void AVIDecoder::readNextPacket() {
uint32 nextTag = _fileStream->readUint32BE();
uint32 size = _fileStream->readUint32LE();
if (_fileStream->eos())
return;
if (nextTag == ID_LIST) {
// A list of audio/video chunks
int32 startPos = _fileStream->pos();
if (_fileStream->readUint32BE() != ID_REC)
error("Expected 'rec ' LIST");
size -= 4; // subtract list type
// Decode chunks in the list
while (_fileStream->pos() < startPos + (int32)size)
readNextPacket();
return;
} else if (nextTag == ID_JUNK || nextTag == ID_IDX1) {
skipChunk(size);
return;
}
Track *track = getTrack(getStreamIndex(nextTag));
if (!track)
error("Cannot get track from tag '%s'", tag2str(nextTag));
Common::SeekableReadStream *chunk = 0;
if (size != 0) {
chunk = _fileStream->readStream(size);
_fileStream->skip(size & 1);
}
if (track->getTrackType() == Track::kTrackTypeAudio) {
if (getStreamType(nextTag) != MKTAG16('w', 'b'))
error("Invalid audio track tag '%s'", tag2str(nextTag));
assert(chunk);
((AVIAudioTrack *)track)->queueSound(chunk);
} else {
AVIVideoTrack *videoTrack = (AVIVideoTrack *)track;
if (getStreamType(nextTag) == MKTAG16('p', 'c')) {
// Palette Change
assert(chunk);
byte firstEntry = chunk->readByte();
uint16 numEntries = chunk->readByte();
chunk->readUint16LE(); // Reserved
// 0 entries means all colors are going to be changed
if (numEntries == 0)
numEntries = 256;
byte *palette = const_cast<byte *>(videoTrack->getPalette());
for (uint16 i = firstEntry; i < numEntries + firstEntry; i++) {
palette[i * 3] = chunk->readByte();
palette[i * 3 + 1] = chunk->readByte();
palette[i * 3 + 2] = chunk->readByte();
chunk->readByte(); // Flags that don't serve us any purpose
}
delete chunk;
videoTrack->markPaletteDirty();
} else if (getStreamType(nextTag) == MKTAG16('d', 'b')) {
// TODO: Check if this really is uncompressed. Many videos
// falsely put compressed data in here.
error("Uncompressed AVI frame found");
} else {
// Otherwise, assume it's a compressed frame
videoTrack->decodeFrame(chunk);
}
}
}
void AVIDecoder::handleStreamHeader(uint32 size) {
AVIStreamHeader sHeader;
sHeader.size = size;
sHeader.streamType = _fileStream->readUint32BE();
if (sHeader.streamType == ID_MIDS || sHeader.streamType == ID_TXTS)
error("Unhandled MIDI/Text stream");
sHeader.streamHandler = _fileStream->readUint32BE();
sHeader.flags = _fileStream->readUint32LE();
sHeader.priority = _fileStream->readUint16LE();
sHeader.language = _fileStream->readUint16LE();
sHeader.initialFrames = _fileStream->readUint32LE();
sHeader.scale = _fileStream->readUint32LE();
sHeader.rate = _fileStream->readUint32LE();
sHeader.start = _fileStream->readUint32LE();
sHeader.length = _fileStream->readUint32LE();
sHeader.bufferSize = _fileStream->readUint32LE();
sHeader.quality = _fileStream->readUint32LE();
sHeader.sampleSize = _fileStream->readUint32LE();
_fileStream->skip(sHeader.size - 48); // Skip over the remainder of the chunk (frame)
if (_fileStream->readUint32BE() != ID_STRF)
error("Could not find STRF tag");
uint32 strfSize = _fileStream->readUint32LE();
uint32 startPos = _fileStream->pos();
if (sHeader.streamType == ID_VIDS) {
if (_frameRateOverride != 0) {
sHeader.rate = _frameRateOverride.getNumerator();
sHeader.scale = _frameRateOverride.getDenominator();
}
BitmapInfoHeader bmInfo;
bmInfo.size = _fileStream->readUint32LE();
bmInfo.width = _fileStream->readUint32LE();
bmInfo.height = _fileStream->readUint32LE();
bmInfo.planes = _fileStream->readUint16LE();
bmInfo.bitCount = _fileStream->readUint16LE();
bmInfo.compression = _fileStream->readUint32BE();
bmInfo.sizeImage = _fileStream->readUint32LE();
bmInfo.xPelsPerMeter = _fileStream->readUint32LE();
bmInfo.yPelsPerMeter = _fileStream->readUint32LE();
bmInfo.clrUsed = _fileStream->readUint32LE();
bmInfo.clrImportant = _fileStream->readUint32LE();
if (bmInfo.clrUsed == 0)
bmInfo.clrUsed = 256;
if (sHeader.streamHandler == 0)
sHeader.streamHandler = bmInfo.compression;
AVIVideoTrack *track = new AVIVideoTrack(_header.totalFrames, sHeader, bmInfo);
if (bmInfo.bitCount == 8) {
byte *palette = const_cast<byte *>(track->getPalette());
for (uint32 i = 0; i < bmInfo.clrUsed; i++) {
palette[i * 3 + 2] = _fileStream->readByte();
palette[i * 3 + 1] = _fileStream->readByte();
palette[i * 3] = _fileStream->readByte();
_fileStream->readByte();
}
track->markPaletteDirty();
}
addTrack(track);
} else if (sHeader.streamType == ID_AUDS) {
PCMWaveFormat wvInfo;
wvInfo.tag = _fileStream->readUint16LE();
wvInfo.channels = _fileStream->readUint16LE();
wvInfo.samplesPerSec = _fileStream->readUint32LE();
wvInfo.avgBytesPerSec = _fileStream->readUint32LE();
wvInfo.blockAlign = _fileStream->readUint16LE();
wvInfo.size = _fileStream->readUint16LE();
// AVI seems to treat the sampleSize as including the second
// channel as well, so divide for our sake.
if (wvInfo.channels == 2)
sHeader.sampleSize /= 2;
addTrack(new AVIAudioTrack(sHeader, wvInfo, _soundType));
}
// Ensure that we're at the end of the chunk
_fileStream->seek(startPos + strfSize);
}
