musikcube/src/plugins/websocket_remote/TranscodingDataStream.cpp

//////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2007-2016 musikcube team
//
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//////////////////////////////////////////////////////////////////////////////

#include "TranscodingDataStream.h"
#include "Util.h"
#include <boost/filesystem.hpp>
#include <algorithm>

#define BUFFER_SIZE 8192
#define SAMPLES_PER_BUFFER BUFFER_SIZE / 4 /* sizeof(float) */

using PositionType = TranscodingDataStream::PositionType;

TranscodingDataStream::TranscodingDataStream(
    Context& context, const std::string& uri, size_t bitrate)
{
    this->input = nullptr;
    this->decoder = nullptr;
    this->pcmBuffer = nullptr;
    this->length = 0;
    this->position = 0;
    this->bitrate = bitrate;
    this->interrupted = false;
    this->eof = false;
    this->lame = nullptr;
    this->outFile = nullptr;

    this->input = context.environment->GetDataStream(uri.c_str());
    if (this->input) {
        this->decoder = context.environment->GetDecoder(this->input);
        if (this->decoder) {
            this->pcmBuffer = context.environment->GetBuffer(SAMPLES_PER_BUFFER);

            /*  note that we purposely under-estimate the content length by a couple
            seconds. we do this because http clients seem to be more likely to be
            throw a fit if we over estimate, instead of under-estimate. */
            this->length = (PositionType)((this->decoder->GetDuration() - 2.0) * 1000.0 * (float)bitrate / 8.0);
        }
    }
}

TranscodingDataStream::TranscodingDataStream(
    Context& context,
    const std::string& uri,
    const std::string& tempFilename,
    const std::string& finalFilename,
    size_t bitrate)
: TranscodingDataStream(context, uri, bitrate)
{
    this->tempFilename = tempFilename;
    this->finalFilename = finalFilename;

    if (tempFilename.size() && finalFilename.size()) {
#ifdef WIN32
        this->outFile = _wfopen(utf8to16(tempFilename.c_str()).c_str(), L"wb");
#else
        this->outFile = fopen(tempFilename.c_str(), "wb");
#endif
    }
}

TranscodingDataStream::~TranscodingDataStream() {
    this->Close();
}

bool TranscodingDataStream::Open(const char *uri, unsigned int options) {
    return true;
}

bool TranscodingDataStream::Close() {
    if (this->pcmBuffer) {
        this->pcmBuffer->Destroy();
        this->pcmBuffer = nullptr;
    }

    if (this->decoder != nullptr) {
        this->decoder->Destroy();
        this->decoder = nullptr;
    }

    if (this->input != nullptr) {
        this->input->Destroy();
        this->input = nullptr;
    }

    if (this->lame) {
        lame_close(this->lame);
        this->lame = nullptr;
    }

    if (this->outFile) {
        fclose(this->outFile);
        this->outFile = nullptr;
        boost::system::error_code ec;
        boost::filesystem::remove(this->tempFilename, ec);
    }

    return true;
}

void TranscodingDataStream::Interrupt() {
    this->interrupted = true;
}

void TranscodingDataStream::Destroy() {
    delete this;
}

PositionType TranscodingDataStream::Read(void *buffer, PositionType bytesToRead) {
    if (this->eof || !this->pcmBuffer) {
        return 0;
    }

    size_t bytesWritten = 0;
    unsigned char* dst = (unsigned char*)buffer;
    bool hasBuffer = false;

    if (this->decoder && !this->lame) {
        hasBuffer = this->decoder->GetBuffer(this->pcmBuffer);
        if (hasBuffer) {
            this->lame = lame_init();
            lame_set_in_samplerate(this->lame, this->pcmBuffer->SampleRate());
            lame_set_VBR(lame, vbr_off);
            lame_set_VBR_mean_bitrate_kbps(lame, this->bitrate);
            lame_set_out_samplerate(lame, this->pcmBuffer->SampleRate());
            lame_init_params(lame);
        }
    }

    /* see if we have some stuff left over from last time through... */
    if (!spillover.empty()) {
        size_t count = std::min(spillover.avail(), (size_t) bytesToRead);
        memcpy(dst, spillover.pos(), count);

        if (this->outFile) {
            fwrite(spillover.pos(), 1, count, this->outFile);
        }

        spillover.inc(count);
        bytesWritten += count;
    }

    if (bytesWritten == bytesToRead) {
        this->position += bytesWritten;
        return bytesWritten; /* filled from the spillover... */
    }

    if (!hasBuffer) {
        hasBuffer = this->decoder->GetBuffer(this->pcmBuffer);
    }

    while (hasBuffer && bytesWritten < (size_t) bytesToRead) {
        /* calculated according to lame.h */
        size_t channels = pcmBuffer->Channels();
        size_t numSamples = pcmBuffer->Samples() / channels;
        size_t requiredBytes = (size_t) (1.25 * (float)numSamples + 7200.0);

        encodedBytes.realloc(requiredBytes);

        /* encode PCM -> MP3 */
        int encodeCount = -1;

        /* stereo is easy, just make sure we send to to the encoder as
        interleaved! */
        if (pcmBuffer->Channels() == 2) {
            encodeCount =
                lame_encode_buffer_interleaved_ieee_float(
                    lame,
                    pcmBuffer->BufferPointer(),
                    numSamples,
                    encodedBytes.data,
                    encodedBytes.length);
        }
        /* the non-stereo case needs to be downmuxed. our downmixing is simple,
        we just use the stereo channels. in the case of mono, we duplicate the
        to left and right */
        else {
            downmix.realloc(numSamples * 2);

            float* from = pcmBuffer->BufferPointer();
            float* to = downmix.data;

            if (channels == 1) {
                /* mono -> stereo */
                for (size_t i = 0; i < numSamples; i++) {
                    *(to + 0) = *from;
                    *(to + 1) = *from;
                    to += 2;
                    ++from;
                }
            }
            else {
                /* 3+ channels -> stereo */
                for (size_t i = 0; i < numSamples; i++) {
                    *(to + 0) = *(from + 0);
                    *(to + 1) = *(from + 1);
                    to += 2;
                    from += channels;
                }
            }

            encodeCount =
                lame_encode_buffer_interleaved_ieee_float(
                    lame,
                    downmix.data,
                    numSamples,
                    encodedBytes.data,
                    encodedBytes.length);
        }

        if (encodeCount < 0) {
            goto internal_error;
        }

        encodedBytes.length = (size_t)encodeCount;

        /* if we got something, let's write it to the output buffer */
        if (encodedBytes.length) {
            size_t toWrite = std::min(
                encodedBytes.length,
                (size_t)(bytesToRead - bytesWritten));

            memcpy(dst + bytesWritten, encodedBytes.data, toWrite);

            if (this->outFile) {
                fwrite(encodedBytes.data, 1, toWrite, this->outFile);
            }

            encodedBytes.inc(toWrite);
            bytesWritten += toWrite;

            /* if we have decoded bytes still available, that means the
            output buffer is exhausted. swap it into the spillover buffer
            so it can be finalized the next time through. */
            if (encodedBytes.avail()) {
                spillover.swap(encodedBytes);
                this->position += bytesWritten;
                return bytesWritten;
            }
        }

        /* if we get here we still need to write some more data to
        the output buffer. get our next buffer of MP3 data and go
        through the loop again. */
        hasBuffer =
            ((size_t) bytesToRead > bytesWritten) &&
            this->decoder->GetBuffer(this->pcmBuffer);
    }

    /* finalize */
    if (bytesWritten == 0) {
        encodedBytes.reset();

        size_t count = lame_encode_flush(
            lame,
            encodedBytes.data,
            encodedBytes.length);

        memcpy(dst + bytesWritten, encodedBytes.data, count);

        if (this->outFile) {
            fwrite(encodedBytes.data, 1, count, this->outFile);
            fclose(this->outFile);
            this->outFile = nullptr;

            boost::system::error_code ec;
            boost::filesystem::rename(this->tempFilename, this->finalFilename, ec);
            if (ec) {
                boost::filesystem::remove(this->tempFilename, ec);
            }
        }

        this->eof = true;
    }

    this->position += bytesWritten;
    return bytesWritten;

internal_error:
    this->eof = true;
    fclose(this->outFile);
    this->outFile = nullptr;
    return 0;
}

bool TranscodingDataStream::SetPosition(PositionType position) {
    return false;
}

PositionType TranscodingDataStream::Position() {
    return this->position;
}

bool TranscodingDataStream::Seekable() {
    return false;
}

bool TranscodingDataStream::Eof() {
    return this->eof;
}

long TranscodingDataStream::Length() {
    return this->length;
}

const char* TranscodingDataStream::Type() {
    return "audio/mpeg";
}

const char* TranscodingDataStream::Uri() {
    if (this->input) {
        return this->input->Uri();
    }
    return "";
}

bool TranscodingDataStream::CanPrefetch() {
    return true;
}