[Bug] 4k HDR + 2.0 AAC to Chromecast Ultra, transcoded when should Direct Play

[BloodyIron 24]

Hey Folks,

 

Finally making time to submit this bug report.

 

I'm trying to get my ecosystem setup for 4k tastiness. Have a 4k panel, with HDR and a built-in Chromecast Ultra, no other Smart TV garbage.

 

When I connect Emby to my TV via Chromecast then send my test video to it, it transcodes to 1080p and the HDR is also stripped.

 

What is expected is for it to actually just Direct Play this, since the content matches what the Direct Play documentation spec says it should be.

 

Naturally, it's also worth pointing out, that if non-compliant 4k HDR content were too be transcoded, that it should stay 4K and HDR, and really only transcode the audio (where necessary), assuming codec compatibility, etc.

 

I'm going to privately pass the logs to Luke due to privacy sensitivity.

 

Hoping we can get this hammered out! Can't wait to do 4K HDR through Emby!

[Luke 37049]

Are you sure it's a chromecast ultra? it's not identifying itself the way the ultra model normally does.

[BloodyIron 24]

When I stream sample YT content that is 4k and HDR, the TV reports 2160p and HDR mode on. There's an info function for the TV to report resolution, and if HDR is present "HDR" is explicitly added to the display.

 

So, the evidence points to it being a Chromecast Ultra, however the TV spec sheet doesn't explicitly say, one way or another. I can't recall for sure if my WAP said explicitly, but I think it might have shown up as AC too (802.11ac), which is only available on the Chromecast Ultra (last I checked).

 

 

Are you sure it's a chromecast ultra? it's not identifying itself the way the ultra model normally does.

[KarlDag 25]

Are you sure it's a chromecast ultra? it's not identifying itself the way the ultra model normally does.

It's not a Chromecast ultra, it's a Google Cast enabled TV, probably similar to what Vizio does with smartcast.

Edited March 17, 2019 by KarlDag

[BloodyIron 24]

I don't see how that's any different, it meets the spec of the Chromecast Ultra.

 

It's not a Chromecast ultra, it's a Google Cast enabled TV, probably similar to what Vizio does with smartcast.

[KarlDag 25]

I don't see how that's any different, it meets the spec of the Chromecast Ultra.

If you didn't buy a chromecast ultra, then it's not a chromecast ultra.

 

That's like saying that because my vizio tv will support airplay2 later this year, they're adding an appletv 4K to it. It's not the case.

 

The TV in this case supports Google Cast, which is a protocol meant to be able to cast from a mobile device, it doesn't have a chromecast ultra attached to it.

 

If there's a bug in the TVs firmware for example, and it doesn't report as 4K or not HDR (or whatever other situation might arise ) to the protocol, then it won't accept the 4k HDR file when casted. Considering YouTube does cast 4K HDR, there's probably some other incompatibility between your file and what the TV firmware accepts. I've seen issues with reference frames being too high in a h264 media file before, but I don't know if that's an issue with hevc too.

 

Sent from my Pixel 2 XL using Tapatalk

Edited March 17, 2019 by KarlDag

[BloodyIron 24]

Not sure what you mean by "reference frames being too high" too high what?

 

 

If you didn't buy a chromecast ultra, then it's not a chromecast ultra.

That's like saying that because my vizio tv will support airplay2 later this year, they're adding an appletv 4K to it. It's not the case.

The TV in this case supports Google Cast, which is a protocol meant to be able to cast from a mobile device, it doesn't have a chromecast ultra attached to it.

If there's a bug in the TVs firmware for example, and it doesn't report as 4K or not HDR (or whatever other situation might arise ) to the protocol, then it won't accept the 4k HDR file when casted. Considering YouTube does cast 5K HDR, there's probably some other incompatibility between your file and what the TV firmware accepts. I've seen issues with reference frames being too high in a h264 media file before, but I don't know if that's an issue with hevc too.

Sent from my Pixel 2 XL using Tapatalk

[BloodyIron 24]

FYI this is the TV : https://www.bestbuy.ca/en-ca/product/toshiba-50-4k-uhd-hdr-led-chromecast-built-in-tv-50l711u18-only-at-best-buy/10575013.aspx?

 

Toshiba 50L711U18

[KarlDag 25]

Not sure what you mean by "reference frames being too high" too high what?

Let's not make it more complicated that it has to be. All I'm saying is that when you cast, the TV tells the server "here are the characteristics is the media files I can play". Emby server then compares that to your media file - if for whatever reason there is some characteristic of the file that your TV downstairs support, it will need to be transcoded.

 

Let's wait for @@Luke to see what is in the logs, I don't understand them.

 

Also, as far I know, when a file is being transcoded it is impossible, right now, to transcode back into HDR, so you'll lose the HDR and colors will be muted. That's a limitation of the current state of tech, Plex has the same issue.

 

Sent from my Pixel 2 XL using Tapatalk

Edited March 17, 2019 by KarlDag

[BloodyIron 24]

Certainly. And when I first got the TV I poured all over the manual (figuratively of course) and unfortunately at the time it was rather short on details/specs. I was namely looking for wifi spec, but I don't recall seeing lots of Chromecast-centric specs either. :S

 

Let's not make it more complicated that it has to be. All I'm saying is that when you cast, the TV tells the server "here are the characteristics is the media files I can play". Emby server then compares that to your media file - if for whatever reason there is some characteristic of the file that your TV downstairs support, it will need to be transcoded.

Let's wait for @@Luke to see what is in the logs, I don't understand them.

Sent from my Pixel 2 XL using Tapatalk

[Luke 37049]

it's reporting itself as a regular chromecast, and we're checking for the ultra model to detect support for certain things. we'll have to see if there's another way we can do that. thanks.

[BloodyIron 24]

@@Luke it seems to me the Youtube app sees the 4k and HDR capability. I wonder how it's getting the spec capabilities of the device.

 

Do you know of a way to connect to such devices and dump the specs from it? Ala, codecs, res, bitrates, etc? Is this anything like EDID info?

 

Very curious!

[BloodyIron 24]

I just noticed your part about the HDR. To clarify, I'm not talking about transcoding back into HDR, I am talking about retaining the HDR info in the transcode process.

 

 

Let's not make it more complicated that it has to be. All I'm saying is that when you cast, the TV tells the server "here are the characteristics is the media files I can play". Emby server then compares that to your media file - if for whatever reason there is some characteristic of the file that your TV downstairs support, it will need to be transcoded.

Let's wait for @@Luke to see what is in the logs, I don't understand them.

Also, as far I know, when a file is being transcoded it is impossible, right now, to transcode back into HDR, so you'll lose the HDR and colors will be muted. That's a limitation of the current state of tech, Plex has the same issue.

Sent from my Pixel 2 XL using Tapatalk

[Luke 37049]

We're looking into it, thanks.

[BloodyIron 24]

Thanks! If there's anything more I can do to help, do let me know

 

Can't wait to watch 4k HDR from my Emby to my TV

 

 

We're looking into it, thanks.

[Luke 37049]

Hi, please try this again and let me know if there's still an issue. Thanks !

[BloodyIron 24]

Is there a version of Emby you want me to update to before testing?

 

Hi, please try this again and let me know if there's still an issue. Thanks !

[Luke 37049]

Latest is fine.

[BloodyIron 24]

OMFG it's working!

 

Okay, so two test results.

 

1.

 

>>Video

Title4K HEVC

CodecHEVC

ProfileMain 10

Level153

Resolution3840x2160

Aspect ratio16:9

AnamorphicNo

InterlacedNo

Framerate23.976

Bitrate64,195 kbps

Video rangeHDR

Color primariesbt2020

Color spacebt2020nc

Color transfersmpte2084

Pixel formatyuv420p10le

Ref frames1

 

>>Audio

TitleEnglish DTS 7.1 (Default)

LanguageEnglish

CodecDTS

ProfileDTS-HD MA

Layout7.1

Channels8 ch

Sample rate48,000 Hz

Bit depth24 bit

DefaultYes

 

That one appears to trigger "Direct streaming" as-per the server Dashboard reporting that.

 

Furthermore, my TV reports 2160p and HDR!

 

My wifi is hating me though, so I may need to do something about that, or switch to wired or something, heh.

 

This one does not use much CPU at all, maybe one thread 50-80%-ish!

 

 

2.

 

>>Video

Title4K H264

CodecH264

Codec tagavc1

AVCYes

ProfileHigh

Level51

Resolution3840x2160

Aspect ratio16:9

AnamorphicNo

InterlacedNo

Framerate29.97

Bitrate95,290 kbps

Color primariesbt709

Color spacebt709

Color transferbt709

Bit depth8 bit

Pixel formatyuv420p

Ref frames1

NAL4

 

>>Audio

TitleUnd AAC stereo (Default)

Languageund

CodecAAC

Codec tagmp4a

ProfileLC

Layoutstereo

Channels2 ch

Bitrate447 kbps

Sample rate48,000 Hz

DefaultYes

 

That one seems to trigger transcoding. 

 

My TV reports 2160p, BUT NOT HDR. That might be because the video doesn't have HDR (maybe?) heh. This is a sample 4K fireworks video.

 

This one chews my CPU up massively! 100% of 6x threads/cores (tuned it down recently from 24). Likely due to no GPU offloading. Doing about 19FPS in transcode.

 

 

So at this point, this looks to be working properly! That is, when I use codecs the device supports!

 

In your findings, should I just reference the Chromecast Ultra codec list? Or what? Since my TV is "not quite a Chromecast Ultra, but looks a bit like it" or something...

 

Thanks a tonne btw! :DD

Edited April 24, 2019 by BloodyIron

[BloodyIron 24]

Oh, also, this TV has a remote with a play/pause button, that works for YouTube/Netflix Chromecasting, but for Emby, pauses only, not plays. Should I make another thread for that? (I'd like unpause to be fixed, so convenient!)

[Luke 37049]

Thanks for the feedback.

[BloodyIron 24]

Thanks for all your help! As for the remote thing, should I open another thread, or are you adding it to the queue, or?

 

Thanks for the feedback.

[Guest asrequested]

Please excuse my butting in   But, it would be nice to have a device override option in the server. Lemme splain. I have a Vizio with Smartcast. If I try to play HDR content with smartcast, it transcodes. (I know this is because of what Smartcast is reporting). But I know it can play these. So it would be nice if I could tell the server to ignore what the app is telling it, and just play the video. That would be a nice power user option

Edited April 24, 2019 by Doofus

[dasfox 3]

I have a smart cast also and try again since the update today fixed 4K HEVC and high bitrate h.264 so all is well

[Luke 37049]

Thanks for the Feedback !