ios ffmpeg(libfdk-aac) aac encode

使用ffmpeg编码aac,使用libfdk-aac。

#import "FFMpegAACEncoder.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

#define ENCODE_SIZE 1024

@interface FFMpegAACEncoder(){
    AVCodecContext                      *_pCodecCtx;
    AVCodec                             *_pCodec;
    AVPacket                             _pkt;
    AVFrame                             *_pFrame;
    uint8_t                             *_frameBuf;
    long                                _length;
    long                                _oneSecBytes;
}

@end


@implementation FFMpegAACEncoder

- (int)initEncoder:(int)bitrate samplerate:(int)samplerate channel:(int)channel{
    
    _oneSecBytes = samplerate*channel*2;
    avcodec_register_all();
    enum AVCodecID codec_id = AV_CODEC_ID_AAC;
    //_pCodec = avcodec_find_encoder(codec_id);
    
    NSString* codecName = @"libfdk_aac";
    _pCodec = avcodec_find_encoder_by_name([codecName UTF8String]);
    if (!_pCodec) {
        printf("Codec not found\n");
        return -1;
    }
    
    _pCodecCtx = avcodec_alloc_context3(_pCodec);
    if (!_pCodecCtx) {
        printf("Could not allocate video codec context\n");
        return -1;
    }
    
    _pCodecCtx->codec_id = codec_id;
    _pCodecCtx->codec_type = AVMEDIA_TYPE_AUDIO;
    _pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16;
    _pCodecCtx->sample_rate= samplerate;
    _pCodecCtx->channel_layout = (channel == 2 ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO);
    _pCodecCtx->channels = av_get_channel_layout_nb_channels(_pCodecCtx->channel_layout);
    _pCodecCtx->bit_rate = bitrate;
    _pCodecCtx->frame_size = ENCODE_SIZE;
    
    int ret = 0;
    if ((ret = avcodec_open2(_pCodecCtx, _pCodec, NULL) < 0)) {
        fprintf(stderr, "Could not open codec\n");
        return -1;
    }
    
    _pFrame = av_frame_alloc();
    _pFrame->format = _pCodecCtx->sample_fmt;
    _pFrame->nb_samples = ENCODE_SIZE;
    int size = av_samples_get_buffer_size(NULL, _pCodecCtx->channels,ENCODE_SIZE,_pCodecCtx->sample_fmt, 1);
    _frameBuf = (uint8_t*)av_malloc(size);
    avcodec_fill_audio_frame(_pFrame, _pCodecCtx->channels, _pCodecCtx->sample_fmt, _frameBuf, size, 1);
    
    return 0;
}

- (int)encodeToAAC:(char*)pcm len:(int)len{
    memcpy(_frameBuf, pcm, len);
    _pFrame->data[0] = _frameBuf;
    //_pFrame->linesize[0] = len;
    _pFrame->pts = _length/_oneSecBytes;
    
    int got_frame = 0;
    //Encode
    int 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);
        if (_delegate && [_delegate respondsToSelector:@selector(onAudioEncBuf:len:)]) {
            [_delegate onAudioEncBuf:_pkt.data len:_pkt.size];
        }
        av_free_packet(&_pkt);
    }
    return 0;
}

- (void)free{
    int ret = [self flushEncoder];
    if (ret < 0) {
        
        printf("Flushing encoder failed\n");
    }
    avcodec_close(_pCodecCtx);
    av_free(_pCodecCtx);
    av_freep(&_pFrame->data[0]);
    av_frame_free(&_pFrame);
}

-(int)flushEncoder{
    int ret;
    int got_frame;
    AVPacket enc_pkt;

    while (1) {
        enc_pkt.data = NULL;
        enc_pkt.size = 0;
        av_init_packet(&enc_pkt);
        ret = avcodec_encode_audio2 (_pCodecCtx, &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);
        //TODO:编码数据回调
    }
    return ret;  
} 

@end

下面这样不行，不知道为嘛，有知道怎么弄的求告知。

    enum AVCodecID codec_id = AV_CODEC_ID_AAC;

    _pCodec = avcodec_find_encoder(codec_id);