[mythtv-users] Problems with vdpau decoding HD content

[R. G. Newbury]

On 05/14/2010 01:40 PM, Scott wrote:
>
> On May 14, 2010, at 1:29 PM, Scott Russell wrote:
>
>>
>> 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
>> EndSection
>>
>> Section "Device"
>>         Identifier      "Default Device"
>>         Driver  "nvidia"
>>         Option  "DPI"           "100x100"
>>         Option  "NoLogo"        "1"
>>         Option  "UseEvents"     "1"
>>         Option  "TripleBuffer"  "1"
>> EndSection
>>
>> Section "Serverflags"
>>         Option  "BlankTime"     "0"
>>         Option  "StandbyTime"   "0"
>>         Option  "SuspendTime"   "0"
>>         Option  "OffTime"       "0"
>> EndSection
>>
>> Section "Extensions"
>>         Option "Composite" "Disable"
>> EndSection
>
>
> errrrr... the TripleBuffer option was causing problems with mythtv crashes and X failing. I had to remove it.

Going from memory here but OpenGL-Vsync-to-Blank has to be 'ON' to make 
use of Triplebuffer. You might check whether that was/is true. On my two 
setups using TripleBuffer did reduce the 'Prebuffer' pause errors, and 
smoothed out playback.

Geoff


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