MicroDVD / . sub subtitle support

[j]

would be nice to have MicroDVD subtitle support. '.sub' is used as extension. The strcuture consists of start and end video frames in curly braces {} for every piece of dialogue, with line breaks defined by pipes: |. A new line marks a new piece of dialogue.

Example:

{6561}{6617}I like to be pretty everyday.
{6631}{6669}I like to be in good shape.
{6695}{6745}That's why I love Avalon.
{6753}{6832}With Avalon,|I know I'm beautiful.
{6842}{6900}And I know I'll remain that way.
{6919}{6984}Avalon,|for a better world.

[astrange]

I'm not sure it's even possible to have frame-level subtitles here. We might not preserve frame numbers from AVI.

[dconrad]

I can only think of two cases where we wouldn't preserve frame numbers in AVI, both of which are due to zero-byte frames. The first is H.264 w/ b-frames in AVI, which usually has one or two null frames before any real ones; I don't think that a difference of a couple frames would matter much in this rare situation. Second is with VFR/120fps AVIs, where null frames extend the previous frame's duration. How MicroDVD is handled in this case is unclear; I would think that it would either be actual frames or a constant 30 fps, but it seems that most implementations assume a constant frame rate that's set to the AVI frame rate, which would be 120fps. So we could pass the AVI's frame rate to the MicroDVD loader to use in this case, though I wonder whether this situation has ever occurred.