2 * LPCM codecs for PCM formats found in Video DVD streams
3 * Copyright (c) 2013 Christian Schmidt
5 * This file is part of Libav.
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * LPCM codecs for PCM formats found in Video DVD streams
28 #include "bytestream.h"
31 typedef struct PCMDVDContext {
32 uint32_t last_header; // Cached header to see if parsing is needed
33 int block_size; // Size of a block of samples in bytes
34 int samples_per_block; // Number of samples per channel per block
35 int groups_per_block; // Number of 20/24bit sample groups per block
36 uint8_t *extra_samples; // Pointer to leftover samples from a frame
37 int extra_sample_count; // Number of leftover samples in the buffer
40 static av_cold int pcm_dvd_decode_init(AVCodecContext *avctx)
42 PCMDVDContext *s = avctx->priv_data;
44 /* Invalid header to force parsing of the first header */
46 /* reserve space for 8 channels, 3 bytes/sample, 4 samples/block */
47 if (!(s->extra_samples = av_malloc(8 * 3 * 4)))
48 return AVERROR(ENOMEM);
53 static av_cold int pcm_dvd_decode_uninit(AVCodecContext *avctx)
55 PCMDVDContext *s = avctx->priv_data;
57 av_freep(&s->extra_samples);
62 static int pcm_dvd_parse_header(AVCodecContext *avctx, const uint8_t *header)
64 /* no traces of 44100 and 32000Hz in any commercial software or player */
65 static const uint32_t frequencies[4] = { 48000, 96000, 44100, 32000 };
66 PCMDVDContext *s = avctx->priv_data;
67 int header_int = (header[0] & 0xe0) | (header[1] << 8) | (header[2] << 16);
69 /* early exit if the header didn't change apart from the frame number */
70 if (s->last_header == header_int)
73 if (avctx->debug & FF_DEBUG_PICT_INFO)
74 av_dlog(avctx, "pcm_dvd_parse_header: header = %02x%02x%02x\n",
75 header[0], header[1], header[2]);
77 * header[0] emphasis (1), muse(1), reserved(1), frame number(5)
78 * header[1] quant (2), freq(2), reserved(1), channels(3)
79 * header[2] dynamic range control (0x80 = off)
82 /* Discard potentially existing leftover samples from old channel layout */
83 s->extra_sample_count = 0;
85 /* get the sample depth and derive the sample format from it */
86 avctx->bits_per_coded_sample = 16 + (header[1] >> 6 & 3) * 4;
87 if (avctx->bits_per_coded_sample == 28) {
88 av_log(avctx, AV_LOG_ERROR, "PCM DVD unsupported sample depth\n");
89 return AVERROR_INVALIDDATA;
91 avctx->sample_fmt = avctx->bits_per_coded_sample == 16 ? AV_SAMPLE_FMT_S16
93 avctx->bits_per_raw_sample = avctx->bits_per_coded_sample;
95 /* get the sample rate */
96 avctx->sample_rate = frequencies[header[1] >> 4 & 3];
98 /* get the number of channels */
99 avctx->channels = 1 + (header[1] & 7);
100 /* calculate the bitrate */
101 avctx->bit_rate = avctx->channels *
103 avctx->bits_per_coded_sample;
105 /* 4 samples form a group in 20/24bit PCM on DVD Video.
106 * A block is formed by the number of groups that are
107 * needed to complete a set of samples for each channel. */
108 if (avctx->bits_per_coded_sample == 16) {
109 s->samples_per_block = 1;
110 s->block_size = avctx->channels * 2;
112 switch (avctx->channels) {
116 /* one group has all the samples needed */
117 s->block_size = 4 * avctx->bits_per_coded_sample / 8;
118 s->samples_per_block = 4 / avctx->channels;
119 s->groups_per_block = 1;
122 /* two groups have all the samples needed */
123 s->block_size = 8 * avctx->bits_per_coded_sample / 8;
124 s->samples_per_block = 1;
125 s->groups_per_block = 2;
128 /* need avctx->channels groups */
129 s->block_size = 4 * avctx->channels *
130 avctx->bits_per_coded_sample / 8;
131 s->samples_per_block = 4;
132 s->groups_per_block = avctx->channels;
137 if (avctx->debug & FF_DEBUG_PICT_INFO)
139 "pcm_dvd_parse_header: %d channels, %d bits per sample, %d Hz, %d bit/s\n",
140 avctx->channels, avctx->bits_per_coded_sample,
141 avctx->sample_rate, avctx->bit_rate);
143 s->last_header = header_int;
148 static void *pcm_dvd_decode_samples(AVCodecContext *avctx, const uint8_t *src,
149 void *dst, int blocks)
151 PCMDVDContext *s = avctx->priv_data;
152 int16_t *dst16 = dst;
153 int32_t *dst32 = dst;
158 bytestream2_init(&gb, src, blocks * s->block_size);
159 switch (avctx->bits_per_coded_sample) {
162 bytestream2_get_buffer(&gb, dst16, blocks * s->block_size);
163 dst16 += blocks * s->block_size / 2;
165 int samples = blocks * avctx->channels;
167 *dst16++ = bytestream2_get_be16u(&gb);
174 for (i = s->groups_per_block; i; i--) {
175 dst32[0] = bytestream2_get_be16u(&gb) << 16;
176 dst32[1] = bytestream2_get_be16u(&gb) << 16;
177 dst32[2] = bytestream2_get_be16u(&gb) << 16;
178 dst32[3] = bytestream2_get_be16u(&gb) << 16;
179 t = bytestream2_get_byteu(&gb);
180 *dst32++ += (t & 0xf0) << 8;
181 *dst32++ += (t & 0x0f) << 12;
182 t = bytestream2_get_byteu(&gb);
183 *dst32++ += (t & 0xf0) << 8;
184 *dst32++ += (t & 0x0f) << 12;
190 for (i = s->groups_per_block; i; i--) {
191 dst32[0] = bytestream2_get_be16u(&gb) << 16;
192 dst32[1] = bytestream2_get_be16u(&gb) << 16;
193 dst32[2] = bytestream2_get_be16u(&gb) << 16;
194 dst32[3] = bytestream2_get_be16u(&gb) << 16;
195 *dst32++ += bytestream2_get_byteu(&gb) << 8;
196 *dst32++ += bytestream2_get_byteu(&gb) << 8;
197 *dst32++ += bytestream2_get_byteu(&gb) << 8;
198 *dst32++ += bytestream2_get_byteu(&gb) << 8;
207 static int pcm_dvd_decode_frame(AVCodecContext *avctx, void *data,
208 int *got_frame_ptr, AVPacket *avpkt)
210 AVFrame *frame = data;
211 const uint8_t *src = avpkt->data;
212 int buf_size = avpkt->size;
213 PCMDVDContext *s = avctx->priv_data;
219 av_log(avctx, AV_LOG_ERROR, "PCM packet too small\n");
220 return AVERROR_INVALIDDATA;
223 if ((retval = pcm_dvd_parse_header(avctx, src)))
228 blocks = (buf_size + s->extra_sample_count) / s->block_size;
230 /* get output buffer */
231 frame->nb_samples = blocks * s->samples_per_block;
232 if ((retval = ff_get_buffer(avctx, frame, 0)) < 0) {
233 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
236 dst = frame->data[0];
238 /* consume leftover samples from last packet */
239 if (s->extra_sample_count) {
240 int missing_samples = s->block_size - s->extra_sample_count;
241 if (buf_size >= missing_samples) {
242 memcpy(s->extra_samples + s->extra_sample_count, src,
244 dst = pcm_dvd_decode_samples(avctx, s->extra_samples, dst, 1);
245 src += missing_samples;
246 buf_size -= missing_samples;
247 s->extra_sample_count = 0;
250 /* new packet still doesn't have enough samples */
251 memcpy(s->extra_samples + s->extra_sample_count, src, buf_size);
252 s->extra_sample_count += buf_size;
257 /* decode remaining complete samples */
259 pcm_dvd_decode_samples(avctx, src, dst, blocks);
260 buf_size -= blocks * s->block_size;
263 /* store leftover samples */
265 src += blocks * s->block_size;
266 memcpy(s->extra_samples, src, buf_size);
267 s->extra_sample_count = buf_size;
275 AVCodec ff_pcm_dvd_decoder = {
277 .long_name = NULL_IF_CONFIG_SMALL("PCM signed 16|20|24-bit big-endian for DVD media"),
278 .type = AVMEDIA_TYPE_AUDIO,
279 .id = AV_CODEC_ID_PCM_DVD,
280 .priv_data_size = sizeof(PCMDVDContext),
281 .init = pcm_dvd_decode_init,
282 .decode = pcm_dvd_decode_frame,
283 .close = pcm_dvd_decode_uninit,
284 .capabilities = CODEC_CAP_DR1,
285 .sample_fmts = (const enum AVSampleFormat[]) {
286 AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE