If you have not already, we suggest setting your Plex username to something else rather than email which is displayed on your posts in forum. You can change the username at https://app.plex.tv/desktop#!/account
Welcome to our forums! Please take a few moments to read through our Community Guidelines (also conveniently linked in the header at the top of each page). There, you'll find guidelines on conduct, tips on getting the help you may be searching for, and more!

TS-251A high CPU usage constantly on 99% - continuous buffering

mr_elementmr_element Posts: 9Members ✭✭

Hi guys,
I am running on continuous 99% CPU usage and very annoyingly often buffering on my QNAP TS-251A NAS. I've checked the online excel compatibility log by PLEX here and it seems like "I've almost got what it takes".

I mean ok, it says it may struggle with medium to high bitrate. But the 1080p I'm looking to play has these properties:

Bit rate mode : Variable
Bit rate : 6 429 kb/s
Maximum bit rate : 15.0 Mb/s

is it enough to justify 99% usage with lots of buffering on my NAS?

Best Answer

Answers

  • JamminRJamminR Posts: 3,480Members, Plex Pass Plex Pass
    edited February 8

    For a low power NAS - Atom/similiar CPU, yes. 15mbps is a reasonably high bitrate. Even more if there is audio transcoding going on.
    I don't think even Netflix 1080p go as high as 15 (but I don't have guarantee of that)

    I have a TS-653 Pro - it's got an intel j1900, basically, a crippled celeron, and I can do 1080p transcode at average of 40-60% cpu, any more streams and I buffer. Needless to say, I only use my nas for backups and some various other slow tinkering.
    Built a much more powerful (relatively speaking) box for running the main server.

    Server - HW: I7-4790K(Haswell), 16GB - SW: Win10 Pro + PMS v1.13.0.5003
    Misc. HW: HDHR Extend + 2TB RAID1(Intel Z87) + 4x4TB RAID5(QNAP TS-653Pro)
    Shares - From: 2  - To: 18(5) - Potential lifetime PlexPass data generating product customer!
    ISP: ~20mbps up/1TB monthly "cap" - (Monthly avg. xfer ~450gb)
    Search the Plex WIKI before asking silly questions.
    Plex stuff I favor - Tautulli - UASv3 - PlexEmail - FMoviesPlus
  • slimshiznslimshizn Posts: 54Members, Plex Pass Plex Pass

    Are you playing the movies direct or transcoding?

  • mr_elementmr_element Posts: 9Members ✭✭

    @slimshizn said:
    Are you playing the movies direct or transcoding?

    To answer indirectly your question and also to contribute more on the thread I 've come back with findings.

    Currently I have to sets of series in my folders.
    A. Big Bang Theory
    B. The Magicians
    Both series have into their respective folders the first 5 episodes which I downloaded for testing purposes. All episodes are 1080p WEB-DL.

    Now on to the curious part...

    Yesterday I wanted to see if playing these "laggy" episodes from PLEX DLNA (instead of PLEX interface) would make any difference since my Samsung TV can also read DLNA sources. I was amazed to find the following:

    First four episodes for which PLEX has found automatically subtitles through the subtitles.org agent have a quality of 12.1 Mbps AND ALSO DLNA "sees" them as being .mpg instead of .mkv which they really appear to be on my filesystem (please read that sentence as many times as needed cause I believe we have something here).

    The last episode of BOTH tv shows (no.5) which for some reason PLEX neglected to download subs for is still 1080p but at 4.1Mbps quality , my TV's DLNA "sees" it as .mkv AND it happens to play on the PLEX interface WITHOUT ANY LAG!!!

    Coincidence?

  • JamminRJamminR Posts: 3,480Members, Plex Pass Plex Pass

    If you're enabling subtitles during playback, it's my understanding Plex will always require transcoding during subtitles overlay, for devices that aren't compatible, and I think, only uses 1 cpu core, not any more or GPU acceleration.

    If you are not and simply stating that as a sidenote, look at the bitrate differences between what seems laggy and doesn't.
    12.1 (AVERAGE, meaning, it COULD be as high as 24), where as 4.1(average, could be up to 8) plays ok.

    With a low power NAS, you'll need to encode your own videos to the exact format you need for each device, perhaps burrning subtitles in yourself if you're using them, for your content.

    That, or get a more capable server and use the NAS to store all the content.

    To answer your original question, yes, 99% is what you can expect when transcoding any content.

    I'm not sure what else you are expecting. There is no miracle cure other than having direct play capable content for each device you may use with subs already encoded.

    Server - HW: I7-4790K(Haswell), 16GB - SW: Win10 Pro + PMS v1.13.0.5003
    Misc. HW: HDHR Extend + 2TB RAID1(Intel Z87) + 4x4TB RAID5(QNAP TS-653Pro)
    Shares - From: 2  - To: 18(5) - Potential lifetime PlexPass data generating product customer!
    ISP: ~20mbps up/1TB monthly "cap" - (Monthly avg. xfer ~450gb)
    Search the Plex WIKI before asking silly questions.
    Plex stuff I favor - Tautulli - UASv3 - PlexEmail - FMoviesPlus
  • greentrancergreentrancer Posts: 34Members ✭✭
    edited February 12

    @mr_element said:
    Hi guys,
    I am running on continuous 99% CPU usage and very annoyingly often buffering on my QNAP TS-251A NAS. I've checked the online excel compatibility log by PLEX here and it seems like "I've almost got what it takes".

    I mean ok, it says it may struggle with medium to high bitrate. But the 1080p I'm looking to play has these properties:

    Bit rate mode : Variable
    Bit rate : 6 429 kb/s
    Maximum bit rate : 15.0 Mb/s

    is it enough to justify 99% usage with lots of buffering on my NAS?

    Are you playing a H.265 or H.264 video? Do you have hardware encoding enabled?

  • mr_elementmr_element Posts: 9Members ✭✭

    @greentrancer said:

    Are you playing a H.265 or H.264 video?

    H.264

    @greentrancer said:

    Do you have hardware encoding enabled?

    Where can I check this?

  • mr_elementmr_element Posts: 9Members ✭✭

    @JamminR said:
    If you're enabling subtitles during playback, it's my understanding Plex will always require transcoding during subtitles overlay, for devices that aren't compatible, and I think, only uses 1 cpu core, not any more or GPU acceleration.

    If you are not and simply stating that as a sidenote, look at the bitrate differences between what seems laggy and doesn't.
    12.1 (AVERAGE, meaning, it COULD be as high as 24), where as 4.1(average, could be up to 8) plays ok.

    With a low power NAS, you'll need to encode your own videos to the exact format you need for each device, perhaps burrning subtitles in yourself if you're using them, for your content.

    That, or get a more capable server and use the NAS to store all the content.

    To answer your original question, yes, 99% is what you can expect when transcoding any content.

    I'm not sure what else you are expecting. There is no miracle cure other than having direct play capable content for each device you may use with subs already encoded.

    So if PLEX is serving H.264 MKV file and my TV's processing unit is perfectly capable of "understanding" H.254 MKV file , it's still going to transcode due to me having enabled subtitles? Can't there be something to "serve" the subtitles in parallel with the file but not "inside" it (aka transcode) ?

    Another question I would have is , isn't it weird that all files I downloaded got "bumped" to 12.1 Mbps the moment they got subtitles from PLEX whereas the ones that didn't stayed at 4.1? I believe that all files initially where at 4.1 Mbps since they come from the same release group and are of the same quality (1080p , WEB-DL) - it's my view that PLEX somehow changed them after appending subs automatically to them. What's your thought on that?

    Regards,
    -G

  • greentrancergreentrancer Posts: 34Members ✭✭
    edited February 12

    @mr_element said:

    @greentrancer said:

    Do you have hardware encoding enabled?

    Where can I check this?

    Settings > Server > Transcoder > Show Advanced >

    • tick "Use hardware acceleration when available"
    • select 'Very Fast' or higher for "Background transcoding x264 preset"
    • select 'Prefer higher speed encoding' for "Transcoder quality"
  • JamminRJamminR Posts: 3,480Members, Plex Pass Plex Pass
    edited February 12

    @mr_element said:

    So if PLEX is serving H.264 MKV file and my TV's processing unit is perfectly capable of "understanding" H.254 MKV file , it's still going to transcode due to me having enabled subtitles? Can't there be something to "serve" the subtitles in parallel with the file but not "inside" it (aka transcode) ?

    Depends on the device. Though all devices might know MKV, not all devices understand sidecar subtitles. Or for that matter, subs embedded in MKV. Your chances of any device understanding MKV with subtitles inside the MKV (therefore not requiring any or less conversion) as to understanding sidecar subtitles (that require injection into the stream, ie, transcoding) are higher though. You mentioned Plex downloading, to me, that means sidecar, meaning, transcoding.

    Another question I would have is , isn't it weird that all files I downloaded got "bumped" to 12.1 Mbps the moment they got subtitles from PLEX whereas the ones that didn't stayed at 4.1? I believe that all files initially where at 4.1 Mbps since they come from the same release group and are of the same quality (1080p , WEB-DL) - it's my view that PLEX somehow changed them after appending subs automatically to them. What's your thought on that?

    Not too weird. Transcode settings may be different at your server or client end versus when direct playing.
    You shouldn't just presume bitrate is same though until you verify what average bitrate each video is using MediaInfo (3rd party app) or Plex Info.

    @greentrancer - I'm pretty sure hardware acceleration is still plex pass required item. Even if it's not, I don't think there is any on an ARM processor such as his QNAP has.

    Server - HW: I7-4790K(Haswell), 16GB - SW: Win10 Pro + PMS v1.13.0.5003
    Misc. HW: HDHR Extend + 2TB RAID1(Intel Z87) + 4x4TB RAID5(QNAP TS-653Pro)
    Shares - From: 2  - To: 18(5) - Potential lifetime PlexPass data generating product customer!
    ISP: ~20mbps up/1TB monthly "cap" - (Monthly avg. xfer ~450gb)
    Search the Plex WIKI before asking silly questions.
    Plex stuff I favor - Tautulli - UASv3 - PlexEmail - FMoviesPlus
  • mr_elementmr_element Posts: 9Members ✭✭

    Just a quick update:

    I downloaded an MKV movie with SRT subtitles into the container itself and not sidecar. The MKV (which has a respectable bitrate of 11.1Mbps) plays wonderfully through my NAS to my TV, but as soon as I turn on the subtitles it starts transcoding and lagging again. I did a bit of digging and according to the answers on this post (https://forums.plex.tv/discussion/246758/subtitle-support-without-transcoding) the PMS shouldn't be transcoding since it should be respecting the Media/Burn subtitles preference from my TV-client and "overlay subtitles that it streams as text from the server".

    Sadly this is not the case. My last question would be - is there a chance that the problem is client-wise? My Samsung TV has a TIZEN OS and I know this is a not very well-known or wide-spread operating system. Could it be that the PLEX TIZEN app misbehaves?

Sign In or Register to comment.