[FFmpeg-devel] [PATCH]lavc/avcodec: Allow libavcodec to overwrite profile and level

Michael Niedermayer michael at niedermayer.cc
Fri Nov 24 18:42:36 EET 2017

On Fri, Nov 24, 2017 at 12:47:16AM +0100, Carl Eugen Hoyos wrote:
> 2017-11-23 22:58 GMT+01:00 Michael Niedermayer <michael at niedermayer.cc>:
> > On Thu, Nov 23, 2017 at 04:01:06PM +0100, Carl Eugen Hoyos wrote:
> >> Hi!
> >>
> >> The (external) encoders may overwrite level and profile because of
> >> requested encoding properties, allowing libavcodec to (also) overwrite
> >> them in the context makes sense (and is already done in some cases
> >> afaict).
> >>
> >> Please comment, Carl Eugen
> >
> > If a user needs to generate a file with a specific profile/level
> > for example because its for broadcast, some specification or a hw
> > decoder.
> > How could he after this patch ensure that exactly the needed profile
> > is used?
> Afair, x264 does change profile and / or level depending on properties
> set by the user. Currently there is no way for the libavcodec user to
> know that libx264 changed something.
> With this change the user can know that he does not get the
> requested values.
> Or am I wrong and libx264 never overwrites requested values
> for level and / or profile?

IIUC (someone please correct me if iam wrong) libx264 can change
the profile/level to a compatible one.

The proposed API would allow any change.
That would add a requirement to the user apps to check if the actual
profile/level is compatible to the users requirements. And that would
make this require special treatment in many user apps, not just pass
user options to ffmpeg

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.
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