diff options
Diffstat (limited to 'sound/decoders')
| -rw-r--r-- | sound/decoders/adpcm.cpp | 48 |
1 files changed, 23 insertions, 25 deletions
diff --git a/sound/decoders/adpcm.cpp b/sound/decoders/adpcm.cpp index 943b1ff7d8..3ee92265a0 100644 --- a/sound/decoders/adpcm.cpp +++ b/sound/decoders/adpcm.cpp @@ -198,9 +198,13 @@ class Apple_ADPCMStream : public Ima_ADPCMStream { protected: // Apple QuickTime IMA ADPCM int32 _streamPos[2]; + int16 _buffer[2][2]; + uint8 _chunkPos[2]; void reset() { Ima_ADPCMStream::reset(); + _chunkPos[0] = 0; + _chunkPos[1] = 0; _streamPos[0] = 0; _streamPos[1] = _blockAlign; } @@ -208,6 +212,8 @@ protected: public: Apple_ADPCMStream(Common::SeekableReadStream *stream, DisposeAfterUse::Flag disposeAfterUse, uint32 size, int rate, int channels, uint32 blockAlign) : Ima_ADPCMStream(stream, disposeAfterUse, size, rate, channels, blockAlign) { + _chunkPos[0] = 0; + _chunkPos[1] = 0; _streamPos[0] = 0; _streamPos[1] = _blockAlign; } @@ -217,15 +223,11 @@ public: }; int Apple_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) { - // Need to write 2 samples per channel - assert(numSamples % (2 * _channels) == 0); + // Need to write at least one samples per channel + assert((numSamples % _channels) == 0); // Current sample positions - int samples[2] = { 0, 0}; - // Current data bytes - byte data[2] = { 0, 0}; - // Current nibble selectors - bool lowNibble[2] = {true, true}; + int samples[2] = { 0, 0}; // Number of samples per channel int chanSamples = numSamples / _channels; @@ -235,7 +237,7 @@ int Apple_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) { while ((samples[i] < chanSamples) && // Last byte read and a new one needed - !((_stream->eos() || (_stream->pos() >= _endpos)) && lowNibble[i])) { + !((_stream->eos() || (_stream->pos() >= _endpos)) && (_chunkPos[i] == 0))) { if (_blockPos[i] == _blockAlign) { // 2 byte header per block @@ -252,27 +254,23 @@ int Apple_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) { _blockPos[i] = 2; } - // First decode the lower nibble, then the upper - if (lowNibble[i]) - data[i] = _stream->readByte(); - - int16 sample; - if (lowNibble[i]) - sample = decodeIMA(data[i] & 0x0F, i); - else - sample = decodeIMA(data[i] >> 4, i); + if (_chunkPos[i] == 0) { + // Decode data + byte data = _stream->readByte(); + _buffer[i][0] = decodeIMA(data & 0x0F, i); + _buffer[i][1] = decodeIMA(data >> 4, i); + } // The original is interleaved block-wise, we want it sample-wise - buffer[_channels * samples[i] + i] = sample; - - samples[i]++; + buffer[_channels * samples[i] + i] = _buffer[i][_chunkPos[i]]; - // Different nibble - lowNibble[i] = !lowNibble[i]; - - // We're about to decode a new lower nibble again, so advance the block position - if (lowNibble[i]) + if (++_chunkPos[i] > 1) { + // We're about to decode the next byte, so advance the block position + _chunkPos[i] = 0; _blockPos[i]++; + } + + samples[i]++; if (_channels == 2) if (_blockPos[i] == _blockAlign) |