ffmpeg提取音频存为PCM

       写的一个小程序,用来测试文件音频,并存储为PCM.

       PCM可用专门软件来读取. 功能很简单,不值一提

      

/*************************************************************************> File Name: audio_test.c> Author: niwenxian> Mail: [e-mail] > Created Time: 2013年10月13日 星期日 21时27分50秒 ************************************************************************/#include    <stdlib.h>#include    <stdio.h>#include    <string.h>#include    <math.h>#include    <libavutil/opt.h>#include    <libavutil/mathematics.h>#include    <libavutil/imgutils.h>#include    <libavutil/samplefmt.h>#include    <libavutil/timestamp.h>#include    <libavformat/avformat.h>#include    <libavcodec/avcodec.h>#include    <libswscale/swscale.h>#include    <libavutil/mathematics.h>#include    <libswresample/swresample.h>#include    <libavutil/channel_layout.h>#include    <libavutil/common.h>int main(int argc, char * argv[]){const char *input;const char *outfilename = "test.pcm";const char *filename = "test.mp3";input = argv[1];av_register_all();avcodec_register_all();AVFormatContext    *iFormatCtx        = NULL;AVCodecContext     *iaCodecCtx        = NULL;AVCodec            *iaCodec           = NULL;AVFrame            *frame             = NULL;AVPacket           ipacket;av_init_packet(&ipacket);AVDictionary       *optionsDict       = NULL;struct SwsContext  *sws_ctx           = NULL;int                AudioStreamIndex;int                frameFinished;int                numBytes;int len;int i;FILE *f, *outfile;uint8_t *outbuf;uint8_t *outbuf3;uint8_t *outbuf2;uint8_t inbuf[1024+ FF_INPUT_BUFFER_PADDING_SIZE];iFormatCtx = avformat_alloc_context();if(avformat_open_input(&iFormatCtx, input, NULL, NULL)!=0){    printf("could not open input_file\n");     return -1;}printf("The url: %s\n", input);if(avformat_find_stream_info(iFormatCtx,NULL) < 0)//获取文件内音视频流的信息    {            printf("find stream info failed\n");            return -1 ;    }     av_dump_format(iFormatCtx, 0, input, 0);AudioStreamIndex = -1;for(i=0; i<iFormatCtx->nb_streams; i++){    if(iFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO && AudioStreamIndex <0 )    {        AudioStreamIndex =  i;        break;    }}if(AudioStreamIndex== -1){    printf("Cannot find VideoStream\n");    return -1;}iaCodecCtx    = iFormatCtx->streams[AudioStreamIndex]->codec;iaCodec       = avcodec_find_decoder(iaCodecCtx->codec_id);if(iaCodec == NULL){    printf("unsupported codec!\n");    return -1;}if(iaCodec->capabilities & CODEC_CAP_TRUNCATED)    iaCodecCtx->flags |= CODEC_CAP_TRUNCATED;if(avcodec_open2(iaCodecCtx, iaCodec, &optionsDict)<0){    printf("could not open the codec\n");    return -1;}outbuf = (uint8_t *)malloc(1024);f = fopen(filename, "rb");    if (f) {        printf("could not open %s\n", filename);        return -1;    }outfile = fopen(outfilename, "wb");if (!outfile) {        printf("open outfile failed\n");        av_free(iaCodecCtx);        return -1 ;    }frame = avcodec_alloc_frame();if (!frame) {        fprintf(stderr, "Could not allocate audio frame\n");        exit(1);    }    //frame->nb_samples     = iaCodecCtx->frame_size;    //frame->format         = iaCodecCtx->sample_fmt;    //frame->channel_layout = iaCodecCtx->channel_layout;int pktsize = 0;uint8_t *pktdata;while(av_read_frame(iFormatCtx, &ipacket)>=0) {    if(ipacket.stream_index == AudioStreamIndex)    {        while(ipacket.size>0)        {            int out_size;        len = avcodec_decode_audio4(iaCodecCtx, frame, &out_size, &ipacket);        if (len < 0)         {            pktsize = 0;            printf("Error while decoding\n");            continue;        }        if (out_size )         {        int data_size1 = av_samples_get_buffer_size(NULL, iaCodecCtx->channels, frame->nb_samples, iaCodecCtx->sample_fmt, 1);                //fwrite(frame->data[0], 1, data_size1, outfile);            fwrite(frame->data[0], 1, frame->linesize[0], outfile);            fflush(outfile);        }            ipacket.size -=len;            ipacket.data +=len;        }     }}return 0;}