memcpy blocks in xvmcvideo
+ //If 1, we memcpy blocks in xvmcvideo.
if(s->avctx->xvmc_acceleration > 1)
XVMC_init_block(s);//set s->block
#endif
/* skip mb handling */
if (s->mb_skip_run == -1) {
- /* read again increment */
+ /* read increment again */
s->mb_skip_run = 0;
for(;;) {
int code = get_vlc2(&s->gb, mbincr_vlc.table, MBINCR_VLC_BITS, 2);
}
/**
- * handles slice ends.
- * @return 1 if it seems to be the last slice of
+ * Handles slice ends.
+ * @return 1 if it seems to be the last slice
*/
static int slice_end(AVCodecContext *avctx, AVFrame *pict)
{
ff_print_debug_info(s, pict);
} else {
s->picture_number++;
- /* latency of 1 frame for I and P frames */
+ /* latency of 1 frame for I- and P-frames */
/* XXX: use another variable than picture_number */
if (s->last_picture_ptr != NULL) {
*pict= *(AVFrame*)s->last_picture_ptr;
s->chroma_inter_matrix[j] = v;
}
#ifdef DEBUG
- dprintf(s->avctx, "non intra matrix present\n");
+ dprintf(s->avctx, "non-intra matrix present\n");
for(i=0;i<64;i++)
dprintf(s->avctx, " %d", s->inter_matrix[s->dsp.idct_permutation[i]]);
dprintf(s->avctx, "\n");
return -1;
}
- /* we set mpeg2 parameters so that it emulates mpeg1 */
+ /* we set MPEG-2 parameters so that it emulates MPEG-1 */
s->progressive_sequence = 1;
s->progressive_frame = 1;
s->picture_structure = PICT_FRAME;
s->frame_pred_frame_dct = 1;
s->chroma_format = 1;
s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG1VIDEO;
- avctx->sub_id = 1; /* indicates mpeg1 */
+ avctx->sub_id = 1; /* indicates MPEG-1 */
s->out_format = FMT_MPEG1;
- s->swap_uv = 0;//AFAIK VCR2 don't have SEQ_HEADER
+ s->swap_uv = 0;//AFAIK VCR2 does not have SEQ_HEADER
if(s->flags & CODEC_FLAG_LOW_DELAY) s->low_delay=1;
if(s->avctx->debug & FF_DEBUG_PICT_INFO)
MpegEncContext *s = &s1->mpeg_enc_ctx;
int i, v;
- /* start new mpeg1 context decoding */
+ /* start new MPEG-1 context decoding */
s->out_format = FMT_MPEG1;
if (s1->mpeg_enc_ctx_allocated) {
MPV_common_end(s);
s->frame_pred_frame_dct = 1;
s->chroma_format = 1;
s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG2VIDEO;
- avctx->sub_id = 2; /* indicates mpeg2 */
+ avctx->sub_id = 2; /* indicates MPEG-2 */
return 0;
}
time_code_pictures, closed_gop, broken_link);
}
/**
- * finds the end of the current frame in the bitstream.
+ * Finds the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
int ret, input_size;
for(;;) {
- /* find start next code */
+ /* find next start code */
uint32_t start_code = -1;
buf_ptr = ff_find_start_code(buf_ptr,buf_end, &start_code);
if (start_code > 0x1ff){
break;
case PICTURE_START_CODE:
- /* we have a complete image : we try to decompress it */
+ /* we have a complete image: we try to decompress it */
mpeg1_decode_picture(avctx,
buf_ptr, input_size);
break;
if(s2->pict_type==FF_B_TYPE) break;
}
if(s2->next_picture_ptr==NULL){
- /* Skip P-frames if we do not have reference frame no valid header. */
+ /* Skip P-frames if we do not have a reference frame or we have an invalid header. */
if(s2->pict_type==FF_P_TYPE && (s2->first_field || s2->picture_structure==PICT_FRAME)) break;
}
/* Skip B-frames if we are in a hurry. */
init_get_bits(&thread_context->gb, buf_ptr, input_size*8);
s->slice_count++;
}
- buf_ptr += 2; //FIXME add minimum num of bytes per slice
+ buf_ptr += 2; //FIXME add minimum number of bytes per slice
}else{
ret = mpeg_decode_slice(s, mb_y, &buf_ptr, input_size);
emms_c();
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