最简单的基于FFMPEG的音频编码器（PCM编码为AAC）

/**
 *最简单的基于FFmpeg的音频编码器
 *Simplest FFmpeg Audio Encoder
 *
 *雷霄骅 Lei Xiaohua
 *leixiaohua1020@126.com
 *中国传媒大学/数字电视技术
 *Communication University of China / Digital TV Technology
 *http://blog.csdn.net/leixiaohua1020
 *
 *本程序实现了音频PCM採样数据编码为压缩码流（MP3。WMA，AAC等）。 *是最简单的FFmpeg音频编码方面的教程。 *通过学习本样例能够了解FFmpeg的编码流程。 *This software encode PCM data to AAC bitstream. *It's the simplest audio encoding software based on FFmpeg.  *Suitable for beginner of FFmpeg  */#include <stdio.h>#define __STDC_CONSTANT_MACROS#ifdef _WIN32//Windowsextern "C"{#include "libavcodec/avcodec.h"#include "libavformat/avformat.h"};#else//Linux...#ifdef __cplusplusextern "C"{#endif#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#ifdef __cplusplus};#endif#endifint flush_encoder(AVFormatContext *fmt_ctx,unsigned int stream_index){	int ret;	int got_frame;	AVPacket enc_pkt;	if (!(fmt_ctx->streams[stream_index]->codec->codec->capabilities &		CODEC_CAP_DELAY))		return 0;	while (1) {		enc_pkt.data = NULL;		enc_pkt.size = 0;		av_init_packet(&enc_pkt);		ret = avcodec_encode_audio2 (fmt_ctx->streams[stream_index]->codec, &enc_pkt,			NULL, &got_frame);		av_frame_free(NULL);		if (ret < 0)			break;		if (!got_frame){			ret=0;			break;		}		printf("Flush Encoder: Succeed to encode 1 frame!\tsize:%5d\n",enc_pkt.size);		/* mux encoded frame */		ret = av_write_frame(fmt_ctx, &enc_pkt);		if (ret < 0)			break;	}	return ret;}int main(int argc, char* argv[]){	AVFormatContext* pFormatCtx;	AVOutputFormat* fmt;	AVStream* audio_st;	AVCodecContext* pCodecCtx;	AVCodec* pCodec;	uint8_t* frame_buf;	AVFrame* pFrame;	AVPacket pkt;	int got_frame=0;	int ret=0;	int size=0;	FILE *in_file=NULL;	                        //Raw PCM data	int framenum=1000;                          //Audio frame number	const char* out_file = "tdjm.aac";          //Output URL	int i;	in_file= fopen("tdjm.pcm", "rb");	av_register_all();	//Method 1.	pFormatCtx = avformat_alloc_context();	fmt = av_guess_format(NULL, out_file, NULL);	pFormatCtx->oformat = fmt;	//Method 2.	//avformat_alloc_output_context2(&pFormatCtx, NULL, NULL, out_file);	//fmt = pFormatCtx->oformat;	//Open output URL	if (avio_open(&pFormatCtx->pb,out_file, AVIO_FLAG_READ_WRITE) < 0){		printf("Failed to open output file!\n");		return -1;	}	audio_st = avformat_new_stream(pFormatCtx, 0);	if (audio_st==NULL){		return -1;	}	pCodecCtx = audio_st->codec;	pCodecCtx->codec_id = fmt->audio_codec;	pCodecCtx->codec_type = AVMEDIA_TYPE_AUDIO;	pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16;	pCodecCtx->sample_rate= 44100;	pCodecCtx->channel_layout=AV_CH_LAYOUT_STEREO;	pCodecCtx->channels = av_get_channel_layout_nb_channels(pCodecCtx->channel_layout);	pCodecCtx->bit_rate = 64000;  	//Show some information	av_dump_format(pFormatCtx, 0, out_file, 1);	pCodec = avcodec_find_encoder(pCodecCtx->codec_id);	if (!pCodec){		printf("Can not find encoder!\n");		return -1;	}	if (avcodec_open2(pCodecCtx, pCodec,NULL) < 0){		printf("Failed to open encoder!\n");		return -1;	}	pFrame = av_frame_alloc();	pFrame->nb_samples= pCodecCtx->frame_size;	pFrame->format= pCodecCtx->sample_fmt;		size = av_samples_get_buffer_size(NULL, pCodecCtx->channels,pCodecCtx->frame_size,pCodecCtx->sample_fmt, 1);	frame_buf = (uint8_t *)av_malloc(size);	avcodec_fill_audio_frame(pFrame, pCodecCtx->channels, pCodecCtx->sample_fmt,(const uint8_t*)frame_buf, size, 1);		//Write Header	avformat_write_header(pFormatCtx,NULL);	av_new_packet(&pkt,size);	for (i=0; i<framenum; i++){		//Read PCM		if (fread(frame_buf, 1, size, in_file) <= 0){			printf("Failed to read raw data! \n");			return -1;		}else if(feof(in_file)){			break;		}		pFrame->data[0] = frame_buf;  //PCM Data		pFrame->pts=i*100;		got_frame=0;		//Encode		ret = avcodec_encode_audio2(pCodecCtx, &pkt,pFrame, &got_frame);		if(ret < 0){			printf("Failed to encode!\n");			return -1;		}		if (got_frame==1){			printf("Succeed to encode 1 frame! \tsize:%5d\n",pkt.size);			pkt.stream_index = audio_st->index;			ret = av_write_frame(pFormatCtx, &pkt);			av_free_packet(&pkt);		}	}		//Flush Encoder	ret = flush_encoder(pFormatCtx,0);	if (ret < 0) {		printf("Flushing encoder failed\n");		return -1;	}	//Write Trailer	av_write_trailer(pFormatCtx);	//Clean	if (audio_st){		avcodec_close(audio_st->codec);		av_free(pFrame);		av_free(frame_buf);	}	avio_close(pFormatCtx->pb);	avformat_free_context(pFormatCtx);	fclose(in_file);	return 0;}

::VS2010 Environment
call "D:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"
::include
@set INCLUDE=include;%INCLUDE%
::lib
@set LIB=lib;%LIB%
::compile and link
cl simplest_ffmpeg_audio_encoder.cpp /link avcodec.lib avformat.lib avutil.lib ^
avdevice.lib avfilter.lib postproc.lib swresample.lib swscale.lib /OPT:NOREF

g++ simplest_ffmpeg_audio_encoder.cpp -g -o simplest_ffmpeg_audio_encoder.exe \
-I /usr/local/include -L /usr/local/lib -lavformat -lavcodec -lavutil

gcc simplest_ffmpeg_audio_encoder.cpp -g -o simplest_ffmpeg_audio_encoder.out \
-I /usr/local/include -L /usr/local/lib -lavformat -lavcodec -lavutil