mpegdecoder.h

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, but now handles other
// hardware as well. These files contain a (mostly) user-space driver 
// for the Unichrome board found on Via's EPIA motherboards.
//
// The information for implementing this driver has been gathered
// from the following sources:
//
// - The DirectFB Unichrome driver
//   Copyright (c) 2003 Andreas Robinson, All rights reserved.
//
// - Andreas Robinson's MPEG-2 decoder for the Unichrome board.
//   Copyright (c) 2003 Andreas Robinson, All rights reserved.
//
// - Via's Unichrome Framebuffer driver
//   Copyright 1998-2003 VIA Technologies, Inc. All Rights Reserved.
//   Copyright 2001-2003 S3 Graphics, Inc. All Rights Reserved.


// 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_UNICHROME_MPEGDECODER_H
#define DXR3PLAYER_UNICHROME_MPEGDECODER_H
//------------------------------------------------------------------------------

#include "mpeg/SequenceHeader.h"
#include "mpeg/PictureHeader.h"

#include "types.h"
#include "enums.h"

#include <cstdlib>

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

namespace mpeg {

class QuantMatrix;

}

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

namespace unichrome {

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

class Unichrome;

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

/**
 * Interface for the MPEG decoder of the Unichrome board.
 */
class MPEGDecoder
{
public:
    /**
     * Various bits of information about a picture.
     */
    struct PictureInfo
    {
        /**
         * The coding of the picture.
         */
        mpeg::PictureHeader::codingType_t codingType;

        /**
         * The number of fields in the picture.
         */
        size_t numFields;

        /**
         * The PTS of the picture. This is valid only for I-pictures.
         */
        pts_t pts;

        /**
         * Construct the picture info with default values.
         */
        PictureInfo();

        /**
         * Setup the picture info from the given sequence and picture
         * header.
         */
        void setup(const mpeg::SequenceHeader& sequenceHeader,
                   const mpeg::PictureHeader& pictureHeader,
                   pts_t& packetPTS);

        /**
         * Reset the picture info to default values.
         */
        void reset();
    };
    
private:
    /**
     * Constant for the invalid buffer.
     */
    static const size_t INVALID_BUFFER = (size_t)-1;

    /**
     * Default intra quantizer matrix.
     */
    static const unsigned char defaultIntraQMX[64];

    /**
     * Quantiser matrix scan order.
     */
    static const size_t quantMatrixScan[64];

    /**
     * Get the default quantiser matrix.
     */
    static const mpeg::QuantMatrix& getDefaultQuantMatrix();

    /**
     * Reference to the Unichrome object to use
     */
    Unichrome& unichrome;

    /**
     * The current aspect ratio to use. It should be noted that the
     * aspect ratio of the MPEG stream is not taken into account,
     * since it does not seem to be always correct for DVDs.
     */
    aspectRatio_t aspectRatio;
    
    /**
     * The base offset of the frame buffers used by the decoder.
     */
    size_t baseOffset;

    /**
     * The current sequence header.
     */
    mpeg::SequenceHeader sequenceHeader;

    /**
     * The aspect ratio used for the current sequence.
     */
    aspectRatio_t sequenceAspectRatio;

    /**
     * Indicate if the quantization matrix from the current sequence
     * has already been loaded.
     */
    bool sequenceQuantMatrixLoaded;

    /**
     * The current picture header.
     */
    mpeg::PictureHeader pictureHeader;

    /**
     * Indicate if the current field is the second field.
     */
    bool isSecondField;

    /**
     * The frame buffers.
     */
    struct {
        size_t yOffset;
        
        size_t cbOffset;

        size_t crOffset;
    } frameBuffers[4];

    /**
     * Backward reference buffer.
     */
    size_t bwRefBuffer;

    /**
     * Forward reference buffer.
     */
    size_t fwRefBuffer;

    /**
     * Current B-frame buffer
     */
    size_t bBuffer;

    /**
     * Idle frame buffer     
     */
    size_t idleBuffer;

    /**
     * Destination frame buffer     
     */
    size_t destBuffer;

    /**
     * Display frame buffer     
     */
    size_t displayBuffer;

    /**
     * The coding of the displayable buffer.
     */
    PictureInfo displayInfo;

    /**
     * The last I or P picture's buffer not yet shown.
     */
    size_t pendingIP;

    /**
     * The coding of the pending I or P picture.
     */
    PictureInfo pendingInfo;
    
    /**
     * The offset of the picture within the buffers.
     * This is for luma, it must be divided by four for chroma.
     */
    size_t pictureOffset;

    /**
     * The PTS of the packet currently being processed.
     */
    pts_t packetPTS;

    /**
     * Indicate if only intra pictures should be decoded.
     */
    bool playIntra;

    /**
     * Indicate if slice data should be processed.
     */
    bool processSlice;

public:
    /**
     * Construct the MPEG decoder.
     */
    MPEGDecoder(Unichrome& unichrome);

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

    /**
     * Flush the MPEG decoder.
     */
    void flush();

    /**
     * Set the aspect ratio. It will be used when the next sequence starts.
     */
    void setAspectRatio(aspectRatio_t ar);

    /**
     * Set if only intra pictures should be decoded.
     */
    void setPlayIntra(bool x);

    /**
     * Set the packet PTS to the given value.
     */
    void setPTS(pts_t pts);

    /**
     * Start a sequence.
     */
    void startSequence(const mpeg::SequenceHeader& header);

    /**
     * Set the given quantization matrix.
     */
    void setQuantMatrix(const mpeg::QuantMatrix& quantMatrix);

    /**
     * Start a picture.
     */
    void startPicture(const mpeg::PictureHeader& header);

    /**
     * Add a slice.
     */
    void addSlice(const unsigned char* slice, size_t length);

    /**
     * Notify the decoder that the sequence has ended. If there is a
     * pending I or P frame, it will be made displayable.
     */
    void endSequence();

    /**
     * Check if we have a valid picture to show.
     */
    bool isDisplayable() const;

    /**
     * Get the picture info about the displayable picture. This is
     * valid only if isDisplayable() return true.
     */
    const PictureInfo& getDisplayInfo() const;

    /**
     * Show the picture displayable.
     * If no picture is displayable, that is an assertion failure.
     */
    void displayPicture();

private:
    /**
     * Load the given quantizer matrix.
     */
    void loadQMX(const unsigned char* qmx);

    /**
     * Check if the MPEG decoder is busy or not.
     */
    bool isBusy();
};

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

} /* namespace unichrome */

//------------------------------------------------------------------------------
#endif // DXR3PLAYER_UNICHROME_MPEGDECODER_H

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