Google Nest Community

Don-K · ‎10-10-2023

Chromecast Ultra FW: 1.56.281627

Hardware: Plex server, Chromecast Ultra (CCU), Ethernet connection, 2019 Toshiba LCD TV

Strange issue I cant figure out. Some HVEC (H.265) movies suffer really annoying stutter/jerkiness whilst watching, making them borderline unwatchable.

I suspect it’s a frame rate issue like skipping or unsynchronised frames.

The strange thing is some (seemingly identical) HVEC (H.265) media will play flawlessly whilst others suffer.

I’ve tried pretty much everything I can think of. It’s defiantly not connection speeds or any CCU/TV settings.

It’s almost as if the CCU isn’t adjusting the frame rate properly or Plex/Played media isn’t transferring the correct info to the CCU for it to set the frame rate properly.

Does anyone have any suggestions on the cause and if there’s a way to fix?

I’ve included working vs Non working media metadata (From Plex) below. They’re virtually identical but one will play perfectly whilst the other will not.

Example Media: Not Working = stutter/jerkiness

Duration 2:22:33

Bitrate 2223 kbps

Width 1920

Height 800

Aspect Ratio 2.35

Video Resolution 1080p

Container MP4

Video Frame Rate 24p

Web Optimized No

Audio Profile lc

Video Profile main 10

Part

File *****************1080p.BluRay.x265.mp4

Size 2.22 GB

Audio Profile lc

Container MP4

Web Optimized No

Video Profile main 10

Codec HEVC

Bitrate 1999 kbps

Bit Depth 10

Chroma Location left

Chroma Subsampling 4:2:0

Codec ID hev1

Coded Height 800

Coded Width 1920

Color Range tv

Frame Rate 23.976 fps

Height 800

Level 4.0

Profile main 10

Ref Frames 1

Stream Identifier 1

Width 1920

Display Title 1080p (HEVC Main 10)

Extended Display Title 1080p (HEVC Main 10)

Codec AAC

Channels 6

Bitrate 224 kbps

Language English

Language Tag en

Audio Channel Layout 5.1

Profile lc

Sampling Rate 48000 Hz

Stream Identifier 2

Display Title English (AAC 5.1)

Extended Display Title English (AAC 5.1)

Example Media: Working = Plays flawlessly

Duration 1:36:48

Bitrate 2224 kbps

Width 1920

Height 800

Aspect Ratio 2.35

Video Resolution 1080p

Container MP4

Video Frame Rate 24p

Web Optimized No

Audio Profile lc

Video Profile main 10

Part

Duration 1:36:48

File *****************1080p.BluRay.x265.mp4

Size 1.51 GB

Audio Profile lc

Container MP4

Web Optimized No

Video Profile main 10

Codec HEVC

Bitrate 2000 kbps

Bit Depth 10

Chroma Location left

Chroma Subsampling 4:2:0

Codec ID hev1

Coded Height 800

Coded Width 1920

Color Range tv

Frame Rate 23.976 fps

Height 800

Level 4.0

Profile main 10

Ref Frames 1

Stream Identifier 1

Width 1920

Display Title 1080p (HEVC Main 10)

Extended Display Title 1080p (HEVC Main 10)

Codec AAC

Channels 6

Bitrate 224 kbps

Language English

Language Tag en

Audio Channel Layout 5.1

Profile lc

Sampling Rate 48000 Hz

Stream Identifier 2

Display Title English (AAC 5.1)

Extended Display Title English (AAC 5.1)

Kimy · ‎10-16-2023

Hi Don-K,

Thanks for posting here in the Google Nest Community. We appreciate all the details you shared. The Chromecast Ultra is a slave device that will accept the content that was cast to it as it is. The fact that other content doesn’t experience the issue means the device itself is doing its job, which is to cast. As long as it receives what it needs to do its task (power, bandwidth, capable display output, etc.), it will proceed as commanded. You can check out this link: Supported Media for Google Cast, which is the guide used by developers. I hope this helps you more. Let us know if you have other questions or concerns.

Thanks,

Kimy

Don-K · ‎10-23-2023

Thanks for the response. I'm still confused as to why these files play so differently and yet are so similar?

It seems to be a chromecast issue because the playback is fine on a PC or Phone.

Could the mp4 file interleaving be an issue? Is the chromecast struggling to play a non interleaved file?

From: https://superuser.com/questions/1753260/what-makes-a-mp4-streamable

"As far as I know, MP4 container files may have their metadata (audio/video tracks, codec information) either at the beginning of the file before the actual data, or at the end. If the metadata is placed at the end, a player can't decode the video stream until it has downloaded the entire thing (unless it can seek through the file, which is e.g. possible using HTTP range requests).

For example, this file has mdat before moov, so it's not streamable as-is:

$ atomicparsley foo.mp4 -T
Atom ftyp @ 0 of size: 32, ends @ 32
Atom free @ 32 of size: 8, ends @ 40
Atom mdat @ 40 of size: 3280091, ends @ 3280131
Atom moov @ 3280131 of size: 139261, ends @ 3419392
     Atom mvhd @ 3280139 of size: 108, ends @ 3280247
     Atom trak @ 3280247 of size: 57400, ends @ 3337647
         Atom tkhd @ 3280255 of size: 92, ends @ 3280347
     ...
     Atom trak @ 3337647 of size: 81158, ends @ 3418805
         Atom tkhd @ 3337655 of size: 92, ends @ 3337747
     ...

See e.g. the FFMPEG "faststart" article.

Additionally (as I just found out), the audio track data can be either interleaved with video data, or not. If it's not interleaved for some reason, the player again needs to wait for the entire audio stream to be downloaded before it starts receiving video data (again unless it can seek back/forward)."

Don-K · ‎10-28-2023

From this forum: https://forums.plex.tv/t/chromecast-ultra-some-hvec-h-265-movies-suffer-really-annoying-stutter-jerk...

Other users have reported this issue too.

The issue seems to be caused by different framerates.

Can't insert pictures here, but if you follow the link above I've attached a screenshot of different VLC Codec information of a working film and a non working one.

The only difference seems to be the framerates.

Anyone have any ideas?

Kimy · ‎11-09-2023

Hello Don-K,

I’m sorry for the delay in response. The link that I shared with you is for developers. The fact that we didn’t get another participant (another user) here probably shows the superiority of your level of expertise. I hope you can run through that link again to figure it out.

That forum that you shared is not something that most users here are aware of. But if they have answers, that would be helpful. Let us know if you have other concerns.

Sincerely,

Kimy

Don-K · ‎11-10-2023

Thanks for the reply. I'll submit a report to the Cast SDK Issue tracker and see what response I get.

Kimy · ‎11-12-2023

Hi Don-K,

Great! I hope you find the answer you’re looking for. Feel free to create a new thread if you have questions or concerns in the future.

Cheers,

Kimy

Google Nest Community

Chromecast Ultra-Some HVEC(H.265) movies suffer really annoying stutter/jerkiness (Framerate issue)?