jsmad/wrapper.cpp

#include "wrapper.h"
#include <string> 
#include <iostream>

MadHeader * mad_header_create()
{
    MadHeader* header = new MadHeader;
    mad_header_init(header);
    return header;
}

MadFrame * mad_frame_create()
{
    MadFrame* frame = new MadFrame;
    mad_frame_init(frame);
    return frame;
}

emscripten::val MadFrame::getOverlap() const
{
    unsigned char* ptr = (unsigned char(*))*overlap;
    return emscripten::val(typed_memory_view(sizeof *overlap, ptr));
}

emscripten::val MadFrame::getSbsample() const
{
    unsigned char* ptr = (unsigned char(*))sbsample;
    return emscripten::val(typed_memory_view(sizeof sbsample, ptr));
}

MadStream* mad_stream_create() {
    MadStream* stream = new MadStream;
    mad_stream_init(stream);
    return stream;
}

emscripten::val MadStream::mainData()
{
    return emscripten::val(typed_memory_view(MAD_BUFFER_MDLEN, (unsigned char(*))main_data));
}

void MadStream::setBuffer(intptr_t bufferPtr, unsigned long length)
{
    mad_stream_buffer(this, (const unsigned char(*))bufferPtr, length);
}

int MadFrame::decode(mad_stream* stream)
{
    return mad_frame_decode(this, stream);
}

emscripten::val MadPCM::samples() const
{
    mad_fixed_t* ptr = (mad_fixed_t(*))mad_pcm::samples;
    return emscripten::val(typed_memory_view(sizeof mad_pcm::samples, ptr));
}

MadPCM* mad_pcm_create() {
    MadPCM* pcm = new MadPCM();
    return pcm;
}

MadSynth* mad_synth_create() {
    MadSynth* synth = new MadSynth();
    mad_synth_init(synth);
    return synth;
}

void MadSynth::frame(const mad_frame* frame)
{
    mad_synth_frame(this, frame);
}

Decoder::Decoder():
    sampleRate(0),
    channels(0),
    cachedLength(0),
    samplesPerFrame(0),
    currentBuffer(0),
    currentBufferLength(0),
    synth(),
    stream(),
    frame(),
    context(0)
{
    mad_frame_init(&frame);
    mad_stream_init(&stream);
    mad_synth_init(&synth);
    
    emscripten::val AudioContext = emscripten::val::global("AudioContext");
    if (!AudioContext.as<bool>()) {
        printf("No global AudioContext, trying webkitAudioContext\n");
        AudioContext = emscripten::val::global("webkitAudioContext");
    }

    printf("Got an AudioContext\n");
    context = AudioContext.new_();
}

Decoder::~Decoder()
{
    context.call<void>("close");
    
    mad_synth_finish(&synth);
    mad_stream_finish(&stream);
    mad_frame_finish(&frame);
    
    if (currentBuffer != 0) {
        free(currentBuffer);
    }
}

void Decoder::addFragment(intptr_t bufferPtr, unsigned long length)
{
    if (currentBuffer != 0) {
        printf("Adding more then 1 fragment is not supported yet");
        throw 1;
    }
    currentBuffer = (unsigned char(*))bufferPtr;
    currentBufferLength = length;
    
    mad_stream_buffer(&stream, currentBuffer, currentBufferLength);
    framesLeft();
}

emscripten::val Decoder::decode(uint32_t count)
{
    emscripten::val ret = emscripten::val::undefined();
    
    int available = framesLeft(count);
    if (available > 0) {
        ret = context.call<val>("createBuffer", channels, available * samplesPerFrame, sampleRate);
        
        std::vector<emscripten::val> chans(channels, emscripten::val::undefined());
        for (int i = 0; i < channels; ++i) {
            chans[i] = ret.call<val>("getChannelData", i);
        } 
        
        for (int i = 0; i < available; ++i) {
            mad_frame_decode(&frame, &stream);
            mad_synth_frame(&synth, &frame);
            
            for (int j = 0; j < samplesPerFrame; ++j) {
                for (int k = 0; k < channels; ++k) {
                    float value = mad_f_todouble(synth.pcm.samples[k][j]);
                    chans[k].set(std::to_string(i * samplesPerFrame + j), val(value));
                }
            }
        }
        
        cachedLength -= available;
        
        if (cachedLength == 0) {
            framesLeft();
        }
    }
    
    return ret;
}

bool Decoder::hasMore() const
{
    if (currentBuffer == 0) {
        return false;
    }
    
    return stream.error != MAD_ERROR_BUFLEN;
}

uint32_t Decoder::framesLeft(uint32_t max)
{
    if (currentBuffer == 0) {
        return 0;
    }
    
    if (cachedLength == 0) {
        mad_stream probe;
        mad_header ph;
        mad_stream_init(&probe);
        mad_header_init(&ph);
        
        mad_stream_buffer(&probe, currentBuffer, currentBufferLength);
        mad_stream_skip(&probe, stream.skiplen);
        
        while (cachedLength < max) {
            if (mad_header_decode(&ph, &probe) == 0) {
                if (sampleRate == 0) {
                    sampleRate = ph.samplerate;
                    channels = MAD_NCHANNELS(&ph);
                    samplesPerFrame = MAD_NSBSAMPLES(&ph) * 32; //not sure why 32, it's in libmad source
                } else {
                    if (sampleRate != ph.samplerate || channels != MAD_NCHANNELS(&ph) || samplesPerFrame != MAD_NSBSAMPLES(&ph) * 32) {
                        break;
                    }
                }
                ++cachedLength;
            } else {
                if (!MAD_RECOVERABLE(probe.error)) {
                    std::cout << "framesLeft::" << probe.error << std::endl;
                    break;
                }
            }
        }
        
        mad_header_finish(&ph);
        mad_stream_finish(&probe);
    } 
    
    return std::min(cachedLength, max);
}