[gentoo-user] ffmpeg "threads" parameter

[gentoo-user] ffmpeg "threads" parameter

[7v5w7go9ub0o]

Some ffmpeg-using applications (e.g. mplayer) allow you to pass numbers
of threads (e.g. I use 6 on my Core-I7) to ffmpeg; others (e.g.
chromium) do not.

So I'm thinking of hardwiring a default threads number=6 into the ffmpeg
source code; recompiling.

Q:     Has anyone done this; if so any surprises?


TIA

[gentoo-user] Re: ffmpeg "threads" parameter

[Nikos Chantziaras]

On 03/28/2010 02:40 AM, 7v5w7go9ub0o wrote:
> Some ffmpeg-using applications (e.g. mplayer) allow you to pass numbers
> of threads (e.g. I use 6 on my Core-I7) to ffmpeg; others (e.g.
> chromium) do not.

First, mplayer uses its own bundled ffmpeg.  It doesn't use 
media-video/ffmpeg at all.

Furthermore, this is not what the "threads" USE flag does for ffmpeg. 
Those applications that allow you to specify an amount of threads assume 
you're using ffmpeg-mt instead of normal ffmpeg.  ffmpeg-mt is a fork of 
ffmpeg and is not in Portage because it's still considered non-stable 
upstream.

There's an ebuild in Gentoo Bugzilla for ffmpeg-mt and an mplayer that 
uses ffmpeg-mt as its bundled ffmpeg version.  The mt mplayer ebuild can 
also be found in the wirelay overlay (it's in layman.)

[gentoo-user] Re: ffmpeg "threads" parameter

[7v5w7go9ub0o]

On 03/27/10 21:17, Nikos Chantziaras wrote:
> On 03/28/2010 02:40 AM, 7v5w7go9ub0o wrote:
>> Some ffmpeg-using applications (e.g. mplayer) allow you to pass
>> numbers of threads (e.g. I use 6 on my Core-I7) to ffmpeg; others
>> (e.g. chromium) do not.
>
> First, mplayer uses its own bundled ffmpeg. It doesn't use
> media-video/ffmpeg at all.
>
> Furthermore, this is not what the "threads" USE flag does for
> ffmpeg.



Thank you for replying!!!

What would you guess the "threads" parameter is for ffmpeg? I've not
found an explanation, and thought it might be the author catching up
with Alexander Strange.

<http://ffmpeg.org/ffmpeg-doc.html>


> Those applications that allow you to specify an amount of threads
> assume you're using ffmpeg-mt instead of normal ffmpeg. ffmpeg-mt is
> a fork of ffmpeg and is not in Portage because it's still considered
> non-stable upstream.

> There's an ebuild in Gentoo Bugzilla for ffmpeg-mt and an mplayer
> that uses ffmpeg-mt as its bundled ffmpeg version. The mt mplayer
> ebuild can also be found in the wirelay overlay (it's in layman.)

AH! I had switched from bugzilla to the overlay for mplayer (thank you for
providing it); but was unaware that ffmpeg-mt had a separate ebuild.
Where is it, please?

So the same question, then, for ffmpeg-mt; if I replace ffmpeg with
ffmpeg-mt after setting a default of 6, can you imagine any problems
(other than it is not stable)?

Thanks for the help!

Re: [gentoo-user] Re: ffmpeg "threads" parameter

[Daniel Troeder]

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On 03/28/2010 04:02 AM, 7v5w7go9ub0o wrote:
> On 03/27/10 21:17, Nikos Chantziaras wrote:
>> On 03/28/2010 02:40 AM, 7v5w7go9ub0o wrote:
>>> Some ffmpeg-using applications (e.g. mplayer) allow you to pass
>>> numbers of threads (e.g. I use 6 on my Core-I7) to ffmpeg; others
>>> (e.g. chromium) do not.
>>
>> First, mplayer uses its own bundled ffmpeg. It doesn't use
>> media-video/ffmpeg at all.
>>
>> Furthermore, this is not what the "threads" USE flag does for
>> ffmpeg.
> 
> 
> 
> Thank you for replying!!!
> 
> What would you guess the "threads" parameter is for ffmpeg? I've not
> found an explanation, and thought it might be the author catching up
> with Alexander Strange.
> 
> <http://ffmpeg.org/ffmpeg-doc.html>
The "normal" ffmpeg probably (just guessing here) uses threads for
asynchronous i/o, buffering etc..
ffmpeg-mt includes a H.264 codec that decodes (and encodes?) HD videos
with multiple threads. Maybe there are even more codecs that they have
multithreaded, and probably a lot of infrastructure code had to be
changed as well.

Bye,
Daniel


>> Those applications that allow you to specify an amount of threads
>> assume you're using ffmpeg-mt instead of normal ffmpeg. ffmpeg-mt is
>> a fork of ffmpeg and is not in Portage because it's still considered
>> non-stable upstream.
> 
>> There's an ebuild in Gentoo Bugzilla for ffmpeg-mt and an mplayer
>> that uses ffmpeg-mt as its bundled ffmpeg version. The mt mplayer
>> ebuild can also be found in the wirelay overlay (it's in layman.)
> 
> AH! I had switched from bugzilla to the overlay for mplayer (thank you for
> providing it); but was unaware that ffmpeg-mt had a separate ebuild.
> Where is it, please?
> 
> So the same question, then, for ffmpeg-mt; if I replace ffmpeg with
> ffmpeg-mt after setting a default of 6, can you imagine any problems
> (other than it is not stable)?
> 
> Thanks for the help!
> 
> 


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