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
23 * libavcodec API use example.
25 * Note that libavcodec only handles codecs (mpeg, mpeg4, etc...),
26 * not file formats (avi, vob, etc...). See library 'libavformat' for the
30 #include "libavcodec/avcodec.h"
31 #include "libavutil/mathematics.h"
33 #define INBUF_SIZE 4096
34 #define AUDIO_INBUF_SIZE 20480
35 #define AUDIO_REFILL_THRESH 4096
38 * Audio encoding example
40 static void audio_encode_example(const char *filename)
43 AVCodecContext *c= NULL;
44 int frame_size, i, j, out_size, outbuf_size;
50 printf("Audio encoding\n");
52 /* find the MP2 encoder */
53 codec = avcodec_find_encoder(CODEC_ID_MP2);
55 fprintf(stderr, "codec not found\n");
59 c = avcodec_alloc_context3(codec);
61 /* put sample parameters */
63 c->sample_rate = 44100;
65 c->sample_fmt = AV_SAMPLE_FMT_S16;
68 if (avcodec_open(c, codec) < 0) {
69 fprintf(stderr, "could not open codec\n");
73 /* the codec gives us the frame size, in samples */
74 frame_size = c->frame_size;
75 samples = malloc(frame_size * 2 * c->channels);
77 outbuf = malloc(outbuf_size);
79 f = fopen(filename, "wb");
81 fprintf(stderr, "could not open %s\n", filename);
85 /* encode a single tone sound */
87 tincr = 2 * M_PI * 440.0 / c->sample_rate;
89 for(j=0;j<frame_size;j++) {
90 samples[2*j] = (int)(sin(t) * 10000);
91 samples[2*j+1] = samples[2*j];
94 /* encode the samples */
95 out_size = avcodec_encode_audio(c, outbuf, outbuf_size, samples);
96 fwrite(outbuf, 1, out_size, f);
109 static void audio_decode_example(const char *outfilename, const char *filename)
112 AVCodecContext *c= NULL;
116 uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
119 av_init_packet(&avpkt);
121 printf("Audio decoding\n");
123 /* find the mpeg audio decoder */
124 codec = avcodec_find_decoder(CODEC_ID_MP2);
126 fprintf(stderr, "codec not found\n");
130 c = avcodec_alloc_context3(codec);
133 if (avcodec_open(c, codec) < 0) {
134 fprintf(stderr, "could not open codec\n");
138 outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
140 f = fopen(filename, "rb");
142 fprintf(stderr, "could not open %s\n", filename);
145 outfile = fopen(outfilename, "wb");
151 /* decode until eof */
153 avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
155 while (avpkt.size > 0) {
156 out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
157 len = avcodec_decode_audio3(c, (short *)outbuf, &out_size, &avpkt);
159 fprintf(stderr, "Error while decoding\n");
163 /* if a frame has been decoded, output it */
164 fwrite(outbuf, 1, out_size, outfile);
168 if (avpkt.size < AUDIO_REFILL_THRESH) {
169 /* Refill the input buffer, to avoid trying to decode
170 * incomplete frames. Instead of this, one could also use
171 * a parser, or use a proper container format through
173 memmove(inbuf, avpkt.data, avpkt.size);
175 len = fread(avpkt.data + avpkt.size, 1,
176 AUDIO_INBUF_SIZE - avpkt.size, f);
191 * Video encoding example
193 static void video_encode_example(const char *filename)
196 AVCodecContext *c= NULL;
197 int i, out_size, size, x, y, outbuf_size;
202 printf("Video encoding\n");
204 /* find the mpeg1 video encoder */
205 codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
207 fprintf(stderr, "codec not found\n");
211 c = avcodec_alloc_context3(codec);
212 picture= avcodec_alloc_frame();
214 /* put sample parameters */
215 c->bit_rate = 400000;
216 /* resolution must be a multiple of two */
219 /* frames per second */
220 c->time_base= (AVRational){1,25};
221 c->gop_size = 10; /* emit one intra frame every ten frames */
223 c->pix_fmt = PIX_FMT_YUV420P;
226 if (avcodec_open(c, codec) < 0) {
227 fprintf(stderr, "could not open codec\n");
231 f = fopen(filename, "wb");
233 fprintf(stderr, "could not open %s\n", filename);
237 /* alloc image and output buffer */
238 outbuf_size = 100000;
239 outbuf = malloc(outbuf_size);
241 /* the image can be allocated by any means and av_image_alloc() is
242 * just the most convenient way if av_malloc() is to be used */
243 av_image_alloc(picture->data, picture->linesize,
244 c->width, c->height, c->pix_fmt, 1);
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);
291 av_free(picture->data[0]);
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, got_picture, len;
320 uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
324 av_init_packet(&avpkt);
326 /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
327 memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
329 printf("Video decoding\n");
331 /* find the mpeg1 video decoder */
332 codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
334 fprintf(stderr, "codec not found\n");
338 c = avcodec_alloc_context3(codec);
339 picture= avcodec_alloc_frame();
341 if(codec->capabilities&CODEC_CAP_TRUNCATED)
342 c->flags|= CODEC_FLAG_TRUNCATED; /* we do not send complete frames */
344 /* For some codecs, such as msmpeg4 and mpeg4, width and height
345 MUST be initialized there because this information is not
346 available in the bitstream. */
349 if (avcodec_open(c, codec) < 0) {
350 fprintf(stderr, "could not open codec\n");
354 /* the codec gives us the frame size, in samples */
356 f = fopen(filename, "rb");
358 fprintf(stderr, "could not open %s\n", filename);
364 avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
368 /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
369 and this is the only method to use them because you cannot
370 know the compressed data size before analysing it.
372 BUT some other codecs (msmpeg4, mpeg4) are inherently frame
373 based, so you must call them with all the data for one
374 frame exactly. You must also initialize 'width' and
375 'height' before initializing them. */
377 /* NOTE2: some codecs allow the raw parameters (frame size,
378 sample rate) to be changed at any frame. We handle this, so
379 you should also take care of it */
381 /* here, we use a stream based decoder (mpeg1video), so we
382 feed decoder and see if it could decode a frame */
384 while (avpkt.size > 0) {
385 len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
387 fprintf(stderr, "Error while decoding frame %d\n", frame);
391 printf("saving frame %3d\n", frame);
394 /* the picture is allocated by the decoder. no need to
396 snprintf(buf, sizeof(buf), outfilename, frame);
397 pgm_save(picture->data[0], picture->linesize[0],
398 c->width, c->height, buf);
406 /* some codecs, such as MPEG, transmit the I and P frame with a
407 latency of one frame. You must do the following to have a
408 chance to get the last frame of the video */
411 len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
413 printf("saving last frame %3d\n", frame);
416 /* the picture is allocated by the decoder. no need to
418 snprintf(buf, sizeof(buf), outfilename, frame);
419 pgm_save(picture->data[0], picture->linesize[0],
420 c->width, c->height, buf);
432 int main(int argc, char **argv)
434 const char *filename;
436 /* must be called before using avcodec lib */
439 /* register all the codecs */
440 avcodec_register_all();
443 audio_encode_example("/tmp/test.mp2");
444 audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");
446 video_encode_example("/tmp/test.mpg");
447 filename = "/tmp/test.mpg";
452 // audio_decode_example("/tmp/test.sw", filename);
453 video_decode_example("/tmp/test%d.pgm", filename);