* Steven M. Schultz on Friday, October 02, 2009 at 15:50:41 -0700
> On Fri, 2 Oct 2009, Christian Ebert wrote:
>> Has bumping up the -M option a negative effect on quality?
>
> No. But it also doesn't improve the encoding speed as much as
> people would prefer. There are enough serialisation points in
> the encoder that prevent effective parallel processing.
>
> In the case of the original poster's thread - look at the size of the
> frames being encoded? They are huge - 1024x768! A standard DVD
> frame is 720x480 or perhaps 720x576 so it's not surprising to me
> that a single cpu system takes 4x realtime to do 1024x768 frames!
>
> One way to speed things up would be to scale the frames down to
> 1/2 the size before encoding.
>
> The other way to speed things up would be a dual core cpu so that
> other programs in the pipeline can run in parallel. The encoder
> will realize some benefit from more cpus but the primary benefit
> is that multiple stages in the pipeline can run in parallel without
> taking cpu time away from the encoder.
Thank you for the detailed explanation. Personally I'm fine with
a potential speed up as long as it does not hurt quality. When
you encode to h264 with x264 using more than 1 thread might have
a slight negative effect on motion estimation, iirc; that's why I
asked.
c
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