Ds918+ problem hw transcode mpeg2

Server Version#: 1.13.9.5439
Player Version#: latest roku

Using ds918+ to record live tv (ATSC antenna 1080i, mpeg2 .ts) and hw transcode playback is not working well. It buffers every 2-3min when I play it back on my roku. When I use plex server on my nvidia shield instead, it transcodes the exact same .ts mpeg2 file and plays perfectly. Also when connected to ds918+ server, playing live tv on my iPhone or anything that needs transcoding also buffers every 2-3min. I think hw transcode implementation for mpeg2 is not working well on intel QSP for the ds918+. Are there plans to make mpeg2 transcode work better on the ds918+ in the future? Thank you!

Would you please recreate the condition with DEBUG logging and then attach the log files?

The Shield is quite different than the Synology but Mpeg2 HW decode works fine.
There are many issues reported with the new Roku client.

I would like to separate the server from the player.

Plex Media Server.1.log (5.0 MB)

I deleted the original recorded file so I can’t recreate the problem exactly. But I have attached the debug logs from last night when this problem occurred. If you go to Oct 19, 2018 21:00:01.177 you can see that the server attempts to transcode the mpeg2, but fails because “TPU: hardware transcoding: enabled, but no hardware decode accelerator found”. The video file is called Crazy Ex Girlfriend. Let me know if you need more logs. Otherwise, I can recreate the problem with another recording. Thank you!

Just restarted Plex Media Server and recreated the issue with another live tv recording of Saturday Night Live. Logs are attached.

Plex Media Server Logs_2018-10-21_10-04-40.zip (3.3 MB)

I see the “end of file”. error

Oct 21, 2018 10:01:30.966 [0x7fe6b7bff700] DEBUG - Transcoder segment range: 0 - 30
Oct 21, 2018 10:01:30.967 [0x7fe6bdfff700] DEBUG - Jobs: '/volume1/@appstore/Plex Media Server/Plex Transcoder' exit code for process 10556 is 0 (success)
Oct 21, 2018 10:01:31.535 [0x7fe6a6b35700] DEBUG - [TranscodeOutputStream] Input processing thread exited after writing 847991 bytes, m_closed=0, m_endOfFileReached=1, session->isStopped()=0
Oct 21, 2018 10:01:31.590 [0x7fe6bfbff700] DEBUG - [TranscodeOutputStream] Reached end of file
Oct 21, 2018 10:01:31.590 [0x7fe6bfbff700] DEBUG - Removed transcode output stream 0x7fe6bb645000, active count 1 => 0
Oct 21, 2018 10:01:52.597 [0x7fe6bf911700] DEBUG - Auth: authenticated user 1 as alexberman
Oct 21, 2018 10:01:52.597 [0x7fe6b7bff700] DEBUG - Request: [192.168.1.14:56730 (Subnet)] GET /m

Either it is still post processing when you try to play it or there is something else.
This is unfortunately a LiveTV/DVR issue (at large) and not something I can help with.
LIveTV/DVR it its own subsystem.

Thanks for taking a look at it! Right now my workaround is to run two plex servers, one on my Synology ds918+ to record live tv and another on my Nvidia shield to decode it. On your test machines, do you get the Synology DS918+ to transcode mpeg2?

Synology DS918+ Hype!!

Clarify please?

Yes. The capture and transcode occurs on the test system in the lab.

The tuners are Silicon Dust and feed the Synology machines.
They playback out to the web browser, TV, and device players.

I have the same Nas and just really like it

It’s a great NAS. The only weakness we find is the J3455 CPU side itself. The HW transcoding ASIC is outstanding. The weakness we see is because the ASIC doesn’t support subtitle video plane merging. The only way to accomplish this is with the CPU which is the weakest part.
There are some audio codecs which are also painful for the CPU. The “Atmos” codecs down to stereo are one example.

I recorded something new and it worked better. HW transcode from mpeg2 recorded tv show with no buffering.

But all live TV buffers constantly when I view it on a device (eg web player) that needs transcoding to h264. Maybe its because I have a bad antenna connection? What behavior should I expect if the signal drops? Will it say something like “poor signal” or will it buffer? I know on my live channels app on the shield, if the signal drops then it will be blocky for a moment or go black in the worst case.

If your signal is becoming ‘blocky’, you’re on the edge of it failing out. The tuner is trying but marginal.

Better (lower loss) splitters or a small amplifier in front of the splitter are the two most common solutions.

My ds918+ still chokes when it tries to transcode certain mpeg2 streams that plex DVR records. I believe the issue is that the stream is interlaced 1080. Does the ds918+ support hw transcode of interlaced mpeg2?

Plex server on my shield can definitely do it.

It’s supposed to do it. The chip is more than capable.

If something happened with the codec then that needs to be checked.
How is it with other hardware transcoding?

I just threw 4k HEVC HDR Bluray rip at it (~50mbps) with TrueHD audio and it transcoded flawlessly to h264 + aac for my web player.

Thanks. I will get on the HQ lab system and start digging around. (I do not have a J3455 here at my location)

I am using a J3355 CPU (DS218+), and it is transcoding 4K 10 bit HEVC flawlessly to 1080 H264.

However, I also spotted high CPU usage when transcoding interlaced content (H264 1080i to 1080p), I suspect this deinterlacing process may be done actually in software, instead of doing it HW as it should.

This is definitely something to look into.

Just adding a voice - I’m seeing the same thing happen on a new DS918+ (transcoding chokes every 2 minutes or so on 1080i content recorded via Plex DVR and played back on both Chrome and an Apple TV). I just came from a DS718+ (same CPU) where transcoding was solid. Glad to see this thread as I’m at a loss.

May I ask for someone to please do the following:

  1. Verify DEBUG logging (not VERBOSE)
  2. Verify HW acceleration is enabled
  3. Start playback of interlaced MPEG2 content.
  4. Play 30 seconds
  5. Stop playback
  6. Wait 30 seconds
  7. Settings - Server - Troubleshoot - Download Logs
  8. Attach the ZIP file please