ffmpeg音频编码

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简介

一个简单编码PCM的demo
代码

/**一个简单编码PCM的demo,参数都是根据PCM数据格式填写的,如果你的PCM不是s16p 44100 双声道,那么你需要自己修改编码上下文参数*注意读取对双声道的处理，因为pcm对双声道是交替存储的*缪国凯*MK（821486004@qq.com）*/#ifdef  __cplusplusextern "C"{#endif#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"#include "libavdevice/avdevice.h"#include "libavfilter/avfilter.h"#include "libavfilter/avfiltergraph.h"#include "libavfilter/buffersink.h"#include "libavfilter/buffersrc.h"#include "libavutil/audio_fifo.h"#include "libavutil/avutil.h"#include "libavutil/fifo.h"#ifdef  __cplusplus}#endif#pragma comment(lib, "avcodec.lib")#pragma comment(lib, "avformat.lib")#pragma comment(lib, "avutil.lib")#pragma comment(lib, "avdevice.lib")#pragma comment(lib, "avfilter.lib")//#pragma comment(lib, "avfilter.lib")//#pragma comment(lib, "postproc.lib")//#pragma comment(lib, "swresample.lib")#pragma comment(lib, "swscale.lib")#include <windows.h>#include <conio.h>#include <time.h>#include <tchar.h>AVFormatContext *pFormatCtx_Out = NULL;  int g_AudioStreamIndex = -1;#include <stdio.h>  int OpenOutPut(){    AVStream *pVideoStream = NULL, *pAudioStream = NULL;    const char *outFileName = "test.MP3";    avformat_alloc_output_context2(&pFormatCtx_Out, NULL, "flv", outFileName); //RTMP     AVCodecContext *pOutputCodecCtx;    g_AudioStreamIndex = 0;    pAudioStream = avformat_new_stream(pFormatCtx_Out, NULL);    pAudioStream->codec->codec = avcodec_find_encoder(pFormatCtx_Out->oformat->audio_codec);    pOutputCodecCtx = pAudioStream->codec;    pOutputCodecCtx->sample_rate = 44100;    pOutputCodecCtx->channel_layout = 3;    pOutputCodecCtx->channels = 2;    pOutputCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16P;    AVRational time_base={1, pAudioStream->codec->sample_rate};    pAudioStream->codec->time_base = time_base;    //audioCodecCtx->time_base = time_base;    pOutputCodecCtx->codec_tag = 0;      if (pFormatCtx_Out->oformat->flags & AVFMT_GLOBALHEADER)          pOutputCodecCtx->flags |= CODEC_FLAG_GLOBAL_HEADER;    if (avcodec_open2(pOutputCodecCtx, pOutputCodecCtx->codec, 0) < 0)    {        //编码器打开失败，退出程序        return -1;    }    if (!(pFormatCtx_Out->oformat->flags & AVFMT_NOFILE))    {        if(avio_open(&pFormatCtx_Out->pb, outFileName, AVIO_FLAG_WRITE) < 0)        {            printf("can not open output file handle!\n");            return -1;        }    }    if(avformat_write_header(pFormatCtx_Out, NULL) < 0)    {        printf("can not write the header of the output file!\n");        return -1;    }    return 0;}int _tmain(int argc, _TCHAR* argv[])  {     av_register_all();      if (OpenOutPut() < 0)      {          printf("failed to open input file");          goto end;      }      FILE *p = NULL;    p = fopen("旅行.mp3_44100_2channel.pcm", "rb");    int linesize = av_get_bytes_per_sample(pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->sample_fmt) * pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size;    uint8_t *PcmData = new uint8_t[2*linesize];    int sampleSize = av_get_bytes_per_sample(pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->sample_fmt);    int AudioFrameIndex = 0;    while(1)      {         if (p)        {            if(2*linesize != fread(PcmData, 1, 2*linesize, p))                break;            AVFrame *frame;            frame = av_frame_alloc();            frame->nb_samples = pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size>0 ? pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size: 1152;            frame->channel_layout = pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->channel_layout;            frame->format = pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->sample_fmt;            frame->sample_rate = pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->sample_rate;            av_frame_get_buffer(frame, 0);            for (int i = 0; i < pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size; i+=2)            {                memcpy(frame->data[0] + i * sampleSize, PcmData + 2 * i * sampleSize, sampleSize);                memcpy(frame->data[0] + i * sampleSize, PcmData + 2 * i * sampleSize + sampleSize, sampleSize);            }            AVPacket pkt_out;            av_init_packet(&pkt_out);            int got_picture = -1;            pkt_out.data = NULL;            pkt_out.size = 0;            frame->pts = AudioFrameIndex * pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size;            if (avcodec_encode_audio2(pFormatCtx_Out->streams[g_AudioStreamIndex]->codec, &pkt_out, frame, &got_picture) < 0)            {                printf("can not decoder a frame");            }            av_frame_free(&frame);            if (got_picture)             {                pkt_out.stream_index = g_AudioStreamIndex;                pkt_out.pts = AudioFrameIndex * pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size;                pkt_out.dts = AudioFrameIndex * pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size;                pkt_out.duration = pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->frame_size;                pkt_out.pts = av_rescale_q_rnd(pkt_out.pts,                     pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->time_base,                    pFormatCtx_Out->streams[g_AudioStreamIndex]->time_base,                    (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));                pkt_out.dts = pkt_out.pts;                pkt_out.duration = av_rescale_q_rnd(pkt_out.duration,                    pFormatCtx_Out->streams[g_AudioStreamIndex]->codec->time_base,                    pFormatCtx_Out->streams[g_AudioStreamIndex]->time_base,                    (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));                int ret = av_interleaved_write_frame(pFormatCtx_Out, &pkt_out);                av_free_packet(&pkt_out);            }            AudioFrameIndex++;        }    }      fclose(p);  end:      av_write_trailer(pFormatCtx_Out);    avio_close(pFormatCtx_Out->pb);    avformat_free_context(pFormatCtx_Out);    printf("enter any key to stop\n");    getchar();      return 0;  }
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http://download.csdn.net/detail/dancing_night/9677013
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