[Libav-user] How to access the struct AVCodecTag?

[Anton Shekhovtsov]

вт, 17 мар. 2020 г. в 22:50, Giuseppe Torelli <giutorcom at gmail.com>:

> Hi Carl,
>
> many thanks for replying. I'm really surprised there is no way to get all
> the encoders linked to a particular container. I was able to use
> avcodec_find_encoder(28) where 28 is the ID for MPEG-4 Part 14 and I
> correctly get "libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10" but of
> course there is also libx265 that encodes a video in the MP4 format. I
> thought it was possible to get sich a list.
>
> Many thanks for replying.
> Giuseppe
> --
> Youtube: www.youtube.com/giutor73
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>
>
> On Tue, 17 Mar 2020 at 20:45, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>
>> Am Di., 17. März 2020 um 20:42 Uhr schrieb Giuseppe Torelli
>> <giutorcom at gmail.com>:
>>
>> > I want to fill two combo boxes in a GTK+3 program with the container
>> and its relevant codecs.
>>
>> You cannot use AVCodecTag to achieve this, library users are not
>> supposed to access it.
>>
>> FFmpeg does not export information about supported codecs in containers,
>> this
>> information is not even always available within libavformat, users are
>> allowed
>> to abuse the library.
>>
>> I believe you - as gui author - are responsible to offer compatible
>> combinations to
>> your users.
>>
>> Carl Eugen
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I'm not sure if this is completely sane but I'm using this method for
testing how FFMpeg can mix codec and container: create memory writing
context, prepare writing of container, add single stream with the specific
encoding format, try to finish.
If there is any error assume the format is not supported in the container.
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