#include <stdio.h>
#include <stdlib.h>
extern "C"{//
#include "avcodec.h"
#include "avformat.h"
}
int main(char arg,char *argv[])
{
char *filename ="02.swf";
av_register_all();//注册所有可解码类型
AVFormatContext *pInFmtCtx=NULL;//文件格式
AVCodecContext *pInCodecCtx=NULL;//编码格式
if (av_open_input_file(&pInFmtCtx,filename,NULL, 0, NULL)!=0)//获取文件格式
printf("av_open_input_file error\n");
if(av_find_stream_info(pInFmtCtx) < 0)//获取文件内音视频流的信息
printf("av_find_stream_info error\n");
unsigned int j;
// Find the first audio stream
int audioStream = -1;
for(j=0; j<pInFmtCtx->nb_streams; j++)//找到音频对应的stream
if(pInFmtCtx->streams[j]->codec->codec_type==CODEC_TYPE_AUDIO)
{
audioStream=j;
break;
}
if(audioStream==-1)
{
printf("input file has no audio stream\n");
return 0; // Didn't find a audio stream
}
printf("audio stream num: %d\n",audioStream);
pInCodecCtx = pInFmtCtx->streams[audioStream]->codec;//音频的编码上下文
AVCodec *pInCodec=NULL;
/* FILE *file3 = fopen("codec_private_data_size.txt","w");
for(int i = 0; i <200000; i++)
{
pInCodec = avcodec_find_decoder((CodecID)i);
if (pInCodec!=NULL)
{
fprintf(file3,"%s %d\n",pInCodec->name,pInCodec->priv_data_size );
}
}
fclose(file3);
system("pause");
*/
pInCodec = avcodec_find_decoder(pInCodecCtx->codec_id);//根据编码ID找到用于解码的结构体
if(pInCodec==NULL)
{
printf("error no Codec found\n");
return -1 ; // Codec not found
}
//使用test的代替pInCodecCtx也可以完成解码，可以看出只要获取以下几个重要信息就可以实现解码和重采样
AVCodecContext *test = avcodec_alloc_context();
test->bit_rate = pInCodecCtx->bit_rate;//重采样用
test->sample_rate = pInCodecCtx->sample_rate;//重采样用
test->channels = pInCodecCtx->channels;//重采样用
test->extradata = pInCodecCtx->extradata;//若有则必有
test->extradata_size = pInCodecCtx->extradata_size;//若有则必要
test->codec_type = CODEC_TYPE_AUDIO;//不必要
test->block_align = pInCodecCtx->block_align ;//必要
if(avcodec_open(test, pInCodec)<0)//将两者结合以便在下面的解码函数中调用pInCodec中的对应解码函数
{
printf("error avcodec_open failed.\n");
return -1; // Could not open codec
}
if(avcodec_open(pInCodecCtx, pInCodec)<0)
{
printf("error avcodec_open failed.\n");
return -1; // Could not open codec
}
static AVPacket packet;
printf(" bit_rate = %d \r\n", pInCodecCtx->bit_rate);
printf(" sample_rate = %d \r\n", pInCodecCtx->sample_rate);
printf(" channels = %d \r\n", pInCodecCtx->channels);
printf(" code_name = %s \r\n", pInCodecCtx->codec->name);
//printf("extra data size: %d :data%x %x %x %x\n",pInCodecCtx->extradata_size,pInCodecCtx->extradata[0]
// ,pInCodecCtx->extradata[1],pInCodecCtx->extradata[2],pInCodecCtx->extradata[3]);
printf(" block_align = %d\n",pInCodecCtx->block_align);
//system("pause");
//////////////////////////////////////////////////////////////////////////
uint8_t *pktdata;
int pktsize;
int out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE*100;
uint8_t * inbuf = (uint8_t *)malloc(out_size);
FILE* pcm,*packetinfo;
packetinfo = fopen("packetinfo.txt","w");
pcm = fopen("result.pcm","wb");
long start = clock();
while(av_read_frame(pInFmtCtx, &packet)>=0)//pInFmtCtx中调用对应格式的packet获取函数
{
//fprintf(packetinfo," packet { pts=%d; dts =%d;%x,%x,%x,%x; size=%d; stream_index=%d; pos=%d;}\n",
// packet.pts,packet.dts,packet.data[0],packet.data[1],packet.data[2],packet.data[3],packet.size,packet.stream_index,packet.pos);
if(packet.stream_index==audioStream)//如果是音频
{
pktdata = packet.data;
pktsize = packet.size;
while(pktsize>0)
{
//fprintf(packetinfo,"packet data:%x %x %x %x %x\n",pktdata[0],pktdata[1],pktdata[2],pktdata[3],pktdata[4]);
//fprintf(packetinfo,"packet size:%d\n\n",pktsize);
out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE*100;
//解码
int len = avcodec_decode_audio2(pInCodecCtx,(short*)inbuf,&out_size,pktdata,pktsize);
if (len<0)
{
printf("Error while decoding.\n");
break;
}
if(out_size>0)
{
fwrite(inbuf,1,out_size,pcm);//pcm记录
fflush(pcm);
}
pktsize -= len;
pktdata += len;
}
}
av_free_packet(&packet);
}
long end = clock();
printf("cost time :%f\n",double(end-start)/(double)CLOCKS_PER_SEC);
free(inbuf);
fclose(pcm);
fclose(packetinfo);
if (pInCodecCtx!=NULL)
{
avcodec_close(pInCodecCtx);
}
if (test!=NULL)
{
avcodec_close(test);
}
av_free(test);
av_close_input_file(pInFmtCtx);
return 0;
}
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