/ac3_function/org/si/sion/module/SiOPMStream.as

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

// Stream buffer class

//  Copyright (c) 2008 keim All rights reserved.

//  Distributed under BSD-style license (see org.si.license.txt).

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



package org.si.sion.module {

    import flash.utils.ByteArray;

    import org.si.utils.SLLint;

    

    

    /** Stream buffer class */

    public class SiOPMStream {

        // valiables

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

        /** number of channels */

        public var channels:int = 2;

        /** stream buffer */

        public var buffer:Vector.<Number> = new Vector.<Number>();



        // coefficient of volume/panning

        private var _panTable:Vector.<Number>;

        private var _i2n:Number;



        

        

        

        // constructor

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

        /** constructor */

        function SiOPMStream()

        {

            var st:SiOPMTable = SiOPMTable.instance;

            _panTable = st.panTable;

            _i2n = st.i2n;

        }

        

        

        

        

        // operation

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

        /** clear buffer */

        public function clear() : void

        {

            var i:int, imax:int = buffer.length;

            for (i=0; i<imax; i++) {

                buffer[i] = 0;

            }

        }

        

        

        /** limit buffered signals between -1 and 1 */

        public function limit() : void

        {

            var n:Number, i:int, imax:int = buffer.length;

            for (i=0; i<imax; i++) {

                n = buffer[i];

                     if (n < -1) buffer[i] = -1;

                else if (n >  1) buffer[i] =  1;

            }

        }

        

        

        /** Quantize buffer by bit rate. */

        public function quantize(bitRate:int) : void

        {

            var i:int, imax:int = buffer.length,

                r:Number = 1<<bitRate, ir:Number = 2/r;

            for (i=0; i<imax; i++) {

                buffer[i] = ((buffer[i] * r) >> 1) * ir;

            }

        }

        

        

        /** write buffer by org.si.utils.SLLint */

        public function write(pointer:SLLint, start:int, len:int, vol:Number, pan:int) : void 

        {

            var i:int, n:Number, imax:int = (start + len)<<1;

            vol *= _i2n;

            if (channels == 2) {

                // stereo

                var volL:Number = _panTable[128-pan] * vol,

                    volR:Number = _panTable[pan] * vol;

                for (i=start<<1; i<imax;) {

                    n = Number(pointer.i);

                    buffer[i] += n * volL;  i++;

                    buffer[i] += n * volR;  i++;

                    pointer = pointer.next;

                }

            } else 

            if (channels == 1) {

                // monoral

                for (i=start<<1; i<imax;) {

                    n = Number(pointer.i) * vol;

                    buffer[i] += n; i++;

                    buffer[i] += n; i++;

                    pointer = pointer.next;

                }

            }

        }

        

        

        /** write buffer by Vector.<Number> */

        public function writeVectorNumber(pointer:Vector.<Number>, startPointer:int, startBuffer:int, len:int, vol:Number, pan:int, sampleChannelCount:int) : void

        {

            var i:int, j:int, n:Number, jmax:int, volL:Number, volR:Number;

            

            if (channels == 2) {

                if (sampleChannelCount == 2) {

                    // stereo data to stereo buffer

                    jmax = (startPointer + len)<<1;

                    for (j=startPointer<<1, i=startBuffer<<1; j<jmax; j++, i++) {

                        buffer[i] += pointer[j] * vol;

                    }

                } else {

                    // monoral data to stereo buffer

                    volL = _panTable[128-pan] * vol;

                    volR = _panTable[pan]     * vol;

                    jmax = startPointer + len;

                    for (j=startPointer, i=startBuffer<<1; j<jmax; j++) {

                        n = pointer[j];

                        buffer[i] += n * volL;  i++;

                        buffer[i] += n * volR;  i++;

                    }

                }

            } else 

            if (channels == 1) {

                if (sampleChannelCount == 2) {

                    // stereo data to monoral buffer

                    jmax = (startPointer + len)<<1;

                    vol  *= 0.6;

                    for (j=startPointer<<1, i=startBuffer<<1; j<jmax;) {

                        n  = pointer[j]; j++;

                        n += pointer[j]; j++;

                        n *= vol;

                        buffer[i] += n; i++;

                        buffer[i] += n; i++;

                    }

                } else {

                    // monoral data to monoral buffer

                    jmax = startPointer + len;

                    for (j=startPointer, i=startBuffer<<1; j<jmax; j++) {

                        n = pointer[j] * vol;

                        buffer[i] += n; i++;

                        buffer[i] += n; i++;

                    }

                }

            }

        }

        

        

        /** write buffer by ByteArray (stereo only). */

        public function writeByteArray(bytes:ByteArray, start:int, len:int, vol:Number) : void

        {

            var i:int, n:Number, imax:int = (start + len)<<1;

            var initPosition:int = bytes.position;



            if (channels == 2) {

                for (i=start<<1; i<imax; i++) {

                    buffer[i] += bytes.readFloat() * vol;

                }

            } else 

            if (channels == 1) {

                // stereo data to monoral buffer

                vol  *= 0.6;

                for (i=start<<1; i<imax;) {

                    n = (bytes.readFloat() + bytes.readFloat()) * vol;

                    buffer[i] += n; i++;

                    buffer[i] += n; i++;

                }

            }

            

            bytes.position = initPosition;

        }

    }

}