Server Version#: 1.18.2.2029
Player Version#: 4.12.2
I am having stuttering issues with a (DTS 5.1) audio transcode, I tried the following:
the file in VLC has no issues whatsoever, neither does playing the content through the plex android app or plex media player on windows (all “direct stream” the audio)
using a chromecast or the web player triggers a transcode, which stutters the audio stream, making it very annoying to listen to
I tried creating an optimized version, as I thought the real time transcoder couldn’t keep up (unlikely however, as my cpu barely hits 5% per thread during audio transcode, so sequential capacity isn’t saturated here), playing this version on above mentioned media players seems to stutter just like the real time transcoding, even when playing the file locally using VLC, which makes me believe this is an issue with the audio transcoder.
Just to be sure, I disabled hardware acceleration (I know this shouldnt be an issue, as audio seems to be always transcoded on the CPU), this did not change anything at all.
I tried some extreme transcoding quality options, but this did not result to anything (do these options even do anything to audio transcoding?).
Am I missing something that could resolve this issue?
Thx in advance for the help.
If transcoding 5.1 is a problem, I need ask what the CPU is.
VLC is an entirely different architecture. It is reader-renderer.
Plex is read-server -> client-render (wherever that client may be)
It would also help to see DEBUG log files because if 5.1 is indeed the true root cause, then the CPU is so grossly underpowered that it , frankly, should be retired in favor of something much stronger.
my plex server CPU is a ryzen 2700X. video transcoding is done on a quadro p2000, so other than some idle vm’s, there is not a lot that could bottleneck audio transcoding performance.
In my mind it would also be strange that its a CPU bottleneck, as I think optimizing video files also transcodes the audio without setting the requirement of it to be transcoded realtime, but even there the issue remains.
I have a few movies now where I had this issue with, and they are all DTS 5.1 audiotracks.
Thank you for the logs. The information you captured is clear.
PMS is not the problem. The problem is either a) networking to the chromecast or b) the casting app.
This output shows the host transcoding, filling the output buffer, then going to sloth (slumber) mode while it waits for the data in the buffer to be consumed.
ratingKey=486&key=%2Flibrary%2Fmetadata%2F486&playbackTime=43038&playQueueItemID=73874&state=paused&hasMDE=1&time=1069000&duration=8348000 (43 live) TLS GZIP 12ms 845 bytes (pipelined: 36)
Jan 20, 2020 22:06:10.304 [0x1471cddfe700] DEBUG - Session ck5q92vmi9smaiddl9dnzrfr (3) is throttling
Jan 20, 2020 22:06:10.305 [0x14720eff7700] DEBUG - [Transcoder] Throttle - Going into sloth mode.
Jan 20, 2020 22:06:10.450 [0x1471e4fe7700] DEBUG - Request: [127.0.0.1:58942 (Loopback)] GET /identity (42 live) Signed-in
Jan 20, 2020 22:06:10.450 [0x14729c7cc700] DEBUG - Completed: [127.0.0.1:58942] 200 GET /identity (42 live) 0ms 398 bytes (pipelined: 1)
Jan 20, 2020 22:06:10.882 [0x14728dfbe700] DEBUG - Request: [84.197.46.234:59321 (WAN)] GET /video/:/transcode/universal/session/ck5q92vmi9smaiddl9dnzrfr/base/01279.ts (43 live) TLS Signed-in
Jan 20, 2020 22:06:10.883 [0x14728dfbe700] DEBUG - Asked for segment 1279 from session.
Jan 20, 2020 22:06:10.883 [0x14728dfbe700] DEBUG - Returning segment 1279 from session
Jan 20, 2020 22:06:10.883 [0x14728dfbe700] DEBUG - Content-Length of /transcode/Transcode/Sessions/plex-transcode-ck5q92vmi9smaiddl9dnzrfr-26e6ab68-be88-4c48-a6d8-49d7f748dc85/media-01279.ts is 787532 (of total: 787532).
Jan 20, 2020 22:06:10.971 [0x1471e63f1700] DEBUG - Session ck5q92vmi9smaiddl9dnzrfr (3) is unthrottling
Jan 20, 2020 22:06:10.972 [0x14728efc6700] DEBUG - [Transcoder] Throttle - Getting back to work.
Jan 20, 2020 22:06:10.982 [0x14728cdb5700] DEBUG - Transcoder segment range: 18 - 1340 (1340)
Jan 20, 2020 22:06:11.001 [0x14729c9cd700] DEBUG - Transcoder segment range: 18 - 1341 (1340)
Jan 20, 2020 22:06:11.080 [0x14729c5cb700] DEBUG - Completed: [84.197.46.234:59321] 200 GET /video/:/transcode/universal/session/ck5q92vmi9smaiddl9dnzrfr/base/01279.ts (44 live) TLS 197ms 787532 bytes (pipelined: 1)
Jan 20, 2020 22:06:11.080 [0x14729c5cb700] DEBUG - Removed transcode data consumer, active count 1 => 0
Jan 20, 2020 22:06:11.408 [0x1471e67f3700] DEBUG - Session ck5q92vmi9smaiddl9dnzrfr (3) is throttling
Jan 20, 2020 22:06:11.408 [0x1471e79fc700] DEBUG - [Transcoder] Throttle - Going into sloth mode.
thx for the response, maybe some additional info on the log (taking a look at it myself reveals that multiple clients were watching at the time, which makes the log file not very straightforward, sorry about that),
The session that seems to have issues is “acg00ux12ydgyh0ryvby44gc”, which at first sight does not seem to be slumbering. The device I am watching this on is connected by cable to the local network the server is located in (all links can handle full duplex gigabit). The player is a plex web client on chrome, local computational resources on the client should not form a bottleneck.
Client is connected by wire, network is not a bottleneck here, the link between client and server is full duplex gigabit, file size is below 20GB, movie length is above 2 hours, so on average 3MBps should suffice
Server direct streams the video, Audio is transcoded from DTS 5.1 to AAC
Gigabit should be fine. The only time it’s not, or even 100 Mbps), is when Jumbo Frames are involved and the network is not 100% perfect.
I apologize if I got Chromecast on the brain.
The only thing which I can now see, from the residual log segment above, is PMS is fine. It has to be in the player somehow. Is the player CPU the same Ryzen?
My guess is that it is a server side transcoder issue. I generated an optimized version real quick and played it on my ryzen 3900x machine using vlc, which stuttered at the same times as it did in the real time transcode using the plex web app.
furthermore, to eliminate both Ryzen and Windows as client devices from being pottential bottlenecks, I played it on an android tv (nvidia shield tv pro), which also showed the same audio stutters at the same time, which it didn’t show on the original file.
So in my mind, either plex is not playing nice with the ryzen 2700x (worth a note though, this is running in an unraid docker container, so maybe the kvm virtualization has some blame here), which would be a bummer, as with the current trend, I’m not planning on switching to intel anytime soon.
Planning of verifying this by hosting a plex server on intel or nvidia hardware and see if the issue persists.
If those issues persist on different hardware however, it seems to me like there is a bug in the audio transcoder for this particular codec, as multiple video files gave me the same issue?
First, you can’t compare against VLC. It reads & direct-renders on the glass. Plex is a Server-client architecture – entirely different animal. The client is the player (renderer).
I need logs and a sample of the video please (about 2 minutes worth)
I will provide a link for you if you wish it.
