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Topic: Bit-perfect output from Typhoon soundcard (Read 4576 times) previous topic - next topic
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Bit-perfect output from Typhoon soundcard

Hi all,

{Advanced apologies for the length of this one, but theres a lot to it}

I have a Fostex FD4 digital 4-track recorder. It has optical SPDIF input/output at 44.1kHz, 16 bits. It has a function to save snapshot of all 4 tracks to DAT via SPDIF output which I want to use. This function saves the audio data, plus some vital control data in this output. When this is played back into the FD4 it must be bit-perfect so that the control data is correctly read.

Now, I don't have DAT, but do have a PC with a large hard-drive, so I (maybe naively  ) thought that it should be possible to buy a soundcard with SPDIF in/out to do the same job as the DAT. However, after having tried various SoundBlaster cards with no success I turned to the web for help, where I discovered that the only non-pro cards that can support bit-perfect transfers are C-Media CMI8738-based cards. So after much investigation I bought a Typhoon Acoustic 5+1 PCI card. This supports up to 24bit/96kHz digital input/output via optical SPDIF and coaxial connections. This looks remarkably similar in physical design to another soundcard that is mentioned in bit-perfect discussions, namely the Zoltrix Nightingale.

I managed to confirm that the SPDIF input is bit-perfect by saving the output from the FD-4 onto a standard uncompressed WAV file on my PC. I then burned this WAV file onto an audio CD and played it back into the FD-4 using my hi-fi CD player which has a SPDIF output: This loaded perfectly into the FD-4  .

However, when attempting to play the WAV file through the SPDIF output on the soundcard into the FD-4, the FD-4 does not recognise the control data and will not load the file. I checked the obvious stuff like ensuring that the SPDIF output sampling rate was set to 44.1kHz, not 96kHz.

Having read several postings on various forums I determined that it was probably due to the Windows 'kmixer' software messing about with the digital data before pumping it out through the SPDIF output. Again various postings informed me that this can be bypassed by using either Kernel Streaming or ASIO. To this end, I've installed a universal ASIO driver and also the Foobar2000 software which supports both KS and ASIO. My PC is running WinXP and is installed with the latest CMI8738 drivers and the associated mixer and 'Audio Rack' software.

However, I've not managed to use either of these methods to get my bit-perfect output from my soundcard onto the FD-4. To get ASIO to actually allow my 16-bit WAV file to play I had to set the Playback setting to '16 bit padded to 32 bit', but I don't understand why. Also, the Kernel Streaming method still seems to be subject to adjustment by the mixer!

Can anybody suggest any other ways I can use my soundcard to get my WAV files out of the SPDIF output such that it is a bit-perfect 44.1kHz 16-bit stream (i.e. mimic the output of my CD player)?

Thanks.

Bit-perfect output from Typhoon soundcard

Reply #1 –
First I would try some digital loopback (play back some test sample, connect digital out with digital in, record the result and compare using a wave editor).

BTW: Have you made sure that foobar2000 doesn't introduce changes? (Disable DSPs, replaygain and dither)
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Bit-perfect output from Typhoon soundcard

Reply #2 –
I've ensured with all my FooBar tests that all DSP features are not selected and that the checkboxes for dithering and all other stream modification are switched off.

Thx for the loopback tip - I've got Audacity which I believe will allow me to do this.
Will try this later and feedback.

Bit-perfect output from Typhoon soundcard

Reply #3 –
Just tried the loopback - played my file from Foobar2K in both Kernel Streaming and ASIO (Wuschel's ASIO4ALL plugin) and recorded the result using the 'Audio Rack' that comes supplied with most CMI8738-based cards. Viewing the results in Audio Editor Pro and also viewing the bit pattern in TextPad show that neither methods seem to result in a bit-perfect copy. I've also tried the DirectSound options, but no luck  .

I've read loads of stuff on various sites about there being no way of bypassing the Windows XP 'kmixer' - can anybody confirm whether this is in fact the case?

If this is the case, has anybody attempted to write any software that can directly access the hardware in a way that ignores any Windows drivers or mixers?

Finally (loads of questions today...  ), I've read somewhere (and now I can't find it) that it may be possible to use M-Audio DIO2496 drivers with other CMI8738-based soundcards, as these work better if you want to use the digital features of such cards. Has anybody out there ever done this?

Cheers again!

Bit-perfect output from Typhoon soundcard

Reply #4 –
You can use the M-Audio DIO2448 drivers -- I used them for a long time when I had my Nightingale card. According to this post, KikeG says with the DIO2448 drivers, the CMI8738 is bit-perfect.

Good luck!

Bit-perfect output from Typhoon soundcard

Reply #5 –
I also have a Typhoon Acoustic 5+1 PCI card and my experience is that the drivers are totally sh*t.
Some drivers only work partly (for example only 48khz output) and others don't work at all.

I have tried lots of combinations of OS and drivers. I always had to install the drivers manually, otherwise the wrong driver was chosen. With WinXP and WinXP-driver it wasn't possible to get bit-true results when recording with the digital-ins; I always thought the reason is the bad driver. I can't test the digital-outs of the card in a secure way, because I don't have a lossless audio recorder (DAT, CDR).

I've analysed all available windows-drivers on my driver-CD so far and the best seems to be the win9x driver, but this driver can't be installed with OS WinXP. With WinME I get bit-true results when recording with the digital-ins. (I'm angry that this forces me to use a special OS.)
I know that I know nothing. But how can I then know that ?

Bit-perfect output from Typhoon soundcard

Reply #6 –
I have a cheap noname CMI8738 soundcard. It has a 10-pin (5x2) SPDIF connector. But what pin is what? Anyone have a suggestion? I guess most cheap cards have the same layout.

Bit-perfect output from Typhoon soundcard

Reply #7 –
Quote
You can use the M-Audio DIO2448 drivers -- I used them for a long time when I had my Nightingale card. According to this post, KikeG says with the DIO2448 drivers, the CMI8738 is bit-perfect.

Good luck!

As I had the soundcard installed on a Win-XP machine I first tried to install the XP-compatible WDM driver for the DIO2448, available on the M-Audio drivers page. No luck, as XP always seems to force what it believes to be the correct driver.

However, on the drivers page there was also a VXD driver which is compatible with Win98SE - I have an old PC with 98SE installed and so transferred the soundcard into this. When asked for a driver when I started the PC I specified the DIO2448 VXD driver and this installed OK. Tried playing my known-bit-perfect WAV file using Foobar2000 into my FD-4 and SUCCESS  . Loaded perfectly, indicating that the transfer is indeed bit-perfect. Thx Polpo.

So in conclusion, if you're trying to get bit-perfect output from such cheap cards using Win-XP you're stuffed irrespective of drivers used, as the WDM drivers are often forced by the O/S and always seem to muck around with the output anyway. However, as 98SE (and 95, 98, ME) isn't so 'clever'(?) it will allow you to install any drivers you want.

Bit-perfect output from Typhoon soundcard

Reply #8 –
Quote
With WinXP and WinXP-driver it wasn't possible to get bit-true results when recording with the digital-ins; I always thought the reason is the bad driver. I can't test the digital-outs of the card in a secure way, because I don't have a lossless audio recorder (DAT, CDR).

Weird - it was only bit-perfect output that I had trouble with on XP using C-Media's own (latest) driver. The digital input was bit-perfect (as per my initial post).

Bit-perfect output from Typhoon soundcard

Reply #9 –
Quote
I have a cheap noname CMI8738 soundcard. It has a 10-pin (5x2) SPDIF connector. But what pin is what? Anyone have a suggestion? I guess most cheap cards have the same layout.

You might want to take a look at some of the documents for the CMI8738 on the CMI Technical Docs page - I'm sure there are pin-outs there.

Having seen that the physical layout of many CMI8738 soundcards look very similar, it wouldn't surprise me if the SPDIF module that should be plugged into the 10pin connector is standard - my Typhoon has a 10-pin, as does the Nightingale. So it might be worth having a dig on the web to try to find places that sell SPDIF connector modules and just giving them a try (I'm sure they can't be more than a couple of £/$)

Bit-perfect output from Typhoon soundcard

Reply #10 –
re: growler1970

Thx. I will pull out the card tomorrow and have a look on it. Work is only 6 hours away now :-(
 

Bit-perfect output from Typhoon soundcard

Reply #11 –
Hi again - another cry for help with this case - I've got my SPDIF working using the DIO2448 driver, but unfortunately this driver doesn't support MIDI, even though the Typhoon has a MIDI connection. I know that the CMI8738 driver that doesn't allow bit-perfect output does support MIDI.

I was previously using the old PC that I've got this working on as a MIDI controller for a drum machine and my Line6 POD guitar effects, but as I've removed the SoundBlaster AWE64 card that was there to allow for the Typhoon this has skuppered it.

So, 2 questions:
(1) Can I install a second driver alongside the DIO2448 just to support the MIDI capabilities of the Typhoon card, or is it one driver per item of hardware?

(2) If its not possible to install a second driver, if I refit my AWE64 is there any way I can disable the 'audio' features of the AWE64 and just install drivers to allow me to use the MIDI features? I ask this, as I've read in various places that Win98 can get very confused if it thinks there are multiple soundcards installed.

Life's never simple is it!?
Thanks again