[FFmpeg-devel] [PATCH 1/6] avformat/format: add av_demuxer_find_by_ext

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Sun Feb 16 13:49:00 EET 2020

Gyan Doshi:
> On 31-01-2020 10:41 pm, Andreas Rheinhardt wrote:
>> Gyan Doshi:
>>> Allows selecting demuxer by extension which are more widely recognized
>>> by users.
>>> Conditional cast added since this function will usually be called
>>> after
>>> av_find_input_format, and so matches its return type.
>> That's not a good point. av_demuxer_find_by_ext() already always
>> returns const AVInputFormat *, so you casting the const away when
>> returning is pointless. Furthermore, any caller that wants to use this
>> new function can simply use a pointer to const AVInputFormat to work
>> with both av_find_input_format() and av_demuxer_find_by_ext(). And
>> after all, adding const makes the code more future-proof
>> (av_find_input_format() will return const AVInputFormat * after the
>> next major bump).
> Ok, I don't think I should add const to the pointers at the receiving
> end (fftools) since they are global variables and may not be
> acceptable as const. So I'll cast away the const when receiving and
> remove the conditional cast.
> Sounds fine?

Given that a user would have to cast the const away for
avformat_open_input() if he worked with pointers to const
AVInputFormat I don't want to block your patch because of
const-correctness. So proceed as you wish.

- Andreas

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