Known Issues

Reading/writing data from/to transport streams is quite a hassle since the formats are usually not well documented and you will always stumble over a stream that either contains authoring errors or uses features so uncommon that they are not documented anywhere. Indeed, most of the time it is impossible to tell if some weird stream is only on the edge of what is allowed or simply faulty. So often enough, programs that read or write transport streams will only support a certain amount of commonly used (and known) sub-features. Therefore it is likely that BDSup2Sub will stumble over the streams created by other programs or other programs will have problems reading the streams created by BDSup2Sub and it's generally hard to tell whose fault it is.

Here is a list of issues that I'm aware of:

• BDSup2Sub exports only plain subtitles (one image with start and end time). If an imported SUP contains anything beyond this (e.g. palette animations, cropping animations, image animations) etc. BDSup2Sub will remove them and output a warning. This might lead to unexpected results. E.g. if a BD-SUP contains animated palettes, only the final state of the palette will be displayed and exported. While BDSup2Sub tries to detect alpha changes for fading in and out and use the most opaque color for display, this detection may fail under certain circumstances or the displayed palette may even be a mixture of different animation/fading stages. Also, if a BD-SUP contains more than one image ("composition object") per frame, only the first image will be displayed and exported.
• Alpha/palette updates are only partly supported for SUB/IDX and SUP/IFO. For the experts among you: only the first LN_CTLI and the first PX_CTLI is considered per update. Also the line/column values are completely ignored and the palette/alpha update is assumed to be valid for the whole bitmap.
• Although BDSup2Sup can export SUB/IDX (or SUP/IFO) in higher resolutions (720p or 1080p), keep in mind that this is not a standard format. While some programs might accept these high resolution files, others might crash or show erratic results (e.g. this seems to be the case for SubRip). Use this feature at your own risk. For full compatibility, especially if the conversion target is a DVD, use PAL or NTSC only. Also read the [notes about SUP/IFO](Supported Formats).
• HD-DVD SUPs don't seem to contain any information about the screen resolution. Therefore BDSup2Sub assumes a resolution of 1920x1080. If there are HD-DVDs with lower resolutions (e.g. 720p), this will be a problem. I'd have to add some kind of resolution selection then. I tried to catch the most common problems (e.g. out of bounds access due to corrupt size information or wrong RLE info), yet it is kinda impossible to catch every possible fault in every possible stream. So don't be surprised if BDSUP2SUB shuts down with or without an error message. I recommend to start it via the command line in this case to see every exception thrown. E.g. a problem of the Java Runtime can't be caught by the application and is therefore only printed to the console.