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bit perfect HDMI audio extractors?

mkawa

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#1
my default pathway into my speaker system is currently toslink from my TV, a vizio m0 from 2016 or so. i have a suspicion that it is not passing bit perfect pcm from the HDMI input (coming out of a fire tv cube 2019) to the SMSL m500. to that end, i'm thinking of pulling PCM directly from the HDMI output of the fire tv. quick amazon search gives me these options that support hdmi 2.0b pass-through

https://www.amazon.com/s?k=hdmi+audio+extractor+4k+60hz&ref=nb_sb_noss_2

has anyone tried these and had better results than what's coming out of their tv otherwise? i'm afraid of hdmi issues coming out of these boxes as well as the toslink outputs being compromised even worse than the tv.

alternatively, we are thinking of getting a new 65" with more local dimming zones or OLED to replace this 55" in the living room and moving the 55" to the bedroom. is anyone aware of specific brands (we'd be looking at LG oled and vizio) that are known to pass HDMI audio bit perfect out of their toslink outs?

alternatively, has anyone been able to get USB togo support for UAC devices from a fire tv cube? i chatted with a friend who knows the fire tv devices pretty intimately and he suspected that the fire tv OS strips UAC drivers, as they are pretty locked down for stability and (ironically) security reasons.

i have an ipad that i'm using as a streamer via USB for critical listening via the tidal app, but every time i switch the input to USB, my partner gets to puzzle over why the tv isn't making any noise...

note that i only have one hdmi source (and a playstation that i don't really care about the audio quality from) and am not looking for an AVR
 

Blumlein 88

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#2
I had a similar device. I did confirm the Toslink output was bit perfect. Had HDMI output on a laptop I fed into it, and a separate device record the Toslink. It worked as it should. However, the extractor had huge amounts of jitter way worse than even the HDMI. If you feed the device into something via Toslink it can filter some of the jitter out of course, but the amount was large enough it wasn't a good result.

Now that doesn't mean they are all that way. The one I had was a different brand from 3 years ago. You can always get it from Amazon and return it with in 30 days if you aren't happy with it.
 

MRC01

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#6
I have a box made by ViewHD that listens to HDMI and outputs the video as component or VGA, and the audio as toslink (in digital form), or 3.5" mini-plug (in analog form). This particular box isn't made anymore, but the company makes other similar boxes. I find them high quality both video and audio, been running for about 8 years without any problem, and the price was around $100.

The audio output for analog is inferior; midrangy quality with noise level around -80 dB. The audio output for digital toslink sounds fine. I don't know if the audio is bit perfect from the HDMI, but I've recorded it with my Tascam digital recorder and it has flat frequency response with no noise above the Tascam's noise floor.

Something like this: https://www.amazon.com/ViewHD-Splitter-Integrated-Extractor-VHD-1X2HSACi/dp/B00L0X2GIU
For the price, you can always buy one, try it, and return if you don't like it.
 

TimW

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#9
I used a ViewHD 4x1 HDMI switch to get a Toslink signal for my miniDSP for a while. I have three HDMI devices so I couldn't just use a simple HDMI audio extractor. There were occasional issues with my older Vizio TV not recognizing the signal from the ViewHD and over time the issue became worse and I couldn't get it to work anymore. So now I just connect all of the devices directly to the TV and use it's optical output. There is no audible difference from what I can tell and I would not recommend purchasing an HDMI audio extractor in hopes of getting better sound quality. I now use LAN streaming direct to the miniDSP for critical listening but to be honest it sounds exactly the same as my Chromecast streaming through the TV.
 
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#10
Is this legal when connected to a BD player? Will it extract Hires audio from copy protected BDs?
Eric from Geerfab had a booth (or at least borrowed some space) at Axpona last year where the D.Bob grabbed my attention something fierce. He had an Oppo 105 (in elusive silver, IIRC) playing hi res discs into the D.Bob, with the D.Bob feeding a Mytek DAC with it's large display showing either DSD or 192/24, I don't remember which (but probably the latter). There were cases of discs of all kinds to play around with. He says he found a way to extract Hi-res while still complying with HDCP. To my limited understanding this is a contradiction in terms, so I resolved to buy one before the legal teams banished it to the shadow realm.
Seeing this thread just reminded me that it finally arrived a couple of days ago to my buddy's place. He gets first dibs on playing around with it and his Kii Threes (a natural match, eh?) and if he doesn't want it I get next to feed my DEQX. MusicDirect had a functional prototype to play around with a few months ago while they were negotiating distribution rights. My discussion with them did nothing to clarify the HDCP issues, but did seem to confirm that it works
 
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#11
You can test if the output over toslink is bit perfect using a DTS CD rip. Just connect via toslink to a DTS capable AV amp and play back the DTSCD file, if it plays 5.1 it is bit perfect, if you just get digital noise it is not bit perfect.
 

MRC01

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#12
I measured a ViewHD. Here are some results from the Toslink out feeding a good quality DAC.
https://www.audiosciencereview.com/...mer-ultrahd-hdmi-3x1-switcher.1560/post-61147
I wonder how much that jitter could be reduced or eliminated by a downstream device buffering and reclocking the samples, like a WM8804 or something like that. The key factor seems to be whether the ViewHD maintains the correct clock rate in the aggregate, even if individual samples are not evenly spaced in time.
 

Blumlein 88

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#13
I wonder how much that jitter could be reduced or eliminated by a downstream device buffering and reclocking the samples, like a WM8804 or something like that. The key factor seems to be whether the ViewHD maintains the correct clock rate in the aggregate, even if individual samples are not evenly spaced in time.
Things that use ASRC for jitter removal likely can get rid of most of it assuming it is all jitter. Other devices likely can filter it some, but not eliminate it. I've not experimented with it all that much in that regard.
 
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