[x264-devel] Performance loss of x.264 codec on POWER

[Janne Grunau]

Hi,

On 2016-01-20 12:46:50 +0530, Priya Duggirala wrote:
> 
> Performance of x.264 codec with FFmpeg on ppc64le is 30%-50% slower than on
> x86(Intel). This is in contrast to what is expected on Power8/LE. The x264
> codec needs to be further optimized for Power8/LE as there is signification
> performance degradation on POWER.

I wouldn't call missing optimizations for a specific architecture 
performance degradation. x264 on x86 is one of the library with the 
largest amount of CPU specific handwritten/optimized ASM. The dominance 
of x86 as main computer architecture (safe bet that every x264 developer 
uses it as workstation/notebook) is the main reason for that and no x264 
developer owns or has access to a Power8 machine. Everyone who cares 
about x264's performance for business reasons uses x86 too.

I see that your input is already a h264 video. You'll see that 
libavcodec's h264 decoder shows the same performance "degradation" (for 
the same reasons). Optimizing open source multimedia software for ppc 
got out of fashion after Apple switched to x86 and none of the 
developers used PPC in their everyday computers.

I can understand that you don't like that but given the current 
availability of Power8 under multimedia developers I don't think that it 
is going to change anytime soon.

cheers

Janne