[FFmpeg-user] Which command line can do dvb_teletext from ts to mp4

Henk D. Schoneveld belcampo at zonnet.nl
Wed Feb 17 20:43:13 CET 2016

On 17 Feb 2016, at 20:32, Marton Balint <cus at passwd.hu> wrote:

> On Tue, 16 Feb 2016, Henk D. Schoneveld wrote:
>> On 16 Feb 2016, at 14:40, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>>> Henk D. Schoneveld <belcampo <at> zonnet.nl> writes:
>>>> Stream #0:5 -> #0:2 (dvb_teletext (libzvbi_teletextdec)
>>>> -> mov_text (native))
>>>> Error while opening encoder for output stream #0:2 - maybe incorrect parameters such as bit_rate, rate,
>>>> width or height
>>> It seems that this is only the effect of my incorrect autodetection patch, it works for samples with correctly signaled teletext.
>>> You could try the patch Marton posted today (instead of mine):
>>> "avformat/dvbtxt: add raw demuxer for dvb teletext probing”
>> I applied the patch, behaviour the same. My probably/maybe ‘crippled’ source files work fine with telxcc/srt and ffmpeg as long as ass and mkv as destination are chosen.
>> What I don’t understand is what makes ass -> mkv work and mov_text -> mp4 fail. What is the relation between one and the other. ffmpeg can decode dvb_teletext, is able to put it in ass format and NOT in mov_text format. It doesn’t make much sense to me.
> Okay, I think I hunted this down, the problem is that the probed dvb teletext stream is only detected during avformat_find_stream_info and is not present after avformat_open_input, therefore it has no options set, so the codec defaults to a bitmap output, which has no avctx->subtitle_header, therefore mov_text encoding fails.
ding <-> thinking, the order might be crucial ;-)
> I'll submit a patch which changes the order of initializations in ffmpeg.c and fixes this issue.
That would be great

> Regards,
> Marton
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