[smallint]

Actually the topic is quite misleading. I had and have always artifacts on some channels (preferably HD) that is not the main issue. I try to track that down for a long time but it is hard. I am operating an Unicable installation which works without problems in combination with a Technisat receiver. On my Cubox-i4 I ran vdr 2.0.6 with vnsiserver and the latest Kodi master + pvr addons and have a Technisat Skystar HD USB connected to it.

Because vdr 2.0.6 exhibits a bug according to FernetMenta with respect to scanning its recordings I upgraded to 2.1.7 and all the latest Git revisions of my plugins: vnsiserver and dvbapi.

The issue I am having now is that LiveTV works as usual (artifacts from time to time, sometimes more often) but when opening the GUI (video control to pause, stop, ...) I get massive artifacts. I know from the iMX6 implementation that memory bus utilization increases when rendering the GUI but those massive artifacts were introduced after upgrading to vdr 2.1.7 and its plugins. Before 2.1.7 the playback was jerky or bumpy with opened GUI but never with more artifacts than during fullscreen playback.

So my question actually is, is there a known increased memory usage (e.g. buffer copies) in either vdr or vnsiserver? The CPU usage during playback is also quite high for both processes: vdr 45%, kodi.bin 50%. Playing from disc keeps Kodis cpu usage below 10%.

Thank you.

[FernetMenta]

I have been using vdr 2.1.6+ for quite some time and have not noticed anything like this. Nor did I get any reports. But that does not mean that there is no issue.
Could you check with htop (or similar) what threads are that busy?

[smallint]

I found the issue. It is related to the iMX6 platform. I changed the AXI bus priorities for IPU and the problem disappears but introduces other issues which are not important for this thread. I think that is related to the usb drivers and I have to investigate further. Thanks for your input.

Regarding top:
thread "device 1 receive" has always a load of 20% which seems to be quite high.

[FernetMenta]

do you have timeshift with file buffer enabled? writing the stream to file can cause this load.

[smallint]

Hehe, I changed it 10 minutes ago to a RAM buffer and it improved a lot although the buffer size is quite limited now. Anyhow, instant recordings are still possible for longer breaks. We are talking round about 2 mb/s which should not cause that load but that is again related to the device and the kernel.

[Ace]

Was the recordings/timeshift dir on usb? If yes, do you mount your usb partition with the syny option? live-tv was unusable on a pi2 with that for me.

[smallint]

No, my disc is connected via eSATA with "/dev/sdaX on / type ext4 (rw,relatime,data=ordered)". With older kernels I had massive problems with usb connected devices and writes (kernel crash after some time) and switched to eSATA. Not sure if the issues have been fixed with my kernel already.