cWavDecoder.cpp

// Copyright (c) 2008-2010 Raynaldo (Wildicv) Rivera, Joshua (Dark_Kilauea) Jones
// This file is part of the "cAudio Engine"
// For conditions of distribution and use, see copyright notice in cAudio.h

#include "../Headers/cWavDecoder.h"
#include <string.h>

#ifdef CAUDIO_COMPILE_WITH_WAV_DECODER

namespace cAudio
{
        cWavDecoder::cWavDecoder(IDataSource* stream) : IAudioDecoder(stream), Valid(false)
    {
        const char* RIFFTAG = "RIFF";
                const char* WAVETAG = "WAVE";
                const char* FORMATTAG = "fmt ";
                const char* DATATAG = "data";

                char ident[4];
                int tempint32 = 0;
                short tempint16 = 0;
                char tempint8 = 0;

                unsigned int startOffset = 0;

                //Read the first 4 bytes
                Stream->seek(0, false);
                Stream->read(ident, 4);
                //Check to see if it is a valid RIFF file
                if(strncmp(ident, RIFFTAG, 4) == 0)
                {
                        Stream->read(&tempint32, 4);
                        //Check to see if the file is big enough to be valid (not completely accurate)
                        if(tempint32 >= 44)
                        {
                                Stream->read(ident, 4);
                                //Check that it is a wave file
                                if(strncmp(ident, WAVETAG, 4) == 0)
                                {
                                        //Save our position
                                        startOffset = Stream->getCurrentPos();

                                        //Scan for the first fmt chuck (not necessarily right after)
                                        do
                                        {
                                                Stream->read(ident, 4);
                                        }
                                        while((strncmp(ident, FORMATTAG, 4) != 0) && (Stream->getCurrentPos() < Stream->getSize()));

                                        //Did we find it?
                                        if(Stream->getCurrentPos() < (Stream->getSize() - 16))
                                        {
                                                //Yes, read it in
                                                Stream->read(&tempint32, 4);
                                                if(tempint32 >= 16)
                                                {
                                                        //Check that it is in PCM format, we don't support compressed wavs
                                                        Stream->read(&tempint16, 2);
                                                        if(tempint16 == 1)
                                                        {
                                                                Stream->read(&tempint16, 2);
                                                                Channels = tempint16;
                                                                //We only support mono or stereo wavs
                                                                if(Channels == 1 || Channels == 2)
                                                                {
                                                                        Stream->read(&tempint32, 4);
                                                                        SampleRate = tempint32;
                                                                        Stream->read(&tempint32, 4);
                                                                        ByteRate = tempint32;
                                                                        Stream->read(&tempint16, 2);
                                                                        BlockAlign = tempint16;
                                                                        Stream->read(&tempint16, 2);
                                                                        BitsPerSample = tempint16;

                                                                        //We only support 8 bit or 16 bit wavs
                                                                        if(BitsPerSample == 8 || BitsPerSample == 16)
                                                                        {
                                                                                //Reset our pointer to start scanning for the data block
                                                                                Stream->seek(startOffset, false);
                                                                                //Scan for the first data chuck (not necessarily right after)
                                                                                do
                                                                                {
                                                                                        Stream->read(ident, 4);
                                                                                }
                                                                                while((strncmp(ident, DATATAG, 4) != 0) && (Stream->getCurrentPos() < Stream->getSize()));

                                                                                //Did we find it?
                                                                                if(Stream->getCurrentPos() < Stream->getSize())
                                                                                {
                                                                                        //Get size of data block
                                                                                        Stream->read(&tempint32, 4);
                                                                                        DataSize = tempint32;
                                                                                        DataOffset = Stream->getCurrentPos();

                                                                                        Valid = true;
                                                                                }
                                                                        }
                                                                }
                                                        }
                                                }
                                        }
                                }
                        }
                }
    }

    cWavDecoder::~cWavDecoder()
    {
                Channels = 0;
                SampleRate = 0;
                ByteRate = 0;
                BlockAlign = 0;
                BitsPerSample = 0;
                DataSize = 0;
                DataOffset = 0;
                Valid = false;
    }

    AudioFormats cWavDecoder::getFormat()
    {
        if(Channels == 1 && BitsPerSample == 8)
            return EAF_8BIT_MONO;
                else if(Channels == 1 && BitsPerSample == 16)
            return EAF_16BIT_MONO;
                else if(Channels == 2 && BitsPerSample == 8)
            return EAF_8BIT_STEREO;
        else
            return EAF_16BIT_STEREO;
    }

    int cWavDecoder::getFrequency()
    {
        return SampleRate;
    }

    bool cWavDecoder::isSeekingSupported()
    {
        return true;
    }

        bool cWavDecoder::isValid()
        {
                return Valid;
        }

    int cWavDecoder::readAudioData(void* output, int amount)
    {
                int currentPos = Stream->getCurrentPos();
                int startPos = DataOffset;
                int endPos = DataOffset + DataSize;
                int amountToRead = amount;

                //Bounds checks (and adjustments if possible)
                if(currentPos > endPos)
                        return 0;

                if(currentPos < startPos)
                {
                        Stream->seek(startPos, false);
                        currentPos = Stream->getCurrentPos();
                }

                if((currentPos + amountToRead) > endPos)
                        amountToRead = endPos - currentPos;

                if(amountToRead < 0)
                        amountToRead = 0;

                return Stream->read(output,amountToRead);

    }

    bool cWavDecoder::setPosition(int position, bool relative)
    {
                int currentPos = Stream->getCurrentPos();
                int startPos = DataOffset;
                int endPos = DataOffset + DataSize;

                //Bounds checks (and adjustments if possible)
                if(!relative && position < startPos)
                        position = startPos;
                if(!relative && position > endPos)
                        position = endPos;
                if(relative && currentPos + position < startPos)
                        position = startPos - currentPos;
                if(relative && currentPos + position > startPos)
                        position = endPos - currentPos;

        Stream->seek(position,relative);
        return true;
    }

    bool cWavDecoder::seek(float seconds,bool relative)
    {
                int amountToSeek = seconds * (float)SampleRate * (float)Channels * (float)(BitsPerSample/8);
        return setPosition(amountToSeek, relative);
    }

        float cWavDecoder::getTotalTime()
        {
                return (float)Stream->getSize() / ((float)SampleRate * (float)Channels * (float)(BitsPerSample/8));
        }

        int cWavDecoder::getTotalSize()
        {
                return Stream->getSize();
        }

        int cWavDecoder::getCompressedSize()
        {
                return Stream->getSize();
        }

        float cWavDecoder::getCurrentTime()
        {
                return (float)Stream->getCurrentPos() / ((float)SampleRate * (float)Channels * (float)(BitsPerSample/8));
        }

        int cWavDecoder::getCurrentPosition()
        {
                return Stream->getCurrentPos();
        }

        int cWavDecoder::getCurrentCompressedPosition()
        {
                return Stream->getCurrentPos();
        }
};

#endif