[FFmpeg-devel] [PATCH] avcodec/allcodecs: add FFMPEG_PREFER_* env vars

Hendrik Leppkes h.leppkes at gmail.com
Thu Apr 19 17:51:37 EEST 2018

On Thu, Apr 19, 2018 at 4:45 PM, wm4 <nfxjfg at googlemail.com> wrote:
> On Thu, 19 Apr 2018 16:33:09 +0200
> Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>> On Thu, Apr 19, 2018 at 12:40 PM, wm4 <nfxjfg at googlemail.com> wrote:
>> >
>> > Regarding this patch, personally I don't think using getenv() to
>> > configure what is pretty much API semantics is acceptable. But a new
>> > API function that restricts what codecs are used based on a string
>> > argument might be ok. Then applications could use it to implement
>> > codec selection control via environment or command line arguments or
>> > something else.
>> >
>> >
>> I agree with no getenv, handling env variables in a library is an iffy concept.
>> A new API  for that seems pretty weird as well, considering we already
>> have functions to select codecs by name, which can be easily used for
>> this purpose - the same way ffmpeg.c for example implements this.
>> And if you need code changes anyway, might as well do it the way its intended.
> I meant an API that can select the correct codec given a list of
> decoders/encoders, and the actual codec. A codec list could for example
> contain "h264,hevc,...", and of course you always want to pick "hevc"
> if the input is HEVC. I don't think we have an API for this yet?

We don't, but I don't think it adds a whole lot of value, you
basically just save a tiny bit of lookup code yourself. But its a tiny
function either way, so if someone wants to make the case for its
usefulness, not stopping you.

- Hendrik

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