[mythtv-users] Performance of the HD MPEG2 decoders

[Todd Ignasiak]

I have seen several reports of performance expectations with the
various MPEG decoders, and what I am seeing is not exactly what other
people have seen, so I wanted to start a discussion here.   Also, I
thought others might be interested in the performance numbers from a
typical system (if anyone has performance info from other CPUs, or
Unichrome XvMC, please post)..

The main unexpected issues I see are:
- libMPEG2 uses much more CPU than the Standard decoder on my system. 
(libmpeg2:80%, Standard: 50%, XvMC: 28%).   The 'help' info in the
GUI, and several posts here, say that libMPEG2 should be have lower
CPU requirements.    Perhaps this is an x86-64 issue.

- In XvMC mode, playback is great until anything comes up on the OSD. 
When that happens, the audio/video becomes choppy until a couple
seconds after the OSD goes away.

- With XvMC and OpenGL-Sync enabled together, the audio/video is
choppy all the time,  I never get smooth playback


Performance Info:

System:  Athlon64 3200+, ASUS K8V Deluxe Motherboard, NVidia FX5200
Graphics card (AGP 8X), Receiver Cards: HD3000, FusionHDTV3, PVR-500.
 Software:  Gentoo x86-64 OS, kernel 2.6.14, NVidia Drivers 7676,
MythTV SVN 7737.

HD Content being used:  720P recording of yesterday's episode of Lost,
on ABC (I'll try some performance tests with 1080i content next).

- Standard MPEG Decoder,  OpenGL Sync ON, Real-Time priority ON,
De-Interlacing OFF (I'm testing with 720P, but I turned it off anyway,
to avoid any potential problems).
 CPU usage:  user: 51%, sys: 5%, idle: 44%
  Video Quality:  good, Audio Quality: good.   OSD effect on playback: None

- libMPEG2 Decoder, OpenGL Sync ON, Real-Time priority ON, Deint: Off
  CPU Usage: u: 72-80%, sys: 4-5%, idle: 19-25%
  Video: good, Audio: good, OSD effect: none

- Standard XvMC Decoder, OpenGL Sync Off, Real-Time ON, Deint OFF
  CPU: u: 28%, sys: 3-4%, idle: 65%
  Video: Good, Audio: Good, OSD effect:  Audio & Video stutter while
OSD is up and for a few seconds after it goes off screen.

- Standard XvMC Decoder, OpenGL Sync ON, Real-Time ON, Deint OFF
  CPU: u:20% sys:2% idle: 78%
   Video: choppy, Audio: choppy,  OSD effect: none - it's already choppy.