audio stream index to be loaded. Other streams are not taken into account (e.g. if stream 0 is video and 1 is audio use index 0 to access it.)

compute the MD5 checksum

the name of the file from which to read

EXAMPLE CODE

#include "audioloader.h" #include "algorithmfactory.h" #include <iomanip> // setw() using namespace std; namespace essentia { namespace streaming { const char* AudioLoader::name = essentia::standard::AudioLoader::name; const char* AudioLoader::category = essentia::standard::AudioLoader::category; const char* AudioLoader::description = essentia::standard::AudioLoader::description; AudioLoader::~AudioLoader() { closeAudioFile(); av_freep(&_buffer); av_freep(&_md5Encoded); av_freep(&_decodedFrame); } void AudioLoader::configure() { av_log_set_level(AV_LOG_QUIET); //av_log_set_level(AV_LOG_VERBOSE); _computeMD5 = parameter("computeMD5").toBool(); _selectedStream = parameter("audioStream").toInt(); reset(); } void AudioLoader::openAudioFile(const string& filename) { E_DEBUG(EAlgorithm, "AudioLoader: opening file: " << filename); // Open file int errnum; if ((errnum = avformat_open_input(&_demuxCtx, filename.c_str(), NULL, NULL)) != 0) { char errorstr[128]; string error = "Unknown error"; if (av_strerror(errnum, errorstr, 128) == 0) error = errorstr; throw EssentiaException("AudioLoader: Could not open file \"", filename, "\", error = ", error); } // Retrieve stream information if ((errnum = avformat_find_stream_info(_demuxCtx, NULL)) < 0) { char errorstr[128]; string error = "Unknown error"; if (av_strerror(errnum, errorstr, 128) == 0) error = errorstr; avformat_close_input(&_demuxCtx); _demuxCtx = 0; throw EssentiaException("AudioLoader: Could not find stream information, error = ", error); } // Check that we have only 1 audio stream in the file _streams.clear(); for (int i=0; i<(int)_demuxCtx->nb_streams; i++) { if (_demuxCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) { _streams.push_back(i); } } int nAudioStreams = _streams.size(); if (nAudioStreams == 0) { avformat_close_input(&_demuxCtx); _demuxCtx = 0; throw EssentiaException("AudioLoader ERROR: found 0 streams in the file, expecting one or more audio streams"); } if (_selectedStream >= nAudioStreams) { avformat_close_input(&_demuxCtx); _demuxCtx = 0; throw EssentiaException("AudioLoader ERROR: 'audioStream' parameter set to ", _selectedStream ,". It should be smaller than the audio streams count, ", nAudioStreams); } _streamIdx = _streams[_selectedStream]; // Load corresponding audio codec _audioCtx = _demuxCtx->streams[_streamIdx]->codec; _audioCodec = avcodec_find_decoder(_audioCtx->codec_id); if (!_audioCodec) { throw EssentiaException("AudioLoader: Unsupported codec!"); } if (avcodec_open2(_audioCtx, _audioCodec, NULL) < 0) { throw EssentiaException("AudioLoader: Unable to instantiate codec..."); } // Configure format convertion (no samplerate conversion yet) int64_t layout = av_get_default_channel_layout(_audioCtx->channels); E_DEBUG(EAlgorithm, "AudioLoader: using sample format conversion from libavresample"); _convertCtxAv = avresample_alloc_context(); av_opt_set_int(_convertCtxAv, "in_channel_layout", layout, 0); av_opt_set_int(_convertCtxAv, "out_channel_layout", layout, 0); av_opt_set_int(_convertCtxAv, "in_sample_rate", _audioCtx->sample_rate, 0); av_opt_set_int(_convertCtxAv, "out_sample_rate", _audioCtx->sample_rate, 0); av_opt_set_int(_convertCtxAv, "in_sample_fmt", _audioCtx->sample_fmt, 0); av_opt_set_int(_convertCtxAv, "out_sample_fmt", AV_SAMPLE_FMT_FLT, 0); if (avresample_open(_convertCtxAv) < 0) { throw EssentiaException("AudioLoader: Could not initialize avresample context"); } av_init_packet(&_packet); _decodedFrame = av_frame_alloc(); if (!_decodedFrame) { throw EssentiaException("AudioLoader: Could not allocate audio frame"); } av_md5_init(_md5Encoded); } void AudioLoader::closeAudioFile() { if (!_demuxCtx) { return; } if (_convertCtxAv) { avresample_close(_convertCtxAv); avresample_free(&_convertCtxAv); } // Close the codec if (_audioCtx) avcodec_close(_audioCtx); // Close the audio file if (_demuxCtx) avformat_close_input(&_demuxCtx); // free AVPacket // TODO: use a variable for whether _packet is initialized or not av_free_packet(&_packet); _demuxCtx = 0; _audioCtx = 0; _streams.clear(); } void AudioLoader::pushChannelsSampleRateInfo(int nChannels, Real sampleRate) { if (nChannels > 2) { throw EssentiaException("AudioLoader: could not load audio. Audio file has more than 2 channels."); } if (sampleRate <= 0) { throw EssentiaException("AudioLoader: could not load audio. Audio sampling rate must be greater than 0."); } _nChannels = nChannels; _channels.push(nChannels); _sampleRate.push(sampleRate); } void AudioLoader::pushCodecInfo(std::string codec, int bit_rate) { _codec.push(codec); _bit_rate.push(bit_rate); } string uint8_t_to_hex(uint8_t* input, int size) { ostringstream result; for(int i=0; i<size; ++i) { result << setw(2) << setfill('0') << hex << (int) input[i]; } return result.str(); } AlgorithmStatus AudioLoader::process() { if (!parameter("filename").isConfigured()) { throw EssentiaException("AudioLoader: Trying to call process() on an AudioLoader algo which hasn't been correctly configured."); } // read frames until we get a good one do { int result = av_read_frame(_demuxCtx, &_packet); //E_DEBUG(EAlgorithm, "AudioLoader: called av_read_frame(), got result = " << result); if (result != 0) { // 0 = OK, < 0 = error or EOF if (result != AVERROR_EOF) { char errstring[1204]; av_strerror(result, errstring, sizeof(errstring)); ostringstream msg; msg << "AudioLoader: Error reading frame: " << errstring; E_WARNING(msg.str()); } // TODO: should try reading again on EAGAIN error? // https://github.com/FFmpeg/FFmpeg/blob/master/ffmpeg.c shouldStop(true); flushPacket(); closeAudioFile(); if (_computeMD5) { av_md5_final(_md5Encoded, _checksum); _md5.push(uint8_t_to_hex(_checksum, 16)); } else { string md5 = ""; _md5.push(md5); } return FINISHED; } } while (_packet.stream_index != _streamIdx); // compute md5 first if (_computeMD5) { av_md5_update(_md5Encoded, _packet.data, _packet.size); } // decode frames in packet while(_packet.size > 0) { if (!decodePacket()) break; copyFFmpegOutput(); } // neds to be freed !! av_free_packet(&_packet); return OK; } int AudioLoader::decode_audio_frame(AVCodecContext* audioCtx, float* output, int* outputSize, AVPacket* packet) { int gotFrame = 0; av_frame_unref(_decodedFrame); //avcodec_get_frame_defaults(_decodedFrame); int len = avcodec_decode_audio4(audioCtx, _decodedFrame, &gotFrame, packet); if (len < 0) return len; // error handling should be done outside if (gotFrame) { int inputSamples = _decodedFrame->nb_samples; int inputPlaneSize = av_samples_get_buffer_size(NULL, _nChannels, inputSamples, audioCtx->sample_fmt, 1); int outputPlaneSize = av_samples_get_buffer_size(NULL, _nChannels, inputSamples, AV_SAMPLE_FMT_FLT, 1); // the size of the output buffer in samples int outputBufferSamples = *outputSize / (av_get_bytes_per_sample(AV_SAMPLE_FMT_FLT) * _nChannels); if (outputBufferSamples < inputSamples) { // this should never happen, throw exception here throw EssentiaException("AudioLoader: Insufficient buffer size for format conversion"); } if (audioCtx->sample_fmt == AV_SAMPLE_FMT_FLT) { // TODO: no need in this check? Not many of common formats support FLT // no conversion needed, direct copy from our frame to output buffer memcpy(output, _decodedFrame->data[0], inputPlaneSize); } else { int samplesWrittern = avresample_convert(_convertCtxAv, (uint8_t**) &output, outputPlaneSize, outputBufferSamples, (uint8_t**)_decodedFrame->data, inputPlaneSize, inputSamples); if (samplesWrittern < inputSamples) { ostringstream msg; msg << "AudioLoader: Incomplete format conversion (some samples missing)" << " from " << av_get_sample_fmt_name(_audioCtx->sample_fmt) << " to " << av_get_sample_fmt_name(AV_SAMPLE_FMT_FLT); throw EssentiaException(msg); } } *outputSize = outputPlaneSize; } else { E_DEBUG(EAlgorithm, "AudioLoader: tried to decode packet but didn't get any frame..."); *outputSize = 0; } return len; } int AudioLoader::decodePacket() { int len = 0; float* buff = _buffer; // _dataSize gets the size of the buffer, in bytes _dataSize = FFMPEG_BUFFER_SIZE; len = decode_audio_frame(_audioCtx, buff, &_dataSize, &_packet); if (len < 0) { char errstring[1204]; av_strerror(len, errstring, sizeof(errstring)); ostringstream msg; if (_audioCtx->codec_id == AV_CODEC_ID_MP3) { msg << "AudioLoader: invalid frame, skipping it: " << errstring; E_WARNING(msg.str()); } else { msg << "AudioLoader: error while decoding, skipping frame: " << errstring; E_WARNING(msg.str()); } return 0; } if (len != _packet.size) { E_WARNING("AudioLoader: more than 1 frame in packet, decoding remaining bytes..."); E_WARNING("at sample index: " << output("audio").totalProduced()); E_WARNING("decoded samples: " << len); E_WARNING("packet size: " << _packet.size); } // update packet data pointer to data left undecoded (if any) _packet.size -= len; _packet.data += len; if (_dataSize <= 0) { // No data yet, get more frames // cout << "no data yet, get more frames" << endl; _dataSize = 0; } return len; } void AudioLoader::copyFFmpegOutput() { int nsamples = _dataSize / (av_get_bytes_per_sample(AV_SAMPLE_FMT_FLT) * _nChannels); if (nsamples == 0) return; // acquire necessary data bool ok = _audio.acquire(nsamples); if (!ok) { throw EssentiaException("AudioLoader: could not acquire output for audio"); } vector<StereoSample>& audio = *((vector<StereoSample>*)_audio.getTokens()); if (_nChannels == 1) { for (int i=0; i<nsamples; i++) { audio[i].left() = _buffer[i]; //audio[i].left() = scale(_buffer[i]); } } else { // _nChannels == 2 // The output format is always AV_SAMPLE_FMT_FLT, which is interleaved for (int i=0; i<nsamples; i++) { audio[i].left() = _buffer[2*i]; audio[i].right() = _buffer[2*i+1]; } } // release data _audio.release(nsamples); } void AudioLoader::reset() { Algorithm::reset(); if (!parameter("filename").isConfigured()) return; string filename = parameter("filename").toString(); closeAudioFile(); openAudioFile(filename); pushChannelsSampleRateInfo(_audioCtx->channels, _audioCtx->sample_rate); pushCodecInfo(_audioCodec->name, _audioCtx->bit_rate); } } }