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A Deep Dive into HDMI Audio Performance

TinkinHD

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#41
Can you look into Google's Preview firmware for their video Chromecasts (1.49.220167)? On the 1080 Chromecast 3rd Gen, it's now passing thru 44.1 kHz just like the Chromecast Audio. Not sure if you have a video Chromecast laying around, but I would be curious how it would compare to a Chromecast Audio, and how both perform jitter-wise with a better power supply, like the Topping P50 Linear Power Supply.
 

Beershaun

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#42
With the recent set of AVR tests is there any progress on this front that merits an update on how HDMI performs in 2020?
 

TinkinHD

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#43
I was thinking this situation might be unique in that the stream can be passed thru to the AVR via HDMI without being resampled to 48 kHz like before on previous video Chromecasts. Sounds like you're saying that would not change measurements in a meaningful way based on how the AVR processes the incoming signal. At a minimum I'd be curious if there's more jitter via HDMI than via optical from a CCA, but maybe I'm over thinking it.
 

Beershaun

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#44
I think both are relevant. Passing bit perfect audio from the source and avrs putting some effort into taking control of the quality of the stream sent to the dac and clock.
 

TinkinHD

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#45
My hunch was that a video Chromecast, passing bit perfect audio to an AVR directly to its onboard DAC (bypassing travesties like HEOS, which I think further resamples) thru its ultra short HMDI cord, and powered by a linear power supply like the Topping P50, might yield surprisingly good results. Possibly even better than the CCA, and much easier to set up without having to use optical. Either way it's a nice surprise that the CC is passing thru a CD quality stream unadulterated.
 

mhsens

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#46
The situation may be changed now. I have a rather high-end pre-amp/processor ($4,500) coming in so I will have a chance to compare HDMI vs S/PDIF on it.
Amir, is there a separate post where you discussed how the HDMI audio was through a higher end pre/pro?

I'm encouraged by Blumlein 88's post above about a Marantz AV7701 having similar audio through HDMI and SPDIF - since mine is an AV7702 - but I'm still wondering if that was an outlier. I have doubt that I can ever hear jitter so, unless the science is really discouraging, I'd like to start feeding a DAC from my 7702's zone 2 HDMI out.
 
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Thread Starter #47
Pre/pros using ESS DAC chip and its built-in resampler can sharply reduce jitter. Those with AKM DACs don't have this facility and tend to have more jitter.
 

mhsens

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#48
A quick glance online finds this on the Marantz AV7702.
  • DACs: TI PCM 1690 (24-bit/192kHz)
  • Four Analog Devices SHARC 32-bit DSPs
  • D/A Conversion for Zones 2 and 3
I'm encouraged by Blumlein's comment about his AV7701's HDMI audio, because I also found this online, at the same article as spec-quoted above - which suggests that this is an issue for a lot of people with mass market receivers:

Marantz also upgraded the DAC compared to the AV7701. Dr. Rich again: “The 7702 DAC has a slight upgrade to the TI PCM 1690, which is the workhorse standard in AVRs these days up to about $1000 – $1500 when the transition to better DACs in Pioneer, Yamaha and Onkyo occur.
https://hometheaterhifi.com/reviews...rantz-av7702-surround-sound-processor-review/


So whether because of the age, or this pre/pro's mass market nature, no ESS or AKM chips. I hope the following article suggests that TI takes pride in their lack of jitter for all digital, even HDMI audio.
https://www10.edacafe.com/nbc/articles/view_article.php?section=ICNews&articleid=361986

I thought that Burr Brown was distinct from TI, but this article - which is way over my head - suggests that some attention went into jitter reduction,
https://www.ti.com/lit/ds/symlink/pcm1690.pdf?ts=1602376552022&ref_url=https%3A%2F%2Fwww.google.com%2F
Page 26:
The PCM1690operatesunderthe systemclock(SCKI)and the audiosamplingrate (LRCK).Therefore,SCKIand LRCKmusthavea specificrelationship.The PCM1690doesnot needa specificphaserelationshipbetweenthe audiointerfaceclocks(LRCK,BCK)and the systemclock(SCKI),but doesrequirea specificfrequencyrelationship(ratiometric)betweenLRCK,BCK,and SCKI.If the relationshipbetweenSCKIand LRCKchangesmorethan±2 BCKclocksbecauseof jitter,samplingfrequencychange,etc.,the DACinternaloperationstopswithin1/fS, and the analogoutputis forcedinto VCOM(0.5 VCC1)until re-synchronizationbetweenSCKI,LRCK,and BCKcompletesand then38/fS(single,dualrate)or 29/fS(quadrate)passes.In the eventthe changeis less than±2 BCKs,re-synchronizationdoesnot occur,and this analogoutputcontroland discontinuitydoesnot occur.

I cannot tell if this relates to HDMI audio as well.

Blumlein's review of the prior TI-based DAC opined "So just as a DAC, this isn't up to some of the better DACs around though it is hardly terrible."

EDIT: Just a reminder, you seemed even less impressed by the DAC in the 7002's successor, the 7705:
https://www.audiosciencereview.com/...z-av7705-home-theater-processor-review.11359/

2 years later, with such great, inexpensive Topping DACs available, I can imagine benefit to using the zone 2's digital output, unless it being HDMI makes that counter-productive. Because of both jitter and connectivity.
 
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#49
noob here.

I am trying to implement Richard Taylors software based dsp for an LX Studio set up.
I have an old IntelNUC lying around, and was hoping to run the dsp on the NUC, and use a downstream converter to convert PCM streams of the HDMI to Analogue.
Am I correct in understanding that this may not be the optimal way to do this, and that one is better of using an external sound card.
 

Beershaun

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#51
noob here.

I am trying to implement Richard Taylors software based dsp for an LX Studio set up.
I have an old IntelNUC lying around, and was hoping to run the dsp on the NUC, and use a downstream converter to convert PCM streams of the HDMI to Analogue.
Am I correct in understanding that this may not be the optimal way to do this, and that one is better of using an external sound card.
You are better off, if possible, to send your audio out of the NUC via USB to your DAC. Using the Nuc is a great idea. Lots of music server/player options for you on your PC. Roon seems to be the most favored software for a complete Hi-fi server/player/PEQ software suite.
 
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#53
I have a relatively new Sony Blu-ray player. It has only HDMI outs, but a separate HDMI for audio only. Since it is capable to play SACD, I am wondering, if it's audio better than for players transmitting video and audio through the same HDMI.
 

JoachimStrobel

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#57
I have a relatively new Sony Blu-ray player. It has only HDMI outs, but a separate HDMI for audio only. Since it is capable to play SACD, I am wondering, if it's audio better than for players transmitting video and audio through the same HDMI.
I am no expert, but I read on an Oppo webpage and believe: Audio is interleaved with video in the HDMI stream, filling more or less holes that the Videostreaming allows. That works better for some video resolutions than for others. The dedicated HDMI-Audio socket restricts the video resolution to the modes that work well.
 
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#59
I am no expert, but I read on an Oppo webpage and believe: Audio is interleaved with video in the HDMI stream, filling more or less holes that the Videostreaming allows. That works better for some video resolutions than for others. The dedicated HDMI-Audio socket restricts the video resolution to the modes that work well.
I understand that Sony player has two HDMI outs for sake of connecting one to TV and another one to an amplifier. It is a pity, they didn't eliminate video signal from the amplifier HDMI.
 

JSmith

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#60
It is a pity, they didn't eliminate video signal from the amplifier HDMI.
There is absolutely no reason to do this, it's not going to make any difference to the embedded audio data. Further there is no reason to reduce the function of a normal HDMI out which could be used for other purposes containing the video.



JSmith
 
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