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Topic: Dolby Atmos Playback (Read 829 times) previous topic - next topic
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Dolby Atmos Playback

Apologies if this is the wrong forum (or if one has already been started on this topic); neither Google nor the forum search gave me what I was looking for.

fb2k is my favorite media player for multi-channel audio (4.0, 5.1, etc). But lately I've upgraded to my system to Atmos and have been acquiring lots of Atmos files in various audio & video formats: mp4, m4a, mka/mkv.  While I've been able to get other players (VLC, Kodi, Windows Movies & TV) to play Atmos files properly via HDMI to my AVR--not every player will handle all formats--I can only get foobar to play their TrueHD 5.1/7.1 core. That is: foobar doesn't seem to be picking up and passing along the object-oriented metadata that, among other things, sends sound to the overhead speakers.

Can anyone shed any light on this? Am I missing a plug-in or a setting? I'm using the latest stable version of fb2k and the most recent version of ffmpeg.

Re: Dolby Atmos Playback

Reply #1
But lately I've upgraded to my system to Atmos and have been acquiring lots of Atmos files in various audio & video formats: mp4, m4a, mka/mkv.
Those are just the container formats. Dolby Atmos formats are either E-AC-3-JOC, AC-4 or TrueHD.
Can anyone shed any light on this? Am I missing a plug-in or a setting? I'm using the latest stable version of fb2k and the most recent version of ffmpeg.

Foobar cannot do bitstreaming to HDMI receivers AFAIK. Atmos requires bitstreaming for the objects, while foobar is using ffmpeg to decode the TrueHD stream to 7.1 PCM. 

You can try setting the output to WASAPI and see if that allows bitstreaming.


Re: Dolby Atmos Playback

Reply #2
Those are just the container formats. Dolby Atmos formats are either E-AC-3-JOC, AC-4 or TrueHD.

Right.

Quote
Foobar cannot do bitstreaming to HDMI receivers AFAIK. Atmos requires bitstreaming for the objects, while foobar is using ffmpeg to decode the TrueHD stream to 7.1 PCM. 

You can try setting the output to WASAPI and see if that allows bitstreaming.

Thanks; I gave it a try. (My understanding was that WASAPI does in fact allow a direct output of the bitstream.) But no luck.

I've always been slightly mystified by the output settings. I generally choose "Default : [my AVR]," but there's also:
WASAPI (push) : [my AVR]
WASAPI (event) : [my AVR]
DSD : WASAPI (push) : [my AVR]
DSD : WASAPI (event) : [my AVR]

I tried each of those settings with the same results. For good measure, I also downloaded and installed the E-AC plugin. Still nothing doing. I'm just wondering what VLC and Kodi do (that fb2k doesn't) that allows them to play Atmos files--and what changes could be made to foobar to add that functionality. I'd rather be able to use foobar as a universal player.

Re: Dolby Atmos Playback

Reply #3
You'll have to remove foo_input_dts, and somehow encode your DTS audio tracks into FLAC or WAV files that appear to be PCM encoded, but are actually S/PDIF encapsulated audio packets. You'll also need to disable all DSPs, and disable ReplayGain processing, and set the volume control to 100%. All this, at the very least.

Re: Dolby Atmos Playback

Reply #4
I'm just wondering what VLC and Kodi do (that fb2k doesn't) that allows them to play Atmos files--and what changes could be made to foobar to add that functionality.

I tried to reply earlier but it seems to either have been deleted for whatever reason.

fb2k appears to be decoding to 7.1 PCM (ffmpeg discards the object data) and outputting that as PCM in WASAPI. 
VLC and other players do not decode the audio to PCM after demuxing and instead set the player format to HDMI bitstream using WASAPI exclusive mode.

https://docs.microsoft.com/en-us/windows/win32/coreaudio/device-formats
https://docs.microsoft.com/en-us/windows/win32/coreaudio/representing-formats-for-iec-61937-transmissions

For any object based format to work, fb2k would need to not decode the audio, and know the format from the demuxer, and then pass that on to the WASAPI output. I have not worked with fb2k (and it's closed source) so I don't know how much work that would be.

Anyway, Peter is the owner of both the ffmpeg and WASAPI components so only he can help. 

You'll have to remove foo_input_dts, and somehow encode your DTS audio tracks into FLAC or WAV files that appear to be PCM encoded, but are actually S/PDIF encapsulated audio packets. You'll also need to disable all DSPs, and disable ReplayGain processing, and set the volume control to 100%. All this, at the very least.

That won't work in general (since this is different from DoP), the output format needs to be set properly for bitstreaming using WASAPI (in the wasapi component) unless I'm mistaken.
And there isn't any decoding or encoding support for the object based codecs at all, and even demuxing support can be poor sometimes.

As for regular DTS/AC3/EAC3/TrueHD, there is really no point in bitstreaming those with fb2k since they can be decoded for 7.1, 24bit/192kHz PCM over HDMI just fine without any loss of (nonexistent) audio object data.

Re: Dolby Atmos Playback

Reply #5

fb2k appears to be decoding to 7.1 PCM (ffmpeg discards the object data) and outputting that as PCM in WASAPI. 
VLC and other players do not decode the audio to PCM after demuxing and instead set the player format to HDMI bitstream using WASAPI exclusive mode.

https://docs.microsoft.com/en-us/windows/win32/coreaudio/device-formats
https://docs.microsoft.com/en-us/windows/win32/coreaudio/representing-formats-for-iec-61937-transmissions

For any object based format to work, fb2k would need to not decode the audio, and know the format from the demuxer, and then pass that on to the WASAPI output. I have not worked with fb2k (and it's closed source) so I don't know how much work that would be.

Anyway, Peter is the owner of both the ffmpeg and WASAPI components so only he can help.

Thanks very much for that convincing explanation, @prajaybasu.

FWIW: in Kodi, even after going into the audio settings, ticking the HDMI passthrough checkbox, and selecting my AVR as the output device, I could at first still only play the TrueHD core of Dolby Atmos files. The trick involved going deeper into the settings (to the "Expert" level), where there's an option to change "Passthrough Output Device" from DirectSound [your AVR] to WASAPI [your AVR]. After that, you check “True HD capable receiver,” and voila: Dolby Atmos playback.

It would be wonderful to come up with a similar solution for foobar, but it sounds like that would start by instructing it to bypass ffmpeg when playing Atmos files. . . .

Re: Dolby Atmos Playback

Reply #6
Sounds like you don't want to use foobar anyway.

Re: Dolby Atmos Playback

Reply #7
Sounds like you don't want to use foobar anyway.

On the contrary: I started my first post by emphasizing that foobar is my favorite media player for multi-channel audio. It does a fabulous job with every other format. I just wish it would play Atmos files so that I could use it for everything.

 

Re: Dolby Atmos Playback

Reply #8
you can download the asio4all driver, setup the speakers to be top right and top left, or however you have your avr setup and attempt it that way.

i have never owned atmos encoded content, but I can regular upmix dts hd, flac 5.1, flac 4.0 and others to utilize the atmos enabled speakers via the avr after setting it up properly with asio4all.

I abandoned atmos and upmixing altogether because there just isn't enough musical content to warrant the frustration of setup.

Re: Dolby Atmos Playback

Reply #9
I wonder if there will ever be a bypass option for the wasapi.
They just redesigned the 1.6 version to always run the DSP for the wasapi output.
 
But Who knows. I foundout that DVDAudioextractor is able to save a blueray soundtrack to a bitstream file file.
And ffmpeg wrapper converts it to 7.1 but the atmos layer is gone
I don't know how to instruct ffmpeg to not convert to 7.1 and see what that does.
the thd (bitstream file)  file is an actual truehd rip with the atmos layer intact. (vlc passes the amtos true the hmdi with succes)

Come on guys at hydrogen! You are so close! :)

Re: Dolby Atmos Playback

Reply #10
Play it with something else.

 
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