ffmepg解碼音訊。

#import "FFMpegAudioDecoder.h"

#ifdef __cplusplus
extern "C" {
#endif
    
#include <libavutil/opt.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
    
#ifdef __cplusplus
};
#endif

@interface FFMpegAudioDecoder(){
    AVCodec *_audioCodec;
    AVCodecContext *_pCodecCtx;
    AVFrame *_pFrame;
    char* _pcmBuf;
}

@end



@implementation FFMpegAudioDecoder

-(int)intDecoder{
    av_register_all();
    
    //NSString* codecName = @"libfdk_aac";
    //_audioCodec = avcodec_find_decoder_by_name([codecName UTF8String]);
    
    _audioCodec = avcodec_find_decoder(AV_CODEC_ID_AAC);
    
    _pCodecCtx = avcodec_alloc_context3(_audioCodec);
    if (!_audioCodec)
        return -1;
    
    _pCodecCtx->codec_id = AV_CODEC_ID_AAC;
    _pCodecCtx->codec_type = AVMEDIA_TYPE_AUDIO;
    
    if(avcodec_open2(_pCodecCtx, _audioCodec,NULL) >= 0)
        _pFrame = av_frame_alloc();// Allocate video frame
    else
        return -1;
    
    return 0;
}

-(int)decode:(char*)pktaudio len:(int)len{
    
    AVPacket pkt = {
        .data = (uint8_t*)pktaudio,
        .size = len,
    };
    int got_frame = 0;
    
    int decLen = avcodec_decode_audio4(_pCodecCtx, _pFrame, &got_frame, &pkt);
    if (!got_frame) {
        NSLog(@"avcodec_decode_audio4 failed .");
        return -1;
    }
    NSLog(@"avcodec_decode_audio4 succ len : %d",decLen);
    return 0;
}

-(void)free{
    if(_pCodecCtx){
        avcodec_close(_pCodecCtx);
        _audioCodec = NULL;
    }
    if (_pFrame) {
        av_frame_free(&_pFrame);
        _pFrame = NULL;
    }
    if (_pcmBuf) {
        free(_pcmBuf);
        _pcmBuf = NULL;
    }
}

@end