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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 uint8_t **audio_dst_data = NULL;

51 static int audio_dst_linesize;

52 static int audio_dst_bufsize;

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

55 static AVFrame *frame = NULL;

56 static AVPacket pkt;

57 static int video_frame_count = 0;

58 static int audio_frame_count = 0;

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

61 {

62 int ret = 0;

64 if (pkt.stream_index == video_stream_idx) {

65 /* decode video frame */

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

67 if (ret < 0) {

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

69 return ret;

70 }

72 if (*got_frame) {

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

74 cached ? "(cached)" : "",

75 video_frame_count++, frame->coded_picture_number,

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

78 /* copy decoded frame to destination buffer:

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

80 av_image_copy(video_dst_data, video_dst_linesize,

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

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

84 /* write to rawvideo file */

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

86 }

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

88 /* decode audio frame */

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

90 if (ret < 0) {

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

92 return ret;

93 }

95 if (*got_frame) {

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

97 cached ? "(cached)" : "",

98 audio_frame_count++, frame->nb_samples,

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

100

101 ret = av_samples_alloc(audio_dst_data, &audio_dst_linesize, av_frame_get_channels(frame),

102 frame->nb_samples, frame->format, 1);

103 if (ret < 0) {

104 fprintf(stderr, "Could not allocate audio buffer\n");

105 return AVERROR(ENOMEM);

106 }

107

108 /* TODO: extend return code of the av_samples_* functions so that this call is not needed */

109 audio_dst_bufsize =

110 av_samples_get_buffer_size(NULL, av_frame_get_channels(frame),

111 frame->nb_samples, frame->format, 1);

112

113 /* copy audio data to destination buffer:

114 * this is required since rawaudio expects non aligned data */

115 av_samples_copy(audio_dst_data, frame->data, 0, 0,

116 frame->nb_samples, av_frame_get_channels(frame), frame->format);

117

118 /* write to rawaudio file */

119 fwrite(audio_dst_data[0], 1, audio_dst_bufsize, audio_dst_file);

120 av_freep(&audio_dst_data[0]);

121 }

122 }

123

124 return ret;

125 }

126

127 static int open_codec_context(int *stream_idx,

128 AVFormatContext *fmt_ctx, enum AVMediaType type)

129 {

130 int ret;

131 AVStream *st;

132 AVCodecContext *dec_ctx = NULL;

133 AVCodec *dec = NULL;

134

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

136 if (ret < 0) {

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

138 av_get_media_type_string(type), src_filename);

139 return ret;

140 } else {

141 *stream_idx = ret;

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

143

144 /* find decoder for the stream */

145 dec_ctx = st->codec;

146 dec = avcodec_find_decoder(dec_ctx->codec_id);

147 if (!dec) {

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

149 av_get_media_type_string(type));

150 return ret;

151 }

152

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

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

155 av_get_media_type_string(type));

156 return ret;

157 }

158 }

159

160 return 0;

161 }

162

163 static int get_format_from_sample_fmt(const char **fmt,

164 enum AVSampleFormat sample_fmt)

165 {

166 int i;

167 struct sample_fmt_entry {

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

169 } sample_fmt_entries[] = {

170 { AV_SAMPLE_FMT_U8, "u8", "u8" },

171 { AV_SAMPLE_FMT_S16, "s16be", "s16le" },

172 { AV_SAMPLE_FMT_S32, "s32be", "s32le" },

173 { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },

174 { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },

175 };

176 *fmt = NULL;

177

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

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

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

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

182 return 0;

183 }

184 }

185

186 fprintf(stderr,

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

188 av_get_sample_fmt_name(sample_fmt));

189 return -1;

190 }

191

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

193 {

194 int ret = 0, got_frame;

195

196 if (argc != 4) {

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

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

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

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

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

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

203 exit(1);

204 }

205 src_filename = argv[1];

206 video_dst_filename = argv[2];

207 audio_dst_filename = argv[3];

208

209 /* register all formats and codecs */

210 av_register_all();

211

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

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

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

215 exit(1);

216 }

217

218 /* retrieve stream information */

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

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

221 exit(1);

222 }

223

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

225 video_stream = fmt_ctx->streams[video_stream_idx];

226 video_dec_ctx = video_stream->codec;

227

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

229 if (!video_dst_file) {

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

231 ret = 1;

232 goto end;

233 }

234

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

236 ret = av_image_alloc(video_dst_data, video_dst_linesize,

237 video_dec_ctx->width, video_dec_ctx->height,

238 video_dec_ctx->pix_fmt, 1);

239 if (ret < 0) {

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

241 goto end;

242 }

243 video_dst_bufsize = ret;

244 }

245

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

247 int nb_planes;

248

249 audio_stream = fmt_ctx->streams[audio_stream_idx];

250 audio_dec_ctx = audio_stream->codec;

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

252 if (!audio_dst_file) {

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

254 ret = 1;

255 goto end;

256 }

257

258 nb_planes = av_sample_fmt_is_planar(audio_dec_ctx->sample_fmt) ?

259 audio_dec_ctx->channels : 1;

260 audio_dst_data = av_mallocz(sizeof(uint8_t *) * nb_planes);

261 if (!audio_dst_data) {

262 fprintf(stderr, "Could not allocate audio data buffers\n");

263 ret = AVERROR(ENOMEM);

264 goto end;

265 }

266 }

267

268 /* dump input information to stderr */

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

270

271 if (!audio_stream && !video_stream) {

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

273 ret = 1;

274 goto end;

275 }

276

277 frame = avcodec_alloc_frame();

278 if (!frame) {

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

280 ret = AVERROR(ENOMEM);

281 goto end;

282 }

283

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

285 av_init_packet(&pkt);

286 pkt.data = NULL;

287 pkt.size = 0;

288

289 if (video_stream)

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

291 if (audio_stream)

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

293

294 /* read frames from the file */

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

296 decode_packet(&got_frame, 0);

297 av_free_packet(&pkt);

298 }

299

300 /* flush cached frames */

301 pkt.data = NULL;

302 pkt.size = 0;

303 do {

304 decode_packet(&got_frame, 1);

305 } while (got_frame);

306

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

308

309 if (video_stream) {

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

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

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

313 video_dst_filename);

314 }

315

316 if (audio_stream) {

317 const char *fmt;

318

319 if ((ret = get_format_from_sample_fmt(&fmt, audio_dec_ctx->sample_fmt)) < 0)

320 goto end;

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

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

323 fmt, audio_dec_ctx->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 av_free(audio_dst_data);

340

341 return ret < 0;

342 }

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