[MPlayer-users] Disable colospace conversion

Reimar Döffinger Reimar.Doeffinger at gmx.de
Fri Jun 28 11:39:11 CEST 2013

Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

>Carl Eugen Hoyos <cehoyos <at> ag.or.at> writes:
>> > CSC is normally done by the -vo so normally hardware 
>> > (gpu) eg. -vo xv or gl or vdpau but may be done by 
>> > cpu eg -vo x11.
>> This is at least very misleading.
>> You are right that vos internally (can) do some 
>> colourspace conversion but - at least imo - that is 
>> irrelevant (since it should happen on the GPU) as 
>> long as we are talking about software OpenGL.
>(Talking about "misleading")
>This meant "as long as we are *not* talking about 
>software OpenGL the internal colourspace conversion 
>should be irrelevant for the overall performance 
>since this conversion happens on the GPU".

If only it was that simple.
This is probably a mobile system.
This means it might be possible that the GPU actually is too slow to do the conversion, especially if gamma correction is enabled.
It also will need quite a bit of memory bandwidth, thus slowing down the CPU. A last effect can be that the additional heat from the GPU means the CPU cores need to the thermally throttled.
So figuring the exact cause might need quite a bit of experimenting.
But -vo null is certainly a good idea, or yuv4mpeg to /dev/null.
But to see where all the CPU cycles go you should also do profiling via e.g. "perf record" (that tool its developed as part of the Linux kernel, and it is a good idea to use a recent kernel).

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