Hardware acceleration : different performance behavior between Windows Webclient and FireTV

Plex Media Server Desktops & Laptops
1

Hi there,
I have purched PlexPass to use hardware based transcoding on my Plex Server running on Debian with Asrock J4205-ITX mainboard.

When I switch hardware acc off, then 4k HEVC encoded videos do not run smoothly - not on Windows WebClient nor on FireTV Stick (V2).
Here are the log for speed and CPU load with an example movie when HW accel is off:

Windows:
HW off -> Windows Webclient:

root@omv:~# sar 1 10
Linux 4.18.0-0.bpo.1-amd64 (omv) 01.11.2018 x86_64 (4 CPU)

11:02:52 CPU %user %nice %system %iowait %steal %idle
11:02:53 all 93,25 4,00 2,25 0,00 0,00 0,50
11:02:54 all 91,48 7,02 0,50 0,00 0,00 1,00
11:02:55 all 91,75 6,75 0,75 0,00 0,00 0,75
11:02:56 all 90,23 8,02 0,50 0,00 0,00 1,25

Nov 01, 2018 11:02:55.940 [0x7f19987ff700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:02:56.500 [0x7f198bdb7700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:02:57.013 [0x7f198bdb7700] VERBOSE - * speed => 0.8
Nov 01, 2018 11:02:57.470 [0x7f199ffff700] VERBOSE - * speed => 1.2
Nov 01, 2018 11:02:58.019 [0x7f198bdb7700] VERBOSE - * speed => 0.7
Nov 01, 2018 11:02:58.520 [0x7f199c7ff700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:02:59.071 [0x7f199ffff700] VERBOSE - * speed => 1.1
Nov 01, 2018 11:02:59.558 [0x7f198bdb7700] VERBOSE - * speed => 0.9
Nov 01, 2018 11:03:00.066 [0x7f19adfff700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:03:00.586 [0x7f19aafff700] VERBOSE - * speed => 0.9

See - that CPU load is under full load.

Same with FireTV:

root@omv:~# sar 1 10
Linux 4.18.0-0.bpo.1-amd64 (omv) 01.11.2018 x86_64 (4 CPU)

11:06:45 CPU %user %nice %system %iowait %steal %idle
11:06:46 all 78,45 20,30 1,00 0,00 0,00 0,25
11:06:47 all 77,94 21,30 0,50 0,00 0,00 0,25
11:06:48 all 80,00 17,75 0,50 0,00 0,00 1,75
11:06:49 all 81,70 17,54 0,50 0,00 0,00 0,25
11:06:50 all 76,50 22,50 0,75 0,00 0,00 0,25
^C
Durchschn.: all 78,92 19,88 0,65 0,00 0,00 0,55
root@omv:~# grep -i “speed =” “/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Logs/Plex Media Server.log”| tail -10
Nov 01, 2018 11:06:47.630 [0x7f19adfff700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:06:48.265 [0x7f199ffff700] VERBOSE - * speed => 0.7
Nov 01, 2018 11:06:48.951 [0x7f198bdb7700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:06:49.322 [0x7f19adfff700] VERBOSE - * speed => 0.3
Nov 01, 2018 11:06:49.999 [0x7f198b5b6700] VERBOSE - * speed => 1.0
Nov 01, 2018 11:06:50.419 [0x7f19adfff700] VERBOSE - * speed => 0.7
Nov 01, 2018 11:06:50.874 [0x7f199c7ff700] VERBOSE - * speed => 0.6
Nov 01, 2018 11:06:51.516 [0x7f19adfff700] VERBOSE - * speed => 1.1
Nov 01, 2018 11:06:52.012 [0x7f199ffff700] VERBOSE - * speed => 0.6
Nov 01, 2018 11:06:52.458 [0x7f198bdb7700] VERBOSE - * speed => 0.5

When I switch HW accel on, playing with Windows is no problem:

root@omv:~# sar 1 3
Linux 4.18.0-0.bpo.1-amd64 (omv) 01.11.2018 x86_64 (4 CPU)

11:00:19 CPU %user %nice %system %iowait %steal %idle
11:00:20 all 9,18 0,00 15,22 5,56 0,00 70,05
11:00:21 all 8,37 0,00 15,02 5,91 0,00 70,69
11:00:22 all 8,70 0,00 14,49 6,76 0,00 70,05
Durchschn.: all 8,75 0,00 14,91 6,08 0,00 70,26
root@omv:~# grep -i “speed =” “/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Logs/Plex Media Server.log”| tail -10
Nov 01, 2018 11:00:21.400 [0x7f199ffff700] VERBOSE - * speed => 2.0
Nov 01, 2018 11:00:21.929 [0x7f19adfff700] VERBOSE - * speed => 2.6
Nov 01, 2018 11:00:22.434 [0x7f199ffff700] VERBOSE - * speed => 1.9
Nov 01, 2018 11:00:22.941 [0x7f19adfff700] VERBOSE - * speed => 2.2
Nov 01, 2018 11:00:23.458 [0x7f199ffff700] VERBOSE - * speed => 2.3
Nov 01, 2018 11:00:23.972 [0x7f19adfff700] VERBOSE - * speed => 2.0
Nov 01, 2018 11:00:24.502 [0x7f199c7ff700] VERBOSE - * speed => 2.3
Nov 01, 2018 11:00:25.011 [0x7f19aafff700] VERBOSE - * speed => 2.0
Nov 01, 2018 11:00:25.530 [0x7f19987ff700] VERBOSE - * speed => 2.4
Nov 01, 2018 11:00:26.046 [0x7f19aafff700] VERBOSE - * speed => 2.1

CPU load dramatically decreased!

But when playing with FireTV there is still “server too weak” messages in Plex Player. But CPU load ist pretty much the same as when I’m using the Windows Client whereas overall speed is still under 1.0

Fire TV with HW accel on:

root@omv:~# sar 1 10
Linux 4.18.0-0.bpo.1-amd64 (omv) 01.11.2018 x86_64 (4 CPU)

11:09:35 CPU %user %nice %system %iowait %steal %idle
11:09:36 all 19,15 0,00 7,71 2,74 0,00 70,40
11:09:37 all 17,33 0,00 6,68 2,72 0,00 73,27
11:09:38 all 17,57 0,00 7,18 2,72 0,00 72,52
11:09:39 all 17,82 0,00 6,68 2,72 0,00 72,77
^C
Durchschn.: all 17,97 0,00 7,06 2,73 0,00 72,24
root@omv:~# grep -i “speed =” “/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Logs/Plex Media Server.log”| tail -10
Nov 01, 2018 11:09:37.226 [0x7f19adfff700] VERBOSE - * speed => 0.8
Nov 01, 2018 11:09:37.770 [0x7f199c7ff700] VERBOSE - * speed => 0.5
Nov 01, 2018 11:09:38.323 [0x7f19adfff700] VERBOSE - * speed => 0.7
Nov 01, 2018 11:09:38.865 [0x7f199ffff700] VERBOSE - * speed => 0.6
Nov 01, 2018 11:09:39.350 [0x7f19adfff700] VERBOSE - * speed => 0.6
Nov 01, 2018 11:09:39.899 [0x7f198adb5700] VERBOSE - * speed => 0.7
Nov 01, 2018 11:09:40.505 [0x7f199ffff700] VERBOSE - * speed => 0.9
Nov 01, 2018 11:09:41.046 [0x7f199ffff700] VERBOSE - * speed => 0.8
Nov 01, 2018 11:09:41.600 [0x7f198adb5700] VERBOSE - * speed => 0.6
Nov 01, 2018 11:09:42.140 [0x7f19adfff700] VERBOSE - * speed => 0.7

What can cause the bad FireTV performance? Why ist there no difference compared with “HW accel” off. As you can see CPU is not the limit with “HW accel” on.

To be clear: I’m only talking about 4k HEVC encodes movies. The rest ist working fine.

Any hint greatly appreciated.

Thanks and regards

Joerg

2

Does your server/FireTV have a wired or wireless connection to your network?

3

Which precise CPU model is in your server?
Are you using subtitles?

4

I have both. Fire TV (2nd Gen) with Cable and Fire TV Stick (2nd Gen) using 5 GHz WLAN. Both show exactly same behaviour.

5

Mainboard is named after CPU type: Intel J4205

Edit: Using no subtitles.

6

@OttoKerner: Great! I was accidently thinking using no subtitels. I checked again and subtitles are on. Now I get this using Fire TV with subs off:

Nov 01, 2018 12:03:32.235 [0x7f19977ff700] VERBOSE - * speed => 3.0
Nov 01, 2018 12:03:32.737 [0x7f198b5b6700] VERBOSE - * speed => 2.5
Nov 01, 2018 12:03:33.238 [0x7f198b5b6700] VERBOSE - * speed => 2.9
Nov 01, 2018 12:03:33.776 [0x7f19987ff700] VERBOSE - * speed => 3.1
Nov 01, 2018 12:03:34.285 [0x7f19aafff700] VERBOSE - * speed => 2.5
Nov 01, 2018 12:03:34.776 [0x7f199c7ff700] VERBOSE - * speed => 2.7
Nov 01, 2018 12:03:35.280 [0x7f19977ff700] VERBOSE - * speed => 2.8
Nov 01, 2018 12:03:35.782 [0x7f19977ff700] VERBOSE - * speed => 2.8
Nov 01, 2018 12:03:36.289 [0x7f19987ff700] VERBOSE - * speed => 2.6
Nov 01, 2018 12:03:36.797 [0x7f198b5b6700] VERBOSE - * speed => 2.6

Hooray! Thank you!

But why is performance dropping so low when using subtitles? Bug?

Thanks again!

Best regards

Joerg

7

Subtitles cannot be burned in with hardware acceleration and the code is not multi-threaded (which means it can only use 1 cpu core and not all 4).

8

Ah! I see. Can live with that.

Many thanks again. Problem solved.

Best regards

9

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