FFmpeg: libavcodec/pcm-dvd.c Source File

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libavcodec

pcm-dvd.c

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1 /*

2 * LPCM codecs for PCM formats found in Video DVD streams

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg 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.

11 *

12 * FFmpeg 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.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 /**

23 * @file

24 * LPCM codecs for PCM formats found in Video DVD streams

25 */

27 #include "avcodec.h"

28 #include "bytestream.h"

29 #include "internal.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 last_block_size; // Size of the last block of samples in bytes

35 int samples_per_block; // Number of samples per channel per block

36 int groups_per_block; // Number of 20/24bit sample groups per block

37 uint8_t *extra_samples; // Pointer to leftover samples from a frame

38 int extra_sample_count; // Number of leftover samples in the buffer

39 } PCMDVDContext;

41 static av_cold int pcm_dvd_decode_init(AVCodecContext *avctx)

42 {

43 PCMDVDContext *s = avctx->priv_data;

45 /* Invalid header to force parsing of the first header */

46 s->last_header = -1;

47 /* reserve space for 8 channels, 3 bytes/sample, 4 samples/block */

48 if (!(s->extra_samples = av_malloc(8 * 3 * 4)))

49 return AVERROR(ENOMEM);

51 return 0;

52 }

54 static av_cold int pcm_dvd_decode_uninit(AVCodecContext *avctx)

55 {

56 PCMDVDContext *s = avctx->priv_data;

58 av_freep(&s->extra_samples);

60 return 0;

61 }

63 static int pcm_dvd_parse_header(AVCodecContext *avctx, const uint8_t *header)

64 {

65 /* no traces of 44100 and 32000Hz in any commercial software or player */

66 static const uint32_t frequencies[4] = { 48000, 96000, 44100, 32000 };

67 PCMDVDContext *s = avctx->priv_data;

68 int header_int = (header[0] & 0xe0) | (header[1] << 8) | (header[2] << 16);

70 /* early exit if the header didn't change apart from the frame number */

71 if (s->last_header == header_int)

72 return 0;

73 s->last_header = -1;

75 if (avctx->debug & FF_DEBUG_PICT_INFO)

76 av_dlog(avctx, "pcm_dvd_parse_header: header = %02x%02x%02x\n",

77 header[0], header[1], header[2]);

78 /*

79 * header[0] emphasis (1), muse(1), reserved(1), frame number(5)

80 * header[1] quant (2), freq(2), reserved(1), channels(3)

81 * header[2] dynamic range control (0x80 = off)

82 */

84 /* Discard potentially existing leftover samples from old channel layout */

85 s->extra_sample_count = 0;

87 /* get the sample depth and derive the sample format from it */

88 avctx->bits_per_coded_sample = 16 + (header[1] >> 6 & 3) * 4;

89 if (avctx->bits_per_coded_sample == 28) {

90 av_log(avctx, AV_LOG_ERROR,

91 "PCM DVD unsupported sample depth %i\n",

92 avctx->bits_per_coded_sample);

93 return AVERROR_INVALIDDATA;

94 }

95 avctx->sample_fmt = avctx->bits_per_coded_sample == 16 ? AV_SAMPLE_FMT_S16

96 : AV_SAMPLE_FMT_S32;

97 avctx->bits_per_raw_sample = avctx->bits_per_coded_sample;

99 /* get the sample rate */

100 avctx->sample_rate = frequencies[header[1] >> 4 & 3];

101

102 /* get the number of channels */

103 avctx->channels = 1 + (header[1] & 7);

104 /* calculate the bitrate */

105 avctx->bit_rate = avctx->channels *

106 avctx->sample_rate *

107 avctx->bits_per_coded_sample;

108

109 /* 4 samples form a group in 20/24bit PCM on DVD Video.

110 * A block is formed by the number of groups that are

111 * needed to complete a set of samples for each channel. */

112 if (avctx->bits_per_coded_sample == 16) {

113 s->samples_per_block = 1;

114 s->block_size = avctx->channels * 2;

115 } else {

116 switch (avctx->channels) {

117 case 1:

118 case 2:

119 case 4:

120 /* one group has all the samples needed */

121 s->block_size = 4 * avctx->bits_per_coded_sample / 8;

122 s->samples_per_block = 4 / avctx->channels;

123 s->groups_per_block = 1;

124 break;

125 case 8:

126 /* two groups have all the samples needed */

127 s->block_size = 8 * avctx->bits_per_coded_sample / 8;

128 s->samples_per_block = 1;

129 s->groups_per_block = 2;

130 break;

131 default:

132 /* need avctx->channels groups */

133 s->block_size = 4 * avctx->channels *

134 avctx->bits_per_coded_sample / 8;

135 s->samples_per_block = 4;

136 s->groups_per_block = avctx->channels;

137 break;

138 }

139 }

140

141 if (avctx->debug & FF_DEBUG_PICT_INFO)

142 av_dlog(avctx,

143 "pcm_dvd_parse_header: %d channels, %d bits per sample, %d Hz, %d bit/s\n",

144 avctx->channels, avctx->bits_per_coded_sample,

145 avctx->sample_rate, avctx->bit_rate);

146

147 s->last_header = header_int;

148

149 return 0;

150 }

151

152 static void *pcm_dvd_decode_samples(AVCodecContext *avctx, const uint8_t *src,

153 void *dst, int blocks)

154 {

155 PCMDVDContext *s = avctx->priv_data;

156 int16_t *dst16 = dst;

157 int32_t *dst32 = dst;

158 GetByteContext gb;

159 int i;

160 uint8_t t;

161

162 bytestream2_init(&gb, src, blocks * s->block_size);

163 switch (avctx->bits_per_coded_sample) {

164 case 16: {

165 #if HAVE_BIGENDIAN

166 bytestream2_get_buffer(&gb, dst16, blocks * s->block_size);

167 dst16 += blocks * s->block_size / 2;

168 #else

169 int samples = blocks * avctx->channels;

170 do {

171 *dst16++ = bytestream2_get_be16u(&gb);

172 } while (--samples);

173 #endif

174 return dst16;

175 }

176 case 20:

177 if (avctx->channels == 1) {

178 do {

179 for (i = 2; i; i--) {

180 dst32[0] = bytestream2_get_be16u(&gb) << 16;

181 dst32[1] = bytestream2_get_be16u(&gb) << 16;

182 t = bytestream2_get_byteu(&gb);

183 *dst32++ += (t & 0xf0) << 8;

184 *dst32++ += (t & 0x0f) << 12;

185 }

186 } while (--blocks);

187 } else {

188 do {

189 for (i = s->groups_per_block; i; i--) {

190 dst32[0] = bytestream2_get_be16u(&gb) << 16;

191 dst32[1] = bytestream2_get_be16u(&gb) << 16;

192 dst32[2] = bytestream2_get_be16u(&gb) << 16;

193 dst32[3] = bytestream2_get_be16u(&gb) << 16;

194 t = bytestream2_get_byteu(&gb);

195 *dst32++ += (t & 0xf0) << 8;

196 *dst32++ += (t & 0x0f) << 12;

197 t = bytestream2_get_byteu(&gb);

198 *dst32++ += (t & 0xf0) << 8;

199 *dst32++ += (t & 0x0f) << 12;

200 }

201 } while (--blocks);

202 }

203 return dst32;

204 case 24:

205 if (avctx->channels == 1) {

206 do {

207 for (i = 2; i; i--) {

208 dst32[0] = bytestream2_get_be16u(&gb) << 16;

209 dst32[1] = bytestream2_get_be16u(&gb) << 16;

210 *dst32++ += bytestream2_get_byteu(&gb) << 8;

211 *dst32++ += bytestream2_get_byteu(&gb) << 8;

212 }

213 } while (--blocks);

214 } else {

215 do {

216 for (i = s->groups_per_block; i; i--) {

217 dst32[0] = bytestream2_get_be16u(&gb) << 16;

218 dst32[1] = bytestream2_get_be16u(&gb) << 16;

219 dst32[2] = bytestream2_get_be16u(&gb) << 16;

220 dst32[3] = bytestream2_get_be16u(&gb) << 16;

221 *dst32++ += bytestream2_get_byteu(&gb) << 8;

222 *dst32++ += bytestream2_get_byteu(&gb) << 8;

223 *dst32++ += bytestream2_get_byteu(&gb) << 8;

224 *dst32++ += bytestream2_get_byteu(&gb) << 8;

225 }

226 } while (--blocks);

227 }

228 return dst32;

229 default:

230 return NULL;

231 }

232 }

233

234 static int pcm_dvd_decode_frame(AVCodecContext *avctx, void *data,

235 int *got_frame_ptr, AVPacket *avpkt)

236 {

237 AVFrame *frame = data;

238 const uint8_t *src = avpkt->data;

239 int buf_size = avpkt->size;

240 PCMDVDContext *s = avctx->priv_data;

241 int retval;

242 int blocks;

243 void *dst;

244

245 if (buf_size < 3) {

246 av_log(avctx, AV_LOG_ERROR, "PCM packet too small\n");

247 return AVERROR_INVALIDDATA;

248 }

249

250 if ((retval = pcm_dvd_parse_header(avctx, src)))

251 return retval;

252 if (s->last_block_size && s->last_block_size != s->block_size) {

253 av_log(avctx, AV_LOG_WARNING, "block_size has changed %d != %d\n", s->last_block_size, s->block_size);

254 s->extra_sample_count = 0;

255 }

256 s->last_block_size = s->block_size;

257 src += 3;

258 buf_size -= 3;

259

260 blocks = (buf_size + s->extra_sample_count) / s->block_size;

261

262 /* get output buffer */

263 frame->nb_samples = blocks * s->samples_per_block;

264 if ((retval = ff_get_buffer(avctx, frame, 0)) < 0)

265 return retval;

266 dst = frame->data[0];

267

268 /* consume leftover samples from last packet */

269 if (s->extra_sample_count) {

270 int missing_samples = s->block_size - s->extra_sample_count;

271 if (buf_size >= missing_samples) {

272 memcpy(s->extra_samples + s->extra_sample_count, src,

273 missing_samples);

274 dst = pcm_dvd_decode_samples(avctx, s->extra_samples, dst, 1);

275 src += missing_samples;

276 buf_size -= missing_samples;

277 s->extra_sample_count = 0;

278 blocks--;

279 } else {

280 /* new packet still doesn't have enough samples */

281 memcpy(s->extra_samples + s->extra_sample_count, src, buf_size);

282 s->extra_sample_count += buf_size;

283 return avpkt->size;

284 }

285 }

286

287 /* decode remaining complete samples */

288 if (blocks) {

289 pcm_dvd_decode_samples(avctx, src, dst, blocks);

290 buf_size -= blocks * s->block_size;

291 }

292

293 /* store leftover samples */

294 if (buf_size) {

295 src += blocks * s->block_size;

296 memcpy(s->extra_samples, src, buf_size);

297 s->extra_sample_count = buf_size;

298 }

299

300 *got_frame_ptr = 1;

301

302 return avpkt->size;

303 }

304

305 AVCodec ff_pcm_dvd_decoder = {

306 .name = "pcm_dvd",

307 .long_name = NULL_IF_CONFIG_SMALL("PCM signed 16|20|24-bit big-endian for DVD media"),

308 .type = AVMEDIA_TYPE_AUDIO,

309 .id = AV_CODEC_ID_PCM_DVD,

310 .priv_data_size = sizeof(PCMDVDContext),

311 .init = pcm_dvd_decode_init,

312 .decode = pcm_dvd_decode_frame,

313 .close = pcm_dvd_decode_uninit,

314 .capabilities = CODEC_CAP_DR1,

315 .sample_fmts = (const enum AVSampleFormat[]) {

316 AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE

317 }

318 };

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