SPDIF to analogue

Jim Lesurf wrote:

Above said, from what few tests I've done on UK HDTV audio I have the
feeling that this is still the 'Wild West' when it comes to standards. Some
involved seem to be experimenting or making 'standards' up as they go
along! :-)

I had a look recently at the pumping audio issue you heard with VLC and
DVB HD AAC and there's a fairly clear bug in libfaad that causes it.

It's to do with normalisation and will only show with drc that
attenuates (the proms for example only seemed to have boost). How bad it
is also depends on the program reference level broadcast.

Anyway I don't want to take this thread OT, so if you're interested in
detail maybe a new one should be started.

Andy Burns wrote:
Jim Lesurf wrote:

Andy Burns wrote:

But the TV would need to have surround decoders built-in to do that, IME
not many TVs do ...

I'd assumed that an HDTV set would generally have two speakers, not
four/five. And that the normal boxes/sets that receive HDTV can 'decode'
the 5.1. Otherwise they'd give no audio at all during programmes that use
surround sound.

True, I've not really looked at many TVs with inbuilt HD tuners, mine's
just HD ready, presumably the manufacturers have to pay some licensing
fees to Dolby now, which is why I'd assumed they largely avoided 5.1 TVs
in the past?


I am not sure about "have to" pay Dolby - I've never actually seen
freeview hd use it - it uses AAC which is mpeg. I suppose they pay mpeg
for the decoders anyway.

I assume (but may be wrong) that they choose to pay Dolby so that they
can be connected digitally to surround amps which seem to all support
Dolby. This would mean they are actually re-encoding from AAC to Dolby
just to send it over s/pdif.

"Adrian C" wrote in message
...
On 23/11/2012 18:03, Rick wrote:

As an aside, some time ago I inherited a Creative Sound Blaster SBO 270
device (which has optical and phono in out, see photo) I originally
thought that maybe it was some kind of DAC, however there doesn't appear
to be any software/drivers still available from Creative and I can't
discover anything really definitive about what it's actually supposed to
do, although when I plug it into my computer Win 7 tells me that it has
found an installed the drivers, out of curiosity I've connected up a
TosLink lead to the optical in, powered it up with a USB lead from my
computer, and fed the phono out to my amplifier, but no joy.

http://dl.dropbox.com/u/11815200/DAC%20(1347%20x%20445).jpg

It's a USB sound card. Nice inheritance. ;-)

http://www.amazon.co.uk/Creative-Lab.../dp/B0000A14S4

Check you get normal computer noises out of the phono, then

Go to Windows control panel, open the Sound Applet, and click the
'Recording' tab on that. Highlight the S/PDIF input in the list, click the
properties button below, and choose the 'listen' tab. Place a tick in
'listen to this device' and that should be it?


Doh! maybe I should have mentioned it sooner, however although there is now
audio it sounds like the DAB bubbling mud syndrome, I've gone into every
setting in the TV and my PC with no success, If I connect it to my DVD
player then I only get cracking, even when I set the output to PCM, I note
that there is only one bit rate 48K in the W7 menu could that be something
to do with it?
I've checked the drivers which are apparently up to date, there's also a
marginal delay on the sound and although there is plenty of compensation in
TV setup menu unfortunately it only goes one way, the wrong way :-(

In message , Jim Lesurf
writes
In article , Rick wrote:


The only problem now will be choosing a half decent one (I've read about
the buzzes, whistles and clicks :-) so if anyone here actually owns
such a device I'd be interested to hear their opinion

Depends how much you want to pay and how much 'audiophile street cred' you
are after. :-)

At one end of the range you could try something like the CYP DAC I used for

http://www.audiomisc.co.uk/HFN/Headp...C/HeadDAC.html

This is tiny and runs off a wall-wart PSU (or batteries). Only cost me
about 35 quid from CPC. Can accept either optical or coax spdif input.
Works for the usual sample rates, etc. I use it some of the time with a DVD
player or DTTV box. I suspect this will do the job, and is a cheap punt.
Fit it somewhere behind the TV and forget it exists.

Further up the cost/fancy scale are the Arcam rDAC and the Cambridge
DACMagic range. I've tested some of these, and happily use them. The
advantage is that the DACMagic/DACMagic Plus have pretty lights that
confirm the audio is arriving at the right sample rate. The 'Plus' also has
a volume control and a headphone output. So quite versatile. but now in the
few hundred quid range.

Further up into the 1000 quid range I can recommend the Cambridge Audio
851C player/DAC. Superb. But expensive and rather big. Plays CDs, as well
as connects to almost any source, though. 8-]

Alternatively you may find an old DAC from a secondhand audio dealer is
good value for money. Can pick up things like Meridian DACs at much lower
than new prices. I've also used these and been happy with them.

Slainte,

Jim

I found this at just over £40, but with shipping and taxes it'll cost
about a third more.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=180-998
--
Ian

On 23/11/2012 18:03, Rick wrote:

Impulse buy Jim, I've just ordered a LINDY SPDIF Digital to Analogue
Stereo Audio Converter from Amazon, it wasn't the cheapest (£35) but
seems to have quite favourable recommendations, apart from the fact that
one or two reviewers have hinted that the sound is out of sync, although
the overwhelming consensus appears to be that it's not a problem and
most of the reviews give it five stars.


My Samsung TV lets me adjust the digital output audio delay. IIRC i use
a delay of 70 to match my HiFi to the TVs speakers. Sometimes the TV
forgets the delay, and I have to adjust it up and down back to the 70
setting.


--
Michael Chare

In article , Michael
Chare wrote:
My Samsung TV lets me adjust the digital output audio delay. IIRC i use
a delay of 70 to match my HiFi to the TVs speakers. Sometimes the TV
forgets the delay, and I have to adjust it up and down back to the 70
setting.

I don't use the sound in my TV so I've had to obtain an external delay
unit. Originally it was rack mounted so I suppose it would have been the
sort of thing they'd use in the PA system at a large scale event such as a
pop concert. The delay is adjustable to more than 300ms and I can switch
it in and out of circuit using the "tape monitor" function on the
amplifier. Nice to find a use for that at last.

It's an annoying problem, sound/vision sync, but it's one of our own
creation. Previously it only applied to film, but thanks to a lot of very
clever people and the invention of digital technology we can now have it
on television as well, and then have the fun of spending even more money
trying to solve it.

Rod.
--

In article , Andy Furniss
wrote:
Jim Lesurf wrote:

Above said, from what few tests I've done on UK HDTV audio I have the
feeling that this is still the 'Wild West' when it comes to standards.
Some involved seem to be experimenting or making 'standards' up as
they go along! :-)

I had a look recently at the pumping audio issue you heard with VLC and
DVB HD AAC and there's a fairly clear bug in libfaad that causes it.

That was one 'issue' (as we are expected to call it these days). But I was
also thinking of other aspects like people sometimes using 5.1 to send 4.0
and variations in assumed mixdown ratios, etc, for recovering stereo from
the 'surround' in the HDTV audio packets. There are multiples 'standards',
and what people do seems to often differ from what other (who should know)
say is done.

It's to do with normalisation and will only show with drc that
attenuates (the proms for example only seemed to have boost). How bad it
is also depends on the program reference level broadcast.

Anyway I don't want to take this thread OT, so if you're interested in
detail maybe a new one should be started.

Yes, please. I've renamed this posting to split it from the other thread.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Roderick Stewart" wrote in
message .myzen.co.uk...
In article , Michael
Chare wrote:
My Samsung TV lets me adjust the digital output audio delay. IIRC i use
a delay of 70 to match my HiFi to the TVs speakers. Sometimes the TV
forgets the delay, and I have to adjust it up and down back to the 70
setting.

I don't use the sound in my TV so I've had to obtain an external delay
unit. Originally it was rack mounted so I suppose it would have been the
sort of thing they'd use in the PA system at a large scale event such as a
pop concert. The delay is adjustable to more than 300ms and I can switch
it in and out of circuit using the "tape monitor" function on the
amplifier. Nice to find a use for that at last.

It's an annoying problem, sound/vision sync, but it's one of our own
creation. Previously it only applied to film, but thanks to a lot of very
clever people and the invention of digital technology we can now have it
on television as well, and then have the fun of spending even more money
trying to solve it.



As pointed out in my previous post Rod, there is an audio delay adjustment
on my Samsung which runs from 0 to 200 in incremental steps, unfortunately
increasing it only makes the delay between the TV and speakers worse when
using the Creative DAC unit, perhaps the Lindy device I've ordered will be
different when I'm able to try it, I'll post here and let you know.

"Rick" wrote in message
...
I have recently acquired a new new TV, unfortunately it only has optical
output and my Philips amplifier is only analogue RCA phono in, browsing the
net shows me that SPDIF to analogue stereo converters don't appear to be
too outrageously priced, however I've read one or two reports to the effect
that they simply don't work with Freeview HD channels, which doesn't appear
to be of much use, especially as DVB-T2 and HD is increasingly going to
become the norm over coming years. I wonder if anyone here has had any
experience with this, or can point me in the general direction of a device
that they know will work. TIA

Aw, just get a 2 x phono to stereo 3.5mm lead and use the headphone output.

--
Max Demian

Jim Lesurf wrote:
In article , Andy Furniss
wrote:
Jim Lesurf wrote:

Above said, from what few tests I've done on UK HDTV audio I have the
feeling that this is still the 'Wild West' when it comes to standards.
Some involved seem to be experimenting or making 'standards' up as
they go along! :-)

I had a look recently at the pumping audio issue you heard with VLC and
DVB HD AAC and there's a fairly clear bug in libfaad that causes it.

That was one 'issue' (as we are expected to call it these days). But I was
also thinking of other aspects like people sometimes using 5.1 to send 4.0
and variations in assumed mixdown ratios, etc, for recovering stereo from
the 'surround' in the HDTV audio packets. There are multiples 'standards',
and what people do seems to often differ from what other (who should know)
say is done.

I've tried to see if mixdown meta data is in any samples, but haven't
seen any (my ffmpeg patch may be flawed).

The spec does have a mixdown section, which recommends that broadcasters
transmit separate stereo if possible. Of course there is also various
mixdowns for 5.1 to 2 specified.


It's to do with normalisation and will only show with drc that
attenuates (the proms for example only seemed to have boost). How bad it
is also depends on the program reference level broadcast.

Anyway I don't want to take this thread OT, so if you're interested in
detail maybe a new one should be started.

Yes, please. I've renamed this posting to split it from the other thread.

I think top level is nicer so I posted -

HDTV volume issue with VLC player using FAAD2 AAC decoder.