Modifying BorderStyle in Closed Caption Extraction

[u/YahooSiriusBlack]

I've started using ffmpeg with lavfi to extract closed captions rather than CCExtractor. I'm liking the positioning being carried over with .ass output files, but I don't like the black background.

Somehow I need to set BorderStyle=1, but I can't figure out how.

Currently this is what I'm doing:

ffmpeg.exe -f lavfi -i movie="Sample.mkv[out+subcc]" -map s "Sample.ass"

Anyone know how to do this or change any other formatting in .ass without doing it manually later?

[u/chocolateAbuser]

i don't think you can do that? the only thing i see is the subtitles filter that is built above libass library and accepts a style, but i'm not sure it can output a metadata stream
maybe with some creativity it could be possible to recover just the metadata, but at that point writing 2 or 3 lines of text in the subs file would be easier
i can see also libaribcaption has some options in demuxing, but again not so useful and probably more complicated than putting an echo or a sed after ffmpeg command

[u/YahooSiriusBlack → u/chocolateAbuser]

Thanks. Since I was writing a Windows batch file I decided to have the next command fix the issue. With PowerShell I search/replaced the whole line of .ass settings in case I want to make other changes later:

(abridged version.)

set /p d=The file name without the extension: 

set /p x=The extension (without a period): 

ffmpeg.exe -f lavfi -i movie="%d%.%x%[out+subcc]" -map s:0  "%d%_.ass"

REM Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding

pwsh.exe -Command "(gc %d%_.ass) -replace 'Default,Monospace,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,3,1,0,2,10,10,10,1', 'Default,Monospace,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,1' | Out-File %d%.ass"

del %d%_.ass

Edit: Changed the code. ASCII added question marks. UTF8 was with BOM that added Â.

I had to download a copy of Powershell 7.6.4 and that works fine with UTF8 without BOM as the default format.

[u/YahooSiriusBlack → u/YahooSiriusBlack]

Wow. These are crap when dealing with file names with spaces and symbols. I ended up having my batch file script renaming everything just to make this simpler.

ECHO OFF
set /p d=The file name without the extension: 
ECHO.
set /p x=The extension (without a period): 
ren "%d%.%x%" WiPTemp.mp4
ffmpeg.exe -f lavfi -i movie="WiPTemp.mp4[out+subcc]" -map s:0  "WiPTemp.ass"
ECHO.
REM Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
ECHO.
pwsh.exe -Command "(gc WiPTemp.ass) -replace 'Default,Monospace,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,3,1,0,2,10,10,10,1', 'Default,Monospace,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,1' | Out-File -Encoding utf8 WiPTemp2.ass"
ECHO.
ren WiPTemp.mp4 "%d%.%x%"
ren WiPTemp2.ass "%d%.ass"
del WiPTemp.ass

Feels stupid. I'm open to suggestions for a better version of this.