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dcx4610 · Nov 13, 2017

Im very confused about the new Bitstream HDMI audio option along with the Blu-ray Bitstream pass through options on the new Xbox One X.

Under audio options, there is an option for either uncompressed or Bitstream. From what I understand, if you pick uncompressed, the Xbox decodes the signal into PCM and sends it to your receiver or TV. Bitstream on the other hand, sends the signal untouched to your receiver to process rather than letting the Xbox handle it.

To me, that sounds like if you have a good receiver then Bitstream would be the way to go. Also from what I understand, Bitstream is required for Atmos and other advanced audio options. That said, when searching for Bitstream vs. Uncompressed, Im seeing lots of people saying uncompressed but why?

As for Blu-ray Bitstream, does this setting override the audio output? Can you set the system to uncompressed for games and then Bitstream for Blu-ray? Would that be the best option?

Dr. Zoidberg · Nov 13, 2017

dcx4610 said:
when searching for Bitstream vs. Uncompressed, I'm seeing lots of people saying uncompressed but why?

The older, more common bitstream formats (Dolby Digital, DTS) feature lossy compression and are limited to 5.1 channels so uncompressed PCM sound is superior. This is true for games for the most part. For blu-ray movies, there are newer uncompressed bitstream options (Dolby TrueHD, DTS Master Audio, Atmos, DTS-X) that don't result in the loss of fidelity or channels, so if you have a good receiver it's better to let it do the job. Bitstream is the ONLY way to get Atmos to a capable receiver, so it's the better option there.

EDIT - So your question about having movies set to bitstream and games set to uncompressed is probably the best option for most people. There are a few games that support Atmos now (Gears 4) so if you have an Atmos set up then it may be better to select the Dolby Atmos output option.

dcx4610 · Nov 13, 2017

Dr. Zoidberg said:
The older, more common bitstream formats (Dolby Digital, DTS) feature lossy compression and are limited to 5.1 channels so uncompressed PCM sound is superior. This is true for games for the most part. For blu-ray movies, there are newer uncompressed bitstream options (Dolby TrueHD, DTS Master Audio, Atmos, DTS-X) that don't result in the loss of fidelity or channels, so if you have a good receiver it's better to let it do the job. Bitstream is the ONLY way to get Atmos to a capable receiver, so it's the better option there.

The audio output option gives Bitstream with Dolby or DTS. Im guessing this is just for games and is best to keep it set to uncompressed? Meanwhile theres a separate Bitstream option under Blu-ray for pass through. Does this ignore the previous setting and pass through Bitstream lossless unlike the other option?

MrBenchmark · Nov 13, 2017

dcx4610 said:
The audio output option gives Bitstream with Dolby or DTS. Im guessing this is just for games and is best to keep it set to uncompressed? Meanwhile theres a separate Bitstream option under Blu-ray for pass through. Does this ignore the previous setting and pass through Bitstream lossless unlike the other option?

It specifically says let my receiver decode audio. So yes its a straight pass thru.

Dr. Zoidberg · Nov 13, 2017

dcx4610 said:
The audio output option gives Bitstream with Dolby or DTS. I'm guessing this is just for games and is best to keep it set to uncompressed? Meanwhile there's a separate Bitstream option under Blu-ray for pass through. Does this ignore the previous setting and pass through Bitstream lossless unlike the other option?

Yes and yes.

EDIT - It's also possible to get Atmos output for games but this may be limited to preview members for now. You have to download the free Dolby app and run it on the Xbox. Worth it if you have an Atmos setup as the demos are pretty cool. As I said, only a few games support it, and the ones that don't default to 7.1 uncompressed PCM in that scenario.

Venuspower · Nov 13, 2017

I do not exactly know if the XBox uses Dolby or DTS when you select bitstream (both are lossy) or if they are using Dolby True HD or DTS HD MSTR (lossless; yea bitstream can also be lossless). I think they are using the compressed formats.

Usually you should do it that way:
While Playing: LPCM (make sure you use an HDMI cable). With Toslink/SPDIF you only have 2.0 Audio when using PCM. Another reason: The console/game does know where the sound is comming from. The AVR does not know. In other words: No reason to "outsource" that work to an AVR.

While watching Movies: Bitstream (on PS4 you have to select Bitstream while you are in the movie; idk how Microsoft handles it with a XBox).

Thats it.

LenHendricks · Nov 13, 2017

dcx4610 said:
The audio output option gives Bitstream with Dolby or DTS. Im guessing this is just for games and is best to keep it set to uncompressed? Meanwhile theres a separate Bitstream option under Blu-ray for pass through. Does this ignore the previous setting and pass through Bitstream lossless unlike the other option?

Like the other poster said, yes to both.

If you set the X for Bitstream (Dolby Atmos) it will send that out for Blu-Ray/UHD and keep everything on PCM for games, which is what you want.

family_guy · Nov 13, 2017

dcx4610 said:
The audio output option gives Bitstream with Dolby or DTS. Im guessing this is just for games and is best to keep it set to uncompressed? Meanwhile theres a separate Bitstream option under Blu-ray for pass through. Does this ignore the previous setting and pass through Bitstream lossless unlike the other option?

If you bitstream DD or DTS for a game, then the Xbox is encoding the PCM audio to that format. The reason why is that some receivers can't accept uncompressed multi-channel PCM audio. They will convert that to stereo. DD or DTS uses less bandwidth and multi-channel audio can also be sent over an optical connection if you have your receiver connected that way.

Poppyseed · Nov 14, 2017

With my Xbox One S or X, set to bitstream gives me a little audio lag compared to uncompressed. I can tell even with the sounds in the system menu. So I leave it as uncompressed 7.1. Annoying as my receiver does Atmos, but I dont like the ~40ms audio lag for gaming.

Dr. Zoidberg · Nov 14, 2017

Poppyseed said:
With my Xbox One S or X, set to bitstream gives me a little audio lag compared to uncompressed. I can tell even with the sounds in the system menu. So I leave it as uncompressed 7.1. Annoying as my receiver does Atmos, but I dont like the ~40ms audio lag for gaming.

1) You can tell it to pass through bitstream just for Blu-Rays so you can get Atmos there while keeping games on PCM.
2) If you set Atmos for games it will default to uncompressed PCM for everything else (i.e. the dash and most games) and only use Atmos for Gears 4 (or other games that support it). The Atmos support doesn't work like the DD/DTS options do.

Poppyseed · Nov 14, 2017

Dr. Zoidberg said:
1) You can tell it to pass through bitstream just for Blu-Rays so you can get Atmos there while keeping games on PCM.
2) If you set Atmos for games it will default to uncompressed PCM for everything else (i.e. the dash and most games) and only use Atmos for Gears 4 (or other games that support it). The Atmos support doesn't work like the DD/DTS options do.

Well, all I know is when testing any games with it set to Bitstream, I get audio lag. I can tell playing something like Castlestorm with the arrow sounds being veeeeery slightly behind the video. If it were playing PCM there wouldnt be this issue (and isnt).

TL24 · Nov 15, 2017

Set the audio to uncompressed and for blu-ray set it to bitstream.

Mentaur · Nov 15, 2017

Venuspower said:
I do not exactly know if the XBox uses Dolby or DTS when you select bitstream (both are lossy) or if they are using Dolby True HD or DTS HD MSTR (lossless; yea bitstream can also be lossless). I think they are using the compressed formats.

Usually you should do it that way:
While Playing: LPCM (make sure you use an HDMI cable). With Toslink/SPDIF you only have 2.0 Audio when using PCM. Another reason: The console/game does know where the sound is comming from. The AVR does not know. In other words: No reason to "outsource" that work to an AVR.

While watching Movies: Bitstream (on PS4 you have to select Bitstream while you are in the movie; idk how Microsoft handles it with a XBox).

Thats it.

I have an LG TV and a sound bar that can handle DTS and Dolby Digital, connected via HDMI ARC. The TV reports via HDMI that it can only do 2.0 PCM so a good reason for selecting bitstream output for games in this type of setup is so that the sound bar gets a chance to decode and do its fake surround stuff. If your TV suggests it can handle multi-channel PCM to the downstream device then it won't be a problem - maybe it is just an LG E6 thing.

Venuspower · Nov 15, 2017

Thats because you are using ARC.
As far as I know ARC only supports 2.0 PCM.
Surround via should only work with DTS or Dolby.

llien · Nov 15, 2017

Dr. Zoidberg said:
The older, more common bitstream formats (Dolby Digital, DTS) feature lossy compression and are limited to 5.1 channels so uncompressed PCM sound is superior.

DTS and Dolby being lossy doesn't mean you are gaining anything by first uncompressing them and then passing over.

Dr. Zoidberg · Nov 15, 2017

llien said:
DTS and Dolby being lossy doesn't mean you are gaining anything by first uncompressing them and then passing over.[/QUOTE]

Uncompressed PCM is the "native" sound format for games on X1. Nothing is being uncompressed in that scenario.

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Bitstream vs. Uncompressed Audio on Xbox One X

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