Re: [Libav-user] Speeding up H264 decoding

[Przemysław Sobala]

W dniu 07.09.2016 o 17:59, Kristijonas Malisauskas pisze:
First thing i would suggest doing is setting your AVCodecContext to 
use more threads


for ex: videoCtx->thread_count = 4;
I've done that and have a significant decoding speedup with some files 
but now some other mp4 files fail with:


[libx264 @ 0x3751e20] invalid DTS: PTS is less than DTS

[mp4 @ 0x35a05e0] pts (1548) < dts (2408) in stream 1


I'm using a modified transcoding.c example that handles my sample mp4 
file correctly with thread_count=1 and fails with 0 , >1 or "auto".


What has to be taken into consideration when using multithreaded decoding?

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Re: [Libav-user] Speeding up H264 decoding

[Henry, David]

> 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 
> mailto:simon.k.br...@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?

Depends on the version of ffmpeg.  I have found that previous to ffmpeg 3.0, 
setting the decode threads to 4 sped up decoding enormously (on a server class 
system with 32+ cpu cores running Ubuntu).
Since ffmpeg 3.0 however, we had to revert to setting the threads to 0 on that 
same system (allow ffmpeg to decide how many decode threads to use) because 
using 4 decode threads was running too slow.

David Henry

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Re: [Libav-user] Speeding up H264 decoding

[Carl Eugen Hoyos]

2016-09-08 15:24 GMT+02:00 Simon Brown :

> When I set the thread_count correctly (using a dict, setting to "auto" and
> before the codec was opened) based on a later reply it made a significant
> difference to speed.  So my guess would be that it defaults to 1 CPU core
> or 1 thread.

Thanks for (testing and) explaining!

Carl Eugen
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Re: [Libav-user] Speeding up H264 decoding

[Simon Brown]

On 8 September 2016 at 14:12, Carl Eugen Hoyos  wrote:

> 2016-09-07 17:59 GMT+02:00 Kristijonas Malisauskas :
> > First thing i would suggest doing is setting your
> > AVCodecContext to use more threads
> >
> > for ex: videoCtx->thread_count = 4;
>
> I believe default is to use all cpu cores.
>
> Please do not top-post here, Carl Eugen


Apologies - I was following what other people were doing - re top-posting.

When I set the thread_count correctly (using a dict, setting to "auto" and
before the codec was opened) based on a later reply it made a significant
difference to speed.  So my guess would be that it defaults to 1 CPU core
or 1 thread.

Simon
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Re: [Libav-user] Speeding up H264 decoding

[Carl Eugen Hoyos]

2016-09-07 17:59 GMT+02:00 Kristijonas Malisauskas :
> First thing i would suggest doing is setting your
> AVCodecContext to use more threads
>
> for ex: videoCtx->thread_count = 4;

I believe default is to use all cpu cores.

Please do not top-post here, Carl Eugen
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Re: [Libav-user] Speeding up H264 decoding

[Simon Brown]

@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  wrote:

> I see. Do you have exactly model name of cpu?
>
> 08.09.2016, 13:40, "Simon Brown" :
> > 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 
> 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 
> wrote:
> >>> Hi!
> >>>
> >>> Which cpu do you use? Most probably there is hardware decoder. Current
> cpu usually can decode 4K@30
> >>> some FullHD@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" :
>  Thank you - I tried that, but got no noticeable difference.
> 
>  On 7 September 2016 at 16:59, Kristijonas Malisauskas <
> k...@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 
> 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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Re: [Libav-user] Speeding up H264 decoding

[Nikita Orlov]

I see. Do you have exactly model name of cpu?

08.09.2016, 13:40, "Simon Brown" :
> 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  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  wrote:
>>> Hi!
>>>
>>> Which cpu do you use? Most probably there is hardware decoder. Current cpu 
>>> usually can decode 4K@30
>>> some FullHD@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" :
 Thank you - I tried that, but got no noticeable difference.

 On 7 September 2016 at 16:59, Kristijonas Malisauskas 
  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  
> 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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>>> Skype: nik_stet
>>> QQ: 2717846083
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Re: [Libav-user] Speeding up H264 decoding

[Simon Brown]

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 
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 
> wrote:
>
>> Hi!
>>
>> Which cpu do you use? Most probably there is hardware decoder. Current
>> cpu usually can decode 4K@30
>> some FullHD@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" :
>>
>> Thank you - I tried that, but got no noticeable difference.
>>
>> On 7 September 2016 at 16:59, Kristijonas Malisauskas 
>> 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 
>> 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
>> ___
>> Libav-user mailing list
>> Libav-user@ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
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>> ___
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>>
>>
>> --
>> Nikita Orlov
>> Skype: nik_stet
>> QQ: 2717846083
>>
>>
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>>
>
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Re: [Libav-user] Speeding up H264 decoding

[Puneet Kapoor]

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  wrote:

> Hi!
>
> Which cpu do you use? Most probably there is hardware decoder. Current cpu
> usually can decode 4K@30
> some FullHD@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" :
>
> Thank you - I tried that, but got no noticeable difference.
>
> On 7 September 2016 at 16:59, Kristijonas Malisauskas 
> 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 
> 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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>
>
> --
> Nikita Orlov
> Skype: nik_stet
> QQ: 2717846083
>
>
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Re: [Libav-user] Speeding up H264 decoding

[Nikita Orlov]

Hi! Which cpu do you use? Most probably there is hardware decoder. Current cpu usually can decode 4K@30some FullHD@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 optionsto increase decoding speed, you have to google them. 08.09.2016, 00:41, "Simon Brown" :Thank you - I tried that, but got no noticeable difference.On 7 September 2016 at 16:59, Kristijonas Malisauskas  wrote:First thing i would suggest doing is setting your AVCodecContext to use more threadsfor ex: videoCtx->thread_count = 4;On Wed, Sep 7, 2016 at 3:05 PM, Simon Brown  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___ Libav-user mailing list Libav-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/libav-user ___ Libav-user mailing list Libav-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/libav-user ,___Libav-user mailing listLibav-user@ffmpeg.orghttp://ffmpeg.org/mailman/listinfo/libav-user  -- Nikita OrlovSkype: nik_stetQQ: 2717846083 ___
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Re: [Libav-user] Speeding up H264 decoding

[Simon Brown]

Thank you - I tried that, but got no noticeable difference.

On 7 September 2016 at 16:59, Kristijonas Malisauskas 
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 
> 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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Re: [Libav-user] Speeding up H264 decoding

[Kristijonas Malisauskas]

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  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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