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AAC 5.1 to Dolby Digital 5.1 transcoding setting


Richard Branches
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Richard Branches

5c8ada8474c22_Screenshot.png

 

The above screenshot from Emby for Android TV shows two audio options that only appear when I connect my device to a TV, HDMI audio extractor or AV receiver with DTS decoding, and we should turn them on or off depending on their decoding capabilities.
 
The same should apply to multichannel PCM/AAC, the option to transcode them to Dolby Digital should only appear when I connect my device to a TV, HDMI audio extractor or AV receiver with Dolby Digital decoding, to still be able to enjoy 5.1 audio from videos with those two codecs.
 
It's important to clarify, this should work only with multichannel PCM/AAC streams, PCM 2.0 and AAC 2.0 should be played directly.
 
THE OPTION SHOULD BE TURNED ON WHEN:
 
- The device is connected to a TV with Dolby Digital decoding by HDMI, where the transcoded stream can be passed-through to the optical/HDMI-ARC of the TV to a home theater.
 
- The device is connected to an HDMI audio extractor with the switch set to "5.1", where multichannel PCM is supported but the extracted PCM audio sent to the optical audio port is NEVER converted to Dolby Digital or downmixed to stereo (only the discrete left channel and the discrete right channel is heard through the speakers).
 
- The device is connected to a cheap AV receiver like the RCA RT2781HB which only supports PCM 2.0 and Dolby Digital by HDMI, so the transcoded stream can be decoded directly by the receiver.
 
THE OPTION SHOULD BE TURNED OFF WHEN:
 
- The device is connected to an AV receiver with multichannel PCM support by HDMI.
 
- The device is connected to a future TV with the new Extended Audio Return Channel feature (eARC) which supports multichannel PCM.
 
- A user wants to avoid transcoding.
Edited by delacosta78
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  • 2 weeks later...
schmitty

I do not see see how this could be possible, as AAC and AC3 are two entirely different codecs. It is my understanding that most Yamaha AV receivers released over the last few years do actually support AAC. You may have to select either DIRECT or STRAIGHT processing though.

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Richard Branches

I do not see see how this could be possible, as AAC and AC3 are two entirely different codecs. It is my understanding that most Yamaha AV receivers released over the last few years do actually support AAC. You may have to select either DIRECT or STRAIGHT processing though.

 

Receivers don't support AAC pass-through decoding, it is decoded as PCM by the device before it's sent to the receiver, that's why they always show "PCM" on their displays, if they add the option to force transcoding of multichannel AAC and multichannel PCM, it will send a Dolby Digital multichannel stream instead.

Edited by delacosta78
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schmitty

This is taken from a spec sheet of a Yamaha RX-V series receiver

MPEG-4 AAC: up to 48 kHz / 16-bit, ALAC: up to 96 kHz

 

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Richard Branches

This is taken from a spec sheet of a Yamaha RX-V series receiver

 

That's what the internal music player supports, they are decoded by the music player and the result is sent as PCM to the amplifier to reproduce the sound.

Edited by delacosta78
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  • 4 months later...
Richard Branches

So you're not looking for changes, but rather clarifications, is that correct?

 

I wanted to provide a better reason why the feature should be added, I felt I wasn't very clear when I created the topic so I hope this time everybody gets the point.

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  • 8 months later...

I support having the option to force transcode of AAC 5.1 / 7.1 to DD in ATV

I have a W10 Emby server with an ATV client on a Mibox.  The Mibox is connected to a Denon AVR-1911 via HDMI.

If I allow pass through of DTS then it also passes through AAC 5.1 and I get no sound.

I can only get sound if I set the Mibox to output all as PCM, however this is not ideal for the non AAC 5.1 streams.

I can also get sound if I force ATV to stereo, again not ideal.

I was considering replacing the MIbox with a new 2019 Shield in the hope of a better result but reading the above it seems not.

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  • 2 months later...
TonkaTuff

I also support this.
The ability to have multi-channel AAC audio streams transcoded to AC3 by the server would be excellent.

Potentially the 'Devices' settings could be expanded to allow admins to configure this on a per-device basis.

 

(2019 non-pro "tube" ShieldTV user)

Edited by TonkaTuff
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Richard Branches

Hey @@TonkaTuff don't forget to up-vote comment # 1, that's the recommended way to show your support in feature requests topics, thanks.

Edited by Richard Branches
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  • 9 months later...
redaktorn

Hi Friends,

I found this thread and I think my request belongs best here.

I am using Emby server and I am very pleased with it. I think it is the best media server available.👍
Normally I have used Kodi to watch my content from the Emby server.
But I also try to use the Emby app to watch my Movies and Shows (as much as possible).
In my case it is the Android TV version of the Emby app (which is what most of my other users use also).
Lately a lot of improvements has made it better and easier to use the Android TV app.
Especially subtitles that now can be adjusted in position (Thanks). And have a "background" (Thanks).
(If you could adjust the position also outside the video into the black bars it would be even better)

Picture and sound quality is also quite good when using the Emby app - except when playing AAC 5.1 or AAC 7.1.
From the Android TV Emby app these videos comes out as a PCM stereo signal.
The AAC multichannel codecs needs to be transcoded before they can be sent over HDMI in order to have surround sound.
HDMI has no protocol for carrying AAC multichannel in the cable (so a "pass through" is not an option).
In Android Kodi app this problem can be fixed by  chosing "Enable AC3 transcoding" in System/Sound settings.
(Please see attachment for the setting in Kodi)

This option is really neccesary in order to enjoy surround sound from video files that has AAC multichannel sound.
Unfortenately this is still not possible in the EMBY app. (Neither in operative settings of the Android TV system)

I believe this is what this thread is about - implementing such option in the Emby app (in my case the Andriod TV Emby app)
I would appreciate it very much and I think that will solve my last issue and I can finally unistall the Kodi app 😃

P.S. Another option could maybe be that Emby server had an option for transcoding all AAC multichannel to AC3 "on the fly"?
Before sending the stream to client.


All the Best
Redaktorn

Enable AC3 transcoding.JPG

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redaktorn

Hi Friends,

I am running latest debian server version and latest Android EMBY beta version of app.
It is attached to a Marantz AVR that can handle ALL sound codecs.
I have 2 ways of playing:
One by a Android advanced TV box with Android TV system direct to AVR by HDMI and further to TV by HDMI.
The other way by Sony TV Android EMBY app by ARC HDMI back to AVR.
(Which can optional be an optical cable to AVR, but it makes no improvement)
 
As reported above there are some issues playing some sound versions.
In any/either way I try to play from the EMBY Android app some issues appear.
Compared to Kodi that in the exact same hardware can solve it.
Kodi can transcode the AAC signal to Dolby 5.1 and Kodi can play all version of DTS-HD and Dolby TrueHD including Atmos (direct no transcoding).

I noticed that in the latest EMBY Android app there is now also a choice for "transcoding".
But I am very sorry to say that it does not seem to work.
It cannot downmix Dolby TrueHD Atmos 7.1 to Dolby 5.1.
Neither can it play Atmos direct or DTS-HD MA direct.
And it can (still) not transcode AAC 5.1. to Dolby 5.1.

I appreciate very much the efforts you do and I hope you continue the nice work.
Making it possible for us users to uninstall the Kodi app 😀

P.S: I have been googling the problem and it seems that Android TV system lack support for the PCM multichannel (LPCM).
If Android had that it should solve the need of transcoding to Dolby and instead send a LPCM signal by HDMI (for the AAC 5.1). 
Transcoding to Dolby 5.1 is an alternative to send LPCM signal.
But the above does not explain why the EMBY app cannot play DTS-HD or TrueHD Atmos direct when Kodi can play it direct?
(same hardware)
Seems that the ExoPlayer in Android is lacking codecs for that.
(I presume Android Kodi's player has these codecs)

All the Best
Redaktorn

Screenshot_20201226-104612.png

Screenshot_20201226-120007.png

Screenshot_20201226-115058.png

Edited by redaktorn
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Richard Branches
4 hours ago, redaktorn said:

P.S: I have been googling the problem and it seems that Android TV system lack support for the PCM multichannel (LPCM).

Yes, unfortunately, Google removed multichannel PCM support on Android 9 globally, except of course on the Nvidia Shield, that's why this option is now a must have for multichannel AAC/PCM streams on Emby for Android TV.

 

4 hours ago, redaktorn said:

But the above does not explain why the EMBY app cannot play DTS-HD or TrueHD Atmos direct when Kodi can play it direct?

What device do you have?

Dolby TrueHD and DTS-HD MA are also codecs not supported in the vast majority of Android TV devices except the Nvidia Shield, however, as far as I know, two devices are supporting DTS-HD MA besides the Shield, one is the Dynalink and the other is the Formuler GTV, the latter is somewhat buggy and the devs are working on a fix.

Edited by Richard Branches
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Richard Branches

I wanted to sign up again to the beta through Google Play but it says it's not available, did you guys remove it or is it some kind of error?

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6 minutes ago, Richard Branches said:

I wanted to sign up again to the beta through Google Play but it says it's not available, did you guys remove it or is it some kind of error?

Not removed.  However, Google is so slow releasing our betas that they are usually a couple versions behind.  I would side-load from the release notes topic.  Amazon versions go out in about an hour though.

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Richard Branches
12 minutes ago, ebr said:

Google is so slow releasing our betas that they are usually a couple versions behind

Yeah, I know that but that's not the problem, the problem is that it says there is no beta program available for the app, in the past I always used to go by typing https://play.google.com/apps/testing/details?id=tv.emby.embyatv and the green button always appeared at the bottom right.

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vdatanet
4 minutes ago, Richard Branches said:

Yeah, I know that but that's not the problem, the problem is that it says there is no beta program available for the app, in the past I always used to go by typing https://play.google.com/apps/testing/details?id=tv.emby.embyatv and the green button always appeared at the bottom right.

Try:

https://play.google.com/apps/testing/tv.emby.embyatv

To join the beta program

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Richard Branches

Yes, I know.

I was testing the new "Convert unsupported Audio to Dolby Digital" and this is what I found:

- It still doesn't convert AAC 5.1 to DD 5.1.

Videos with DTS codecs don't play with audio or play fast when the aforementioned option is ON, the DTS option is ON and the DTS-HD option is OFF.

- Dolby codecs played fine as usual.

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2 minutes ago, Richard Branches said:

It still doesn't convert AAC 5.1 to DD 5.1.

Can we please look at a specific example including a log from the app.  Not in here - please start a new thread in testing forum.

2 minutes ago, Richard Branches said:

DTS codecs don't play with audio or play fast when the aforementioned option is ON, the DTS option is ON and the DTS-HD

If you have enabled DTS, then it is passing it through and the conversion option is going to have no effect on DTS.  So this would be a problem with the device and DTS.  Disable it and you should get proper conversion to AC3.

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