针对FFMPEG0.49版本API编写的简单解码程序

#include <avcodec.h>
#include <avformat.h>
#include <stdlib.h>
#include <stdio.h>
void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame)
{
FILE *pFile;
char szFilename[32];
int y;
// Open file
sprintf(szFilename, "frame%d.ppm", iFrame);
pFile=fopen(szFilename, "w+b");
if(pFile==NULL)
{fprintf(stderr, "open frame file error/n");
return;}
// Write header
fprintf(pFile, "P6/n%d %d/n255/n", width, height);
// Write pixel data
for(y=0; y<height; y++)
fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, width*3, pFile);

// Close file
fclose(pFile);
}
static AVInputFormat *file_iformat;
int main(int argc, char *argv[])
{
static AVPacket packet;
AVFormatContext *pFormatCtx;
int i, videoStream;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame;
AVFrame *pFrameRGB;
int numBytes;
uint8_t *buffer;
int frameFinished;
// Register all formats and codecs
av_register_all();
// file_iformat = av_find_input_format(argv[1]);
// pFormatCtx = (AVFormatContext *) malloc (sizeof (AVFormatContext));
// Open video file
if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL) < 0){
fprintf(stderr, "Open video file/n");
return -1; // Couldn't open file
}
if (av_find_stream_info(pFormatCtx) < 0){
fprintf(stderr, "av_find_stream_info error/n");
}
fprintf(stderr, "Open video file and nb_streams is %d/n", pFormatCtx->nb_streams);
// Retrieve stream information
if( (pFormatCtx)<0){
fprintf(stderr, "Retrieve stream information/n");
return -1; // Couldn't find stream information
}
// Dump information about file onto standard error
dump_format(pFormatCtx, 0, argv[1], false);
// Find the first video stream
videoStream=-1;
for(i = 0; i < pFormatCtx->nb_streams; i ++)
if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO)
{
videoStream=i;
break;
}
if(videoStream==-1)
{
fprintf(stderr, "Didn't find a video stream and pFormatCtx->nb_streams is %d/n", pFormatCtx->nb_streams);
return -1; // Didn't find a video stream
}
// Get a pointer to the codec context for the video stream
pCodecCtx=pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL){
fprintf(stderr, "Codec not found/n");
return -1; // Codec not found
}
// Inform the codec that we can handle truncated bitstreams -- i.e.,
// bitstreams where frame boundaries can fall in the middle of packets
if(pCodec->capabilities & CODEC_CAP_TRUNCATED)
pCodecCtx->flags|=CODEC_FLAG_TRUNCATED;
// Open codec
if(avcodec_open(pCodecCtx, pCodec)<0){
fprintf(stderr, "pFrameRGB==NULL/n");
return -1; // Could not open codec
}
// Hack to correct wrong frame rates that seem to be generated by some
// codecs
// if(pCodecCtx->frame_rate>1000 && pCodecCtx->frame_rate_base==1) /
pCodecCtx->frame_rate_base=1000;
// Allocate video frame
pFrame=avcodec_alloc_frame();
// Allocate an AVFrame structure
pFrameRGB=avcodec_alloc_frame();
if(pFrameRGB==NULL){
fprintf(stderr, "pFrameRGB==NULL/n");
return -1;
}
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
pCodecCtx->height);
buffer=new uint8_t[numBytes];
printf("Determine required buffer size and allocate buffer/n");
// Assign appropriate parts of buffer to image planes in pFrameRGB
avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,
pCodecCtx->width, pCodecCtx->height);
printf("Assign appropriate parts of buffer to image planes in pFrameRGB/n");
// Read frames and save first five frames to disk
i=0;
while(av_read_frame(pFormatCtx,&packet)>=0)
{
if(packet.stream_index==videoStream)
{
avcodec_decode_video(pCodecCtx, pFrame, &frameFinished,
packet.data, packet.size);
if(frameFinished)
{
img_convert((AVPicture *)pFrameRGB, PIX_FMT_RGB24, (AVPicture*)pFrame,
pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
// Save the frame to disk
if(++i<=5)
//printf("%d/n",*pFrameRGB);
SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);
//printf("/n/n%",sizeof(pFrameRGB));
}
}
av_free_packet(&packet);
}
// Free the RGB image
delete [] buffer;
av_free(pFrameRGB);
// Free the YUV frame
av_free(pFrame);
// Close the codec
avcodec_close(pCodecCtx);
// Close the video file
av_close_input_file(pFormatCtx);
return 0;
}

操作系统FC4

本程序能够成功运行

Makefile 如下

CC=g++

TARGET=main1
SOURCE=main1.cpp
OBJECT=main1.o
CFLAGS+=-g -I. -I.. -I../libavcodec -I../libavformat/
-I../libavutil -I/usr/include/SDL
#LFLAGS+=-Wl,--warn-common -rdynamic -L../libavformat/
-lavformat -L../libavcodec -lavcodec /
-L../libutil -lavutil -lz -lSDL/
-lm -lz -ldl -L/usr/lib -lSDL -lpthread
LFLAGS+=-Wl,--warn-common -rdynamic -L../libavformat/
-lavformat -L../libavcodec -lavcodec/
-L../libavutil -lavutil -lSDL -lz/
-lm -lz -ldl -L/usr/lib -lpthread

$(TARGET):$(OBJECT)
$(CC) -o $(TARGET) $(OBJECT) $(CFLAGS) $(LFLAGS)
$(OBJECT):$(SOURCE)
$(CC) -o $(OBJECT) -c $(SOURCE) $(CFLAGS)
clean:
rm -f $(TARGET) $(OBJECT)