Stuttering playback on some movies on Roku Ultra

[ayo444 1]

Server: Emby 4.7.6.0 (Windows 10, 24GB RAM, Intel i7-4790 CPU 3.60 GHz)
Client: 4.0.63 (Roku Ultra - Roku STB 4800X)

I have recently upgraded my old Roku 3 to a Roku Ultra. I had no issues with Emby playback on the Roku 3 but am experiencing constant/permanent video stuttering with some movies on the Ultra. There is no issue with the audio. The movies are x265 .mp4 files (although as stated, some seem to play without an issue).

I have tried playing one of the affected movies on Plex and had the same problem, although I was able to get it to play smoothly by disabling Direct Stream and Direct Play.

From reviewing the community posts I understand others have had this issue with Emby and one possible solution is to downgrade the quality settings to force transcode. I have tried downgrading to various quality settings (as low as 480p) and it does not fix the problem (the stats for nerds output shows DirectPlay even at the lower quality settings).

I really don't want to have to use Plex if I can avoid it (or reformat the files to .mkv using MKVToolNix which I understand may be another solution) so was wondering if there is anything else I can try?

Please see attached:
- embyserver.txt (playing the movie Red (2010).mp4 which stutters)
- stats for nerds output from Roku client.

Notes:
- Hardware acceleration is switched OFF in Emby server
- Allow HEVC at 60fps is switched OFF in Roku client (switching it on makes no difference)
- As stated above, reducing video quality does not fix the problem
- Switching subtitles off makes no difference.

Thank you!

embyserver.txt

Edited August 17, 2022 by ayo444

[ebr 14921]

Hi.  Under the "cog" menu during playback, there is an option labeled "Playback Correction".  Can you try choosing that and see if that solves the issue?  You can choose it multiple times until the player finally gives up.

[ayo444 1]

Thanks @ebr! I had also tried pressing Playback Correction originally with no luck (forgot to mention it my post - sorry for that), but pressing it multiple times fixed the problem and I can see in stats for nerds that the file is transcoding now. Thanks again for your help!

[Happy2Play 8296]

Each click changes the playback method

One click potentially changes from Direct Play to Direct Stream.

Second click will change Direct Stream to Transcode.

But depends on the starting playback method.

[ebr 14921]

So that tells us that something about this media requires transcoding for smooth playback.  It may be that something is out of spec for the container.  How were the items created?

[Happy2Play 8296]

@ebrCould it be the audio track AAC 5.1?

[ayo444 1]

@Happy2PlayThanks for the background - yep, it was the second click that fixed the problem. Also, other files with AAC 5.1 audio seem to play fine so on the face of it that may not be the problem (?)

@ebr They are from a third party source so I don't have any info on the file creation process, sorry!

 

[speechles 1920]

The issue is the MP4 you are attempting to play is not streaming friendly. The Roku cannot accurately judge the end of file with some headers on some media. You can tell if this is the case with your file if it cannot be resumed and always starts over at the beginning. Because the Roku must fully download the entire item because some part of the header is stored at the end of the file. A header should always be stored at the front but for some embeds there is no other way. Because the container does not support it. So they just put things inside an MP4 that do not belong there. There is extra data at the end of the file to make up for those extra things that could not be contained inside the header. That makes the file not streaming friendly because they used the wrong container.

To convert those problem files into MKV is very simple. Just drag the MP4 onto MKVToolNix GUI and tell it start remux. It will take a few seconds. Once this is done the file is streaming friendly and the Roku can read the entire header for the file and accurately judge the framerate, the end of the file, etc. In other words you can fix the mistakes the encoder made. It will not impact video/audio quality as all the streams are copied. You are just going to change container and rebuild a new header with accurate information based upon those streams inside.

The MKV container is much more tolerant of what can be embedded. Subtitles, codecs, etc are much more friendly within an MKV container on the Roku. When you encounter problem files like this try a quick remux with MKVToolNix GUI and immediately have proper playback without transcoding. This best solution isn't transcoding that file every time you want to watch it. The best solution is fixing the file so it plays correctly without glitching your Roku player requiring you to transcode.

Edited August 18, 2022 by speechles

[ayo444 1]

Thanks for further info @speechles, I understand converting to mkv using MKVToolNix is a solution and the program itself is easy to use but at this time I'd strongly prefer to avoid that. Fortunately the Roku has no issue pausing/resuming playback on the affected files, it is simply the stuttering issue. Solving it with two clicks on the fly is a better outcome for me right now although I'll definitely keep the mkv convert in mind as a longer term solution.