void LibavReader::setupDecoder_() {
int ret = -1;
for( std::size_t i = 0 ; i < this->pFormatContext_->nb_streams; ++i ) {
if( this->pFormatContext_->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO ) {
ret = i;
break;
}
}
if( ret == -1 ) {
throw CodecError( "LibavReader: Find no audio stream!", __FILE__, __LINE__ );
}
this->pStream_ = this->pFormatContext_->streams[ret];
AVCodecContext * pCC = this->pStream_->codec;
// getting codec information
this->setBitRate( pCC->bit_rate );
// setup sample format
AudioFormat format;
format.setFrequency( 44100 );
format.setChannels( pCC->channels );
switch( pCC->channels ) {
case 1:
this->setChannelLayout( LayoutMono );
break;
case 2:
this->setChannelLayout( LayoutStereo );
break;
default:
this->setChannelLayout( LayoutNative );
}
format.setSampleType( AudioFormat::SignedInt );
format.setSampleSize( 16 );
this->setAudioFormat( format );
AVCodec * pC = avcodec_find_decoder( pCC->codec_id );
if( pC == NULL ) {
throw CodecError( tr( "find no decoder" ), __FILE__, __LINE__ );
}
if( avcodec_open2( pCC, pC, NULL ) < 0 ) {
throw CodecError( tr( "can not open decoder" ), __FILE__, __LINE__ );
}
this->pCodecContext_.reset( pCC, avcodec_close );
// resampling
if( pCC->channel_layout > 0 || format.frequency() != pCC->sample_rate || pCC->sample_fmt != AV_SAMPLE_FMT_S16 ) {
auto rsc = av_audio_resample_init( format.channels(), pCC->channels, format.frequency(), pCC->sample_rate, AV_SAMPLE_FMT_S16, pCC->sample_fmt, 16, 10, 0, 0.8 );
if( !rsc ) {
throw CodecError( QObject::tr( "ReSampleContext open failed" ), __FILE__, __LINE__ );
}
this->pArContext_.reset( rsc, []( ReSampleContext * p )->void {
audio_resample_close( p );
} );
}
}
