lpcmdecoder.cc

Linux下比较早的基于命令行的DVD播放器

//
// Copyright (c) 2004 by Istv醤 V醨adi
//
// This file is part of dxr3Player, a DVD player written specifically 
// for the DXR3 (aka Hollywood+) decoder card.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

//------------------------------------------------------------------------------

#include "LPCMDecoder.h"

#include "AudioProcessor.h"

#include "util/Log.h"

//------------------------------------------------------------------------------

using output::LPCMDecoder;

//------------------------------------------------------------------------------

const AudioFormat LPCMDecoder::audioFormat(LPCM_LE, 48000, 2);

//------------------------------------------------------------------------------

void LPCMDecoder::reset()
{
}

//------------------------------------------------------------------------------

void LPCMDecoder::decodePacket(const unsigned char* data,
                               size_t length, pts_t packetPTS)
{
    size_t ptsOffset = data[1]; ptsOffset <<= 8;
    ptsOffset |= data[2];

    Log::verboseDebug("output::LPCMDecoder::decodePacket: pts=%llu, length=%u, ptsOffset=%u\n", packetPTS, length, ptsOffset);

    size_t format = data[4];

    if ((format&0x10)==0x10) {
        // FIXME: constant
        Log::warning("output::LPCMDecoder::decodePacket: sampling frequency of 96kHz not supported\n");
        return;
    }

    size_t sampleRate = 48000;

    size_t numChannels = (format&0x07) + 1;  // FIXME: constant
    if (numChannels!=2) {
        Log::warning("output::LPCMDecoder::decodePacket: number of channels not supported: %u\n", numChannels);
        return;
    }

    size_t quantizationIndex = (format&0xc0)>>6;

    size_t frameSize = 0;

    switch(quantizationIndex) {
      case 0: // 16 bit, FIXME: constant
        frameSize = numChannels * 2;
        break;
      case 1: // 20 bit, FIXME: constant
        Log::warning("output::LPCMDecoder::decoderPacket: 20 bit samples not supported\n");
        return;
      case 2: // 24 bit, FIXME: constant
        Log::warning("output::LPCMDecoder::decodePacket: 24 bit samples not supported\n");
        return;
      default:
        Log::warning("output::LPCMDecoder::decodePacket: unsupported quantization index: %u\n", quantizationIndex);
        return;
    }

    if (packetPTS!=INVALID_PTS) {
        packetPTS -= ptsOffset / frameSize * 90000 / sampleRate;
    }

    unsigned char* buffer = audioProcessor.getOutputBuffer();

    data += 6; length -= 6;
    for(size_t i = 0; i<length; i+=4, data += 4) {
        buffer[i]   = data[1];
        buffer[i+1] = data[0];
        buffer[i+2] = data[3];
        buffer[i+3] = data[2];
    }

    audioProcessor.setOutputLength(length);
    audioProcessor.setOutputPTS(packetPTS);
    audioProcessor.setOutputFormat(audioFormat);

    audioProcessor.outputPacket();
}

//------------------------------------------------------------------------------