FFmpeg outputs invalid ASS files

[gjdfgh]

ffmpeg -i test.sub out.ass produces an ASS file with this header:

[Events]
Format: Layer, Start, End, Style, Text

The "Format:" line, as well as all events following it, is semi-invalid. While it does look like the ASS format is flexible about the headers, and libass actually parses this, it's not accepted by most other ASS readers, such as the (very important) vsfilter.

FFmpeg should output standard headers instead.

Here's an example of users actually running into this problem: ​http://www.cccp-project.net/forums/index.php?topic=6826.0

It's possible that libass will drop the header parsing in the future to avoid compatibility problems with real-world scripts.

[Clément Bœsch]

So does vsfilter only accept the events in the following form Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text?

Is the Style header also affected?

Any other incompatibilities?

[gjdfgh]

Is the Style header also affected?

Yes. Note that it might accept older variants, SSA at least.

Any other incompatibilities?

Not that I know of.

[plorkyeran]

The headers assumed by VSFilter for SSA are:
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text

and for ASS:
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text

[Clément Bœsch]

Hopefully fixed in 40b9f28641b696c6bb73ce49dc97c2ce2700cbdb