long awaited simple libavformat output API example

Originally committed as revision 2069 to svn://svn.ffmpeg.org/ffmpeg/trunk

Makefile

@@ -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 $@ $< 
 

output_example.c

+/*
+ * 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;
+}