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Post by thezone on May 9, 2020 22:01:18 GMT -5
Hi Keith,
I have a question about the USB input of the XMC-2:
Does the USB input on the XMC-2 accept multi channel PCM? The XMC-1 did not.
If so, as I am using JRiver MC on my HTPC to decode all HD audio to PCM would this be a better way to send audio to the XMC-2 rather than HDMI due to Asynchronous clock in the USB path? Eg lower jitter?
Thanks
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Post by creimes on May 9, 2020 22:07:23 GMT -5
It will accept the same as the XMC-1, 2ch only.
Cheers,
Chad
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Post by megash0n on May 9, 2020 22:09:20 GMT -5
Hi Keith, I have a question about the USB input of the XMC-2: Does the USB input on the XMC-2 accept multi channel PCM? The XMC-1 did not. If so, as I am using JRiver MC on my HTPC to decode all HD audio to PCM would this be a better way to send audio to the XMC-2 rather than HDMI due to Asynchronous clock in the USB path? Eg lowe r jitter? Thanks I'll let Keith correct this it needed, but I think it is only stereo. When I used mine, it only showed up as 2 channel stereo. I didn't see any way to change it. |
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Post by thezone on May 9, 2020 22:28:55 GMT -5
Thanks guys, the USB Stream section of the XMC-2 manual dos not specify that it is limited to 2ch PCM, unlike the XMC-1 manual which specifically dictates that only 2ch pcm or multi ch DTS is supported.
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Post by AudioHTIT on May 10, 2020 1:03:08 GMT -5
Thanks guys, the USB Stream section of the XMC-2 manual dos not specify that it is limited to 2ch PCM, unlike the XMC-1 manual which specifically dictates that only 2ch pcm or multi ch DTS is supported. I could be wrong, but I believe USB multichannel audio has been mentioned as a possible future upgrade for the new Processors. I don’t know when or how likely, but I do think it’s possible. |
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KeithL
Administrator 
Posts: 10,261
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Post by KeithL on May 18, 2020 12:53:00 GMT -5
This is sort of a tricky question.....
The main limitation on the USB input is bandwidth....
In theory it could carry a DTS, Dolby Digital, or Dolby Digital Plus signal... (NOT something like Dolby TrueHD... because it requires a different sort of bitstream.)
And, in theory, if we were to receive such a signal, we would cheerfully decode it...
However, because of the limited bandwidth, other than a few DTS audio CDs, we rarely if ever see a USB surround sound audio signal. (To be honest, I don't know of any program that would send such a signal, and I don't know if we've ever tested it... but it should be possible.)
Thanks guys, the USB Stream section of the XMC-2 manual dos not specify that it is limited to 2ch PCM, unlike the XMC-1 manual which specifically dictates that only 2ch pcm or multi ch DTS is supported. I could be wrong, but I believe USB multichannel audio has been mentioned as a possible future upgrade for the new Processors. I don’t know when or how likely, but I do think it’s possible. |
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Post by millst on May 19, 2020 11:38:53 GMT -5
Bandwidth? That doesn't sound right. A blu-ray LPCM stream is less than 28Mbit/s. USB 2.0 may not hit its theoretical peak of 480Mbit/s, but plenty enough for that. A compressed stream like TrueHD would need even less bandwidth.
USB audio class 2 provides support for multiple hi-res streams and has been around for a decade+.
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Post by thezone on May 20, 2020 1:25:40 GMT -5
Thanks for the reply Keith, I guess I'll wait till I get mine and try it! As stated I use JRiver MC on my HTPC to decode all HD audio to PCM (so as to use the in built video clock) and I thought if I could use the usb stream to send multi channel pcm it might be better than HDMI.
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Post by thezone on Aug 29, 2020 6:12:03 GMT -5
This is sort of a tricky question.....
The main limitation on the USB input is bandwidth....
In theory it could carry a DTS, Dolby Digital, or Dolby Digital Plus signal... (NOT something like Dolby TrueHD... because it requires a different sort of bitstream.)
And, in theory, if we were to receive such a signal, we would cheerfully decode it...
However, because of the limited bandwidth, other than a few DTS audio CDs, we rarely if ever see a USB surround sound audio signal. (To be honest, I don't know of any program that would send such a signal, and I don't know if we've ever tested it... but it should be possible.)
I could be wrong, but I believe USB multichannel audio has been mentioned as a possible future upgrade for the new Processors. I don’t know when or how likely, but I do think it’s possible. So back to this thread. Now I have tried the USB stream input on my XMC-2 and it does not accept multi channel audio of any resolution. Can I ask that this be added to the list of potential inclusions for a firmware upgrade? The reason I ask is because USB is the only way I can stream multi channel hi-res audio from my NAS using a plex client on my Nvidia Shield to the XMC-2 ( I have tested 2ch hi-res and it works flawlessly). For some strange reason Plex, Jriver, Kodi, VLC and many other Android apps will not allow multi channel hi-res audio over HDMI from the Shield, only USB. Obviously they allow multi channel Movie Sound tracks though HDMI but I guess this is a completely different protocol and not playing solely through their audio engine. And the XMC-2 does not have any multi-channel audio inputs so I cant even use an external USB DAC. |
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Post by AudioHTIT on Aug 29, 2020 10:32:52 GMT -5
This is sort of a tricky question..... The main limitation on the USB input is bandwidth.... In theory it could carry a DTS, Dolby Digital, or Dolby Digital Plus signal... (NOT something like Dolby TrueHD... because it requires a different sort of bitstream.)
And, in theory, if we were to receive such a signal, we would cheerfully decode it...
However, because of the limited bandwidth, other than a few DTS audio CDs, we rarely if ever see a USB surround sound audio signal. (To be honest, I don't know of any program that would send such a signal, and I don't know if we've ever tested it... but it should be possible.)
So back to this thread. Now I have tried the USB stream input on my XMC-2 and it does not accept multi channel audio of any resolution. Can I ask that this be added to the list of potential inclusions for a firmware upgrade? The reason I ask is because USB is the only way I can stream multi channel hi-res audio from my NAS using a plex client on my Nvidia Shield to the XMC-2 ( I have tested 2ch hi-res and it works flawlessly). For some strange reason Plex, Jriver, Kodi, VLC and many other Android apps will not allow multi channel hi-res audio over HDMI from the Shield, only USB. Obviously they allow multi channel Movie Sound tracks though HDMI but I guess this is a completely different protocol and not playing solely through their audio engine. And the XMC-2 does not have any multi-channel audio inputs so I cant even use an external USB DAC. Being that HDMI is the standard way to send multi-channel, not being able to send it that way seems like a big limitation. While they may add it to the G3P, getting it prioritized could be the challenge. |
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Post by thezone on Aug 29, 2020 17:56:29 GMT -5
Being that HDMI is the standard way to send multi-channel, not being able to send it that way seems like a big limitation. While they may add it to the G3P, getting it prioritized could be the challenge. Sorry what is G3P? Yes not allowing multi channel audio thru HDMI is a worry. The forum's are clogged with people complaining about it with no no answer given by the developers. Even worse, all hi-res 2ch audio only through HDMI is dithered down to 48/16. |
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Post by AudioHTIT on Aug 29, 2020 20:54:51 GMT -5
Being that HDMI is the standard way to send multi-channel, not being able to send it that way seems like a big limitation. While they may add it to the G3P, getting it prioritized could be the challenge. Sorry what is G3P? Yes not allowing multi channel audio thru HDMI is a worry. The forum's are clogged with people complaining about it with no no answer given by the developers. Even worse, all hi-res 2ch audio only through HDMI is dithered down to 48/16. Sorry, my short for any of the latest, Gen 3 Processors, to me because they came after the Gen 2 processor (XMC-1), and use the same firmware; specifically the RMC-1/L or XMC-2. I’m sure it’s based on demand, and most can do it well another way. So that’s all a limitation of your player? As it’s not an HDMI limitation. Still, I would put multichannel USB as a ‘nice to have’. |
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Post by vcautokid on Aug 29, 2020 21:32:37 GMT -5
Hmmm that is very interesting. I can process 48 channels of audio from my USB interface and that feeds my computer and we only need USB 2.0. Maybe I just have a bitchin' Interface eh?
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Post by thezone on Aug 30, 2020 3:24:57 GMT -5
I'm guessing there is some underlying deliberate reason that the Shield platform has recently chosen to limit audio only files to 2ch 48/16. I have a dodgy work around. If I create an mkv file with blank or actually any video and mux in some multi channel audio using MKVtoolnix, Plex will play the hi-res multi channel audio file through hdmi as it thinks it's a video file.
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