Speed Problems although 50Mbits Upload Speed

Plex Media Server NAS & Devices
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Although i have 50Mbits Upload on Internet Connection, when i try to stream a film with DTS or TrueHDSound is lagging and every 10secs the looping circle appears.

I tried a lot of diff. settings in remote streaming, from original / max quality to 2Mbps and 96k Sound trancoding. Nothing worked for me.

In my Homenetwork with 1,3Gbps everything works fine and the Dashboard Shows only 20Mbps Bandwith in use, way less then i can expect from my 50Mbits Upload Speed for remote streaming.

Can anyone explain this?

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There are a lot of hops between you and that device on the other end.
Every step along the way adds latency (delay) to the round-trip time between server and client.

When the server sends a block of data, it waits for a reply before sending the next. It wants to know it was received OK or not (so it can resend or advance to the next).

You might have 50 Mbps upload and the player might have 50 Mbps download but if the slowest point in between is slow, it’s not uncommon to see even 2 Mbps fail.

As prime example, a friend in California has 40M up/1G down.
I have 2M up, 40M down.

The fastest I can pull a raw file from him is 2.8 Mbps. Why? All the slow peering points as the packets cross from ISP node to node .

The best way to test is for you to setup an iperf server on your system.
Let that other person run iperf to your host and test the available bandwidth.
That will give you definitive throughput capability

1 Like
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Thanks for your reply.
Reading your Post makes me thinking about the fire TV stick with its 2.4Ghz bandwith only. I will try another Stick 3. Generation with a 5Ghz Bandwith. Maybe this solves the bottleneck of Sendling and recieving packages.

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Considering the “DTS or TrueHDSound” and that your post is tagged server-synology, what processor does it have. Many of the low power cpu’s will lag during transcoding of HD audio.

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I am running a Synology DS220J. It has a Realtek RTD1296 4-Core 1,4 GHz CPU.

Maybe my Plex Server Setup or my Telekom Speedport Smart3 is faulty or the end device FireTVStick is to weak and i have to replace it.

So 3 different scenarios i will check the next days.

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So, i am very disappointed and dont know what else to fix.
I tried a plex reset, media analysing, set my synology to zero, i installed plex new to my synology an nothing works for me and none of my tv sticks or laptop although is working. the statistic shows a 25mps connection speed rate but the circle turns and turns and turn, but no media comes up. everthing is set to original quality but nonetheless infobox shows me, it is converting the media.

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  1. In addition to your server remote access settings, check the settings in the Plex app on the FireStick. The default for remote streaming is 2-4 Mbps. This would force a video transcode. Your 220j has limited transcoding capability (720p max) (Reference: Plex NAS Compatibility Guide).

  2. You can monitor playback via Plex Dashboard. The Dashboard will show you if the audio or video is transcoding and the CPU utilization of your DS220j.

  3. Amazon FireTV devices cannot decode TrueHD audio. Plex Media Server transcodes it to AAC. Movies released on Blu-ray disc with TrueHD audio include a Dolby Digital (AC-3) version of the audio track. If available, try playing the movie with the AC-3 audio track, as that audio format direct plays on Amazon FireTV devices.

  4. dts audio direct plays on a FireStick 4K. It is converted on the FireStick to AC3/EAC3/PCM depending on the FireStick audio settings. I’m unsure what happens with dts audio on older FireTV devices. You’ll have to test and monitor via the Plex Dashboard.

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May I please see the DEBUG log files ZIP file which captures this happening?

  1. Verify DEBUG logging ON, VERBOSE logging OFF
  2. Start the playback
  3. Let play until problem or stop after 1 minute
  4. Wait 20 seconds for logs to flush
  5. Download logs ZIP file
  6. Attach here please
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Oh wow, these infos are very interessting. Did not know, that my 220j ist limited to such capability. Though it could stream without further quality restrictions. OK.
And the fireTVstick are not capeable of playing back TrueHD is in my mind, but though the 220j would have enough power to transcode sound in a good quality and speed.
thanks a lot. everything makes sense.

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Plex Media Server Logs_2020-10-28_20-11-43.zip (4.4 MB)

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Thank you for the logs.
I see a lot going on in there.

  1. You’re using VC1 video codec. This is extremely hard on a CPU. You must also convert the 1920 width to 1280 for the player. This conversion will easily consume 50% of the CPU.
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] Harry Potter und die Kammer des Schreckens - video.width limitation applies: 1920 > 1280
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): Direct Streaming is disabled, so video stream will be transcoded
Oct 28, 2020 19:36:02.989 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no remuxable profile found, so video stream will be transcoded
Oct 28, 2020 19:36:02.990 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Cannot direct stream video stream due to profile or setting limitations

Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): media must be transcoded in order to use the hls protocol
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/pcm_bluray
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
Oct 28, 2020 19:36:02.910 [0x7f0288f1a0] DEBUG - [Transcode] MDE: Harry Potter und die Kammer des Schreckens (2002): no direct play video profile exists for http/mpegts/vc1/ac3
  1. PGS subtitles are going to put a heavy load on the machine. It likely won’t be able to send at full speed. Subtitle burning is single threaded. On this CPU, you will see an additionaly 25% CPU load (1 core of the CPU dedicated to the subtitles). The rest of the CPU will do audio & sending of the data.
Oct 28, 2020 19:36:05.056 [0x7f89f521a0] DEBUG - Completed: [127.0.0.1:35932] 200 PUT /video/:/transcode/session/2229962c3ca439ab-com-plexapp-android/13064619-62c3-416a-a774-91c72469eb23/progress/streamDetail?index=43&id=4636&codec=hdmv_pgs_subtitle&type=subtitle (10 live) 0ms 195 bytes (pipelined: 63) (range: bytes=0-)
  1. AC3 audio must also be converted to AAC for the player. About 1/2 of a core.

At this point, you are most likely using 90% of the CPU just for this one video.

I’m not at all surprised that it can’t keep up.

The RTD1296 CPUs (ARMv8) is capable of about 20 Mbps of H.264. This does not speak to the additional computational requirements of H.265 or VC1 nor does it speak to burning PGS (image based) subtitles into the output video.

Options here:

  1. Don’t use VC1 video – pre-process to H.264
  2. Don’t use PGS subtitles – use SRT (text based) which do not require burning.

It’s a good little CPU but this is really making more demand of it than it’s capable of.

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