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demuxing.c

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1 /*

3 *

4 * Permission is hereby granted, free of charge, to any person obtaining a copy

5 * of this software and associated documentation files (the "Software"), to deal

6 * in the Software without restriction, including without limitation the rights

7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

8 * copies of the Software, and to permit persons to whom the Software is

9 * furnished to do so, subject to the following conditions:

10 *

11 * The above copyright notice and this permission notice shall be included in

12 * all copies or substantial portions of the Software.

13 *

14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

20 * THE SOFTWARE.

21 */

23 /**

24 * @file

25 * libavformat demuxing API use example.

26 *

27 * Show how to use the libavformat and libavcodec API to demux and

28 * decode audio and video data.

29 * @example doc/examples/demuxing.c

30 */

32 #include <libavutil/imgutils.h>

33 #include <libavutil/samplefmt.h>

34 #include <libavutil/timestamp.h>

35 #include <libavformat/avformat.h>

37 static AVFormatContext *fmt_ctx = NULL;

38 static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;

39 static AVStream *video_stream = NULL, *audio_stream = NULL;

40 static const char *src_filename = NULL;

41 static const char *video_dst_filename = NULL;

42 static const char *audio_dst_filename = NULL;

43 static FILE *video_dst_file = NULL;

44 static FILE *audio_dst_file = NULL;

46 static uint8_t *video_dst_data[4] = {NULL};

47 static int video_dst_linesize[4];

48 static int video_dst_bufsize;

50 static int video_stream_idx = -1, audio_stream_idx = -1;

51 static AVFrame *frame = NULL;

52 static AVPacket pkt;

53 static int video_frame_count = 0;

54 static int audio_frame_count = 0;

56 static int decode_packet(int *got_frame, int cached)

57 {

58 int ret = 0;

59 int decoded = pkt.size;

61 if (pkt.stream_index == video_stream_idx) {

62 /* decode video frame */

63 ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt);

64 if (ret < 0) {

65 fprintf(stderr, "Error decoding video frame\n");

66 return ret;

67 }

69 if (*got_frame) {

70 printf("video_frame%s n:%d coded_n:%d pts:%s\n",

71 cached ? "(cached)" : "",

72 video_frame_count++, frame->coded_picture_number,

73 av_ts2timestr(frame->pts, &video_dec_ctx->time_base));

75 /* copy decoded frame to destination buffer:

76 * this is required since rawvideo expects non aligned data */

77 av_image_copy(video_dst_data, video_dst_linesize,

78 (const uint8_t **)(frame->data), frame->linesize,

79 video_dec_ctx->pix_fmt, video_dec_ctx->width, video_dec_ctx->height);

81 /* write to rawvideo file */

82 fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file);

83 }

84 } else if (pkt.stream_index == audio_stream_idx) {

85 /* decode audio frame */

86 ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);

87 if (ret < 0) {

88 fprintf(stderr, "Error decoding audio frame\n");

89 return ret;

90 }

91 /* Some audio decoders decode only part of the packet, and have to be

92 * called again with the remainder of the packet data.

93 * Sample: fate-suite/lossless-audio/luckynight-partial.shn

94 * Also, some decoders might over-read the packet. */

95 decoded = FFMIN(ret, pkt.size);

97 if (*got_frame) {

98 size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);

99 printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",

100 cached ? "(cached)" : "",

101 audio_frame_count++, frame->nb_samples,

102 av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));

103

104 /* Write the raw audio data samples of the first plane. This works

105 * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,

106 * most audio decoders output planar audio, which uses a separate

107 * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).

108 * In other words, this code will write only the first audio channel

109 * in these cases.

110 * You should use libswresample or libavfilter to convert the frame

111 * to packed data. */

112 fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);

113 }

114 }

115

116 return decoded;

117 }

118

119 static int open_codec_context(int *stream_idx,

120 AVFormatContext *fmt_ctx, enum AVMediaType type)

121 {

122 int ret;

123 AVStream *st;

124 AVCodecContext *dec_ctx = NULL;

125 AVCodec *dec = NULL;

126

127 ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);

128 if (ret < 0) {

129 fprintf(stderr, "Could not find %s stream in input file '%s'\n",

130 av_get_media_type_string(type), src_filename);

131 return ret;

132 } else {

133 *stream_idx = ret;

134 st = fmt_ctx->streams[*stream_idx];

135

136 /* find decoder for the stream */

137 dec_ctx = st->codec;

138 dec = avcodec_find_decoder(dec_ctx->codec_id);

139 if (!dec) {

140 fprintf(stderr, "Failed to find %s codec\n",

141 av_get_media_type_string(type));

142 return ret;

143 }

144

145 if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {

146 fprintf(stderr, "Failed to open %s codec\n",

147 av_get_media_type_string(type));

148 return ret;

149 }

150 }

151

152 return 0;

153 }

154

155 static int get_format_from_sample_fmt(const char **fmt,

156 enum AVSampleFormat sample_fmt)

157 {

158 int i;

159 struct sample_fmt_entry {

160 enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;

161 } sample_fmt_entries[] = {

162 { AV_SAMPLE_FMT_U8, "u8", "u8" },

163 { AV_SAMPLE_FMT_S16, "s16be", "s16le" },

164 { AV_SAMPLE_FMT_S32, "s32be", "s32le" },

165 { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },

166 { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },

167 };

168 *fmt = NULL;

169

170 for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {

171 struct sample_fmt_entry *entry = &sample_fmt_entries[i];

172 if (sample_fmt == entry->sample_fmt) {

173 *fmt = AV_NE(entry->fmt_be, entry->fmt_le);

174 return 0;

175 }

176 }

177

178 fprintf(stderr,

179 "sample format %s is not supported as output format\n",

180 av_get_sample_fmt_name(sample_fmt));

181 return -1;

182 }

183

184 int main (int argc, char **argv)

185 {

186 int ret = 0, got_frame;

187

188 if (argc != 4) {

189 fprintf(stderr, "usage: %s input_file video_output_file audio_output_file\n"

190 "API example program to show how to read frames from an input file.\n"

191 "This program reads frames from a file, decodes them, and writes decoded\n"

192 "video frames to a rawvideo file named video_output_file, and decoded\n"

193 "audio frames to a rawaudio file named audio_output_file.\n"

194 "\n", argv[0]);

195 exit(1);

196 }

197 src_filename = argv[1];

198 video_dst_filename = argv[2];

199 audio_dst_filename = argv[3];

200

201 /* register all formats and codecs */

202 av_register_all();

203

204 /* open input file, and allocate format context */

205 if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {

206 fprintf(stderr, "Could not open source file %s\n", src_filename);

207 exit(1);

208 }

209

210 /* retrieve stream information */

211 if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {

212 fprintf(stderr, "Could not find stream information\n");

213 exit(1);

214 }

215

216 if (open_codec_context(&video_stream_idx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {

217 video_stream = fmt_ctx->streams[video_stream_idx];

218 video_dec_ctx = video_stream->codec;

219

220 video_dst_file = fopen(video_dst_filename, "wb");

221 if (!video_dst_file) {

222 fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);

223 ret = 1;

224 goto end;

225 }

226

227 /* allocate image where the decoded image will be put */

228 ret = av_image_alloc(video_dst_data, video_dst_linesize,

229 video_dec_ctx->width, video_dec_ctx->height,

230 video_dec_ctx->pix_fmt, 1);

231 if (ret < 0) {

232 fprintf(stderr, "Could not allocate raw video buffer\n");

233 goto end;

234 }

235 video_dst_bufsize = ret;

236 }

237

238 if (open_codec_context(&audio_stream_idx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {

239 audio_stream = fmt_ctx->streams[audio_stream_idx];

240 audio_dec_ctx = audio_stream->codec;

241 audio_dst_file = fopen(audio_dst_filename, "wb");

242 if (!audio_dst_file) {

243 fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);

244 ret = 1;

245 goto end;

246 }

247 }

248

249 /* dump input information to stderr */

250 av_dump_format(fmt_ctx, 0, src_filename, 0);

251

252 if (!audio_stream && !video_stream) {

253 fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");

254 ret = 1;

255 goto end;

256 }

257

258 frame = avcodec_alloc_frame();

259 if (!frame) {

260 fprintf(stderr, "Could not allocate frame\n");

261 ret = AVERROR(ENOMEM);

262 goto end;

263 }

264

265 /* initialize packet, set data to NULL, let the demuxer fill it */

266 av_init_packet(&pkt);

267 pkt.data = NULL;

268 pkt.size = 0;

269

270 if (video_stream)

271 printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);

272 if (audio_stream)

273 printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);

274

275 /* read frames from the file */

276 while (av_read_frame(fmt_ctx, &pkt) >= 0) {

277 AVPacket orig_pkt = pkt;

278 do {

279 ret = decode_packet(&got_frame, 0);

280 if (ret < 0)

281 break;

282 pkt.data += ret;

283 pkt.size -= ret;

284 } while (pkt.size > 0);

285 av_free_packet(&orig_pkt);

286 }

287

288 /* flush cached frames */

289 pkt.data = NULL;

290 pkt.size = 0;

291 do {

292 decode_packet(&got_frame, 1);

293 } while (got_frame);

294

295 printf("Demuxing succeeded.\n");

296

297 if (video_stream) {

298 printf("Play the output video file with the command:\n"

299 "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",

300 av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height,

301 video_dst_filename);

302 }

303

304 if (audio_stream) {

305 enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt;

306 int n_channels = audio_dec_ctx->channels;

307 const char *fmt;

308

309 if (av_sample_fmt_is_planar(sfmt)) {

310 const char *packed = av_get_sample_fmt_name(sfmt);

311 printf("Warning: the sample format the decoder produced is planar "

312 "(%s). This example will output the first channel only.\n",

313 packed ? packed : "?");

314 sfmt = av_get_packed_sample_fmt(sfmt);

315 n_channels = 1;

316 }

317

318 if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)

319 goto end;

320

321 printf("Play the output audio file with the command:\n"

322 "ffplay -f %s -ac %d -ar %d %s\n",

323 fmt, n_channels, audio_dec_ctx->sample_rate,

324 audio_dst_filename);

325 }

326

327 end:

328 if (video_dec_ctx)

329 avcodec_close(video_dec_ctx);

330 if (audio_dec_ctx)

331 avcodec_close(audio_dec_ctx);

332 avformat_close_input(&fmt_ctx);

333 if (video_dst_file)

334 fclose(video_dst_file);

335 if (audio_dst_file)

336 fclose(audio_dst_file);

337 av_free(frame);

338 av_free(video_dst_data[0]);

339

340 return ret < 0;

341 }

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