[maemo-developers] [maemo-developers] gstreamer launcher (proper video sink?)

From: Frantisek Dufka dufkaf at seznam.cz
Date: Wed Apr 26 15:47:17 EEST 2006
David D. Hagood wrote:
> Also, 
> many of the operations in video codecs are multiply-and-accumulate 
> operations ( a += b*c ), which DSPs have a single instruction to do.
> In short, clock per clock, I suspect the DSP can do more video work than 
> the ARM can.

Well OMAP 1710 is ARM5-TEJ - the E letter means EDSP extensions so it 
has MAC operations too.

> Remember what step 0 of optimization is: MEASURE IT FIRST!
> Until somebody can actually measure where all the time is going, making 
> pronouncements like "It's slow because of X - I just know it" are the 
> root of all evil - you spend a great deal of time tweaking that one 
> thing only to find out that it was only 1% of the time to begin with.

True. Well, as for the measuring, I only know my Tungsten T2 (OMAP 
1510,168Mhz) can play 320x240, 25FPS, 300Kbits mp4 videos better than my 
N770. And TCPMP (palmos video player) uses ARM core only. So I suppose 
even ARM4 core is good enough. I guess 250Mhz ARM5 together with DSP 
helping with decoding audio (and maybe some video step - blitting with 
color space conversion?) could do much better.

You can watch /sys/devices/platform/dsp/loadinfo while playing video, 
the DSP is constantly at 100% when playing video.

But I admit these are just my theories. I still had no time to 
investigate gstreamer framework on N770 in detail.


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