2 * Copyright (c) 2012 Stefano Sabatini
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25 * Demuxing and decoding example.
27 * Show how to use the libavformat and libavcodec API to demux and
28 * decode audio and video data.
29 * @example demuxing_decoding.c
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;
53 static int video_frame_count = 0;
54 static int audio_frame_count = 0;
56 /* The different ways of decoding and managing data memory. You are not
57 * supposed to support all the modes in your application but pick the one most
58 * appropriate to your needs. Look for the use of api_mode in this example to
59 * see what are the differences of API usage between them */
61 API_MODE_OLD = 0, /* old method, deprecated */
62 API_MODE_NEW_API_REF_COUNT = 1, /* new method, using the frame reference counting */
63 API_MODE_NEW_API_NO_REF_COUNT = 2, /* new method, without reference counting */
66 static int api_mode = API_MODE_OLD;
68 static int decode_packet(int *got_frame, int cached)
71 int decoded = pkt.size;
75 if (pkt.stream_index == video_stream_idx) {
76 /* decode video frame */
77 ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt);
79 fprintf(stderr, "Error decoding video frame (%s)\n", av_err2str(ret));
84 printf("video_frame%s n:%d coded_n:%d pts:%s\n",
85 cached ? "(cached)" : "",
86 video_frame_count++, frame->coded_picture_number,
87 av_ts2timestr(frame->pts, &video_dec_ctx->time_base));
89 /* copy decoded frame to destination buffer:
90 * this is required since rawvideo expects non aligned data */
91 av_image_copy(video_dst_data, video_dst_linesize,
92 (const uint8_t **)(frame->data), frame->linesize,
93 video_dec_ctx->pix_fmt, video_dec_ctx->width, video_dec_ctx->height);
95 /* write to rawvideo file */
96 fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file);
98 } else if (pkt.stream_index == audio_stream_idx) {
99 /* decode audio frame */
100 ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
102 fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
105 /* Some audio decoders decode only part of the packet, and have to be
106 * called again with the remainder of the packet data.
107 * Sample: fate-suite/lossless-audio/luckynight-partial.shn
108 * Also, some decoders might over-read the packet. */
109 decoded = FFMIN(ret, pkt.size);
112 size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
113 printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
114 cached ? "(cached)" : "",
115 audio_frame_count++, frame->nb_samples,
116 av_ts2timestr(frame->pts, &audio_dec_ctx->time_base));
118 /* Write the raw audio data samples of the first plane. This works
119 * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
120 * most audio decoders output planar audio, which uses a separate
121 * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
122 * In other words, this code will write only the first audio channel
124 * You should use libswresample or libavfilter to convert the frame
126 fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
130 /* If we use the new API with reference counting, we own the data and need
131 * to de-reference it when we don't use it anymore */
132 if (*got_frame && api_mode == API_MODE_NEW_API_REF_COUNT)
133 av_frame_unref(frame);
138 static int open_codec_context(int *stream_idx,
139 AVFormatContext *fmt_ctx, enum AVMediaType type)
143 AVCodecContext *dec_ctx = NULL;
145 AVDictionary *opts = NULL;
147 ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
149 fprintf(stderr, "Could not find %s stream in input file '%s'\n",
150 av_get_media_type_string(type), src_filename);
154 st = fmt_ctx->streams[*stream_idx];
156 /* find decoder for the stream */
158 dec = avcodec_find_decoder(dec_ctx->codec_id);
160 fprintf(stderr, "Failed to find %s codec\n",
161 av_get_media_type_string(type));
162 return AVERROR(EINVAL);
165 /* Init the decoders, with or without reference counting */
166 if (api_mode == API_MODE_NEW_API_REF_COUNT)
167 av_dict_set(&opts, "refcounted_frames", "1", 0);
168 if ((ret = avcodec_open2(dec_ctx, dec, &opts)) < 0) {
169 fprintf(stderr, "Failed to open %s codec\n",
170 av_get_media_type_string(type));
178 static int get_format_from_sample_fmt(const char **fmt,
179 enum AVSampleFormat sample_fmt)
182 struct sample_fmt_entry {
183 enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
184 } sample_fmt_entries[] = {
185 { AV_SAMPLE_FMT_U8, "u8", "u8" },
186 { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
187 { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
188 { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
189 { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
193 for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
194 struct sample_fmt_entry *entry = &sample_fmt_entries[i];
195 if (sample_fmt == entry->sample_fmt) {
196 *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
202 "sample format %s is not supported as output format\n",
203 av_get_sample_fmt_name(sample_fmt));
207 int main (int argc, char **argv)
209 int ret = 0, got_frame;
211 if (argc != 4 && argc != 5) {
212 fprintf(stderr, "usage: %s [-refcount=<old|new_norefcount|new_refcount>] "
213 "input_file video_output_file audio_output_file\n"
214 "API example program to show how to read frames from an input file.\n"
215 "This program reads frames from a file, decodes them, and writes decoded\n"
216 "video frames to a rawvideo file named video_output_file, and decoded\n"
217 "audio frames to a rawaudio file named audio_output_file.\n\n"
218 "If the -refcount option is specified, the program use the\n"
219 "reference counting frame system which allows keeping a copy of\n"
220 "the data for longer than one decode call. If unset, it's using\n"
221 "the classic old method.\n"
226 const char *mode = argv[1] + strlen("-refcount=");
227 if (!strcmp(mode, "old")) api_mode = API_MODE_OLD;
228 else if (!strcmp(mode, "new_norefcount")) api_mode = API_MODE_NEW_API_NO_REF_COUNT;
229 else if (!strcmp(mode, "new_refcount")) api_mode = API_MODE_NEW_API_REF_COUNT;
231 fprintf(stderr, "unknow mode '%s'\n", mode);
236 src_filename = argv[1];
237 video_dst_filename = argv[2];
238 audio_dst_filename = argv[3];
240 /* register all formats and codecs */
243 /* open input file, and allocate format context */
244 if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
245 fprintf(stderr, "Could not open source file %s\n", src_filename);
249 /* retrieve stream information */
250 if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
251 fprintf(stderr, "Could not find stream information\n");
255 if (open_codec_context(&video_stream_idx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
256 video_stream = fmt_ctx->streams[video_stream_idx];
257 video_dec_ctx = video_stream->codec;
259 video_dst_file = fopen(video_dst_filename, "wb");
260 if (!video_dst_file) {
261 fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
266 /* allocate image where the decoded image will be put */
267 ret = av_image_alloc(video_dst_data, video_dst_linesize,
268 video_dec_ctx->width, video_dec_ctx->height,
269 video_dec_ctx->pix_fmt, 1);
271 fprintf(stderr, "Could not allocate raw video buffer\n");
274 video_dst_bufsize = ret;
277 if (open_codec_context(&audio_stream_idx, fmt_ctx, AVMEDIA_TYPE_AUDIO) >= 0) {
278 audio_stream = fmt_ctx->streams[audio_stream_idx];
279 audio_dec_ctx = audio_stream->codec;
280 audio_dst_file = fopen(audio_dst_filename, "wb");
281 if (!audio_dst_file) {
282 fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
288 /* dump input information to stderr */
289 av_dump_format(fmt_ctx, 0, src_filename, 0);
291 if (!audio_stream && !video_stream) {
292 fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
297 /* When using the new API, you need to use the libavutil/frame.h API, while
298 * the classic frame management is available in libavcodec */
299 if (api_mode == API_MODE_OLD)
300 frame = avcodec_alloc_frame();
302 frame = av_frame_alloc();
304 fprintf(stderr, "Could not allocate frame\n");
305 ret = AVERROR(ENOMEM);
309 /* initialize packet, set data to NULL, let the demuxer fill it */
310 av_init_packet(&pkt);
315 printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
317 printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
319 /* read frames from the file */
320 while (av_read_frame(fmt_ctx, &pkt) >= 0) {
321 AVPacket orig_pkt = pkt;
323 ret = decode_packet(&got_frame, 0);
328 } while (pkt.size > 0);
329 av_free_packet(&orig_pkt);
332 /* flush cached frames */
336 decode_packet(&got_frame, 1);
339 printf("Demuxing succeeded.\n");
342 printf("Play the output video file with the command:\n"
343 "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
344 av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height,
349 enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt;
350 int n_channels = audio_dec_ctx->channels;
353 if (av_sample_fmt_is_planar(sfmt)) {
354 const char *packed = av_get_sample_fmt_name(sfmt);
355 printf("Warning: the sample format the decoder produced is planar "
356 "(%s). This example will output the first channel only.\n",
357 packed ? packed : "?");
358 sfmt = av_get_packed_sample_fmt(sfmt);
362 if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
365 printf("Play the output audio file with the command:\n"
366 "ffplay -f %s -ac %d -ar %d %s\n",
367 fmt, n_channels, audio_dec_ctx->sample_rate,
372 avcodec_close(video_dec_ctx);
373 avcodec_close(audio_dec_ctx);
374 avformat_close_input(&fmt_ctx);
376 fclose(video_dst_file);
378 fclose(audio_dst_file);
379 if (api_mode == API_MODE_OLD)
380 avcodec_free_frame(&frame);
382 av_frame_free(&frame);
383 av_free(video_dst_data[0]);