Comskip prevents Playback

Channels DVR Server
#1

I've been experimenting with comskip and I'm seeing problems with it that may ChannelsDVR unusable. I've found a number of scenarios where this feature eats too much CPU. Any chance we can reduce the priority of these tasks so that playback is always given the highest priority? For sure, commercial skip is only a nice to have and often could take hours to finish if not being watched live.

Tonight, I had two simultaneous recordings with comskip while recording enabled. Had 2 threads allocated. When trying to watch one of the live recordings, playback was anywhere between terrible and "Unable to fetch playlist". While watching CPU loads, it was about 60-70% loaded, then when a play request came in, it hit 100% CPU and stayed there for a while, but at the same time, it failed to start the playback successfully.

My suggested priority:

  1. Playback (Live or Recorded)
  2. Comskip while watching live
  3. All other Comskip

If CPU load exceeds whatever buffer is needed to initiate a new playback request, then start shedding load for non-essentials. Always allow a playback to start.

Observations: I even tried TRASHing a show that had comskip runnning and it did not stop that process. I also tried reducing the thread count to see if this was dynamic and it did not stop anything.

1 Like
#3

IIRC, Comskip is run with a lower nice value by default, giving way to other processes.

If your hardware cannot handle more than a single thread, then change the setting. (I use a crappy 4th gen Intel Core i3, and have no problem with up to 3 threads. If your system cannot handle Comskip with 2 threads while playing back live, you need to change your settings.)

Another possibility: your drive I/O is the issue. Recording places near-zero stress on the processor, nor does playback. (Assuming you are not transcoding.) If you cannot record two streams while playing back another, that points to either an extremely congested network, or failing hardware.

#4

Thanks. I'm running on an i5-5300 with 16 gb ram, 50% utilization and a USB SSD drive. Each comskip process is taking about 30% CPU each, but if they are at a lower priority than ChannelsDVR, then it should not matter. Drive utilization is 0-1%. Network utilization is nil other than ChannelsDVR usage.

At this point, I have 2 comskip running on already recorded shows and playback on ChannelsDVR is but 1% and is working normally. So, I'm going to guess that comskip of live is the beast that is hogging the system. I've only recently turned this on. I've not had playback issues until today, but don't often watch live of recordings. I had 2 recordings in progress and I was trying to watch one of them live.

#5

Mine is an i3-4330 with 24GB RAM. All recordings are on externally powered USB3 drives. Prime time will certainly hear the case fans buzz, but there are no hiccups or quality issues.

This is your bugaboo. Just because your aren't watching live, every recording is processed, live. And because Comskip doesn't know when it ends or whether it's being watched, it is constantly being scanned.

(I personally felt this feature was a poor addition, and you are the shining example as to why. I'm sure if you disable the feature you should have a great continuing experience.)

#6

I should have tested playback of a different recording to see if this changed things. But, I was hellbent on watching Survivor, so I popped over to Tivo.

When it was failing, there were 2 recordings and 2 comskips of active recordings in progress. Later when I returned, it had 2 comskips running, 1 for an active recording and one for a completed recording. However, I experienced no issues what-so-ever watching recordings. I'll experiment with this a bit more before turning the feature off.

1 Like
#7

Linking to a previous thread on the subject. I agree not all tasks require the same priority.

#8

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