Method DecodeNextBlock

src/core/audiosource.cpp:303–371

}

int FFMS_AudioSource::DecodeNextBlock(CacheIterator *pos) {
    AVPacket *Packet = av_packet_alloc();
    if (!Packet)
        throw FFMS_Exception(FFMS_ERROR_PARSER, FFMS_ERROR_ALLOCATION_FAILED,
            "Could not allocate packet.");
    if (!ReadPacket(Packet)) {
        av_packet_free(&Packet);
        throw FFMS_Exception(FFMS_ERROR_PARSER, FFMS_ERROR_UNKNOWN,
            "ReadPacket unexpectedly failed to read a packet");
    }

    CurrentFrame = &Frames[PacketNumber];
    CurrentSample = CurrentFrame->SampleStart;

    // Value code intentionally ignored, combined with the checks when indexing this mostly gives the expected behavior
    avcodec_send_packet(CodecContext, Packet);

    int NumberOfSamples = 0;
    AudioBlock *CachedBlock = nullptr;

    while (true) {
        av_frame_unref(DecodeFrame);
        int Ret = avcodec_receive_frame(CodecContext, DecodeFrame);
        if (Ret == 0) {
            NumberOfSamples += DecodeFrame->nb_samples;
            if (DecodeFrame->nb_samples > 0) {
                if (pos)
                    CachedBlock = CacheBlock(*pos);
            }
            break;
        } else if (Ret == AVERROR(EAGAIN)) {
            if (!ReadPacket(Packet)) {
                av_packet_free(&Packet);
                throw FFMS_Exception(FFMS_ERROR_PARSER, FFMS_ERROR_UNKNOWN,
                    "ReadPacket unexpectedly failed to read a packet");
            }
            avcodec_send_packet(CodecContext, Packet);
        } else if (Ret == AVERROR_EOF) {
            break;
        } else {
            throw FFMS_Exception(FFMS_ERROR_CODEC, FFMS_ERROR_DECODING, "Audio decoding error");
        }
    }

    av_packet_free(&Packet);

    // Zero sample packets aren't included in the index
    if (!NumberOfSamples)
        return NumberOfSamples;
    ++PacketNumber;

    // Add padding after the packet, if needed
    if (!CachedBlock || CachedBlock->Samples == CurrentFrame->SampleCount)
        return NumberOfSamples;

    const int64_t MissingSamples = static_cast<int64_t>(CurrentFrame->SampleCount - CachedBlock->Samples);
    // This can apparently happen in some rare circumstances, caused by inaccurate seeking?
    if (MissingSamples <= 0)