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

[Paul B Mahol]

On 6/14/20, Marton Balint <cus at passwd.hu> wrote:
>
>
> On Sun, 14 Jun 2020, Paul B Mahol wrote:
>
>> Nothing happened of this, so this patch should be merged.
>
> What do you mean? Ass output support got added to libzvbi-teletextdec in
> 2018.

And how is ass output support relevant to give FFmpeg decoder support?

>
> Regards,
> Marton
>
>
>>
>> On 4/26/18, Marton Balint <cus at passwd.hu> wrote:
>>>
>>> On Thu, 26 Apr 2018, Aman Gupta wrote:
>>>
>>>> On Thu, Apr 26, 2018 at 8:12 AM, Nicolas George <george at nsup.org> wrote:
>>>>
>>>>> Aman Gupta (2018-04-26):
>>>>> > Another reason I discounted libzvbi is because it seems unmaintained,
>>>>> > without a new release is over 5 years.
>>>>>
>>>>> Did the teletext standard evolve in the past five years?
>>>>>
>>>>
>>>> I don't know, but there it is atleast one bug causing tests to fail on
>>>> macOS which has been unfixed for 4 years.
>>>>
>>>> I managed to install libzvbi by hand and try it out. With `-txt_format
>>>> text`, the generated output text is the same but without
>>>> positions/colors.
>>>> The ASS positioning code could be ported over, but it looks like
>>>> vbi_print_page_region() strips out all the color information so there
>>>> doesn't seem to be an obvious way to support text coloring.
>>>>
>>>> The zvbi decoder also hardcodes a (configurable) 30s end time per
>>>> subtitle,
>>>> which causes them to pile up on the screen and not disappear when
>>>> they're
>>>> supposed to. The logic from my decoder could also probably be ported
>>>> over,
>>>> under a new `-real_time 1` flag like I added to ccaption_dec last year.
>>>>
>>>> Here's a side by side comparison:
>>>> https://dzwonsemrish7.cloudfront.net/items/2x1z3k0C0X3v0Z2j1F3b/teletext-sub-comparison.jpg
>>>>
>>>> I agree it would be ideal to have only one teletext decoder that works
>>>> for
>>>> everyone. However I'm done with my teletext project, and don't have time
>>>> right now to redo all that work in the zvbi encoder. I also live in an
>>>> ATSC
>>>> region and don't use teletext myself, so I don't really care whether or
>>>> not
>>>> my decoder is merged into ffmpeg. I only shared it because some people
>>>> on
>>>> IRC expressed interest.
>>>
>>> I will try integrating the ASS formatting part of your patch to the
>>> libzvbi decoder, and see how it goes.
>>>
>>> Regards,
>>> Marton
>>> _______________________________________________
>>> ffmpeg-devel mailing list
>>> ffmpeg-devel at ffmpeg.org
>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
>> To unsubscribe, visit link above, or email
>> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".