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Cannot play DTS-CD in pass-through mode with M-Audio Transit USB
ThoBar:
As an aside, it may be a nice feature for MC, that a "Pass Though Mode" be made available, especially if it could be associated to DTS, DD, or other formats that are supported by HT Receivers etc, but not to files that should not be passed through. I know this could be a bit dangerous (ie the volume level changes as a pass-through file follows a non pass-through file, with internal volume set lower), but may be worth thinking about?
I banged my head against this for a while too, and managed to get it to work, I'll have to dig around and see if the problems I had were the same as yours, and if so, provide some feedback for you, but I suspect mine were slightly different.
Alex B:
--- Quote from: Fonzo on May 09, 2007, 04:57:52 am ---However, when playing .dts/.wav files, DTS-CD-images (on my hard disk as .cue with.wav files) or loaded in a virtual drive (.ngc and .img), the signal can only be played when selecting the "2-In/2-Out, 24-bit, 8000 – 48000 Hz" option in the M-Audio control panel. The output to the speakers is 5.1 and the receiver indicates DTS 3/2.1 output, BUT I noticed a quality difference between these two M-Audio control panel options mentioned above when playing DTS-DVD. Output though "pass-through" just sounds better.
--- End quote ---
I reread your original question. I think this quoted part means that the ".wav DTS" pass through already works correctly. It is supposed to deliver the apparently 2-channel PCM audio stream in fully unaltered form to the external decoder. If the DTS sign on your receiver shows up and you can hear multichannel audio then the decoder works. Otherwise you would hear only very unpleasant static noise.
With SPDIF pass through the perceived audio quality is depended on what your source material contains and how your receiver handles the signal. It is not possible to alter the quality on PC when an external decoder is used. This is the very nature of "pass through". You can only try to enhance the quality with the receiver's adjustments.
It is not possible to transmit decoded multichannel PCM stream through SPDIF. With usual home audio systems SPDIF is limited to 2-channel PCM or undecoded DD or DTS (or in some cases WMA Pro Multichannel) pass through.
AFAIK, if the files have .dts extension MC uses DirectShow filters for signal processing. I have not recently experimented with possible DirectShow filter combinations, but in any case if the source is decoded on PC you would need to use a soundcard that has 5.1 (or 7.1) analog outputs and use the analog connection or have installed a real-time software encoder that re-encodes the stream to DD or DTS before sending it to SPDIF. Possibly some DirectShow fiter combination/option can redirect the .dts files to SPDIF without decoding.
Fonzo:
Ok, thanks. Your answer sounds logical.
I assumed the .wav decoding was indeed done in the external decoder, because the DTS sign indeed shows up on my Sony DTS-receiver. So somehow the undecoded signal _seems_ to arrive through SPDIF.
The thing that got me confusing was the fact that the DVD DTS 5.1 (Donald Fagen's Kamakiriad) sounds -just a little bit- better in "Dolby Digital/DTS pass-through 16-bit/48000Hz", rather than in "2-In/2-Out, 24-bit, 8000 - 48000 Hz" mode. So, I was wondering whether .wav DTS is really passed-thru undecoded to the external decoder.
Now that you mention "WMA Pro": I saw this somewhere in the options of Windows Media Player 11, where you can select to play WM Audio Professional over SPDIF (requires external audio decoder which should be compatible with WM Audio Pro and DirectX 9.0b or higher. I could not select this option (grayed-out), because the M-Audio is (apparantly) not supported. At this point I started to try alternative media players. Could this have something to do with it? When installing the official and latest M-Audio drivers downloaded from their website for the first time, I got a warning these were non WDM-certified drivers, which I of course ignored.
I contact M-Audio Technical Support and reffered to this topic. Maybe they have some suggestions.
Alex B:
--- Quote from: Fonzo on May 11, 2007, 09:27:38 am ---The thing that got me confusing was the fact that the DVD DTS 5.1 (Donald Fagen's Kamakiriad) sounds -just a little bit- better in "Dolby Digital/DTS pass-through 16-bit/48000Hz", rather than in "2-In/2-Out, 24-bit, 8000 - 48000 Hz" mode.
--- End quote ---
Possibly your decoder software detected the 2-in/2-out mode and sent signal that was decoded to matrixed surround or even plain 2-channel PCM stereo and your receiver used automatically matrix decoding or a simulated 5.1 surround mode, like DTS Neo:6.
--- Quote ---Now that you mention "WMA Pro": I saw this somewhere in the options of Windows Media Player 11, where you can select to play WM Audio Professional over SPDIF (requires external audio decoder which should be compatible with WM Audio Pro and DirectX 9.0b or higher. I could not select this option (grayed-out), because the M-Audio is (apparantly) not supported. At this point I started to try alternative media players. Could this have something to do with it? When installing the official and latest M-Audio drivers downloaded from their website for the first time, I got a warning these were non WDM-certified drivers, which I of course ignored.
I contact M-Audio Technical Support and reffered to this topic. Maybe they have some suggestions.
--- End quote ---
MC supports WMA Pro Multichannel pass through. You can find the option here: Plugin Manager > Input > WMA > Configure... I don't know if it works with a Transit. In addition your receiver must support WMA Pro decoding.
This thread has more info: http://yabb.jriver.com/interact/index.php?topic=30804.0
JimH:
I've added this thread to the FAQ. Thanks, Alex. As usual.
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