[FFmpeg-devel] Load balancing problem with ffh264 deblock filter

Andreas Öman andreas
Thu Sep 11 18:32:59 CEST 2008

Goga777 wrote:
>> 2008/9/11 Stefan Ellenberger <stefan_ell at hotmail.com>:
>> [...]
>>> I do not understand why deblocking does not use several threads although the parameters I used do request it:
>>> "mplayer -cache 16000 -vfm ffmpeg -vc ffh264 -lavdopts threads=2 -framedrop -ao oss -vo xv hdsuisse_testrec.ts"
>>> I increased threads to 3 and 4 resulting in the same deadlock situation: one core at max, the second stays at 30%. The only way I found to get around this is to skip deblocking by using skiploopfilter=all and option "fast". Cpu load on both cores now varies at 70% leaving 30% to the max.
>> Firstly, this is the wrong mailing list. If you wish to submit a patch
>> to improve the situation, great. If not then you should send items
>> like this to the user mailing list.
>> Secondly, ffh264 is not yet multi-threaded. There is work ongoing to
>> implement this.
> afaik - ffh264 is not yet multi-threaded only for frame based video. For slice based video ffh264 supports multi-threading. I'm correct ?

Yes, unless the deblocking needs to be performed across slices (Which
is controlled in the stream itself). It's possible to ignore this
"constraint" by specifying '-flags2 fast' on the ffmpeg
command line.

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