3 * Copyright (c) 2022 Jack Bruienne
4 * Copyright (c) 2012, 2016 Ben "GreaseMonkey" Russell
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 #include "libavutil/internal.h"
31 #include "codec_internal.h"
38 // DFPWM codec from https://github.com/ChenThread/dfpwm/blob/master/1a/
39 // Licensed in the public domain
41 static void au_decompress(DFPWMState *state, int fs, int len,
42 uint8_t *outbuf, const uint8_t *inbuf)
45 for (int i = 0; i < len; i++) {
48 for (int j = 0; j < 8; j++) {
49 int nq, lq, st, ns, ov;
51 int t = ((d&1) ? 127 : -128);
55 nq = state->q + ((state->s * (t-state->q) + 512)>>10);
56 if(nq == state->q && nq != t)
57 nq += (t == 127 ? 1 : -1);
62 st = (t != state->lt ? 0 : 1023);
65 ns += (st != 0 ? 1 : -1);
69 // FILTER: perform antijerk
70 ov = (t != state->lt ? (nq+lq+1)>>1 : nq);
72 // FILTER: perform LPF
73 state->fq += ((fs*(ov-state->fq) + 0x80)>>8);
77 *(outbuf++) = ov + 128;
84 static av_cold int dfpwm_dec_init(struct AVCodecContext *ctx)
86 DFPWMState *state = ctx->priv_data;
93 ctx->sample_fmt = AV_SAMPLE_FMT_U8;
94 ctx->bits_per_raw_sample = 8;
99 static int dfpwm_dec_frame(struct AVCodecContext *ctx, AVFrame *frame,
100 int *got_frame, struct AVPacket *packet)
102 DFPWMState *state = ctx->priv_data;
105 if (packet->size * 8LL % ctx->ch_layout.nb_channels)
106 return AVERROR_PATCHWELCOME;
108 frame->nb_samples = packet->size * 8LL / ctx->ch_layout.nb_channels;
109 if (frame->nb_samples <= 0) {
110 av_log(ctx, AV_LOG_ERROR, "invalid number of samples in packet\n");
111 return AVERROR_INVALIDDATA;
114 if ((ret = ff_get_buffer(ctx, frame, 0)) < 0)
117 au_decompress(state, 140, packet->size, frame->data[0], packet->data);
123 const FFCodec ff_dfpwm_decoder = {
125 CODEC_LONG_NAME("DFPWM1a audio"),
126 .p.type = AVMEDIA_TYPE_AUDIO,
127 .p.id = AV_CODEC_ID_DFPWM,
128 .priv_data_size = sizeof(DFPWMState),
129 .init = dfpwm_dec_init,
130 FF_CODEC_DECODE_CB(dfpwm_dec_frame),
131 .p.capabilities = AV_CODEC_CAP_DR1,