3
* avcodec API use example.
5
* Note that this library only handles codecs (mpeg, mpeg4, etc...),
6
* not file formats (avi, vob, etc...). See library 'libavformat' for the
15
#ifdef HAVE_AV_CONFIG_H
16
#undef HAVE_AV_CONFIG_H
21
#define INBUF_SIZE 4096
24
* Audio encoding example
26
void audio_encode_example(const char *filename)
29
AVCodecContext *c= NULL;
30
int frame_size, i, j, out_size, outbuf_size;
36
printf("Audio encoding\n");
38
/* find the MP2 encoder */
39
codec = avcodec_find_encoder(CODEC_ID_MP2);
41
fprintf(stderr, "codec not found\n");
45
c= avcodec_alloc_context();
47
/* put sample parameters */
49
c->sample_rate = 44100;
53
if (avcodec_open(c, codec) < 0) {
54
fprintf(stderr, "could not open codec\n");
58
/* the codec gives us the frame size, in samples */
59
frame_size = c->frame_size;
60
samples = malloc(frame_size * 2 * c->channels);
62
outbuf = malloc(outbuf_size);
64
f = fopen(filename, "w");
66
fprintf(stderr, "could not open %s\n", filename);
70
/* encode a single tone sound */
72
tincr = 2 * M_PI * 440.0 / c->sample_rate;
74
for(j=0;j<frame_size;j++) {
75
samples[2*j] = (int)(sin(t) * 10000);
76
samples[2*j+1] = samples[2*j];
79
/* encode the samples */
80
out_size = avcodec_encode_audio(c, outbuf, outbuf_size, samples);
81
fwrite(outbuf, 1, out_size, f);
94
void audio_decode_example(const char *outfilename, const char *filename)
97
AVCodecContext *c= NULL;
98
int out_size, size, len;
101
uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE], *inbuf_ptr;
103
printf("Audio decoding\n");
105
/* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
106
memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
108
/* find the mpeg audio decoder */
109
codec = avcodec_find_decoder(CODEC_ID_MP2);
111
fprintf(stderr, "codec not found\n");
115
c= avcodec_alloc_context();
118
if (avcodec_open(c, codec) < 0) {
119
fprintf(stderr, "could not open codec\n");
123
outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
125
f = fopen(filename, "r");
127
fprintf(stderr, "could not open %s\n", filename);
130
outfile = fopen(outfilename, "w");
136
/* decode until eof */
139
size = fread(inbuf, 1, INBUF_SIZE, f);
145
len = avcodec_decode_audio(c, (short *)outbuf, &out_size,
148
fprintf(stderr, "Error while decoding\n");
152
/* if a frame has been decoded, output it */
153
fwrite(outbuf, 1, out_size, outfile);
169
* Video encoding example
171
void video_encode_example(const char *filename)
174
AVCodecContext *c= NULL;
175
int i, out_size, size, x, y, outbuf_size;
178
uint8_t *outbuf, *picture_buf;
180
printf("Video encoding\n");
182
/* find the mpeg1 video encoder */
183
codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
185
fprintf(stderr, "codec not found\n");
189
c= avcodec_alloc_context();
190
picture= avcodec_alloc_frame();
192
/* put sample parameters */
193
c->bit_rate = 400000;
194
/* resolution must be a multiple of two */
197
/* frames per second */
199
c->frame_rate_base= 1;
200
c->gop_size = 10; /* emit one intra frame every ten frames */
204
if (avcodec_open(c, codec) < 0) {
205
fprintf(stderr, "could not open codec\n");
209
/* the codec gives us the frame size, in samples */
211
f = fopen(filename, "w");
213
fprintf(stderr, "could not open %s\n", filename);
217
/* alloc image and output buffer */
218
outbuf_size = 100000;
219
outbuf = malloc(outbuf_size);
220
size = c->width * c->height;
221
picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
223
picture->data[0] = picture_buf;
224
picture->data[1] = picture->data[0] + size;
225
picture->data[2] = picture->data[1] + size / 4;
226
picture->linesize[0] = c->width;
227
picture->linesize[1] = c->width / 2;
228
picture->linesize[2] = c->width / 2;
230
/* encode 1 second of video */
233
/* prepare a dummy image */
235
for(y=0;y<c->height;y++) {
236
for(x=0;x<c->width;x++) {
237
picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
242
for(y=0;y<c->height/2;y++) {
243
for(x=0;x<c->width/2;x++) {
244
picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
245
picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
249
/* encode the image */
250
out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
251
printf("encoding frame %3d (size=%5d)\n", i, out_size);
252
fwrite(outbuf, 1, out_size, f);
255
/* get the delayed frames */
256
for(; out_size; i++) {
259
out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
260
printf("write frame %3d (size=%5d)\n", i, out_size);
261
fwrite(outbuf, 1, out_size, f);
264
/* add sequence end code to have a real mpeg file */
269
fwrite(outbuf, 1, 4, f);
281
* Video decoding example
284
void pgm_save(unsigned char *buf,int wrap, int xsize,int ysize,char *filename)
289
f=fopen(filename,"w");
290
fprintf(f,"P5\n%d %d\n%d\n",xsize,ysize,255);
292
fwrite(buf + i * wrap,1,xsize,f);
296
void video_decode_example(const char *outfilename, const char *filename)
299
AVCodecContext *c= NULL;
300
int frame, size, got_picture, len;
303
uint8_t inbuf[INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE], *inbuf_ptr;
306
/* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
307
memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
309
printf("Video decoding\n");
311
/* find the mpeg1 video decoder */
312
codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
314
fprintf(stderr, "codec not found\n");
318
c= avcodec_alloc_context();
319
picture= avcodec_alloc_frame();
321
if(codec->capabilities&CODEC_CAP_TRUNCATED)
322
c->flags|= CODEC_FLAG_TRUNCATED; /* we dont send complete frames */
324
/* for some codecs, such as msmpeg4 and mpeg4, width and height
325
MUST be initialized there because these info are not available
329
if (avcodec_open(c, codec) < 0) {
330
fprintf(stderr, "could not open codec\n");
334
/* the codec gives us the frame size, in samples */
336
f = fopen(filename, "r");
338
fprintf(stderr, "could not open %s\n", filename);
344
size = fread(inbuf, 1, INBUF_SIZE, f);
348
/* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
349
and this is the only method to use them because you cannot
350
know the compressed data size before analysing it.
352
BUT some other codecs (msmpeg4, mpeg4) are inherently frame
353
based, so you must call them with all the data for one
354
frame exactly. You must also initialize 'width' and
355
'height' before initializing them. */
357
/* NOTE2: some codecs allow the raw parameters (frame size,
358
sample rate) to be changed at any frame. We handle this, so
359
you should also take care of it */
361
/* here, we use a stream based decoder (mpeg1video), so we
362
feed decoder and see if it could decode a frame */
365
len = avcodec_decode_video(c, picture, &got_picture,
368
fprintf(stderr, "Error while decoding frame %d\n", frame);
372
printf("saving frame %3d\n", frame);
375
/* the picture is allocated by the decoder. no need to
377
snprintf(buf, sizeof(buf), outfilename, frame);
378
pgm_save(picture->data[0], picture->linesize[0],
379
c->width, c->height, buf);
387
/* some codecs, such as MPEG, transmit the I and P frame with a
388
latency of one frame. You must do the following to have a
389
chance to get the last frame of the video */
390
len = avcodec_decode_video(c, picture, &got_picture,
393
printf("saving last frame %3d\n", frame);
396
/* the picture is allocated by the decoder. no need to
398
snprintf(buf, sizeof(buf), outfilename, frame);
399
pgm_save(picture->data[0], picture->linesize[0],
400
c->width, c->height, buf);
412
// simple example how the options could be used
413
int options_example(int argc, char* argv[])
415
AVCodec* codec = avcodec_find_encoder_by_name((argc > 1) ? argv[2] : "mpeg4");
417
AVCodecContext* avctx;
418
char* def = av_malloc(5000);
419
const char* col = "";
425
avctx = avcodec_alloc_context();
429
const AVOption *stack[FF_OPT_MAX_DEPTH];
435
c = (const AVOption*)c->help;
443
int t = c->type & FF_OPT_TYPE_MASK;
444
printf("Config %s %s\n",
445
t == FF_OPT_TYPE_BOOL ? "bool " :
446
t == FF_OPT_TYPE_DOUBLE ? "double " :
447
t == FF_OPT_TYPE_INT ? "integer" :
448
t == FF_OPT_TYPE_STRING ? "string " :
449
"unknown??", c->name);
451
case FF_OPT_TYPE_BOOL:
452
i += sprintf(def + i, "%s%s=%s",
454
c->defval != 0. ? "on" : "off");
456
case FF_OPT_TYPE_DOUBLE:
457
i += sprintf(def + i, "%s%s=%f",
458
col, c->name, c->defval);
460
case FF_OPT_TYPE_INT:
461
i += sprintf(def + i, "%s%s=%d",
462
col, c->name, (int) c->defval);
464
case FF_OPT_TYPE_STRING:
466
char* d = av_strdup(c->defstr);
467
char* f = strchr(d, ',');
470
i += sprintf(def + i, "%s%s=%s",
481
printf("Default Options: %s\n", def);
487
int main(int argc, char **argv)
489
const char *filename;
491
/* must be called before using avcodec lib */
494
/* register all the codecs (you can also register only the codec
495
you wish to have smaller code */
496
avcodec_register_all();
499
options_example(argc, argv);
502
audio_encode_example("/tmp/test.mp2");
503
audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");
505
video_encode_example("/tmp/test.mpg");
506
filename = "/tmp/test.mpg";
511
// audio_decode_example("/tmp/test.sw", filename);
512
video_decode_example("/tmp/test%d.pgm", filename);