Hoontech Digital (YMF754)'s AC3 on SPDIF: amplifier says "Unknown Digital"

Hoontech Digital (YMF754)'s AC3 on SPDIF: amplifier says "Unknown Digital"

Post by Antti Lanki » Wed, 17 Jul 2002 18:29:04

Hi all,

I recently acquired one of those Yamaha DSP-AX3200 amplifiers. It's a
good box but with good signal-to-noise characteristics and plenty of
power to satisfy the needs to drive a home theater.

I also have this Hoontech Sound Tracker Digital XP card with the DB I
so here we got optical input and output. The output is clocked at 48
kHz and
xine's, mplayer's, etc. manuals all state that this is one of the
cards where
ac3 pass-through over the spdif works.

I had the pleasure to verify this with another amplifier, which I had
in my
previous setup (one of those aging Technics SA-DX950 models). With
that amp,
putting xine to use output device
would work.

However, since connecting that new amplifier, it simply mutes on me
and says
"Unknown Digital" on the front panel. The manual of the amplifier
notes that
"If the DTS signal has been modified in any way, you may not be able
perform digital decoding even if you make a digital connection between
and this unit."

I'm assuming here that the manual knows what it is talking about, so,
there something I could do to fix this? This spdif stuff is pretty
much like black box for me, I can't get any relevant debug. :-(

Currently, I'm trying to attack the problem on these fronts:

1) Maybe there is some magic IEC958 status bytes that cause the
   to work. So far, the only flag with significance is the bit #1 on
   namely the data / not-data flag. If the not-data flag is on, amp
plays the
   unprocessed signal on main channels. Yuch.

I have been testing on xine and the alsa-tools programs extract_ac3
and ac3dec, like this:

extract_ac3 /trailers/whatever.vob | ac3dec -C

The card can't do professional iec958 so -P option is out. -R results
in raw PCM played, ac3 downmixed into 2 channels, which works fine.
The -4 option uses the analog connectors, so I can get 4 channel
discrete sound by hooking the front and rear channels into the amp's

2) Maybe the AC3 data is modified somehow as it moves through my
system --
   resampled, remixed, some header words changed, anything. To test
   I'd probably need to record the digital signal output by the card
   compare, but alas, I haven't been able to get anything recorded
from the
   digital input! :-(

zsh% arecord -l
card 0: card0 [Yamaha DS-XG PCI (YMF754)], device 0: YMFPCI [YMFPCI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: card0 [Yamaha DS-XG PCI (YMF754)], device 3: YMFPCI - AC'97
[YMFPCI - AC'97]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

The analog inputs recording seems to work finely, that's on hw:0,0;
but the spdif capture is not responding to the presence of any kind of
digital signal.
I grabbed the optical out of my cd player and plugged it in the input
feed. Then, I was trying to forward data in this manner:

arecord -f cd -D hw:0,3 | aplay

which should have yielded the sound of my cd player in the output, had
it worked. But no twiddling on the mixer knobs seemed to help here. If
I did something like:

arecord -f cd | od

I could view the sampled data. It looked a lot like faint analog
noise, which isn't what I expected. Setting the "Digital 1" mixer to 0
caused the data to fade into stream of 0s, indicating that's the mixer
control for hw:0,3.

Here are my options, if I can't get this fixed...

1) Get a ac3->6ch decoder box, hook into amp's 6 channel input.

2) Get a real dvd player and forget about the soundcard AC3.

Thanks in advance,


1. I say "Hello" Linux says "Goodbye" ... aaarghhh

Hello all,
after much blood, sweat, tears and swearing I got Linux running on a
Compaq 386/20. It has 10MB RAM, about 1GB disk space and a CD-ROM.
It recently gone on the internet as an ftp resource.

Everything worked fine at first but now Telnet & ftp have become unreliable.
When they work, they work fine. However when they don't:

- FTP session
  Open <symbolic address> says:

  "Connected to <Symbolic address>"
  "Escape character is '^]'."
  "Connection closed by foreign host."

- Telnet session

  "Connected to <Symbolic address>"
  "421 Service not available, remote server has closed connection"

  and drops me back to the Linux prompt.

It does this regardless of the client (DOS, Windows, Mac or Un*x).
Ping finds the box and since it sometimes works I'm a bit stuck on
what to try next. I've tried "kill -HUP <inetd PID>". The damn
thing is visible and connect-to-able...

Our campus uses nameservers and I've included four in resolv.conf.
Name resolution uses "named" nameservers first. (Order bind, host
in host.conf).

I've just tried *again* and ... then damn thing is now working!!!
I have a few ideas but don't know how to test them, they are:

- Could it be something is timing out (our network is very busy
  and slow quite often) ? How do I confirm this ?

- Could it be some connection limit (shouldn't be, it's very rare
  that more than one person are connected at once).
  Where is this info held ?

- Could it be a name resolution funny (would "host" help here ?).
  Can I test this ?

- Could it be the first Telnet request(s) fail until some
  sort of dynamic table somewhere is updated ?

- Is inetd not loading telnetd for some reason ?

I've checked that the symbolic name and IP number are correct.
The system does a reboot (via a cron script) but this is
identical to another (486) Linux box which works fine ...

I've read books, scanned FAQs etc. but don't really know
where I can sensibly look next. I don't expect answers,
just suggestions of what/where to looknext.
I apologise if this is a trivial or stupid question, I'm
an acting sysadmin with my "L" plates still on ...

Also, another query:
Where is lpd loaded at boot-time ?
Can it safely be *not* loaded to save CPU and RAM ?
(the machine doesn't have a printer attached).

Thanks in advance for any information/suggestions,

2. ext2

3. "syslogd: unknown priority "24" " error - won't boot!

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5. """"""""My SoundBlast 16 pnp isn't up yet""""""""""""

6. Add POSIX Access Control Lists to ext2/3

7. Hey Digital, what about Linux's role in "Titanic"?

8. whitch DVB Hardware for SUSE

9. GETSERVBYNAME()????????????????????"""""""""""""

10. sh says: test "$1" = "" when $1="-b"

11. PPP says "ERROR: Unknown Protocol (80fd) received"

12. 'insmod st' says "kernel_version needed, but can't be found" ???

13. Help! passwd says "module is unknown"