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4K UHD playback on 720p TCL RokuTV

4k uhd 720p rokutv tcl transcode

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#1 StLDreiling OFFLINE  

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Posted 07 October 2019 - 12:28 PM

I am starting to add 4K UHD (w/ or w/out HDR) titles to my library as I own a few 4K HDR TVs, tablets, & phones. However, the majority of my streaming devices are still max. 1080p or less. When attempting to playback my 4K titles, my 720p 32" TCL RokuTVs initiate playback (green progress bar on device completes and playback shows in my server Dashboard) and then show a blank screen: no picture, no sound. I can fast-forward and rewind and the video thumbnails appear to function normally. My server hardware is fairly robust and appears to be transcoding video from h.265/HEVC to h.264/AVC and audio from 5.1 AAC to 5.1 AC3 as expected. I've tested this with both Emby and Emby Beta apps on the TV. HEVC 60p playback was disabled by default, but frame rate of movie is 24p, like all my titles, so I can't see that mattering as non-UHD movies play without issue.

 

I was researching this in the forums extensively this morning and found what may or may not be a related issue on the Fire Stick/TV.

 

 

‚Äčhttps://emby.media/c...080#entry792447

 

I checked my logs (attached) and found that the transcoder was not stepping down the resolution of the video stream from 2160 to 720. I then went and tested other videos and found that video stream with a resolution of 720p or less played fine, but anything 1080p or greater experienced the exact issue described above, to include 1080p videos encoded w/ h.264/AVC video and 5.1 AC3 audio streams that show as "Direct Playing" on the Dashboard while the device screen remains blank.

 

Any thoughts?

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#2 speechles OFFLINE  

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Posted 07 October 2019 - 01:20 PM

Sure. We are happy to help. I know why the Roku will play the higher resolution file directly that is because Roku has internal hardware to downscale. It is always preferable to direct play than transcode. We error on this side of judgement. If you make a mistake or have to default one way or the other we always default or make a mistake of direct playing.

 

You can use the "Playback Correction" button in the app to alleviate most of this or you can use the quality setting. The quality setting shows resolution next to it but I do not believe at this time it is making use of the Resolution (aka MaxHeight) yet on the sever. I could also be wrong and it might work just fine and that is all you need to do is pick a resolution and quality/bitrate.

 

I am in the middle of testing some other playback issues and will gladly help you with this if these do not fix your issue.  It may mean your RokuTV model does not support downscaling and we would just need to know the make/model number of your RokuTV. We can make an exception for that model and give different capabilities for ability to downscale. Right now we only know of the Roku express models 3700 and 3900 as lacking ability to downscale.

 

Please get back to us and follow up with the make and model number of your RokuTV. Thanks. :)

 

Edit: On closer reading of your log your file transcoded and still kept the 4K. I bet your RokuTV does not support downscale. 98.9% sure. 1.1% is ffmpeg being the cause.


Edited by speechles, 07 October 2019 - 01:27 PM.


#3 StLDreiling OFFLINE  

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Posted 07 October 2019 - 01:56 PM

Sure. We are happy to help. I know why the Roku will play the higher resolution file directly that is because Roku has internal hardware to downscale. It is always preferable to direct play than transcode. We error on this side of judgement. If you make a mistake or have to default one way or the other we always default or make a mistake of direct playing.

 

You can use the "Playback Correction" button in the app to alleviate most of this or you can use the quality setting. The quality setting shows resolution next to it but I do not believe at this time it is making use of the Resolution (aka MaxHeight) yet on the sever. I could also be wrong and it might work just fine and that is all you need to do is pick a resolution and quality/bitrate.

 

I am in the middle of testing some other playback issues and will gladly help you with this if these do not fix your issue.  It may mean your RokuTV model does not support downscaling and we would just need to know the make/model number of your RokuTV. We can make an exception for that model and give different capabilities for ability to downscale. Right now we only know of the Roku express models 3700 and 3900 as lacking ability to downscale.

 

Please get back to us and follow up with the make and model number of your RokuTV. Thanks. :)

 

Edit: On closer reading of your log your file transcoded and still kept the 4K. I bet your RokuTV does not support downscale. 98.9% sure. 1.1% is ffmpeg being the cause.

 

@speechles I think you're right about the TV lacking the ability to downscale. Here are the details of my particular device:
RokuTV 8103X

TCL model no. 32S305

Current OS build: RokuOS 9.1.0 4917-48

 

I tried alternating playback correction and I've attached the log files in case you see something different. This was a pretty popular model last Christmas on Amazon, so hopefully your efforts to fix this are helpful to more than just my family and me! :) Thank you, as always!

Attached Files



#4 speechles OFFLINE  

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Posted 07 October 2019 - 02:18 PM

@speechles I think you're right about the TV lacking the ability to downscale. Here are the details of my particular device:
RokuTV 8103X

TCL model no. 32S305

Current OS build: RokuOS 9.1.0 4917-48

 

I tried alternating playback correction and I've attached the log files in case you see something different. This was a pretty popular model last Christmas on Amazon, so hopefully your efforts to fix this are helpful to more than just my family and me! :) Thank you, as always!

 

I will add code to merge that adds your model number 8103. What this does is it will follow the resolution you have set on that Roku device. So if you set 720P as your display on that 32 inch RokuTV after this change that is what you will get. It will not downscale. If this fixes it we can then possibly add a setting for RokuTV users to disable downscale as that might be tedious tracking this entirely by model number with RokuTV. 

 

When this appears in Beta we will let you know as we want you to be the person testing this. Apologies for the problem. Thanks very much for everything so far. Happy streaming. :)

 

Here is the ticket for your issue:

Reference: Fix #611: [Capabilities] Adapt capabilities for RokuTV model 8103 (cannot downscale) 


Edited by speechles, 07 October 2019 - 02:33 PM.


#5 matumbrem OFFLINE  

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Posted 02 November 2019 - 10:07 AM

I just want to add that the TCL model 40S325 exhibits the same behavior.  It is "RokuTV 8113X".  This TV is capable of displaying 1080p, so the problem only exists when trying to stream 4k resolution.  I believe that it is a down scaling issue as well.  It seems that the TV is reporting the ability to downscale when it cannot.



#6 speechles OFFLINE  

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Posted 02 November 2019 - 10:32 AM

I just want to add that the TCL model 40S325 exhibits the same behavior.  It is "RokuTV 8113X".  This TV is capable of displaying 1080p, so the problem only exists when trying to stream 4k resolution.  I believe that it is a down scaling issue as well.  It seems that the TV is reporting the ability to downscale when it cannot.

 

We do have changes for this in our pipeline already in testing:

 

Reference: Fix #611: [Capabilties] Adapt capabilities for RokuTV model 8103 (cannot downscale) 

 

This affects all 8xxx model numbers on Roku. This is the same limitation on the 3700/3900 Roku express. We apologize for the issue. The fix will be in Beta very shortly. Thanks for reporting. ^_~



#7 matumbrem OFFLINE  

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Posted 02 November 2019 - 10:41 AM

We do have changes for this in our pipeline already in testing:

 

Reference: Fix #611: [Capabilties] Adapt capabilities for RokuTV model 8103 (cannot downscale) 

 

This affects all 8xxx model numbers on Roku. This is the same limitation on the 3700/3900 Roku express. We apologize for the issue. The fix will be in Beta very shortly. Thanks for reporting. ^_~

 

 

This is great news.  Thanks for all the work that goes into dealing with things like this.



#8 speechles OFFLINE  

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Posted 02 November 2019 - 10:46 AM

This is great news.  Thanks for all the work that goes into dealing with things like this.

 

It starts with people like you who bring these problems to our attention. Without you we cannot solve issues like this. We first need to know they exist. Thank you for bringing this to our attention so that we can address it. The squeaky wheel gets the grease. We do not own every possible combination of Roku device but we do try to cover the bases as best we can. Thanks for being part of the solution. :)


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