VIDEO: Further work on 2-track AVI videos

It turns out that at least one video in Starship Titanic, for the
Lift Indicator, has only a single transparency frame in track 2.
The added code, therefore, when it doesn't find an index entry
for the desired frame number, works backwards until it finds a valid
frame (likely frame 0), and then scans forward. If it hits the end
of the video, then it simply uses whatever last frame it last decoded.

1 files changed, 2 insertions, 2 deletions

diff --git a/video/avi_decoder.cpp b/video/avi_decoder.cpp
index c2c485c1eb..32aa9f9044 100644
--- a/video/avi_decoder.cpp
+++ b/video/avi_decoder.cpp
@@ -726,7 +726,7 @@ bool AVIDecoder::seekIntern(const Audio::Timestamp &time) {
 		OldIndex *entry = nullptr;
 		do {
 			entry = _indexEntries.find(_videoTracks.back().index, indexFrame);
-		} while (!entry && --indexFrame >= 0);
+		} while (!entry && indexFrame-- > 0);
 		assert(entry);
 
 		// Read in the frame
@@ -740,7 +740,7 @@ bool AVIDecoder::seekIntern(const Audio::Timestamp &time) {
 
 		if (indexFrame < frame) {
 			TrackStatus &status = _videoTracks.back();
-			while (indexFrame++ < frame) {
+			while (status.chunkSearchOffset < _movieListEnd && indexFrame++ < frame) {
 				// There was no index entry for the desired frame, so an earlier one was decoded.
 				// We now have to sequentially decode frames until we get to the desired frame
 				handleNextPacket(status);