osssoundcard.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 "OSSSoundcard.h"

#include "util/Log.h"

#include <cassert>

#include <linux/soundcard.h>

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

using output::OSSSoundcard;

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

OSSSoundcard::OSSSoundcard(const char* dsp) :
    Thread("output::OSSSoundcard"),
    bytesWritten(0),
    data(0),
    dataLength(0)
{
    fd = POSIX::open(dsp, O_RDWR, "Cannot open DSP device");

    int caps;
    ioctl(SNDCTL_DSP_GETCAPS, &caps, "Cannot query capabilities from the sound card!");
    
    realTime = (caps&DSP_CAP_REALTIME)==DSP_CAP_REALTIME;
    triggerable = (caps&DSP_CAP_TRIGGER)==DSP_CAP_TRIGGER;

    audio_buf_info abi;
    ioctl(SNDCTL_DSP_GETOSPACE, &abi, "Cannot query output buffer info from the sound card!");
    
    bufferSize = abi.fragstotal;
    bufferSize *= abi.fragsize;

    Log::debug("output::OSSSoundcard::OSSSoundcard: %sreal-time capable, %striggerable, buffer size: %u\n",
               realTime ? "" : "not ", triggerable ? "" : "not ", bufferSize);
    if (!realTime) {
        Log::debug("output::OSSSoundcard::OSSSoundcard: without real-time capability, audio and video may go out of sync!\n");
    }
    
    setup(audioMode, sampleRate, stereo);
    stopPlayback();

    start();
}

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

OSSSoundcard::~OSSSoundcard()
{
}

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

void OSSSoundcard::startPlayback()
{
    assert(triggerable);

    int trigger;
    ioctl(SNDCTL_DSP_GETTRIGGER, &trigger, "Error querying the trigger");
    trigger |= PCM_ENABLE_OUTPUT;
    ioctl(SNDCTL_DSP_SETTRIGGER, &trigger, "Error setting the trigger");
}

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

size_t OSSSoundcard::play(const void* buf, size_t count, bool /*interruptible*/)
{
    assert(data==0);
    
    data = buf;
    dataLength = count;

    trigger();
    
    assert(data==0);

    bytesWritten += dataLength;

    return dataLength;
}

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

unsigned long long OSSSoundcard::getNumberOfSamplesPlayed()
{
    assert(realTime);

    count_info info;
    ioctl(SNDCTL_DSP_GETOPTR, &info, "Error querying the number of samples played");

    int delay;
    ioctl(SNDCTL_DSP_GETODELAY, &delay, "Error querying the output delay");
    assert(delay>=0);

    // Due to bugs/inaccuracies in drivers, we need to do some tricks.

    // This is the maximum position, the samples played cannot be
    // bigger than this. ('delay' seems to be a lower bound on the real
    // delay...)
    unsigned long long maxPosition = bytesWritten - delay;

    // The current position may be some number of full buffers
    // plus the DMA pointer. The 'bytes' member of 'info' is not
    // always correct, at least for ALSA OSS emulation. And it would
    // overflow anyway after about 3 hours.
    unsigned long long position = (bytesWritten / bufferSize) * bufferSize;
    position += info.ptr;
    
    // The position may not be bigger than the maximal one, but
    // the difference may only be one or more bufferful.
    while(position>maxPosition && position>=bufferSize) position -= bufferSize;

    return position/getSampleSize();
}

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

unsigned long long OSSSoundcard::getNumberOfSamplesBuffered()
{
    assert(realTime);

    int delay;
    ioctl(SNDCTL_DSP_GETODELAY, &delay, "Error querying the output delay");
    assert(delay>=0);

    return delay/getSampleSize();
}

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

void OSSSoundcard::stopPlayback()
{
    ioctl(SNDCTL_DSP_RESET, 0, "Error resetting DSP device");
    
    bytesWritten = 0;
    
    if (triggerable) {
        int trigger;
        ioctl(SNDCTL_DSP_GETTRIGGER, &trigger, "Error querying the trigger");
        trigger &= ~PCM_ENABLE_OUTPUT;
        ioctl(SNDCTL_DSP_SETTRIGGER, &trigger, "Error setting the trigger");
    }
}

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

void OSSSoundcard::stop()
{
    Thread::stop();
}

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

void OSSSoundcard::doSetup(audioMode_t& mode, unsigned& rate, bool& s)
{
    int dspFormat = (mode==AM_DIGITAL_AC3) ? AFMT_AC3 : AFMT_S16_LE;
    int dspSpeed = (int)rate;
    int dspStereo = s ? 1 : 0;

    ioctl(SNDCTL_DSP_SPEED, &dspSpeed, "Error setting audio sample rate to %d", dspSpeed);
    ioctl(SNDCTL_DSP_STEREO, &dspStereo, "Error setting DSP stereo to %d", dspStereo);
    ioctl(SNDCTL_DSP_SETFMT, &dspFormat, "Error setting audio format to %d", dspFormat);
}

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

void OSSSoundcard::perform()
{
    assert(data!=0);
    
    size_t written = write(data, dataLength);
    if (written!=dataLength) {
        Log::debug("output::sdl::SoundThread: written=%u, dataLength=%u\n",
                   written, dataLength);
    }

    data = 0;
    dataLength = written;
    
}

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