FFMPEG解复用、解码测试，音频保存WAV文件，视频保存为PPM图像

1.WAV(PCM)文件格式分析

WAVE文件作为多媒体中使用的声波文件格式之一，它是以RIFF格式为标准的。RIFF是英文ResourceInterchangeFileFormat的缩写，每个WAVE文件的头四个字节便是“RIFF”。WAVE文件由文件头和数据体两大部分组成。其中文件头又分为RIFF／WAV文件标识段和声音数据格式说明段两部分。WAVE文件各部分内容及格式见附表。　　常见的声音文件主要有两种，分别对应于单声道（11.025KHz采样率、8Bit的采样值）和双声道（44.1KHz采样率、16Bit的采样值）。采样率是指：声音信号在“模→数”转换过程中单位时间内采样的次数。采样值是指每一次采样周期内声音模拟信号的积分值。　　对于单声道声音文件，采样数据为八位的短整数（shortint00H-FFH）；而对于双声道立体声声音文件，每次采样数据为一个16位的整数（int），高八位和低八位分别代表左右两个声道。   WAVE文件数据块包含以脉冲编码调制（PCM）格式表示的样本。WAVE文件是由样本组织而成的。   在单声道WAVE文件中，声道0代表左声道，声道1代表右声道。在多声道WAVE文件中，样本是交替出现的。　　WAVE文件格式说明表　　　　偏移地址  字节数  数据类型     内容　　　文件头　　00H        4      char      "RIFF"标志　　04H        4     longint     文件长度　　08H        4      char       "WAVE"标志　　0CH       4      char       "fmt"标志　　10H       4　              过渡字节（不定）　　14H       2      int        格式类别（10H为PCM形式的声音数据)　　16H       2      int        通道数，单声道为1，双声道为2　　18H       2      int        采样率（每秒样本数），表示每个通道的播放速度，　　1CH       4     longint      波形音频数据传送速率，其值为通道数×每秒数据位数×每 样本的数据位数／8。播放软件利用此值可以估计缓冲区的大小。　　20H       2       int       数据块的调整数（按字节算的），其值为通道数×每样本的数据位值／8。播放软件需要一次处理多个该值大小的字节数据，以便将其值用于缓冲区的调整。　　22H       2　              每样本的数据位数，表示每个声道中各个样本的数据位数。如果有多个声道，对每个声道而言，样本大小都一样。　　24H       4     char        数据标记符＂data＂　　28H       4    longint      语音数据的长度　　PCM数据的存放方式：　　样本1样本2　　8位单声道0声道0声道　　8位立体声0声道（左）1声道（右）0声道（左）1声道（右）　　16位单声道0声道低字节0声道高字节0声道低字节0声道高字节　　16位立体声0声道（左）低字节0声道（左）高字节1声道（右）低字节1声道（右）高字节　　WAVE文件的每个样本值包含在一个整数i中，i的长度为容纳指定样本长度所需的最小字节数。首先存储低有效字节，表示样本幅度的位放在i的高有效位上，剩下的位置为0，这样8位和16位的PCM波形样本的数据格式如下所示。　　　样本大小   数据格式        最大值   最小值　　8位PCM     unsignedint     225     0　　16位PCM    int            32767  -327672. FFMPEG解复用、解码测试，保存WAV音频文件和PPM图像文件，字幕的处理与保存未做完。代码如下：

/*************************************************************************************

**Notice:Copyright(c)2011AVITCorporation-AllRightsReserved

**

**Name:example.c

**

**Author:TangQi

**

**Date:2011-08-02

**

**Version:1.0

**

**Description:TheexampleisuseffmepgtoDemuxVideoFiles.Wecanprovetheresult

**ofdemuxisright.

**

**History:2011-08-02TangQiCreated

**

*************************************************************************************/

#include<libavcodec/avcodec.h>

#include<libavformat/avformat.h>

#include<libswscale/swscale.h>

#include<stdio.h>

#include<pthread.h>

/*Maybefollowheaderfiledon'tneed*/

#include<stdlib.h>

#include<time.h>

#defineMAX_SAVE_FRAME40

#defineMAX_AUDIO_BUF20000000

/*定义全局变量*/

pthread_mutex_tmutex;

pthread_cond_tcond;

intquit=0;

/*DefineDWORDandWORD*/

typedefunsignedlongDWORD;/*4Bytes*/

typedefunsignedshortWORD;/*2Bytes*/

/*Thestructofwaveheader*/

/*-------------------------*/

typedefstructRIFF_HEADER{

charavit_szRiffID[4];/*char="RIFF"*/

DWORDavit_dwRiffSize;/*filesize-8*/

charavit_szRiffFormat[4];/*char="WAVE"*/

}RIFF_HEADER;

typedefstructWAVE_FORMAT{

charavit_szWaveID[4];/*char="fmt"*/

DWORDavit_dwFSize;/*过渡字节Ox10*/

WORDavit_wFormaTag;/*编码格式，包括WAVE_FORMAT_PCM，WAVEFORMAT_ADPCM等*/

WORDavit_wChannels;/*声道数，单声道为1，双声道为2*/

DWORDavit_dwSamplesPerSec;/*采样频率*/

DWORDavit_dwAvgBytesPerSec;/*每秒的数据量*/

WORDavit_wBlockAlign;/*块对齐*/

WORDavit_wBitsPerSample;/*WAVE文件的采样大小*/

//WORDsbSize;/*PCM中忽略此值*/

}WAVE_FORMAT;

typedefstructDATA_BLOCK{

charavit_szDataID[4];/*char="data"*/

DWORDavit_dwDataSize;/*datasize=filesize-44*/

}DATA_BLOCK;

/*ThestructofPacketQueueisusedtosavepacket.*/

/*-------------------------------------------------*/

typedefstructPacketQueue{

AVPacketList*first_pkt,*last_pkt;

intnb_packets;

intsize;

}PacketQueue;

/*defineaudioandvideoPacketQueue*/

PacketQueueaudioq;

PacketQueuevideoq;

PacketQueuesubtitleq;

/*Thehandleofpacketqueue*/

/*--------------------------*/

voidpacket_queue_init(PacketQueue*q)

{

memset(q,0,sizeof(PacketQueue));

pthread_mutex_init(&mutex,NULL);//createmutex

pthread_cond_init(&cond,PTHREAD_PROCESS_PRIVATE);//createcond

}

intpacket_queue_put(PacketQueue*q,AVPacket*pkt)

{

AVPacketList*pkt1;

if(av_dup_packet(pkt)<0){

return-1;

}

pkt1=av_malloc(sizeof(AVPacketList));

if(!pkt1)

return-1;

pkt1->pkt=*pkt;

pkt1->next=NULL;

pthread_mutex_lock(&mutex);

if(!q->last_pkt)

q->first_pkt=pkt1;

else

q->last_pkt->next=pkt1;

q->last_pkt=pkt1;

q->nb_packets++;

q->size+=pkt1->pkt.size;

pthread_cond_signal(&cond);

pthread_mutex_unlock(&mutex);

return0;

}

staticintpacket_queue_get(PacketQueue*q,AVPacket*pkt,intblock)

{

AVPacketList*pkt1;

intret;

pthread_mutex_lock(&mutex);

for(;;){

if(quit){

ret=-1;

break;

}

pkt1=q->first_pkt;

if(pkt1){

q->first_pkt=pkt1->next;

if(!q->first_pkt)

q->last_pkt=NULL;

q->nb_packets--;

q->size-=pkt1->pkt.size;

*pkt=pkt1->pkt;

av_free(pkt1);

ret=1;

break;

}elseif(!block){

ret=0;

break;

}else{

pthread_cond_signal(&cond);

}

}

pthread_mutex_unlock(&mutex);

returnret;

}

voidsave_video_frame(AVFrame*pFrame,intwidth,intheight,intiFrame)

{

FILE*frameFile;

charszFilename[32];

inth;

/*Createfilenameandopenfile*/

sprintf(szFilename,"frame%d.ppm",iFrame);

frameFile=fopen(szFilename,"wb");

if(frameFile==NULL)

return;

/*WriteframeFileheader*/

fprintf(frameFile,"P6\n%d%d\n255\n",width,height);

/*Writepixeldata*/

for(h=0;h<height;h++)

fwrite(pFrame->data[0]+h*pFrame->linesize[0],1,width*3,frameFile);

/*ClosetheframeFile*/

fclose(frameFile);

return;

}

voidvideo_thread(AVCodecContext*pCodecCtx)

{

AVPacketpkt1,*packet=&pkt1;

intlen1,frameFlag,numBytes,i;

AVFrame*pFrame,*pFrameRGB;

uint8_t*buffer;

printf("EC:video_threadIn\n");

i=0;

pFrame=avcodec_alloc_frame();

/*AllocbuffertopFrameRGB*/

if((pFrameRGB=avcodec_alloc_frame())==NULL)

return;

/*Determinerequiredbuffersizeandallocatebuffer*/

numBytes=avpicture_get_size(PIX_FMT_RGB24,pCodecCtx->width,pCodecCtx->height);

buffer=(uint8_t*)av_malloc(numBytes*sizeof(uint8_t));

avpicture_fill((AVPicture*)pFrameRGB,buffer,PIX_FMT_RGB24,pCodecCtx->width,pCodecCtx->height);

for(;;){

if(packet_queue_get(&videoq,packet,1)<0){

break;//quitgettingpackets

}

/*Decodevideoframe*/

len1=avcodec_decode_video2(pCodecCtx,pFrame,&frameFlag,packet);

/*Didwegetavideoframe?*/

if(frameFlag){

/*ConverttheimagefromitsnativeformattoRGB*/

structSwsContext*img_convert_ctx;

img_convert_ctx=sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,

pCodecCtx->width,pCodecCtx->height,PIX_FMT_RGB24,

SWS_BICUBIC,NULL,NULL,NULL);

sws_scale(img_convert_ctx,pFrame->data,pFrame->linesize,0,

pCodecCtx->height,pFrame->data,pFrameRGB->linesize);

/*Savetheframetodisk*/

if(++i<=MAX_SAVE_FRAME)

save_video_frame(pFrameRGB,pCodecCtx->width,pCodecCtx->height,i);

}

av_free_packet(packet);

}

av_free(buffer);

av_free(pFrameRGB);

av_free(pFrame);

return;

}

voidwrite_wave_header(AVCodecContext*aCodecCtx,FILE*pFile,intfilesize)

{

/*AddHeaderintothefilewhichisfilluppcmdata，andmakethisfilecanplay*/

/*Writeheaderfromthebeginningoffile*/

fseek(pFile,0,SEEK_SET);

RIFF_HEADERriffHeader;

memcpy(riffHeader.avit_szRiffID,"RIFF",4);//1-4byte

riffHeader.avit_dwRiffSize=filesize-8;

memcpy(riffHeader.avit_szRiffFormat,"WAVE",4);

fwrite(&riffHeader,1,sizeof(riffHeader),pFile);

/*Writewaveformat*/

WAVE_FORMATwaveFormat;

aCodecCtx->bits_per_coded_sample=16;/*这个值未找到，AVCodecContext中没有。需自己定义?*/

memcpy(waveFormat.avit_szWaveID,"fmt",4);

waveFormat.avit_dwFSize=0x10;

waveFormat.avit_wFormaTag=1;

waveFormat.avit_wChannels=aCodecCtx->channels;

waveFormat.avit_dwSamplesPerSec=aCodecCtx->sample_rate;/*44100、22050、48000HZ*/

waveFormat.avit_wBlockAlign=(aCodecCtx->bits_per_coded_sample)/8*waveFormat.avit_wChannels;

waveFormat.avit_dwAvgBytesPerSec=waveFormat.avit_dwSamplesPerSec*waveFormat.avit_wBlockAlign;

waveFormat.avit_wBitsPerSample=aCodecCtx->bits_per_coded_sample;

fwrite(&waveFormat,1,sizeof(waveFormat),pFile);

printf("channels=%d,sample_rate=%d,BlockAlign=%d,BytesPerSec=%d,BitsPerSample=%d\n",

waveFormat.avit_wChannels,waveFormat.avit_dwSamplesPerSec,waveFormat.avit_wBlockAlign,

waveFormat.avit_dwAvgBytesPerSec,waveFormat.avit_wBitsPerSample);

/*DataBlock*/

DATA_BLOCKdatablock;

memcpy(datablock.avit_szDataID,"data",4);

datablock.avit_dwDataSize=filesize-44;//41-44byte,calculated

fwrite(&datablock,1,sizeof(datablock),pFile);

printf("EC:audio_thread(),THelenofthePCMFileis%d,Endoftheaudio_decode\n",filesize);

fclose(pFile);

return;

}

/*ReadpacketfromPakcetQueue,anddecodeaudiodata*/

intaudio_decode_frame(AVCodecContext*aCodecCtx,uint8_t*audio_buf,intbuf_size)

{

staticAVPacketpkt,pkt_temp;

staticuint8_t*audio_pkt_data=NULL;

staticintaudio_pkt_size=0;

intlen1,data_size;

for(;;){

while(pkt_temp.size>0){

data_size=buf_size;

len1=avcodec_decode_audio3(aCodecCtx,(int16_t*)audio_buf,&data_size,&pkt_temp);/*avcodec_decode_audio2()tooold,changetoavcodec_decode_audio3()*/

if(len1<0){

/*iferror,skipthisframe*/

pkt_temp.size=0;

break;

}

pkt_temp.data+=len1;

pkt_temp.size-=len1;

if(data_size<=0){

/*Nodatayet,getmoreframes*/

continue;

}

/*Wehavedata,returnitandcomebackformorelater*/

returndata_size;

}

/*freethecurrentpacket*/

if(pkt.data)

av_free_packet(&pkt);

/*

if(quit){

return-1;

}*/

/*readnextpacketfromaudioPacketQueue*/

if(packet_queue_get(&audioq,&pkt,1)<0){

return-1;

}

pkt_temp.data=pkt.data;

pkt_temp.size=pkt.size;

}

}

voidaudio_thread(AVCodecContext*aCodecCtx)

{

intlen1,audio_size,len,ture,filesize,n;

staticuint8_taudio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE*3)/2];

staticunsignedintaudio_buf_size=0;

staticunsignedintaudio_buf_index=0;

len=MAX_AUDIO_BUF;

n=1;

/*CreatandopenaFile*/

FILE*pFile;

charfilename[32];

sprintf(filename,"test%d.wav",n);

pFile=fopen(filename,"wb");

/*AT44bytespointer,writedatatopFile*/

fseek(pFile,44,SEEK_SET);

filesize=44;

//ture=1;

/*decodeaudioframe*/

while(len>0){

if(audio_buf_index>=audio_buf_size){

/*Wehavealreadysentallourdata;getmore*/

audio_size=audio_decode_frame(aCodecCtx,audio_buf,sizeof(audio_buf));

/*Saveaudio_buftothePCMFile.*/

if(audio_size>0){

	fwrite(audio_buf,1,audio_size,pFile);

	filesize+=audio_size;

	printf("EC:audio_thread()THelenofthePCMFileis%d\n",filesize);

}

if(audio_size<0){

	/*Iferror,outputsilence*/

	audio_buf_size=1024;//arbitrary?

	memset(audio_buf,0,audio_buf_size);

	printf("EC:audio_thread()*****Outputsilence*****\n");

}else{

	audio_buf_size=audio_size;

}

audio_buf_index=0;

}

len1=audio_buf_size-audio_buf_index;

if(len1>len)

len1=len;

printf("EC:audio_thread(),audio_size=%d,audio_buf_size=%d,audio_buf_index=%d,len=%d,len1=%d\n",

	audio_size,audio_buf_size,audio_buf_index,len,len1);

//memcpy(stream,(uint8_t*)audio_buf+audio_buf_index,len1);

//stream+=len1;

len-=len1;

c241audio_buf_index+=len1;

}

/*writewaveheadertothisfile*/

write_wave_header(aCodecCtx,pFile,filesize);

return;

}

voidsubtitle_thread(AVCodecContext*sCodecCtx)

{

SubPicture*sp;

AVPacketpkt1,*pkt=&pkt1;

intlen1,got_subtitle;

inti;

FILE*textFile;

charfilename[32];

inttext_id=1;

sprintf(filename,"subtitle%d.txt",text_id);

textFile=fopen(filename,"wb");

for(;;){

if(packet_queue_get(&subtitleq,pkt,1)<0)

break;

len1=avcodec_decode_subtitle2(sCodecCtx,&sp->sub,&got_subtitle,pkt);

if(got_subtitle&&len1>0){

printf("EC:subtitle_thread()sub.format=%d,len1=%d\n",sp->sub.format,len1);

for(i=0;i<sp->sub.num_rects;i++){

switch(sp->sub.rects[i]->type){

caseSUBTITLE_TEXT:

printf("EC:subtitle()EnterinsaveSUBTITLE_TEXT\n");

fwrite(sp->sub.rects[i]->text,1,sizeof(sp->sub.rects[i]->text),textFile);

break;

caseSUBTITLE_ASS:

printf("EC:subtitle()EnterinsaveSUBTITLE_ASS\n");

break;

caseSUBTITLE_BITMAP:

printf("EC:subtitle()EnterinsaveSUBTITLE_BITMAP\n");

break;

default:

printf("EC:subtitle()EnterinsaveSUBTITLE_NONE\n");

break;

}

}

}

av_free_packet(pkt);

}

return;

}

voidavit_decode(AVFormatContext*pFormatCtx,AVCodecContext*pCodecCtx,

AVCodecContext*aCodecCtx,AVCodecContext*sCodecCtx,intsubtitle_flag)

{

pthread_taudio_id;

pthread_tvideo_id;

pthread_tsubtitle_id;

/*Createvideodecodethread*/

if(pthread_create(&video_id,NULL,(void*)video_thread,pCodecCtx)!=0)

printf("Createvideothreadfailure!\n");

/*Createaudiodecodethread*/

if(pthread_create(&audio_id,NULL,(void*)audio_thread,aCodecCtx)!=0)

printf("Createaudiothreadfailure!\n");

/*Createsubtitledecodethread*/

if(subtitle_flag!=-1){

if(pthread_create(&subtitle_id,NULL,(void*)subtitle_thread,sCodecCtx)!=0)

printf("Createsubtitlethreadfailure!\n");

}

return;

}

intmain(intargc,char*argv[])

{

inti,videoStream,audioStream,subtitleStream,frameFinished;

AVFormatContext*pFormatCtx;

AVCodecContext*pCodecCtx,*aCodecCtx,*sCodecCtx;

AVCodec*pCodec,*aCodec,*sCodec;

AVPacketpacket;

if(argc<2){

fprintf(stderr,"Usage:test<file>\n");

exit(1);

}

/*Registerallformatsandcodecs*/

av_register_all();

/*InitaudioPacketQueueandvideoPacketQueue.*/

packet_queue_init(&audioq);

packet_queue_init(&videoq);

packet_queue_init(&subtitleq)

/*Openvideofile*/

if(av_open_input_file(&pFormatCtx,argv[1],NULL,0,NULL)!=0){

printf("Couldn'topenthisfile,Pleaseprovideanotherone!\n");

return-1;//Couldn'topenthisfile

}

/*Findstreaminformation*/

if(av_find_stream_info(pFormatCtx)<0){

printf("Couldn'tfindstreaminformationfromfile!\n");

return-1;//Couldn'tfindstreaminformation

}

/*Dumpinformationaboutfileontostandarderror*/

dump_format(pFormatCtx,0,argv[1],0);

/*Findthefirstvideoandaudiostream*/

videoStream=-1;

audioStream=-1;

subtitleStream=-1;

for(i=0;i<pFormatCtx->nb_streams;i++){

if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO&&videoStream<0)

videoStream=i;

elseif(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO&&audioStream<0)

audioStream=i;

else(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_SUBTITLE&&subtitleStream<0)

subtitleStream=i;

}

if(videoStream==-1){

printf("Couldn'tfineavideostream!\n");

return-1;

}

if(audioStream==-1){

printf("Couldn'tfindaaudiostream!\n");

return-1;

}

if(subtitleStream==-1){

printf("Couldn'tfindasubtitleStream!\n");

//Don'treturn-1,weplaythisfilewhithoutsubtitle.

}

/*Getapointertothecodeccontextforthevideostream,andopenthsvideocodec.*/

pCodecCtx=pFormatCtx->streams[videoStream]->codec;

if((pCodec=avcodec_find_decoder(pCodecCtx->codec_id))==NULL){

printf("UnsupportedpCodec,pleaseprovideanothervideofile!\n");

return-1;

}

if(avcodec_open(pCodecCtx,pCodec)<0){

printf("Couldn'topenvideocodec!\n");

return-1;

}

/*Getapointertothecodeccontextfortheaudiostream,andopentheaudiocodec.*/

aCodecCtx=pFormatCtx->streams[audioStream]->codec;

if((aCodec=avcodec_find_decoder(aCodecCtx->codec_id))==NULL){

printf("UnsupportedaCodec,pleaseprovideanothervideofile!\n");

return-1;

}

if(avcodec_open(aCodecCtx,aCodec)<0){

printf("Couldn'topenauciocodec!\n");//Don'treturn-1,playthevideofilewhitsilence.

return-1;

}

/*Getapointertothecodeccontextforthesubtitlestream,andopenthesubtitlecodec.*/

sCodecCtx=pFormatCtx->streams[subtitleStream]->codec;

if((sCodec=avcodec_find_decoder(aCodecCtx->codec_id))==NULL){

prinft("UnsuppertedsCodec,wewillnotdecodesubtitlestream!\n");

//Don'treturn-1,weplaythiefilewhithoutsubtitle.

}

if(avcodec_open(sCodecCtx,sCodec)<0){

printf("Couldn'topensubtitlecodec!\n");

}

/*Enterintodecodefunction,itcreatedecodethread*/

avit_decode(pFormatCtx,aCodecCtx,pCodecCtx,sCodecCtx,subtitleStream);

/*ReadframeintopacketandputthepacketintoPacketQueues*/

while(av_read_frame(pFormatCtx,&packet)>=0){

switch(packet.stream_index){

casevideoStream:

packet_queue_put(&videoq,&packet);

break;

caseaudioStream:

packet_queue_put(&audioq,&packet);

break;

casesubtitleStream:

packet_queue_put(&subtitleq,&packet);

break;

default:

av_free_packet(&packet);

break;

}

}

/*WhenreadpackettotheQueuePacketFinish,waitfordecodefinish.*/

/*Waitforthreadfinished*/

/*------------------------*/

sleep(60);

quit=1;

//Closethecodec

avcodec_close(pCodecCtx);

avcodec_close(aCodecCtx);

avcodec_close(sCodecCtx);

av_close_input_file(pFormatCtx);

return0;

}