Why is this Transcoding Throttled? Ubuntu PMS to Roku 3

Plex Media Server Desktops & Laptops
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Server Version#: Version 1.18.9.2578
Player Version#:Plex Media Server Logs_2020-04-15_10-26-09.zip (9.4 MB)

Can’t figure out why this transcoding is throttled.

My own bluray, ripped and compressed at RF20 in handbrake for my home network. Player is Roku 3, with all quality options set to “original”, running wired ethernet on a gigabit connection.

I know the audio should be transcoding because the roku is only attached to a soundbar, but I don’t understand why this title is being throttled when others don’t seem to be.

General
Complete name : N:\KIDS MOVIES\Tangled (2010)\Tangled (2010) - [RF20dtsma].mkv
Format : Matroska
Format version : Version 4
File size : 6.61 GiB
Duration : 1 h 40 min
Overall bit rate mode : Variable
Overall bit rate : 9 440 kb/s
Movie name : Tangled
Encoded date : UTC 2020-02-28 03:45:34
Writing application : HandBrake 1.2.2 2019022300
Writing library : Lavf58.20.100
ErrorDetectionType : Per level 1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1 h 40 min
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Writing library : x264 core 157 r2935 545de2f
Encoding settings : cabac=1 / ref=4 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=5 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=20000 / vbv_bufsize=25000 / crf_max=0.0 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
Default : Yes
Forced : No
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio #1
ID : 2
Format : DTS XLL
Format/Info : Digital Theater Systems
Commercial name : DTS-HD Master Audio
Codec ID : A_DTS
Duration : 1 h 40 min
Bit rate mode : Variable
Channel(s) : 8 channels
Channel layout : C L R LFE Lb Rb Lss Rss
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 SPF)
Bit depth : 24 bits
Compression mode : Lossless
Title : Surround
Language : English
Default : Yes
Forced : No

Audio #2
ID : 3
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : A_AAC-2
Duration : 1 h 40 min
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Delay relative to video : -21 ms
Title : Stereo
Language : English
Default : No
Forced : No

Tautulli - Home _

2

Throttling is not a bad thing. It means the transcoder is actually sufficiently ahead of where it needs to be, and so can take a “break.”

If you’re experiencing playback issues, that’s another story.

2 Likes
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That’s true, but the video looks like it would Direct Play - therefore Direct Stream and not transcode. <— the report is transcode in one spot and Direct Stream in another. More consistency would probably be welcome and lead to a more accurate description of the streams in play.

Is the Quality for the Roku App in the Family Room set to ‘Original’ for local content?

I’m not that surprised 7.1 Super-Duper is transcoding - to stereo is up for debate considering there’s a stereo track right there - unused. Not sure what’s going on in that area.

4

It’s re-muxing because of the transcode from TrueHD to Stereo (why it needs an MPEGTS container for this I don’t know); I can reproduce the same behavior here. It can be made to direct play in at least two ways:

  • Configure either the movie or the global Roku settings to force direct play
  • Choose an audio stream other than TrueHD for playback of the movie.

In my case, on a Roku Premiere, picking the AC3 5.1 audio stream resulted in direct play. Or, I can achieve direct play by forcing it in the Video settings and still leave the audio stream at TrueHD 7.1. In either case, the MKV container is maintained (obviously).

Something is tickling in the back of my brain that this behavior is intentional due to the way Roku does its own down-mixing of TrueHD, but I could be mistaken.

1 Like
5

Plex unfortunately doesn’t look through the MKV’s available audio streams and choose the best compatible…
Plex only looks at the first audio stream to match your language… or the first if none do… and process from there.

Which is better probably… at least on some of my media. Audio1 is the DTS/HD/True whatever, and subsequent, more compatible AC3 might have directors comments etc that may or may not be clearly tagged. Audio transcode uses such little cpu power, it’s NBD.

1 Like
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No playback issues whatsoever. But the playback info just looked “off” to me.

I didn’t know “Throttling” wasn’t bad. So thats good. Thanks for that link and the speedy reply.

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Sure is. In fact, I had just changed it this morning, thinking that the 12Mbits it was set to might have been the problem.

8

Super helpful. Thanks, @Menel. And Thanks @JuiceWSA and @pshanew. You guys all provided some great info to try and put my mind at ease. And in barely any time.

Maybe this whole quarantine thing has some upside?

1 Like
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