Seeking help for some video stuttering

[jmos1277 9]

I run emby in a docker container on my unRAID server.  Many videos work perfectly when streaming to my Apple TV 4k.  However, some have major stuttering issues that make them unwatchable.  Basically they play about 1/2 second of video, then the video pauses for about a second (audio continues uninterrupted), then another 1/2 second of video, and more stuttering ... 

My environment:

• emby server v4.5.3 (in a docker container)
• unRAID server v6.8.3
• Apple TV client v1.5.0 (2) en-US
• Apple TV 4k (most recent model) (match dynamic range and match frame rate both enabled)
• all hardwired over 1Gbps Ethernet

For some reason, the entire Blu-ray collection of Die Hard has issues (among others), so I grabbed some logging into from that movie.  It's a Blu-ray rip: 1080p H.264, DTS-HD & DTS audio tracks.  

When I play the video, my emby dashboard says that video is direct streaming but also that there is some transcoding (see image).  I assume it's transcoding the DTS to AC3.  I've also attached my emby log file (with debug logging enabled) and the FFmpeg log file from this transcode session.

Some addition info:

• the video file plays properly when playing through VLC on both my Apple TV and on my laptop
• the video file plays properly when playing through the emby web interface on my laptop
• my server has plenty of horsepower to run any transcoding necessary -- it hardly hits even 10% CPU utilization while actively transcoding the video file

I'd appreciate any tips or guidance or any additional debugging steps that anyone might suggest.  I'm tempted to blame the Apple TV, but it plays some 1080p H.264, DTS without issue.  I feel like I'm missing something, I just don't know what it is.

 

 

embyserver.txt ffmpeg-remux-10740e23-4abe-46d8-b48b-6001e0c3643a_1.txt

[jmos1277 9]

Almost immediately after posting my question above, I made a little discovery.  I still had my emby client settings open and went into the Playback options.  I didn't know what "Enable MPV" was so I google a bit and discovered that it's a different video player.  When I ran my above test, I did not have this option selected.

I selected "Enable MPV", rebooted my Apple TV, and now Die Hard plays properly.

Is this simply a matter of the native Apple TV video player being bad?  If that's the case, what advantages would the Apple player have over MPV?  If MPV is better, why isn't it the default setting?

[vdatanet 1549]

13 minutes ago, jmos1277 said:

Almost immediately after posting my question above, I made a little discovery.  I still had my emby client settings open and went into the Playback options.  I didn't know what "Enable MPV" was so I google a bit and discovered that it's a different video player.  When I ran my above test, I did not have this option selected.

I selected "Enable MPV", rebooted my Apple TV, and now Die Hard plays properly.

Is this simply a matter of the native Apple TV video player being bad?  If that's the case, what advantages would the Apple player have over MPV?  If MPV is better, why isn't it the default setting?

MPV supports more formats than Apple native player, but native player supports framerate and dynamic range match. The best player depens on your media, if you have mp4 files that can direct play, native player may be better. If you need to play MKV HEVC content, then MPV player is mandatory to avoid video transcoding.

The MPV player has been improved a lot lately, maybe it would be a good idea to enable it by default.

Edited December 13, 2020 by vdatanet

[jmos1277 9]

Thanks for the response, vdatanet.  I forgot to mention this in my original post, but my video files are all MKV files.  I didn't realize that Apple TV cared much about the container.  I assumed it was only the underlying CODECs that mattered.  Is this why emby transcodes video files that contain CODECs that I know the Apple TV supports?  For example, one of my movies is 1080p H.264 with TrueHD audio.  I know the Apple TV supports those CODECs, but emby still shows the file as being transcoded when I play it (see attached image).

[vdatanet 1549]

TrueHD should be remuxed to AC3, It's strange that you get a full transcode. Can you post the transcoding log?

You can also take a look at this post requesting direct play support for DTS / TrueHD, decoding audio to LPCM like Plex and Infuse do.

 

[sooty234 266]

My guess is that neither the audio nor container are supported, and at that point the server will switch to full transcode.

[vdatanet 1549]

33 minutes ago, jmos1277 said:

Thanks for the response, vdatanet.  I forgot to mention this in my original post, but my video files are all MKV files.  I didn't realize that Apple TV cared much about the container.  I assumed it was only the underlying CODECs that mattered.  Is this why emby transcodes video files that contain CODECs that I know the Apple TV supports?  For example, one of my movies is 1080p H.264 with TrueHD audio.  I know the Apple TV supports those CODECs, but emby still shows the file as being transcoded when I play it (see attached image).

Are you using native player or MPV player? MPV player should remux that instead of full transcode.

[ebr 14910]

Hi.  Some subtitles could also cause a transcode with an unsupported container.  Apple does not natively support mkv.  They pretty much expect everything to be in mp4 (their container).  As mentioned, the mpv player should be able to handle it though.

[jmos1277 9]

I've switched over to using MPV.  Everything seems to play perfectly now.  Some content is "Direct Streamed" with some transcoding happening ... possible the subs like ebr suggested.  Other content seems to have the video transcoded but still plays fine.  

[Luke 37060]

Thanks for the feedback.