2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of FFmpeg.
6 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 * @file libavcodec/apiexample.c
23 * avcodec API use example.
25 * Note that this library only handles codecs (mpeg, mpeg4, etc...),
26 * not file formats (avi, vob, etc...). See library 'libavformat' for the
34 #ifdef HAVE_AV_CONFIG_H
35 #undef HAVE_AV_CONFIG_H
39 #include "libavutil/mathematics.h"
41 #define INBUF_SIZE 4096
44 * Audio encoding example
46 static void audio_encode_example(const char *filename)
49 AVCodecContext *c= NULL;
50 int frame_size, i, j, out_size, outbuf_size;
56 printf("Audio encoding\n");
58 /* find the MP2 encoder */
59 codec = avcodec_find_encoder(CODEC_ID_MP2);
61 fprintf(stderr, "codec not found\n");
65 c= avcodec_alloc_context();
67 /* put sample parameters */
69 c->sample_rate = 44100;
73 if (avcodec_open(c, codec) < 0) {
74 fprintf(stderr, "could not open codec\n");
78 /* the codec gives us the frame size, in samples */
79 frame_size = c->frame_size;
80 samples = malloc(frame_size * 2 * c->channels);
82 outbuf = malloc(outbuf_size);
84 f = fopen(filename, "wb");
86 fprintf(stderr, "could not open %s\n", filename);
90 /* encode a single tone sound */
92 tincr = 2 * M_PI * 440.0 / c->sample_rate;
94 for(j=0;j<frame_size;j++) {
95 samples[2*j] = (int)(sin(t) * 10000);
96 samples[2*j+1] = samples[2*j];
99 /* encode the samples */
100 out_size = avcodec_encode_audio(c, outbuf, outbuf_size, samples);
101 fwrite(outbuf, 1, out_size, f);
114 static void audio_decode_example(const char *outfilename, const char *filename)
117 AVCodecContext *c= NULL;
118 int out_size, size, len;
121 uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE], *inbuf_ptr;
123 printf("Audio decoding\n");
125 /* find the mpeg audio decoder */
126 codec = avcodec_find_decoder(CODEC_ID_MP2);
128 fprintf(stderr, "codec not found\n");
132 c= avcodec_alloc_context();
135 if (avcodec_open(c, codec) < 0) {
136 fprintf(stderr, "could not open codec\n");
140 outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
142 f = fopen(filename, "rb");
144 fprintf(stderr, "could not open %s\n", filename);
147 outfile = fopen(outfilename, "wb");
153 /* decode until eof */
156 size = fread(inbuf, 1, INBUF_SIZE, f);
162 out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
163 len = avcodec_decode_audio2(c, (short *)outbuf, &out_size,
166 fprintf(stderr, "Error while decoding\n");
170 /* if a frame has been decoded, output it */
171 fwrite(outbuf, 1, out_size, outfile);
187 * Video encoding example
189 static void video_encode_example(const char *filename)
192 AVCodecContext *c= NULL;
193 int i, out_size, size, x, y, outbuf_size;
196 uint8_t *outbuf, *picture_buf;
198 printf("Video encoding\n");
200 /* find the mpeg1 video encoder */
201 codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
203 fprintf(stderr, "codec not found\n");
207 c= avcodec_alloc_context();
208 picture= avcodec_alloc_frame();
210 /* put sample parameters */
211 c->bit_rate = 400000;
212 /* resolution must be a multiple of two */
215 /* frames per second */
216 c->time_base= (AVRational){1,25};
217 c->gop_size = 10; /* emit one intra frame every ten frames */
219 c->pix_fmt = PIX_FMT_YUV420P;
222 if (avcodec_open(c, codec) < 0) {
223 fprintf(stderr, "could not open codec\n");
227 f = fopen(filename, "wb");
229 fprintf(stderr, "could not open %s\n", filename);
233 /* alloc image and output buffer */
234 outbuf_size = 100000;
235 outbuf = malloc(outbuf_size);
236 size = c->width * c->height;
237 picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
239 picture->data[0] = picture_buf;
240 picture->data[1] = picture->data[0] + size;
241 picture->data[2] = picture->data[1] + size / 4;
242 picture->linesize[0] = c->width;
243 picture->linesize[1] = c->width / 2;
244 picture->linesize[2] = c->width / 2;
246 /* encode 1 second of video */
249 /* prepare a dummy image */
251 for(y=0;y<c->height;y++) {
252 for(x=0;x<c->width;x++) {
253 picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
258 for(y=0;y<c->height/2;y++) {
259 for(x=0;x<c->width/2;x++) {
260 picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
261 picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
265 /* encode the image */
266 out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
267 printf("encoding frame %3d (size=%5d)\n", i, out_size);
268 fwrite(outbuf, 1, out_size, f);
271 /* get the delayed frames */
272 for(; out_size; i++) {
275 out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
276 printf("write frame %3d (size=%5d)\n", i, out_size);
277 fwrite(outbuf, 1, out_size, f);
280 /* add sequence end code to have a real mpeg file */
285 fwrite(outbuf, 1, 4, f);
297 * Video decoding example
300 static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
306 f=fopen(filename,"w");
307 fprintf(f,"P5\n%d %d\n%d\n",xsize,ysize,255);
309 fwrite(buf + i * wrap,1,xsize,f);
313 static void video_decode_example(const char *outfilename, const char *filename)
316 AVCodecContext *c= NULL;
317 int frame, size, got_picture, len;
320 uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE], *inbuf_ptr;
323 /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
324 memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
326 printf("Video decoding\n");
328 /* find the mpeg1 video decoder */
329 codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
331 fprintf(stderr, "codec not found\n");
335 c= avcodec_alloc_context();
336 picture= avcodec_alloc_frame();
338 if(codec->capabilities&CODEC_CAP_TRUNCATED)
339 c->flags|= CODEC_FLAG_TRUNCATED; /* we do not send complete frames */
341 /* For some codecs, such as msmpeg4 and mpeg4, width and height
342 MUST be initialized there because this information is not
343 available in the bitstream. */
346 if (avcodec_open(c, codec) < 0) {
347 fprintf(stderr, "could not open codec\n");
351 /* the codec gives us the frame size, in samples */
353 f = fopen(filename, "rb");
355 fprintf(stderr, "could not open %s\n", filename);
361 size = fread(inbuf, 1, INBUF_SIZE, f);
365 /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
366 and this is the only method to use them because you cannot
367 know the compressed data size before analysing it.
369 BUT some other codecs (msmpeg4, mpeg4) are inherently frame
370 based, so you must call them with all the data for one
371 frame exactly. You must also initialize 'width' and
372 'height' before initializing them. */
374 /* NOTE2: some codecs allow the raw parameters (frame size,
375 sample rate) to be changed at any frame. We handle this, so
376 you should also take care of it */
378 /* here, we use a stream based decoder (mpeg1video), so we
379 feed decoder and see if it could decode a frame */
382 len = avcodec_decode_video(c, picture, &got_picture,
385 fprintf(stderr, "Error while decoding frame %d\n", frame);
389 printf("saving frame %3d\n", frame);
392 /* the picture is allocated by the decoder. no need to
394 snprintf(buf, sizeof(buf), outfilename, frame);
395 pgm_save(picture->data[0], picture->linesize[0],
396 c->width, c->height, buf);
404 /* some codecs, such as MPEG, transmit the I and P frame with a
405 latency of one frame. You must do the following to have a
406 chance to get the last frame of the video */
407 len = avcodec_decode_video(c, picture, &got_picture,
410 printf("saving last frame %3d\n", frame);
413 /* the picture is allocated by the decoder. no need to
415 snprintf(buf, sizeof(buf), outfilename, frame);
416 pgm_save(picture->data[0], picture->linesize[0],
417 c->width, c->height, buf);
429 int main(int argc, char **argv)
431 const char *filename;
433 /* must be called before using avcodec lib */
436 /* register all the codecs */
437 avcodec_register_all();
440 audio_encode_example("/tmp/test.mp2");
441 audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");
443 video_encode_example("/tmp/test.mpg");
444 filename = "/tmp/test.mpg";
449 // audio_decode_example("/tmp/test.sw", filename);
450 video_decode_example("/tmp/test%d.pgm", filename);