Re: [ARMini-support] ARMX6 HDMI/video/audio ROM now live
- From: Jim Lesurf <jcgl@xxxxxxxxxxxxxxx>
- To: armini-support@xxxxxxxxxxxxx
- Date: Sun, 24 Jan 2016 15:24:42 +0000 (GMT)
In article <5546f7f5dajcgl@xxxxxxxxxxxxxxx>, Jim Lesurf
<jcgl@xxxxxxxxxxxxxxx> wrote:
My current monitor only supports a few LPCM modes/rates so I can't check
it fully here. Hence I'd welcome feedback, particularly from use with
monitors that can accept non-LPCM input.
It suddenly occurred to me that the computer monitor my wife uses on her
ARMiniX might differ from mine. I checked, and found that it is a 'TV' and
does have an optical spdif audio output.
So I just did a brief test using an HDMI lead to feed it from my ARMX6,
then taking an optical lead from the TV/monitor to a DAC Magic Plus.
The good news is that this worked and I could hear the music via headphones
connected to the DAC Magic Plus. Also, when I run my 'experimental' version
of !SoundCheck it duly listed the audio modes it accepts over HDMI with
included some non-LPCM 6-channel.
The not-so-good-news was that the rates for LPCM still were limited to 48k
max. And that even when I played 44.1k (i.e. Audio CD type) files the DAC
was a sent *48k* digital stream.
!SoundCheck confirmed that so far as my ARMX6 was concerned, the sound
system was playing out via HDMI at 44.1k. So it seems that the TV/monitor
simply resamples this regardless before sending the stream out again via
optical.
A look at the menus for the TV/monitor gave no sign of how to correct this.
So a moral here for users is to bear in mind that when using such devices
as TVs and monitors, the fact that it is accepting a given input rate
doesn't mean it simply 'passes the parcel' to any spdif output. It may
needlessly fiddle with the data. The only way to tell is to be able to
measure what comes out! Knowing what went *in* may not tell you.
This is a phenomenon that comms engineers know as "Well, it was OK leaving
here!" 8-]
I had briefly thought of quietly swapping over the monitors if the optical
output was 'perfect'. But it isn't, so her monitor is safe. :-)
More generally, the details I've given on my monitor and my wife's may give
people a basis for realising why I tend to ask what equipment people use
when they comment on sound quality. This is a particular issue when
discussing if 'high resolution' material actually sounds any better than
Audio CD.
The sad fact is that various consumer kit may *seem* to let you compare and
decide, but sometimes - perhaps often - actually limits what comes out so
that you simply don't get given a chance to really tell. :-/
Jim
--
Electronics
http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Audio Misc
http://www.audiomisc.co.uk/index.html
Armstrong Audio
http://www.audiomisc.co.uk/Armstrong/armstrong.html
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