Re: [FFmpeg-devel] Captions SCC

From: Devin Heitmueller <devin.heitmueller@ltnglobal.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] Captions SCC
Date: Sun, 9 Feb 2025 09:03:04 -0500
Message-ID: <CAHGibzFZfcjozCE=2jCRqoyZ4EwJDGVvdXbUnS1QykpSrOiVMA@mail.gmail.com> (raw)
In-Reply-To: <7794F879-F6A2-4DDC-A9EC-BDED78189004@tvaughan.com>

On Sat, Feb 8, 2025 at 10:39 PM Tom Vaughan <tom@tvaughan.com> wrote:
>
> I'm excited to see this discussion. There are many leading video distributors (streaming services, etc.) that would love to see solid support in FFMPEG for closed captions. No promises, but my sense is that additional money can be raised to sponsor this development.
>
> WebVTT as a sidecar captions file is the modern way to handle captions. The latest streaming client devices / applications support WebVTT captions. New movies and TV shows are produced with WebVTT captions.

Not to start an argument, but WebVTT is kind of a terrible format.
It's a lowest common denominator and loses most formatting information
available even in 608 (which is now more than 40 years old).  Stuff
like rollup captions for live programming, color (to distinguish
speakers) and caption positioning are pretty important to the hearing
impaired.

Yesterday I watched a DVD I ripped (purely for personal use) of a TV
show with VTT captions for something that I knew what the original 608
looked like, and wow what a difference (the WebVTT looked dramatically
worse than the original 608).

To my point: no, I don't think normalizing everything down to WebVTT
is a good idea.

Much of the goal, at least in the work that I do, is to conform to the
FCC requirements, which generally require that the original 608/708
from the content provider be preserved.

There can be money to support such efforts.  Most of my work in
captioning within ffmpeg was funded by my employer, and most of the
work I did improving 608 captions in VLC was financed by contract work
I did for commercial customers who were embedding VLC into solutions
and needed decent caption support.

Devin

-- 
Devin Heitmueller, Senior Software Engineer
LTN Global Communications
o: +1 (301) 363-1001
w: https://ltnglobal.com  e: devin.heitmueller@ltnglobal.com
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