[mythtv-users] Problems with vdpau decoding HD content

Scott Russell list-mythtv at bluecamel.eml.cc
Fri May 14 17:29:02 UTC 2010

On May 13, 2010, at 1:14 AM, Scott wrote:

> This is a general query to help me with my troubleshooting of a playback problem on my FE. 
> I have an ASRock 330 ION loaded with Mythbuntu 10.04 and the 0.23-fixes SVN 24572. The system uses the VDPAU Normal profile and is configured for 512MB of GPU RAM in BIOS.
> Playback with both recorded 720p and 1080i (OTA ATSC from a HDHR) shows seems to run into a glitch. The show starts off fine and pausing, FF/RW, and commercial skip all work fine. At some point, usually 12-30 minutes, the video starts jumping and sometimes the audio too. I see "prebuffering pause" messages logged in mythfrontend.log. 
> To resolve the problem I have to reboot the system. To be sure, the following does NOT resolve the problem:
> 1) pause/unpause the show
> 2) stop/start playback again
> 3) exit mythfrontned and start mythfrontend again
> 4) exit X11 and start it again
> Thoughts? Is anyone else having trouble with vdpau and HD recordings on 0.23?

This is an update based on the suggestions given in this thread. Summary is that so far the root cause has not been found and the problem continues.

I've done the following and continue to see a problem when watching 720p or 1080i content:

1) Verified bios is set for 512MB of video memory
2) Modified xorg.conf as shown below.
3) Verified from the nvidia settings utility that the display is showing 1920x1080 at 60hz. The TV menus confirm this is a 1080p signal.
4) Simplified the network connection; changed from 3 switches to one switch (DLink DGS 1216T) and used only store bought cables.
5) Reset all FE settings and then made the following changes:
	- Using VDPAU Normal Profile
	- Using ALSA:hdmi with DTS/AC3 pass through
6) Followed VDPAU troubleshooting recommendations form the wiki making changes to MythTV FE settings as indicated
7) Verified CPU is not over heating, scaling, or running excessive (3-5% usage in TOP)

Open Items to explore:

1) Network trace to ensure nothing funny is going on. Look for dup acks, retransmissions, or out of order packets. This isn't expected to reveal anything
2) Investigate exactly what the "Always stream recordings" option does. Can recordings be played from an NFS mount instead and would that make a difference?
3) The ASRock 330 has a CPU fan and there is no indication of overheating. I tried to check the Nvidia GPU temp but received no output. Need to follow up on this.

Current suspect:

I think the problem is with the nvidia driver or a vdpau playback bug in 0.23. I state this assumption because with JYA 0.22 on Mythbuntu Karmic playback was working okay. However, because this was a major upgrade of both OS and MythTV I have not yet ruled out OS level problems either. That's why I'm looking at things outside of MythTV too.

I've also been rapidly eliminating problems outside of MythTV through testing (as shown). I'm also suspicious of vdpau/nvidia driver problems because once the issue happens so far the only way I can clear it is to reboot the FE. 

I'm not sure yet how to collect debug logs on VDPAU problems other than mythfrontend -v 'general,important,playback'. I've done that much already but would like to get a new set. Can the users list help analyze the logs or should a bug be opened? 

My current xorg.conf:

Section "Screen"
        Identifier      "Default Screen"
        DefaultDepth    24

Section "Device"
        Identifier      "Default Device"
        Driver  "nvidia"
        Option  "DPI"           "100x100"
        Option  "NoLogo"        "1"
        Option  "UseEvents"     "1"
        Option  "TripleBuffer"  "1"

Section "Serverflags"
        Option  "BlankTime"     "0"
        Option  "StandbyTime"   "0"
        Option  "SuspendTime"   "0"
        Option  "OffTime"       "0"

Section "Extensions"
        Option "Composite" "Disable"

-- Scott

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