[FFmpeg-user] mov_text

[Mark Filipak]

On 10/06/2025 14.01, Paul B Mahol wrote:
> On Tue, Jun 10, 2025 at 5:50 PM Mark Filipak <
> markfilipak.imdb-at-gmail.com at ffmpeg.org> wrote:
> 
>> ffmpeg-all.html
>> "18.31 text2movsub
>> Convert text subtitles to MOV subtitles (as used by the mov_text codec)
>> with metadata headers."
>>
>> ffmpeg-codecs.html
>> ("mov_text" not found.)
>>
>> Is there a mov_text codec? What is mov_text?
> 
> 
> # ffmpeg -hide_banner -codecs|grep mov_text
>   DES... mov_text             MOV text

Thank you, Paul.

Ah, yes. I knew about "ffmpeg -codecs" but that was a long time ago. Thank you for reminding me.

If mov_text is indeed a codec -- 'ffmpeg -codecs' says it's a codec -- one would think it would be 
listed, somehow, in ffmpeg-codecs.html, eh?

Methinks it's not a codec at all -- that subtitles are not coded. Methinks it's really 
textual-subtitles-as-metadata, in which case ffmpeg-all.html, section 18.31 is misleading, eh?

If mov_text is really textual-subtitles-as-metadata, then it must be in private packets, eh? And is 
it correct to say that mp4 players -- perhaps only _some_ or _most_ mp4 players -- support textual 
subtitles as metadata in private packets within an MPEG TS?

So, in ffmpeg-all.html section 18.31, wouldn't it be more accurate to say that text2movsub is
"A metadata writer that muxes textual subtitles into the transport stream"
instead of
"Convert text subtitles to MOV subtitles (as used by the mov_text codec) with metadata headers"?

These are not small details, eh?