ALACEncoder.h

/*
 * Copyright (c) 2011 Apple Inc. All rights reserved.
 *
 * @APPLE_APACHE_LICENSE_HEADER_START@
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * @APPLE_APACHE_LICENSE_HEADER_END@
 */
 
/*
    File:       ALACEncoder.h
*/
 
#pragma once
 
#include <stdint.h>
 
#include "ALACAudioTypes.h"
 
 
struct BitBuffer;
 
class ALACEncoder
{
    public:
        ALACEncoder();
        virtual ~ALACEncoder();
 
        virtual int32_t Encode(AudioFormatDescription theInputFormat, AudioFormatDescription theOutputFormat,
                                   unsigned char * theReadBuffer, unsigned char * theWriteBuffer, int32_t * ioNumBytes);
        virtual int32_t Finish( );
 
        void                SetFastMode( bool fast ) { mFastMode = fast; };
 
        // this must be called *before* InitializeEncoder()
        void                SetFrameSize( uint32_t frameSize ) { mFrameSize = frameSize; };
 
        void                GetConfig( ALACSpecificConfig & config );
        uint32_t            GetMagicCookieSize(uint32_t inNumChannels);
        void                GetMagicCookie( void * config, uint32_t * ioSize ); 
 
        virtual int32_t InitializeEncoder(AudioFormatDescription theOutputFormat);
 
    protected:
        virtual void        GetSourceFormat( const AudioFormatDescription * source, AudioFormatDescription * output );
        
        int32_t         EncodeStereo( struct BitBuffer * bitstream, void * input, uint32_t stride, uint32_t channelIndex, uint32_t numSamples );
        int32_t         EncodeStereoFast( struct BitBuffer * bitstream, void * input, uint32_t stride, uint32_t channelIndex, uint32_t numSamples );
        int32_t         EncodeStereoEscape( struct BitBuffer * bitstream, void * input, uint32_t stride, uint32_t numSamples );
        int32_t         EncodeMono( struct BitBuffer * bitstream, void * input, uint32_t stride, uint32_t channelIndex, uint32_t numSamples );
 
 
        // ALAC encoder parameters
        int16_t                 mBitDepth;
        bool                    mFastMode;
 
        // encoding state
        int16_t                 mLastMixRes[kALACMaxChannels];
 
        // encoding buffers
        int32_t *               mMixBufferU;
        int32_t *               mMixBufferV;
        int32_t *               mPredictorU;
        int32_t *               mPredictorV;
        uint16_t *              mShiftBufferUV;
        
        uint8_t *                   mWorkBuffer;
 
        // per-channel coefficients buffers
        int16_t                 mCoefsU[kALACMaxChannels][kALACMaxSearches][kALACMaxCoefs];
        int16_t                 mCoefsV[kALACMaxChannels][kALACMaxSearches][kALACMaxCoefs];
 
        // encoding statistics
        uint32_t                    mTotalBytesGenerated;
        uint32_t                    mAvgBitRate;
        uint32_t                    mMaxFrameBytes;
        uint32_t                  mFrameSize;
        uint32_t                  mMaxOutputBytes;
        uint32_t                  mNumChannels;
        uint32_t                  mOutputSampleRate;        
};