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    Anyone with a i7-3770 transcoding 1080p in Plex?
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    Anyone with a i7-3770 transcoding 1080p in Plex?

    This is an octa core Cpu with a 9000+ passmark yet plex says the server isn't powerful enough to transcode a single 1080p stream. That's clearly bs so I'm wondering what I'm doing wrong. I don't have plex pass so can't enable HW acceleration. Maybe that's related? Any optimization I can do? The library is in a striped ZFS array capable of 350 MB/s reads so it's obviously not that.

    Assistance appreciated!

    Thx

    Comments

    • Well it certainly is powerful enough for several transcodes never mind one. What is Plex actually doing? What have you got your internet streaming quality set at?

      It's better to keep your mouth shut and appear stupid than open it and remove all doubt

    • hacktek said: This is an octa core Cpu

      It's actually quad core with HT. However, it should pack enough punch for at least a couple 1080p transcodes. Something might be amiss in your transcoder settings.

    • Plex is set up to do the fastest type of transcoding and this is a hetzner box that easily maxes my 25 Mbps connection. Most content works fine direct played but every once in a while my internet becomes slow which is why I'd like for transcoding to work. Even setting the lowest 1080p setting which is like 8 Mbps content becomes unwatchable with the same message.

    • 9k benchmark should be more as enough for that, I think its not cpu bottlenecked.
      Did you took a look at the CPU, I/O wait?

    • hacktekhacktek Member
      edited September 2018

      @saibal said:

      hacktek said: This is an octa core Cpu

      It's actually quad core with HT. However, it should pack enough punch for at least a couple 1080p transcodes. Something might be amiss in your transcoder settings.

      Yeah that's my guess. I'll get a screenshot of what plex is doing when it transcodes using htop but in the meantime these are the transcoding settings in the app:

      https://imgur.com/a/q90iwKO

      Edit: and this is how the cpu looks like while transcoding to 1080p 8 Mbps:

      https://imgur.com/a/SfV6tCG

      It literally played for like 7 seconds before stopping.

    • hacktekhacktek Member
      edited September 2018

      @Neoon said:
      9k benchmark should be more as enough for that, I think its not cpu bottlenecked.
      Did you took a look at the CPU, I/O wait?

      Not sure. Here's iotop: https://imgur.com/a/X8DXtbv

      And a dd read on the ZFS array:

      [email protected]:~# dd if=/content/test.bin of=/dev/null
      2097152+0 records in
      2097152+0 records out
      1073741824 bytes (1.1 GB, 1.0 GiB) copied, 5.12208 s, 210 MB/s

      The iotop looks kind of pathetic at 9 MB/s, I'd expect much higher but not sure if that's related.

    • hacktek said: I don't have plex pass so can't enable HW acceleration

      I don't recommend HW acceleration - it helps transcoding performance, but the quality is just horrible - like unwatchable with some animations.

      I personally run plex on a i7-4790 (Haswell Refresh) + a 12 disk ceph cluster - so in theory, my only bottleneck is the CPU. Although, that said, I had to move plex's metadata library to a SSD backed portion of my ceph cluster - latency was a huge factor in UI performance.

      From my experience, depending on the video encoding, if subtitles are being burned in, etc. - performance can vary widely. For example, hevc @ 1080p takes a huge hit in transcoding performance. I eventually had to switch to the Windows 10 app which is one of the only platforms that supports client side, hardware supported, hevc decoding (so no transcoding needs to occur on plex's side). I also have issues with decoding random AVI files (even locally via VLC is painfully slow).

    • hacktekhacktek Member
      edited September 2018

      Thanks for the comment. This is all quite odd and I wonder if the ZFS stripe is what's causing issues. I'm gonna move one file that fails consistently to a regular partition and see if that changes anything

      Edit: so it looks like it was indeed ZFS. Doing it from a regular partition hits 300 MB/s in reads and never stutters. Now I wish I had tested that before syncing 3 TB of video to it. You live you learn I guess. I'm gonna do some more debugging before nuking the pool.

    • I think I know what happened. I probably wasn't paying a lot of attention but instead of striping two drives like I thought I did, I striped a drive and a (much smaller) partition. I believe that may have caused some internal funkyness. In any case, I got rid of ZFS since I don't need the stripe anyway and just used LVM with two partitions performance is much better now:

      [email protected]:~# dd if=/dev/zero of=/content/test.bin bs=64k count=16k conv=fdatasync
      16384+0 records in
      16384+0 records out
      1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.58563 s, 163 MB/s
      
      [email protected]:~# dd if=/content/test.bin of=/dev/null
      2097152+0 records in
      2097152+0 records out
      1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.63237 s, 658 MB/s
      

      Case closed. Thanks to everyone who jumped on it to help, really appreciate it.

      Thanked by 2netomx vimalware
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