const Graphics::Surface *AVIDecoder::decodeNextFrame() {
AVIVideoTrack *track = nullptr;
bool isReversed = false;
int frameNum = 0;
// Check whether the video is playing in revese
for (int idx = _videoTracks.size() - 1; idx >= 0; --idx) {
track = static_cast<AVIVideoTrack *>(_videoTracks[idx].track);
isReversed |= track->isReversed();
}
if (isReversed) {
// For reverse mode we need to keep seeking to just before the
// desired frame prior to actually decoding a frame
frameNum = getCurFrame();
seekIntern(track->getFrameTime(frameNum));
}
// Decode the next frame
const Graphics::Surface *frame = VideoDecoder::decodeNextFrame();
if (isReversed) {
// In reverse mode, set next frame to be the prior frame number
for (int idx = _videoTracks.size() - 1; idx >= 0; --idx) {
track = static_cast<AVIVideoTrack *>(_videoTracks[idx].track);
track->setCurFrame(frameNum - 1);
findNextVideoTrack();
}
}
return frame;
}
bool AVIDecoder::seekIntern(const Audio::Timestamp &time) {
uint frame;
// Can't seek beyond the end
if (time > getDuration())
return false;
// Get our video
AVIVideoTrack *videoTrack = (AVIVideoTrack *)_videoTracks[0].track;
uint32 videoIndex = _videoTracks[0].index;
if (time == getDuration()) {
videoTrack->setCurFrame(videoTrack->getFrameCount() - 1);
if (!videoTrack->isReversed()) {
// Since we're at the end, just mark the tracks as over
for (TrackListIterator it = getTrackListBegin(); it != getTrackListEnd(); it++)
if ((*it)->getTrackType() == Track::kTrackTypeAudio)
((AVIAudioTrack *)*it)->resetStream();
return true;
}
frame = videoTrack->getFrameCount() - 1;
} else {
// Get the frame we should be on at this time
frame = videoTrack->getFrameAtTime(time);
}
// Reset any palette, if necessary
videoTrack->useInitialPalette();
int lastKeyFrame = -1;
int frameIndex = -1;
uint curFrame = 0;
// Go through and figure out where we should be
// If there's a palette, we need to find the palette too
for (uint32 i = 0; i < _indexEntries.size(); i++) {
const OldIndex &index = _indexEntries[i];
// We don't care about RECs
if (index.id == ID_REC)
continue;
// We're only looking at entries for this track
if (getStreamIndex(index.id) != videoIndex)
continue;
uint16 streamType = getStreamType(index.id);
if (streamType == kStreamTypePaletteChange) {
// We need to handle any palette change we see since there's no
// flag to tell if this is a "key" palette.
// Decode the palette
_fileStream->seek(_indexEntries[i].offset + 8);
Common::SeekableReadStream *chunk = 0;
if (_indexEntries[i].size != 0)
chunk = _fileStream->readStream(_indexEntries[i].size);
videoTrack->loadPaletteFromChunk(chunk);
} else {
// Check to see if this is a keyframe
// The first frame has to be a keyframe
if ((_indexEntries[i].flags & AVIIF_INDEX) || curFrame == 0)
lastKeyFrame = i;
// Did we find the target frame?
if (frame == curFrame) {
frameIndex = i;
break;
}
curFrame++;
}
}
if (frameIndex < 0) // This shouldn't happen.
return false;
// Update all the audio tracks
for (uint32 i = 0; i < _audioTracks.size(); i++) {
AVIAudioTrack *audioTrack = (AVIAudioTrack *)_audioTracks[i].track;
// Recreate the audio stream
audioTrack->resetStream();
// Set the chunk index for the track
audioTrack->setCurChunk(frame);
uint32 chunksFound = 0;
for (uint32 j = 0; j < _indexEntries.size(); j++) {
const OldIndex &index = _indexEntries[j];
// Continue ignoring RECs
if (index.id == ID_REC)
continue;
if (getStreamIndex(index.id) == _audioTracks[i].index) {
if (chunksFound == frame) {
_fileStream->seek(index.offset + 8);
Common::SeekableReadStream *audioChunk = _fileStream->readStream(index.size);
audioTrack->queueSound(audioChunk);
_audioTracks[i].chunkSearchOffset = (j == _indexEntries.size() - 1) ? _movieListEnd : _indexEntries[j + 1].offset;
break;
}
chunksFound++;
}
}
// Skip any audio to bring us to the right time
audioTrack->skipAudio(time, videoTrack->getFrameTime(frame));
}
// Decode from keyFrame to curFrame - 1
for (int i = lastKeyFrame; i < frameIndex; i++) {
if (_indexEntries[i].id == ID_REC)
continue;
if (getStreamIndex(_indexEntries[i].id) != videoIndex)
continue;
uint16 streamType = getStreamType(_indexEntries[i].id);
// Ignore palettes, they were already handled
if (streamType == kStreamTypePaletteChange)
continue;
// Frame, hopefully
_fileStream->seek(_indexEntries[i].offset + 8);
Common::SeekableReadStream *chunk = 0;
if (_indexEntries[i].size != 0)
chunk = _fileStream->readStream(_indexEntries[i].size);
videoTrack->decodeFrame(chunk);
}
// Update any transparency track if present
if (_transparencyTrack.track)
seekTransparencyFrame(frame);
// Set the video track's frame
videoTrack->setCurFrame(frame - 1);
// Set the video track's search offset to the right spot
_videoTracks[0].chunkSearchOffset = _indexEntries[frameIndex].offset;
return true;
}
void AVIDecoder::handleNextPacket(TrackStatus &status) {
// If there's no more to search, bail out
if (status.chunkSearchOffset + 8 >= _movieListEnd) {
if (status.track->getTrackType() == Track::kTrackTypeVideo) {
// Horrible AVI video has a premature end
// Force the frame to be the last frame
debug(7, "Forcing end of AVI video");
((AVIVideoTrack *)status.track)->forceTrackEnd();
}
return;
}
// See if audio needs to be buffered and break out if not
if (status.track->getTrackType() == Track::kTrackTypeAudio && !shouldQueueAudio(status))
return;
// Seek to where we shall start searching
_fileStream->seek(status.chunkSearchOffset);
bool isReversed = false;
AVIVideoTrack *videoTrack = nullptr;
for (;;) {
// If there's no more to search, bail out
if ((uint32)_fileStream->pos() + 8 >= _movieListEnd) {
if (status.track->getTrackType() == Track::kTrackTypeVideo) {
// Horrible AVI video has a premature end
// Force the frame to be the last frame
debug(7, "Forcing end of AVI video");
((AVIVideoTrack *)status.track)->forceTrackEnd();
}
break;
}
uint32 nextTag = _fileStream->readUint32BE();
uint32 size = _fileStream->readUint32LE();
if (nextTag == ID_LIST) {
// A list of audio/video chunks
if (_fileStream->readUint32BE() != ID_REC)
error("Expected 'rec ' LIST");
continue;
} else if (nextTag == ID_JUNK || nextTag == ID_IDX1) {
skipChunk(size);
continue;
}
// Only accept chunks for this stream
uint32 streamIndex = getStreamIndex(nextTag);
if (streamIndex != status.index) {
skipChunk(size);
continue;
}
Common::SeekableReadStream *chunk = 0;
if (size != 0) {
chunk = _fileStream->readStream(size);
_fileStream->skip(size & 1);
}
if (status.track->getTrackType() == Track::kTrackTypeAudio) {
if (getStreamType(nextTag) != kStreamTypeAudio)
error("Invalid audio track tag '%s'", tag2str(nextTag));
assert(chunk);
((AVIAudioTrack *)status.track)->queueSound(chunk);
// Break out if we have enough audio
if (!shouldQueueAudio(status))
break;
} else {
videoTrack = (AVIVideoTrack *)status.track;
isReversed = videoTrack->isReversed();
if (getStreamType(nextTag) == kStreamTypePaletteChange) {
// Palette Change
videoTrack->loadPaletteFromChunk(chunk);
} else {
// Otherwise, assume it's a compressed frame
videoTrack->decodeFrame(chunk);
break;
}
}
}
if (!isReversed) {
// Start us off in this position next time
status.chunkSearchOffset = _fileStream->pos();
}
}
