[FFmpeg-devel] [PATCH] avcodec: add minimal teletext subtitle decoder

[Marton Balint]

On Sun, 14 Jun 2020, Carl Eugen Hoyos wrote:

> Am So., 14. Juni 2020 um 17:40 Uhr schrieb Marton Balint <cus at passwd.hu>:
>>
>>
>>
>> On Sun, 14 Jun 2020, Carl Eugen Hoyos wrote:
>>
>> > Am So., 14. Juni 2020 um 16:26 Uhr schrieb Marton Balint <cus at passwd.hu>:
>> >>
>> >>
>> >>
>> >> On Sun, 14 Jun 2020, Carl Eugen Hoyos wrote:
>> >>
>> >> > Am So., 14. Juni 2020 um 12:05 Uhr schrieb Paul B Mahol <onemda at gmail.com>:
>> >> >>
>> >> >> [...] this patch should be merged.
>> >> >
>> >> > I still believe this is one of the most important missing
>> >> > features
>> >>
>> >> Which one? As far as I remember I integrated all the features (including
>> >> colorized ass output) to libzvbi-teletextdec, so I am curious what is the
>> >> feature that you still miss from that.
>> >
>> > You mean apart from the fact that this project was always about
>> > re-inventing the wheel (like it or not)?
>> >
>> > Since this morning, I (very seriously) wonder if you have ever used
>> > the existing teletext decoder (and how): Both "ffplay file.ts" and
>> > "ffmpeg -i file.ts out.mkv" do not work as expected, and even if you
>> > know that you have to specify "-txt_format ass" the output is still
>> > completely unusable.
>>
>> Are implying that the default txt_page should be changed to "subtitle"
>> from "*"? Beacuse that is all it takes to make it a regular subtitle from
>> a list of all the pages (if that is what you mean when you write
>> *unusable*)
>
> No.
>
> I am implying that FFmpeg needs an internal teletext decoder that
> does not produce the specified graphical output as libzvbi allows
> but decodes teletext to usable text subtitles (including automatic
> page detection) without an external dependency (that we should
> of course keep for the valid usecase of overlaying the intended
> graphics).

I kind of thought that havig something internal to ffmpeg was always 
justifed with something, e.g.: features, or speed, or licensing. I just 
don't see a distinctive reason here to do teletext decoding internally, so 
that is why I am against adding an internal decoder.

Regards,
Marton