Black flashes/cut outs regularly every 30s or so. Only happens with specific rips

[Dodgexander 8]

Roku running on my TCL R517. Latest emby and system firmware.

Server running on Ubuntu Server 18.04 LTS via official docker image.

Logs and media info attached.

Video showing the flicker: https://photos.app.goo.gl/mhScWWc9MDg7h65h9

There's 3 flashes in total in the video

I've tried:

Other rips, problem isn't present.

Playing back on phone with the same rips, problem isn't present.

Updating server, emby and docker to latest versions. Problem was reduced but not solved.

Limiting to 30fps.

Transcoding to 720p.

Any idea what the problem could be? I've only seen this happen with this sample (s) and can play back much higher bitrate media without an issue.

embyserver.txt embyserver-63731921228.txt mediainfo.txt hardware_detection-63731921234.txt

Edited August 2, 2020 by Dodgexander

[Carlo 4330]

By any chance are your problem files all AAC LC and possibly 25 fps content?

[Dodgexander 8]

17 minutes ago, cayars said:

By any chance are your problem files all AAC LC and possibly 25 fps content?

1080p files with AAC-LC. The same audio with a 720p rip doesn't have this problem (see attached media info) they are taken from broadcast TV. I did notice in the info audio frame rate is mentioned as being twice the video frame rate..I didn't even know audio had a frame rate!

When the flashes happen audio isn't interrupted.

Great.British.Railway.Journeys.S09E03.720p.iP.WEB-DL.AAC2.0.H.264-BTW-Obfuscated.mkv.Text

[Luke 36997]

Hi @Dodgexander, looks like in your server log it is direct playing, which unfortunately means there's not a whole lot we can about this other than report it to Roku.

[Dodgexander 8]

2 hours ago, Luke said:

Hi @Dodgexander, looks like in your server log it is direct playing, which unfortunately means there's not a whole lot we can about this other than report it to Roku.

thanks for checking. Is there anything I can do?

[Luke 36997]

Can you provide a sample video for testing?

In the meantime you should be able to use the playback correction feature in the video player to force transocding, which will likely correct whatever problem exists in the source file that Roku is having trouble handling.

[Dodgexander 8]

4 hours ago, Luke said:

Can you provide a sample video for testing?

In the meantime you should be able to use the playback correction feature in the video player to force transocding, which will likely correct whatever problem exists in the source file that Roku is having trouble handling.

thanks. Unfortunately engaging the playback correction doesn't solve the issue. Yes the file no longer direct plays but stats says its 'HLS' and  video: 'direct stream' instead, but the drop outs are still there.

I also did some testing out of interest:

1. Set to downscale 1080p 4mbps (lowest setting) - stats for nerds shows 1280x720?? and the cut outs still happen.
2. Set to downscale to 720p and the cut outs still happen until you reach 4mbps or lower. As soon as I set 720p 5mbps they start again.

Why is Emby choosing 720p as a resolution when I specify 1080p 4mbps? And why are the cut outs only present when its set to 720p 4mbps or less?

During these tests AAC audio is always direct playing. Could that be the culprit?

Here's a sample I cut: https://drive.google.com/file/d/1WjytsGpN5M89jOvXzs9ssiOZb_HMXU4I/view?usp=sharing

[speechles 1917]

You can use the Playback Correction multiple times. Enable the stats for nerds. Once the stats show "Play Method: Transcoding" the problem should disappear. Once fully transcoding the CPU load will be noticeable. The playback correction will first choose to copy streams if it hasn't already. If you press it a second time it will disregard copy and full transcode. That will solve the issue but may not be desireable.

Roku is hopefully working on correcting these problems. All we can do until then is work around the issue with playback correction. Apologies for the issue.

[Dodgexander 8]

thanks. I didn't realize you could do that. Forcing transcoding, even at 1080p works now. Thanks for the excellent support. Hopefully it can be fixed!

[Luke 36997]

Thanks for the feedback.