[mythtv] [mythtv-commits] Ticket #6986: max CPUs setting for Multithreading ffmpeg h264 has no affect.
John
reidjr at btconnect.com
Sun Sep 6 07:05:56 UTC 2009
MythTV wrote:
> #6986: max CPUs setting for Multithreading ffmpeg h264 has no affect.
> -----------------------------------+----------------------------------------
> Reporter: reidjr_at_lineone_net | Owner: ijr
> Type: defect | Status: closed
> Priority: major | Milestone:
> Component: MythTV - General | Version: head
> Severity: medium | Resolution: invalid
> Mlocked: 0 |
> -----------------------------------+----------------------------------------
>
> Comment(by anonymous):
>
> Replying to [comment:1 janne]:
> > slice based multi threading requires disabled or not slice spanning loop
> filter.
> >
> > so this is a known limitation and I close this as feature request
> without patch. it will be fixed when frame based multithreading is merged
> to ffmpeg.
>
> Thanks for the clarification. Patch to disable the loop filter is attached
> to #4653
>
>
I spent some time checking if this was a known issue, and trying to
backtrack through versions to see where it "stopped working". I had
obviously never noticed that you needed to disable loop filter to use
multi threaded, as I have always needed both. It wasn't in the mailing
archives, but now I have the magic key words "slice based multi
threading" Google puts it in the first few hits.
Strangely I found that loop filter disabled on a single core made no difference, and multi threading appeared to increase the overall usage. As I am sure that on a single core disabling the loop filter used to reduce the cpu load by about 40%, as my first attempts with the skip loop patch was on a 3200+ Athlon. Any I idea why this is, has the underlying ffmpeg loop filter code improved significantly, or why is disabling the loop filter making little or no difference ?
I guess theres still no chance of disabling the loop filter by default with a 1 line patch ?
Thanks again.
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