[FFmpeg-devel] pipeline multithreading

Reimar Döffinger Reimar.Doeffinger at gmx.de
Tue Nov 25 11:33:41 CET 2014

On 25.11.2014, at 10:01, Daniel Oberhoff <danieloberhoff at gmail.com> wrote:
>> Am 24.11.2014 um 17:16 schrieb Reimar Döffinger <Reimar.Doeffinger at gmx.de>:
>>> On Mon, Nov 24, 2014 at 12:35:58PM +0100, Daniel Oberhoff wrote:
>>> inout -> filter1 -> filter2 -> output
>>> some threads processing frame n in the output (i.e. encoding), other threads procesing frame n+1 in filter2, others processing frame n+2 in filter1, and yet others processing frame n+3 decoding. This way non-parallel filters can be sped up, and diminishing returns for too much striping can be avoided. With modern cpus scaling easily up to 24 hardware threads I see this as neccessary to fully utilize the hardware.
>> Keep in mind the two things:
>> 1) It only works for cases where many filters are used, which is not
>> necessarily a common case
> Also, not quite. Even just decode/encode had a pipeline depth of 2 (the decoder could decode frame n+1 while the encoder encodes frame n). Every filter deepens this more...

If you run encode and decode with multithreading, they already run in different threads.
So if you have only one filter, you should not have any gains at all from per-frame filter multithreading.

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