[FFmpeg-devel] [PATCH] vf_scale: Detecting changes of incoming frame properties and dinamically evaluate width and height expressions

Paul B Mahol onemda at gmail.com
Tue Jan 19 21:42:03 CET 2016

On 1/19/16, wm4 <nfxjfg at googlemail.com> wrote:
> On Tue, 19 Jan 2016 19:00:18 +0100
> Bodecs Bela <bodecsb at vivanet.hu> wrote:
>> 2016.01.19. 16:53 keltezessel, Carl Eugen Hoyos irta:
>> > Bodecs Bela <bodecsb <at> vivanet.hu> writes:
>> >
>> >> To retain the current behaviour and not to break any
>> >> earlier app, a new config parameter has been introduced.
>> > Is the current behaviour useful or do you consider it a bug?
>> First I thought that it was a bug, but I borrowed an idea from
>> vf_overlay filter, where there is a very same config parameter causing a
>> very similar behaviour distinction on expression evaluation.
>> I will soon post a patch to vf_overlay where there was really a bug in
>> this behaviour.
> I think it's actually a bug. From what I can tell libavfilter's design
> doesn't actually support mid-stream reconfiguration, although it
> happens to work in some cases?

It appears it's undocumented feature. Filter which changes parameters just calls

But not all filter have been tested with this in mind.

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