2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of Libav.
6 * Libav is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * Libav is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * libavcodec API use example.
26 * Note that this library only handles codecs (mpeg, mpeg4, etc...),
27 * not file formats (avi, vob, etc...). See library 'libavformat' for the
35 #ifdef HAVE_AV_CONFIG_H
36 #undef HAVE_AV_CONFIG_H
39 #include "libavcodec/avcodec.h"
40 #include "libavutil/channel_layout.h"
41 #include "libavutil/common.h"
42 #include "libavutil/imgutils.h"
43 #include "libavutil/mathematics.h"
44 #include "libavutil/samplefmt.h"
46 #define INBUF_SIZE 4096
47 #define AUDIO_INBUF_SIZE 20480
48 #define AUDIO_REFILL_THRESH 4096
50 /* check that a given sample format is supported by the encoder */
51 static int check_sample_fmt(AVCodec *codec, enum AVSampleFormat sample_fmt)
53 const enum AVSampleFormat *p = codec->sample_fmts;
55 while (*p != AV_SAMPLE_FMT_NONE) {
63 /* just pick the highest supported samplerate */
64 static int select_sample_rate(AVCodec *codec)
67 int best_samplerate = 0;
69 if (!codec->supported_samplerates)
72 p = codec->supported_samplerates;
74 best_samplerate = FFMAX(*p, best_samplerate);
77 return best_samplerate;
80 /* select layout with the highest channel count */
81 static int select_channel_layout(AVCodec *codec)
84 uint64_t best_ch_layout = 0;
85 int best_nb_channels = 0;
87 if (!codec->channel_layouts)
88 return AV_CH_LAYOUT_STEREO;
90 p = codec->channel_layouts;
92 int nb_channels = av_get_channel_layout_nb_channels(*p);
94 if (nb_channels > best_nb_channels) {
96 best_nb_channels = nb_channels;
100 return best_ch_layout;
104 * Audio encoding example
106 static void audio_encode_example(const char *filename)
109 AVCodecContext *c= NULL;
112 int i, j, k, ret, got_output;
118 printf("Audio encoding\n");
120 /* find the MP2 encoder */
121 codec = avcodec_find_encoder(AV_CODEC_ID_MP2);
123 fprintf(stderr, "codec not found\n");
127 c = avcodec_alloc_context3(codec);
129 /* put sample parameters */
132 /* check that the encoder supports s16 pcm input */
133 c->sample_fmt = AV_SAMPLE_FMT_S16;
134 if (!check_sample_fmt(codec, c->sample_fmt)) {
135 fprintf(stderr, "encoder does not support %s",
136 av_get_sample_fmt_name(c->sample_fmt));
140 /* select other audio parameters supported by the encoder */
141 c->sample_rate = select_sample_rate(codec);
142 c->channel_layout = select_channel_layout(codec);
143 c->channels = av_get_channel_layout_nb_channels(c->channel_layout);
146 if (avcodec_open2(c, codec, NULL) < 0) {
147 fprintf(stderr, "could not open codec\n");
151 f = fopen(filename, "wb");
153 fprintf(stderr, "could not open %s\n", filename);
157 /* frame containing input raw audio */
158 frame = av_frame_alloc();
160 fprintf(stderr, "could not allocate audio frame\n");
164 frame->nb_samples = c->frame_size;
165 frame->format = c->sample_fmt;
166 frame->channel_layout = c->channel_layout;
168 /* the codec gives us the frame size, in samples,
169 * we calculate the size of the samples buffer in bytes */
170 buffer_size = av_samples_get_buffer_size(NULL, c->channels, c->frame_size,
172 samples = av_malloc(buffer_size);
174 fprintf(stderr, "could not allocate %d bytes for samples buffer\n",
178 /* setup the data pointers in the AVFrame */
179 ret = avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt,
180 (const uint8_t*)samples, buffer_size, 0);
182 fprintf(stderr, "could not setup audio frame\n");
186 /* encode a single tone sound */
188 tincr = 2 * M_PI * 440.0 / c->sample_rate;
190 av_init_packet(&pkt);
191 pkt.data = NULL; // packet data will be allocated by the encoder
194 for (j = 0; j < c->frame_size; j++) {
195 samples[2*j] = (int)(sin(t) * 10000);
197 for (k = 1; k < c->channels; k++)
198 samples[2*j + k] = samples[2*j];
201 /* encode the samples */
202 ret = avcodec_encode_audio2(c, &pkt, frame, &got_output);
204 fprintf(stderr, "error encoding audio frame\n");
208 fwrite(pkt.data, 1, pkt.size, f);
209 av_packet_unref(&pkt);
215 av_frame_free(&frame);
223 static void audio_decode_example(const char *outfilename, const char *filename)
226 AVCodecContext *c= NULL;
229 uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
231 AVFrame *decoded_frame = NULL;
233 av_init_packet(&avpkt);
235 printf("Audio decoding\n");
237 /* find the mpeg audio decoder */
238 codec = avcodec_find_decoder(AV_CODEC_ID_MP2);
240 fprintf(stderr, "codec not found\n");
244 c = avcodec_alloc_context3(codec);
247 if (avcodec_open2(c, codec, NULL) < 0) {
248 fprintf(stderr, "could not open codec\n");
252 f = fopen(filename, "rb");
254 fprintf(stderr, "could not open %s\n", filename);
257 outfile = fopen(outfilename, "wb");
263 /* decode until eof */
265 avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
267 while (avpkt.size > 0) {
270 if (!decoded_frame) {
271 if (!(decoded_frame = av_frame_alloc())) {
272 fprintf(stderr, "out of memory\n");
277 len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt);
279 fprintf(stderr, "Error while decoding\n");
283 /* if a frame has been decoded, output it */
284 int data_size = av_samples_get_buffer_size(NULL, c->channels,
285 decoded_frame->nb_samples,
287 fwrite(decoded_frame->data[0], 1, data_size, outfile);
291 if (avpkt.size < AUDIO_REFILL_THRESH) {
292 /* Refill the input buffer, to avoid trying to decode
293 * incomplete frames. Instead of this, one could also use
294 * a parser, or use a proper container format through
296 memmove(inbuf, avpkt.data, avpkt.size);
298 len = fread(avpkt.data + avpkt.size, 1,
299 AUDIO_INBUF_SIZE - avpkt.size, f);
310 av_frame_free(&decoded_frame);
314 * Video encoding example
316 static void video_encode_example(const char *filename)
319 AVCodecContext *c= NULL;
320 int i, ret, x, y, got_output;
324 uint8_t endcode[] = { 0, 0, 1, 0xb7 };
326 printf("Video encoding\n");
328 /* find the mpeg1 video encoder */
329 codec = avcodec_find_encoder(AV_CODEC_ID_MPEG1VIDEO);
331 fprintf(stderr, "codec not found\n");
335 c = avcodec_alloc_context3(codec);
336 picture = av_frame_alloc();
338 /* put sample parameters */
339 c->bit_rate = 400000;
340 /* resolution must be a multiple of two */
343 /* frames per second */
344 c->time_base= (AVRational){1,25};
345 c->gop_size = 10; /* emit one intra frame every ten frames */
347 c->pix_fmt = AV_PIX_FMT_YUV420P;
350 if (avcodec_open2(c, codec, NULL) < 0) {
351 fprintf(stderr, "could not open codec\n");
355 f = fopen(filename, "wb");
357 fprintf(stderr, "could not open %s\n", filename);
361 ret = av_image_alloc(picture->data, picture->linesize, c->width, c->height,
364 fprintf(stderr, "could not alloc raw picture buffer\n");
367 picture->format = c->pix_fmt;
368 picture->width = c->width;
369 picture->height = c->height;
371 /* encode 1 second of video */
373 av_init_packet(&pkt);
374 pkt.data = NULL; // packet data will be allocated by the encoder
378 /* prepare a dummy image */
380 for(y=0;y<c->height;y++) {
381 for(x=0;x<c->width;x++) {
382 picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
387 for(y=0;y<c->height/2;y++) {
388 for(x=0;x<c->width/2;x++) {
389 picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
390 picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
396 /* encode the image */
397 ret = avcodec_encode_video2(c, &pkt, picture, &got_output);
399 fprintf(stderr, "error encoding frame\n");
404 printf("encoding frame %3d (size=%5d)\n", i, pkt.size);
405 fwrite(pkt.data, 1, pkt.size, f);
406 av_packet_unref(&pkt);
410 /* get the delayed frames */
411 for (got_output = 1; got_output; i++) {
414 ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
416 fprintf(stderr, "error encoding frame\n");
421 printf("encoding frame %3d (size=%5d)\n", i, pkt.size);
422 fwrite(pkt.data, 1, pkt.size, f);
423 av_packet_unref(&pkt);
427 /* add sequence end code to have a real mpeg file */
428 fwrite(endcode, 1, sizeof(endcode), f);
433 av_freep(&picture->data[0]);
434 av_frame_free(&picture);
439 * Video decoding example
442 static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
448 f=fopen(filename,"w");
449 fprintf(f,"P5\n%d %d\n%d\n",xsize,ysize,255);
451 fwrite(buf + i * wrap,1,xsize,f);
455 static void video_decode_example(const char *outfilename, const char *filename)
458 AVCodecContext *c= NULL;
459 int frame, got_picture, len;
462 uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
466 av_init_packet(&avpkt);
468 /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
469 memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
471 printf("Video decoding\n");
473 /* find the mpeg1 video decoder */
474 codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);
476 fprintf(stderr, "codec not found\n");
480 c = avcodec_alloc_context3(codec);
481 picture = av_frame_alloc();
483 if (codec->capabilities & AV_CODEC_CAP_TRUNCATED)
484 c->flags |= AV_CODEC_FLAG_TRUNCATED; // we do not send complete frames
486 /* For some codecs, such as msmpeg4 and mpeg4, width and height
487 MUST be initialized there because this information is not
488 available in the bitstream. */
491 if (avcodec_open2(c, codec, NULL) < 0) {
492 fprintf(stderr, "could not open codec\n");
496 /* the codec gives us the frame size, in samples */
498 f = fopen(filename, "rb");
500 fprintf(stderr, "could not open %s\n", filename);
506 avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
510 /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
511 and this is the only method to use them because you cannot
512 know the compressed data size before analysing it.
514 BUT some other codecs (msmpeg4, mpeg4) are inherently frame
515 based, so you must call them with all the data for one
516 frame exactly. You must also initialize 'width' and
517 'height' before initializing them. */
519 /* NOTE2: some codecs allow the raw parameters (frame size,
520 sample rate) to be changed at any frame. We handle this, so
521 you should also take care of it */
523 /* here, we use a stream based decoder (mpeg1video), so we
524 feed decoder and see if it could decode a frame */
526 while (avpkt.size > 0) {
527 len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
529 fprintf(stderr, "Error while decoding frame %d\n", frame);
533 printf("saving frame %3d\n", frame);
536 /* the picture is allocated by the decoder. no need to
538 snprintf(buf, sizeof(buf), outfilename, frame);
539 pgm_save(picture->data[0], picture->linesize[0],
540 c->width, c->height, buf);
548 /* some codecs, such as MPEG, transmit the I and P frame with a
549 latency of one frame. You must do the following to have a
550 chance to get the last frame of the video */
553 len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
555 printf("saving last frame %3d\n", frame);
558 /* the picture is allocated by the decoder. no need to
560 snprintf(buf, sizeof(buf), outfilename, frame);
561 pgm_save(picture->data[0], picture->linesize[0],
562 c->width, c->height, buf);
570 av_frame_free(&picture);
574 int main(int argc, char **argv)
576 const char *filename;
578 /* register all the codecs */
579 avcodec_register_all();
582 audio_encode_example("/tmp/test.mp2");
583 audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");
585 video_encode_example("/tmp/test.mpg");
586 filename = "/tmp/test.mpg";
591 // audio_decode_example("/tmp/test.sw", filename);
592 video_decode_example("/tmp/test%d.pgm", filename);