[Libav-user] Speeding up H264 decoding

Simon Brown simon.k.brown at gmail.com
Thu Sep 8 15:30:22 EEST 2016


@Nikita: No, it's built into an FPGA.
@Puneet: That's working much better now.

I've also managed to include the Neon libraries correctly and have noticed
a decent speed improvement, so am much happier.  Now, of course, I need to
make it twice as fast again, but that's going to need a different CPU, I
think.

Cheers,
Simon

On 8 September 2016 at 11:44, Nikita Orlov <nikitos1550 at yandex.ru> wrote:

> I see. Do you have exactly model name of cpu?
>
> 08.09.2016, 13:40, "Simon Brown" <simon.k.brown at gmail.com>:
> > That's excellent - thank you.  I had changed number of threads, but only
> after the codec was opened.
> >
> > The CPU is a dual core Cortex-A9 running at 950MHz.  There is no
> hardware coprocessor, so was hoping to eek out what I could from this.
> >
> > I know FFMpeg has some Neon options (and the libraries have been built
> with HAVE_NEON=1, but does anyone know how much of the H.264 decoder has
> Neon code, if any?
> >
> > Cheers,
> > Simon
> >
> > On 8 September 2016 at 11:11, Puneet Kapoor <puneet.cse.iitd at gmail.com>
> wrote:
> >> I had a similar question sometime back.
> >> Try following this thread: https://ffmpeg.org/
> pipermail/libav-user/2016-July/009365.html see if it helps you.
> >>
> >> Cheers
> >>
> >> On Thu, Sep 8, 2016 at 11:36 AM, Nikita Orlov <nikitos1550 at yandex.ru>
> wrote:
> >>> Hi!
> >>>
> >>> Which cpu do you use? Most probably there is hardware decoder. Current
> cpu usually can decode 4K at 30
> >>> some FullHD at 30 at least.
> >>>
> >>> Another thing, that maybe can suit your case, is to prepare video
> optimized for decode.
> >>> Very simple optimization is to use simplest profile - baseline. I
> believe that there are some other options
> >>> to increase decoding speed, you have to google them.
> >>>
> >>> 08.09.2016, 00:41, "Simon Brown" <simon.k.brown at gmail.com>:
> >>>> Thank you - I tried that, but got no noticeable difference.
> >>>>
> >>>> On 7 September 2016 at 16:59, Kristijonas Malisauskas <
> km at sportcaster.dk> wrote:
> >>>>> First thing i would suggest doing is setting your AVCodecContext to
> use more threads
> >>>>>
> >>>>> for ex: videoCtx->thread_count = 4;
> >>>>>
> >>>>> On Wed, Sep 7, 2016 at 3:05 PM, Simon Brown <simon.k.brown at gmail.com>
> wrote:
> >>>>>> I'm running a decode operation using doc/examples/demuxing_decoding.c
> I'm running on an Arm A9 with Neon enabled.  Sending a 1280x720p stream at
> 24fps it can only decode about 15fps.  Is there any way of speeding up the
> decode operation?
> >>>>>>
> >>>>>> Regards,
> >>>>>> Simon
> >>>>>> _______________________________________________
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> >>>>>
> >>>>> _______________________________________________
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> >>>> ,
> >>>>
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> >>> --
> >>> Nikita Orlov
> >>> Skype: nik_stet
> >>> QQ: 2717846083
> >>>
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> >>
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> > ,
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> --
> Nikita Orlov
> Skype: nik_stet
> QQ: 2717846083
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