TheoraDecoder.cpp

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//===========================================================================
//Copyright (C) 2003, 2004 Zentaro Kavanagh
//
//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions
//are met:
//
//- Redistributions of source code must retain the above copyright
//  notice, this list of conditions and the following disclaimer.
//
//- Redistributions in binary form must reproduce the above copyright
//  notice, this list of conditions and the following disclaimer in the
//  documentation and/or other materials provided with the distribution.
//
//- Neither the name of Zentaro Kavanagh nor the names of contributors 
//  may be used to endorse or promote products derived from this software 
//  without specific prior written permission.
//
//THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
//``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
//LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
//PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ORGANISATION OR
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//EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
//PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
//PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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//SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//===========================================================================

#include "stdafx.h"
#include "theoradecoder.h"

TheoraDecoder::TheoraDecoder(void)
        : mFirstPacket(true)
        , mFirstHeader(true)
        , mPacketCount(0)
{
}

TheoraDecoder::~TheoraDecoder(void)
{
}

bool TheoraDecoder::initCodec() 
{
        theora_comment_init(&mTheoraComment);
        theora_info_init(&mTheoraInfo);
        
        return true;
 }



yuv_buffer* TheoraDecoder::decodeTheora(StampedOggPacket* inPacket) {           //Accepts packet and deletes it.

        if (mPacketCount < 3) {
                decodeHeader(inPacket);         //Accepts header and deletes it.
                
                return NULL;
        } else {
                if (mFirstPacket) {
                        theora_decode_init(&mTheoraState, &mTheoraInfo);
                        mFirstPacket = false;
                }
                if ((inPacket->packetSize() > 0) && ((inPacket->packetData()[0] & 128) != 0)) {
                        //Ignore header packets
                        delete inPacket;
                        return NULL;
                }

                ogg_packet* locOldPack = simulateOldOggPacket(inPacket);                //Accepts the packet and deletes it.
                theora_decode_packetin(&mTheoraState, locOldPack);
                delete locOldPack->packet;
                delete locOldPack;
                
                //Ignore return value... always returns 0 (or crashes :)
                theora_decode_YUVout(&mTheoraState, &mYUVBuffer);
                
                return &mYUVBuffer;
        }

}

ogg_packet* TheoraDecoder::simulateOldOggPacket(StampedOggPacket* inPacket) {           //inPacket is accepted and deleted.
        const unsigned char NOT_USED = 0;
        ogg_packet* locOldPacket = new ogg_packet;              //Returns this... the caller is responsible for it.
        if (mFirstHeader) {
                locOldPacket->b_o_s = 1;
                mFirstHeader = false;
        } else {
                locOldPacket->b_o_s = NOT_USED;
        }
        locOldPacket->e_o_s = NOT_USED;
        locOldPacket->bytes = inPacket->packetSize();
        locOldPacket->granulepos = inPacket->endTime();
        locOldPacket->packet = inPacket->packetData();
        locOldPacket->packetno = NOT_USED;
        
        //Set this to NULL do it doesn't get deleted by the destructor we are about invoke.
        inPacket->setPacketData(NULL);
        delete inPacket;

        return locOldPacket;            //Gives a poitner to the caller.
}

bool TheoraDecoder::isKeyFrame(StampedOggPacket* inPacket)
{
        const unsigned char KEY_FRAME_FLAG = 0x40;
        if ((inPacket->packetSize() > 0) && (inPacket->packetData() != NULL)) {
                return ((inPacket->packetData()[0] & KEY_FRAME_FLAG) == KEY_FRAME_FLAG) ? false : true;
        } else {
                return false;
        }
}
bool TheoraDecoder::decodeHeader(StampedOggPacket* inHeaderPacket) {            //inHeaderPacket is accepted and deleted.

        ogg_packet* locOldPack = simulateOldOggPacket(inHeaderPacket);          //Accepts packet and deletes it.
        theora_decode_header(&mTheoraInfo, &mTheoraComment, locOldPack);

        delete locOldPack->packet;
        delete locOldPack;
        mPacketCount++;
        return true;
}

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