Another case of Decoder timed out waiting for free video buffers

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dborn
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Another case of Decoder timed out waiting for free video buffers

Post by dborn »

Hi all,

I have a 5 computer MythTV setup, 1 combined BE/FE and 4 FEs with varied hardware setups, ranging from a 10+ year-old BE/FE with a GT210 graphics card, a RaspberryPi 3, a couple of low-power computers with integrated nVidia graphic cards, a more powerful desktop (for 4K viewing) with a GeForce 1050GTX and Intel i3 processor.

All are running xubuntu 18.04 and MythTV 29.1 and all suffer this intermittent problem: either Live TV or recorded shows will hang on error "Decoder timed out waiting for free video buffers" pretty regularly, usually once a day or more.

This has started happening more and more in the recent months. I've read the posts related to this problem on this forum and none seem to apply to my problem.

Any help would be appreciated,
Daniel
Last edited by dborn on Fri Feb 21, 2020 7:06 pm, edited 1 time in total.
dborn
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Re: Another case of Decoder timed out waiting for free video buffers

Post by dborn »

No one? this only happens to me?

I believe this problem is frontend related and not backend..? strange that all my 5 frontends suffer the same issue.
I sometimes see a freeze at the hour change (such as 7:00) but these usually recover before the timeout occurs.
I also see a "Please Wait..." message on the screen when I start a new playback which lasts much longer than it used to, in the order of 15-20 seconds. I used to see maybe 2-3 seconds of this message but now it's much longer.

To me the worst thing is when you're watching a several-hours-long show that hangs and then returns to the menu. You have to then go back in and skip forward (of fast forward) for a very long time to return to where we were. I'd sure love to be able to figure out and fix this issue, and so would my wife, which usually looks at me with angry eyes (as if it was *my* fault) when this happens... Sure doesn't help the WAF... :roll:
wesnewell
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Re: Another case of Decoder timed out waiting for free video buffers

Post by wesnewell »

I've also got 1 be/fe combo and 4 other fe only machines and don't have a problem now. A while back I hd problems with something similar. Turns out it was a disk hardware problem. Had 2 750GB disk running in raid 0. It worked fine for a few years but then I'd get freezes and the HD light would come on solid and may or may not start playing the recording again before it timed out. Since replacing those disk with a single new drive the problem went away. I use built in nvdia on all but my new master be/fe which is an amd ryzen 2200G with built in graphics. I use normal playback on all of them. V30
BE/FE-Asrock AB350 Pro Ryzen 3 3200G, 6 atsc tuners. FE's-GF8200's Athlon II, Ryzen 3 2200G. Mythtv user since 2005.
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pvr4me
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Re: Another case of Decoder timed out waiting for free video buffers

Post by pvr4me »

dborn wrote:
Sun Feb 09, 2020 3:41 pm
Hi all,

I have a 5 computer MythTV setup, 1 combined BE/FE and 4 FEs with varied hardware setups, ranging from a 10+ year-old BE/FE with a GT210 graphics card, a RaspberryPi 3, a couple of low-power computers with integrated nVidia graphic cards, a more powerful desktop (for 4K viewing) with a GeForce 1050GTX and Intel i3 processor.

All are running xubuntu 18.04 and MythTV 29.1 and all suffer this intermittent problem: either Live TV or recorded shows will hang on error "Decoder timed out waiting for free video buffers" pretty regularly, usually once a day or more.

This has started happening more and more in the recent months. I've read the posts related to this problem on this forum and none seem to apply to my problem.

Any help would be appreciated,
Daniel
Not sure where you are located but I have semi-regular problems with Global Toronto. I record the news at 11:00 pm and in the last few months, have experienced many damaged recordings. Shows recorded earlier in the evening are fine. I suspect it is due to Global changing their broadcast output power but I've never really tried to verify what is going on.

Craig
Formerly the MacPorts guy.
tarmacalastair
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Re: Another case of Decoder timed out waiting for free video buffers

Post by tarmacalastair »

You're not alone! Not sure I can help but I do share your frustration.

For me it's been happening for six months or more and I'm pretty sure it's a frontend problem too - when my FE/BE combined system locks up I can still play back my recordings from my Raspberry Pi (a Pi3 and a Pi4) running Kodi.

Before this I've been running the FE/BE setup on the same hardware since 2007 with very few problems and running HD via VDPAU for several years. I've always used Ubuntu, from 8.04 up to my current setup running 16.04. Oh, I said with very few problems but the NVidia drivers have always been a nightmare to get working but that's another story!

I've been on MythTV 30 for over a year (via ppa) and reckon the problems have been going on for well over six months.

Been meaning to post for ages, sorry.

My symptoms/observations:
  • During playback the most likely cause seems to be when skipping forward and back (especially backwards) when trying to find the right part of a recording or going back to see something again. It often takes several skips to make it happen.
  • I see the same message as you in the logs.
  • The backend continues to record successfully and recordings can be played on other systems despite the main system locking up.
  • My whole PC seems to seize up and become totally unresponsive. Switching to a different tty via CTRL/ALT F1, etc does nothing. The only way I can access it is via ssh and then top shows sky high CPU usage with the main culprits being the processes:
    mythfrontend
    X
    Xorg
    Often, only mythfrontend looks to be gobbling up the CPU until I stop it and then the other processes suddenly ramp up their CPU.
  • For months I used to press the power button but that meant losing lots of recordings if they were in progress.
  • For years my recordings were going to my Synology via NFS. Thinking this might be an issue, I started new recordings to the local drive but that doesn't seem to have helped.
  • Out of frustration over the last few months I've tried with limited success to stop the rogue processes but stopping mythfrontend only led to the other processes hanging. I've eventually settled on the following script that I run from my Android phone using Scriptkitty. You can see from the comments that I've tried various sleep timeouts to wait for the commands to complete but the current iteration works fairly well - although I often have to restart lightdm a further time once the script completes:

    Code: Select all

    #!/bin/bash
    pkill -9 mythfrontend
    pkill -9 mythwelcome
    pkill -9 mythfrontend
    #sleep 2 &&pkill -9 mythfrontend
    #sleep 2 &&pkill -9 mythwelcome
    #sleep 2 &&pkill -9 mythfrontend
    sudo pkill -9 X
    sudo pkill -9 Xorg
    sudo /etc/init.d/lightdm restart
    
    (I had to add pkill and lightdm restart to my sudoers file, forgotten exactly how)
  • Even though I eventually realised that I don't need the sleep commands, be patient if you try this as it still takes ages to run - I usually go and make a cuppa as it seems like nothing is happening. When it does eventually come back though, at least I can carry on watching without losing what's currently recording.
I've been frustrated by this issue for a long time now and have considered giving up on Mythfrontend altogether and using Kodi instead but I'm hoping that someone might be able to help!

Cheers,
Alastair
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paulh
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Re: Another case of Decoder timed out waiting for free video buffers

Post by paulh »

The video playback has been almost completely rewritten for MythTV 31.0 which will be released very soon :)

I do anticipate some video playback teething problems with the new release which will only become apparent as more people test it but the hope is it should be easier to maintain and be more stable in the long run.

You can test it now by switching to the fixes/31 PPA (https://launchpad.net/~mythbuntu/+archive/ubuntu/31).
tarmacalastair
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Re: Another case of Decoder timed out waiting for free video buffers

Post by tarmacalastair »

Thanks Paul. I'll get onto 31.0 in the next few days and see how it goes. I hope it works in 16.04 as I'm too scared to update due to NVidia driver issues as it never goes smoothly!
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paulh
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Re: Another case of Decoder timed out waiting for free video buffers

Post by paulh »

Unfortunately 31.0 needs a newer version of Qt than is available in 16.04 so no packages will be built for it. We do support the 18.04 LTS release though.

I use the propitiatory NVidia driver on several systems and can't say I've had any problems. The only time you will have problems is if your video card is really old and no longer supported by NVidia.

For me the secret is to keep things up to date so update at lease once a month then things just work. It's when you wait many years to update that you end up with not one but many problems that can be hard to figure out what is causing what problem. Just my 2 pence worth others will probably disagree :)
tarmacalastair
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Re: Another case of Decoder timed out waiting for free video buffers

Post by tarmacalastair »

Thanks again. Looks like I'm going to have to be brave then. I've got 2 systems with NVidia and they've both been a nightmare. I always have to try lots of different versions (latest never seems to work) and do lots of fiddling with Xorg.conf. Even when Xorg.conf works fine on the old OS, as soon as I upgrade it stops working. SImilar problems with my LCDd setup. Hence I update as little as possible.

Oh well, thanks for the heads up.
wesnewell
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Re: Another case of Decoder timed out waiting for free video buffers

Post by wesnewell »

Until recently all 5 of my system used nvidia chipsets, and all work perfectly using the kernel driver. Before that I had lot's of problems too with the prop driver versions. Switch to the non prop drivers and you should be ok. All of my video is onboard video. Most are GF8200, with one 6150 on an old Athlon 4800+ machine.
BE/FE-Asrock AB350 Pro Ryzen 3 3200G, 6 atsc tuners. FE's-GF8200's Athlon II, Ryzen 3 2200G. Mythtv user since 2005.
tarmacalastair
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Re: Another case of Decoder timed out waiting for free video buffers

Post by tarmacalastair »

Thanks wesnell. I'll give it another go but I seem to remember that the Nouveau driver (is that what you mean by non prop?) didn't work for HD recordings.
Anyway it'll be a few days before I get to try it and I'll have to do a Clonezilla image first so I can revert if (when) it goes horribly wrong!

Sorry to hijack the thread, Daniel. Hope you get to the bottom of your issue!
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