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FFmpeg
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long awaited simple libavformat output API example 

Originally committed as revision 2069 to svn://svn.ffmpeg.org/ffmpeg/trunk
tags/v0.5
Fabrice Bellard 22 years ago
parent
6a6362f088
commit
8de65d4f11
2 changed files with 355 additions and 1 deletions
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  1. +5
    -1
      Makefile
  2. +350
    -0
      output_example.c

+ 5
- 1
Makefile View File

@@ -25,6 +25,7 @@ endif
endif

PROG=ffmpeg$(EXE)
PROGTEST=output_example$(EXE)

ifeq ($(CONFIG_FFSERVER),yes)
PROG+=ffserver$(EXE)
@@ -75,7 +76,7 @@ OBJS = ffmpeg.o ffserver.o cmdutils.o ffplay.o
SRCS = $(OBJS:.o=.c) $(ASM_OBJS:.o=.s)
FFLIBS = -L./libavformat -lavformat -L./libavcodec -lavcodec

all: lib $(PROG) $(VHOOK)
all: lib $(PROG) $(PROGTEST) $(VHOOK)

lib: $(AMRLIBS)
$(MAKE) -C libavcodec all
@@ -98,6 +99,9 @@ ffplay$(EXE): ffplay_g$(EXE)
cp -p $< $@
$(STRIP) $@

output_example$(EXE): output_example.o .libs
$(CC) $(LDFLAGS) -o $@ output_example.o $(FFLIBS) $(EXTRALIBS)

ffplay.o: ffplay.c
$(CC) $(CFLAGS) $(SDL_CFLAGS) -c -o $@ $<



+ 350
- 0
output_example.c View File

@@ -0,0 +1,350 @@
/*
* Libavformat API example: Output a media file in any supported
* libavformat format. The default codecs are used.
*
* Copyright (c) 2003 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#include "avformat.h"

/* 5 seconds stream duration */
#define STREAM_DURATION 5.0


/**************************************************************/
/* audio output */

float t, tincr;
int16_t *samples;
uint8_t *audio_outbuf;
int audio_outbuf_size;
int audio_input_frame_size;

/*
* add an audio output stream
*/
AVStream *add_audio_stream(AVFormatContext *oc, int codec_id)
{
AVCodec *codec;
AVCodecContext *c;
AVStream *st;

st = av_new_stream(oc, 1);
if (!st) {
fprintf(stderr, "Could not alloc stream\n");
exit(1);
}

/* find the MP2 encoder */
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
c = &st->codec;

avcodec_get_context_defaults(c);

c->codec_type = CODEC_TYPE_AUDIO;

/* put sample parameters */
c->bit_rate = 64000;
c->sample_rate = 44100;
c->channels = 2;

/* open it */
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}

/* init signal generator */
t = 0;
tincr = 2 * M_PI * 440.0 / c->sample_rate;

audio_outbuf_size = 10000;
audio_outbuf = malloc(audio_outbuf_size);

/* ugly hack for PCM codecs (will be removed ASAP with new PCM
support to compute the input frame size in samples */
if (c->frame_size <= 1) {
audio_input_frame_size = audio_outbuf_size / c->channels;
switch(st->codec.codec_id) {
case CODEC_ID_PCM_S16LE:
case CODEC_ID_PCM_S16BE:
case CODEC_ID_PCM_U16LE:
case CODEC_ID_PCM_U16BE:
audio_input_frame_size >>= 1;
break;
default:
break;
}
} else {
audio_input_frame_size = c->frame_size;
}
samples = malloc(audio_input_frame_size * 2 * c->channels);

return st;
}

void write_audio_frame(AVFormatContext *oc, AVStream *st)
{
int j, out_size;
AVCodecContext *c;


c = &st->codec;

for(j=0;j<audio_input_frame_size;j++) {
samples[2*j] = (int)(sin(t) * 10000);
samples[2*j+1] = samples[2*j];
t += tincr;
}
out_size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);

/* write the compressed frame in the media file */
if (av_write_frame(oc, st->index, audio_outbuf, out_size) != 0) {
fprintf(stderr, "Error while writing audio frame\n");
exit(1);
}
}

/**************************************************************/
/* video output */

AVFrame *picture;
uint8_t *video_outbuf;
int frame_count, video_outbuf_size;

/* add a video output stream */
AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
{
AVCodec *codec;
AVCodecContext *c;
AVStream *st;
uint8_t *picture_buf;
int size;

st = av_new_stream(oc, 0);
if (!st) {
fprintf(stderr, "Could not alloc stream\n");
exit(1);
}
/* find the mpeg1 video encoder */
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}

c = &st->codec;
avcodec_get_context_defaults(c);

c->codec_type = CODEC_TYPE_VIDEO;

/* put sample parameters */
c->bit_rate = 400000;
/* resolution must be a multiple of two */
c->width = 352;
c->height = 288;
/* frames per second */
c->frame_rate = 25;
c->frame_rate_base= 1;
c->gop_size = 12; /* emit one intra frame every twelve frames */

/* open it */
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}

/* alloc various buffers */
picture= avcodec_alloc_frame();
video_outbuf_size = 100000;
video_outbuf = malloc(video_outbuf_size);

size = c->width * c->height;
picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
picture->data[0] = picture_buf;
picture->data[1] = picture->data[0] + size;
picture->data[2] = picture->data[1] + size / 4;
picture->linesize[0] = c->width;
picture->linesize[1] = c->width / 2;
picture->linesize[2] = c->width / 2;

return st;
}

void write_video_frame(AVFormatContext *oc, AVStream *st)
{
int x, y, i, out_size;
AVCodecContext *c;

c = &st->codec;
/* prepare a dummy image */
/* Y */
i = frame_count++;
for(y=0;y<c->height;y++) {
for(x=0;x<c->width;x++) {
picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
}
}
/* Cb and Cr */
for(y=0;y<c->height/2;y++) {
for(x=0;x<c->width/2;x++) {
picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
}
}

/* encode the image */
out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);

/* write the compressed frame in the media file */
if (av_write_frame(oc, st->index, video_outbuf, out_size) != 0) {
fprintf(stderr, "Error while writing video frame\n");
exit(1);
}
}

/**************************************************************/
/* media file output */

int main(int argc, char **argv)
{
const char *filename;
AVOutputFormat *fmt;
AVFormatContext *oc;
AVStream *st, *audio_st, *video_st;
int i;
double audio_pts, video_pts;
/* initialize libavcodec, and register all codecs and formats */
av_register_all();
if (argc != 2) {
printf("usage: %s output_file\n"
"API example program for to output media file with libavformat\n"
"\n", argv[0]);
exit(1);
}
filename = argv[1];

/* auto detect the output format from the name. default is
mpeg. */
fmt = guess_format(NULL, filename, NULL);
if (!fmt) {
printf("Could not deduce output format from file extension: using MPEG.\n");
fmt = guess_format("mpeg", NULL, NULL);
}
if (!fmt) {
fprintf(stderr, "Could not find suitable output format\n");
exit(1);
}
/* allocate the output media context */
oc = av_mallocz(sizeof(AVFormatContext));
if (!oc) {
fprintf(stderr, "Memory error\n");
exit(1);
}
oc->oformat = fmt;

/* add the audio and video streams using the default format codecs
and initialize the codecs */
video_st = NULL;
audio_st = NULL;
if (fmt->video_codec != CODEC_ID_NONE) {
video_st = add_video_stream(oc, fmt->video_codec);
}
if (fmt->audio_codec != CODEC_ID_NONE) {
audio_st = add_audio_stream(oc, fmt->audio_codec);
}

dump_format(oc, 0, filename, 1);

/* open the output file, if needed */
if (!(fmt->flags & AVFMT_NOFILE)) {
if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
fprintf(stderr, "Could not open '%s'\n", filename);
exit(1);
}
}
/* set the output parameters (must be done even if no parameters) */
av_set_parameters(oc, NULL);

/* write the stream header, if any */
av_write_header(oc);
for(;;) {
/* compute current audio and video time */
if (audio_st)
audio_pts = (double)audio_st->pts.val * oc->pts_num / oc->pts_den;
else
audio_pts = 0.0;
if (video_st)
video_pts = (double)video_st->pts.val * oc->pts_num / oc->pts_den;
else
video_pts = 0.0;

if ((!audio_st || audio_pts >= STREAM_DURATION) &&
(!video_st || video_pts >= STREAM_DURATION))
break;
/* write interleaved audio and video frames */
if (!video_st || (video_st && audio_pts < video_pts)) {
write_audio_frame(oc, audio_st);
} else {
write_video_frame(oc, video_st);
}
}

/* close each codec */
for(i = 0;i < oc->nb_streams; i++) {
st = oc->streams[i];
avcodec_close(&st->codec);
}

/* write the trailer, if any */
av_write_trailer(oc);
if (!(fmt->flags & AVFMT_NOFILE)) {
/* close the output file */
url_fclose(&oc->pb);
}

/* free the stream */
av_free(oc);

return 0;
}

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