[FFmpeg-devel] [PATCH] Fix quadratic memory use in ff_h2645_extract_rbsp() when multiple NALUs exist in packet.

Kieran Kunhya kierank at obe.tv
Tue Oct 31 03:42:28 EET 2017

On Tue, 24 Oct 2017 at 00:56 Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 2017-10-24 1:43 GMT+02:00 Niki Bowe <nbowe-at-google.com at ffmpeg.org>:
> > On Thu, Oct 19, 2017 at 3:39 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com>
> > wrote:
> >> Does the patch have a measurable speed impact?
> >>
> > Is there a standard set of benchmarks I can run?
> >
> > For typical videos the speed impact is small, due to NALU fitting in
> cache,
> > but for videos with many large NALUs there can be some slowdown.
> (5% overall slowdown would make every patch unacceptable
> but I doubt this is the case.)
> Use the TIMER makros from libavutil/timer.h, put them around all
> calls to ff_h2645_extract_rbsp().

Related to https://trac.ffmpeg.org/ticket/6789, we see huge memory
allocations in this code so if this patch fixes, it should be committed
irrespective of any speed loss.


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