[mythtv] Sucess! mythtv no X-Window

Steve wilton at hal.humberc.on.ca
Wed Dec 3 15:28:05 EST 2003


> I will be getting an ssh daemon running tonight or tomorrow, I'll let
> you know what the CPU usage, etc is then.

Executive summary: 720x480 at 32bpp seems to be the best for combination of
CPU utilization and output quality. Anything less than 1024x768 should
be OK for CPU, but may not look good on TV (underscanned).

For all these tests, video source is PVR-250 on remote backend, 640x480
mpeg-ps at 3200kbps avg, 6400kbps max, audio is layer 2 at 224kbps 48000
samples/s.

Hardware:
EPIA-M9000
256MB DDR
Output to TV set on S-Video
Output to receiver on S/PDIF

Software:
2.4.23-pre7-epia2 - using cle266vgaio and viafb
alsa-0.9.8 - using snd-via82xx
NFS root filesystem
DirectFB-0.9.20
qt-embedded-free-3.2.3
mythtv-0.12 with directfb patch

I set the framebuffer using:

insmod viafb TVon=1 TVoverscan=1 TVtype=1 refresh=60 bpp=$bpp mode=$mode


640x480
16bpp: 50-60% CPU no jitter/stutter, bottom 1" of TV is underscanned
24bpp: 55-65% CPU same as 16bpp otherwise
32bpp: 50-65% CPU same as 16bpp otherwise (less CPU than 24bpp)

720x480
16bpp: 55-65% CPU no jitter/stutter, full overscan (looks good)
24bpp: 60-70% CPU same as 16bpp otherwise
32bpp: 50-60% CPU same as 16bpp otherwise

800x600
16bpp: 55-65% CPU no jitter/stutter, bottom 1" of TV is underscanned
24bpp: 55-70% CPU same as 16bpp otherwise
32bpp: 65-75% CPU same as 16bpp otherwise

848x480
16bpp: 55-75% CPU no jitter/stutter, bottom 1" of TV is underscanned
24bpp: 55-65% CPU same as 16bpp otherwise
32bpp: 50-75% CPU (all over the place), some "tearing" during pans

1024x768
16bpp: 65-80% CPU, occasional jitter/stutter, full overscan
24bpp: same as 16bpp
32bpp: same as 16bpp

From the tests above, it should be clear that 640x480 is probably the
best, but not if you want to display to TV. In that case 720x480 at 32bpp
offers the lowest CPU to have full overscan. 720x480 also offers the
benefit of not having to scale DVDs for playback.
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