ac3decoder.h

Linux下比较早的基于命令行的DVD播放器

//
// Copyright (c) 2003 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

#ifndef DXR3PLAYER_OUTPUT_AC3DECODER_H
#define DXR3PLAYER_OUTPUT_AC3DECODER_H
//------------------------------------------------------------------------------

#include "AudioDecoder.h"

#include <inttypes.h>

extern "C" { 
#include <liba52/a52.h>
}

#include "util/AudioFormat.h"

#include <cstdlib>
#include <cassert>

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

namespace output {

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

/**
 * AC-3 Decoder.
 */
class AC3Decoder : public AudioDecoder
{
private:
    /**
     * The size of the frame buffer. An AC-3 frame may be at most this
     * many bytes (including synchronization info).
     */
    static const size_t maxFrameSize = 3840;

    /**
     * The size of the output buffer. An AC-3 frame is decoded to exactly
     * this many bytes.
     */
    static const size_t outputLength = 6144;

    /**
     * Convert the given 32-bit integer representing a float value
     * into a 16-bit integer.
     */
    static int16_t blah(int32_t i);

    /**
     * Convert the given array of float samples into an array of
     * 16-bit integer samples.
     */
    static void float_to_int(float * _f, int16_t * s16, int num_channels);

    /**
     * The samples.
     */
    sample_t* samples;

    /**
     * Frame buffer.
     */
    unsigned char frameBuffer[maxFrameSize];

    /**
     * The offset into the frame being decoded.
     */
    size_t frameOffset;

    /**
     * The length of the current frame being decoded.
     * Valid after the sync info (first 7 bytes of a frame) has been
     * decoded.
     */
    size_t frameLength;

    /**
     * A52 State
     */
    a52_state_t a52State;

    /**
     * Output flags
     */
    int outputFlags;

    /**
     * The output level.
     */
    unsigned outputLevel;

    /**
     * Indicate if audio is enabled or not.
     */
    bool audioEnabled;
    
public:
    /**
     * Construct the AC-3 decoder.
     *
     * FIXME: remove the defautl value!!!
     */
    AC3Decoder(AudioProcessor* audioProcessor);

    /**
     * Reset the decoder.
     */
    virtual void reset();

    /**
     * @see AudioDecoder::decodePacket
     */
    virtual void decodePacket(const unsigned char* data,
                              size_t length, pts_t packetPTS);

public:
    /**
     * Get the output level. It is a number between 0 and 100.
     */
    unsigned getOutputLevel() const;
    
    /**
     * Set the output level.
     */
    void setOutputLevel(unsigned level);

    /**
     * Toggle the audio.
     *
     * @return true if the audio is enabled as a result of this call.
     */
    bool toggleAudio();

private:
    /**
     * Check if the decoder is empty, i.e. the last frame has been
     * completely decoded, and no new frame has started.'
     */
    bool isEmpty() const;

    /**
     * Decode the data in the given block.
     *
     * @return if a frame has been made available.
     */
    bool decode(const unsigned char*& data, 
                const unsigned char* end);

    /**
     * Copy the data from the given address into the frame buffer,
     * until the given target offset is reached.
     */
    void copy(const unsigned char*& data,
              const unsigned char* end,
              size_t targetOffset);

    /**
     * Set the format based on the flags and the given sample rate.
     */
    void setFormat(int flags, int sampleRate);

    /**
     * Decode the frame buffered.
     */
    bool decodeFrame();

    /**
     * Encode the frame buffered for hardware decoding.
     */
    bool prepareFrameForHardwareDecoding();
};

//------------------------------------------------------------------------------
// Inline definitions
//------------------------------------------------------------------------------

inline unsigned AC3Decoder::getOutputLevel() const
{
    return outputLevel;
}

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

inline void AC3Decoder::setOutputLevel(unsigned level)
{
    assert(level<=100);
    outputLevel = level;
}

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

} /* namespace output */

//------------------------------------------------------------------------------
#endif // DXR3PLAYER_OUTPUT_AC3DECODER_H

// Local variables:
// mode: c++
// End: