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Loosening the 2 samples per channel requirement of Apple_ADPCMStream to 1 sample per channel

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svn-id: r47864
This commit is contained in:
Sven Hesse 2010-02-03 19:55:14 +00:00
parent 87534da624
commit 51d0365818
1 changed files with 23 additions and 25 deletions
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48
sound/decoders/adpcm.cpp
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@ -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
@ -252,28 +254,24 @@ 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;
buffer[_channels * samples[i] + i] = _buffer[i][_chunkPos[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]++;
// Different nibble
lowNibble[i] = !lowNibble[i];
// We're about to decode a new lower nibble again, so advance the block position
if (lowNibble[i])
_blockPos[i]++;
if (_channels == 2)
if (_blockPos[i] == _blockAlign)
// We're at the end of the block.