Hello. Yesterday I updated my OSMC boxes to the latest Krypton version, which for the most part went smoothly and is working really well for almost everything. Congratulations and thanks for the continual hard work by everyone 
However, since the update, movies which contain 7.1 audio tracks (both DTS-MA and Dolby TrueHD) are not playing well on the RBP1 - with severe choppy or stuttering playback. The first 5 seconds of the movie takes more than 30 seconds of elapsed time to play. Waiting for caching or buffering to catch up doesnt seem to help.
The setup is quite basic, with files playing across a wired LAN from an SMB fileserver, through the RBP1 connected directly via HDMI to a TV. The same files played on the previous January version of OSMC quite happily, and still continue to play quite happily on the February version of OSMC using an RBP2 in another room.
The reason im suggesting it may have something to do with the 7.1 audio track is because remuxing (but not reencoding) the file to remove the 7.1 audio, leaving only the DTS/AC3 5.1 track behind, fixes the problem.
I’ve played around with speaker setup and passthrough settings according to @popcornmix suggestions in this thread https://discourse.osmc.tv/t/audio-downmix-issue-with-v17/22323/7 but i’ve not been able to find a combination which helps.
Debug is here: http://paste.osmc.io/ivaqugozow
Mediainfo from example files are here: http://paste.osmc.io/cegenuribo.tex
and here: http://paste.osmc.io/carejuqage.tex
Any advice, help or suggestions would be most welcome.
Thanks.
This should explain things pretty clearly.
http://forum.kodi.tv/showthread.php?tid=307470&pid=2530228#pid2530228
Disable passthrough on your Pi, select 5.1 or 7.1 channel output, and you’ll get lossless decode to 5.1 or 7.1 PCM.
Thanks very much for the reply. That thread seems to be suggesting the same kind of thing as the audio-downmix-issue post that I linked originally.
I had already followed those suggestions, and i’ve since gone back and done it again to recheck, but it doesn’t provide an improvement. I don’t have a receiver between the RBP1 and the TV, so the logical solution to me would be to set the speakers to 2.0 (as per the TV), turn off passthrough (to process/downmix the audio on the Pi), and away we go. That said, i’ve also tried various combinations of turning passthrough on, and setting 5.1 and 7.1 speaker output, just to test whether the TV can handle whats being thrown at it, but the result is always pretty much the same - choppy playback.
My first guess would have been that the RBP1 cant handle the load of processing 7.1 DTS-MA or TrueHD, but like I said, these files played ok before the Krypton upgrade.
Are there any other configuration options you can suggest?
Cheers.
I hate to bump my own post, but does anybody have any advice or suggestions? I’ll even take requests for additional information at this point. Or are we just saying that OSMC has moved beyond playing HD audio on Pi 1 hardware?
Thanks.
Does top show high cpu load?
Does playing back a file locally help?
Top shows the kodi.bin process fluctuating anywhere between about 85% and 95% CPU while an affected file is played, mostly in the top half of that range. Memory for the process is pretty static around 40%. CPU for the whole OS is flatlined at 100%, as you’d expect with one process using that much processor. There doesn’t seem to be any significant change to that depending on whether the stuttering is actively happening or whether playback is normal at the time.
Interestingly, that seems to be the case even when no playback is happening. With Kodi just idle sitting at the GUI (no screensaver running), CPU still seems to be sitting around the 90% mark for the kodi.bin process. Like I said though, 1080p files that don’t have HD audio still play back fine, despite the high CPU.
Playing a file locally is slightly more problematic. All my pi’s boot from NFS roots, so there is no “local” per se, apart from /boot. I’ve copied an affected file onto USB and played it from that, and there isn’t any difference. There’s still a significant amount of intermittent stuttering in the playback.
I’ve also reverted back to the default OSMC skin, just in case my current skin had become too bloated. That also didn’t improve things at all unfortunately.
Thanks again for continuing to help.