[FFmpeg-devel] [PATCH]lavf/matroska: Also support WebVTT in Matroska

[Andreas Rheinhardt]

Carl Eugen Hoyos:
> Hi!
> 
> Attached patch is supposed to fix HandBrake issue 1964, FFmpeg
> currently fails to identify WebVTT in Matroska (only webm is supported
> as container). I don't have the original sample to test though.
> 
> Please comment, Carl Eugen
The way WebVTT is stored in Matroska is different from the way it is
stored in WebM: The Matroska way uses an optional BlockAdditional to
store the information that would be contained at the beginning of the
subtitle payload (the actual data of the Block inside the BlockGroup)
in WebM, namely the stuff that ends up as
AV_PKT_DATA_WEBVTT_IDENTIFIER and AV_PKT_DATA_WEBVTT_SETTINGS side
data. It also contains another form of information, namely WebVTT
Comment Blocks (for which no side data has been defined yet). Your
patch would export this data as part of a general
AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL and not as its components. This
is suboptimal.

- Andreas