Audiotrak Prodigy 7.1 HiFi AC3/DTS SPDIF-passthru (and bit-perfect audio)

[OleJ]

These tips are specific to the Audiotrak Prodigy 7.1 HiFi, but they might be useful for others. Please post a reply with your sound card brand+model if this was the solution you needed so others may search and find this

Contents:
Prerequisites:
Reason for these tips:
AC3/DTS pass-thru (with MPA Decoder Filter)
AC3/DTS Pass-thru with InterVideo Audio Decoder (WinDVD)
Bit-perfect stereo playback


Prerequisites:
Latest driver (I'm using "Prodigy_71_HiFi-x2v-v0_978.zip" - Get it here)
DVD with surround soundtrack
Divx with AC3 soundtrack
(MP3 file; for the bit-perfect part)


Reason for these tips:
I haven't previously been able to get spdif pass-thru to play AC3/DTS without stutter / lag in the images and sound. The stutter and lag caused audio to randomly skip a few seconds forward and video to slow down and then go really fast for a few seconds.
I finally found the solution and underway I picked up a few tips I think others may find useful.


AC3/DTS pass-thru (with MPA Decoder Filter)
In Mediaportal Configuration:
- Under "General" make sure that "Enable GUI sound effects" is UNchecked.
- Under "DVD -> DVD Codec" and "Movies -> Movie Player" set the following:
Audio Decoder = MPA Decoder Filter
*Audio Renderer = QVE for Prodigy 7.1 HiFi
- Under "Directshow Filter Control -> MPA Decoder" set "AC3 Decoder Settings" and "DTS Decoder Settings" to "S/PDIF" (I have "AC3/AAC/DTS/LPCM Format" set to "PCM 24 bit" but not sure if it matters)

*=This is the crucial part. You may use another audio decoder if so desired. E.g. ffdshow or even "InterVideo Audio Decoder" (but then please see note below concerning this decoder)

And that is basically it. You should now be able to play both your DVD and Divx and enjoy sweet spdif pass-thru.

Using "QVE for Prodigy 7.1 HiFi" is the magic part as the other audio renderers ("Prodigy 7.1 HiFi", "Default DirectSound Device", "Default WaveOut Device", "DirectSound: QVE for Prodigy 7.1 HiFi" and "DirectSound: Prodigy 7.1 HiFi") all break SPDIF pass-thru and introduce stutter and lag and other "funny" stuff.


AC3/DTS Pass-thru with InterVideo Audio Decoder
Usually when using this decoder your reciever will only recieve a PCM stereo signal.
Whether or not MediaPortals interface (Directshow Filter Control -> WinDVD 7 Decoder Filter) is defunct or not I shall not say. But:
To force this decoder to output directly (correctly) to S/PDIF you need to edit your registry.
Which value to input is a matter of trial and error though.

Step by step:
0: MediaPortal Configuration -> DVD -> DVD Codec -> set "Audio codec" to "InterVideo Audio Decoder" and set "Audio renderer" to "QVE for Prodigy HiFi"
1: Fire up regedit (Start->Run->"Regedit")
2: Navigate to HKEY_CURRENT_USER\Software\InterVideo\Common\AUDIO DEC\MediaPortal
3: Right-click and Modify the "AUDIO" key.
4: Now it's time for guessing. Some users have reported 6, some 7 and for me it was 8 that enabled SPDIF. Just try your luck and restart MediaPortal and play the DVD to see if your reciever suddenly recieves multi-channel input.
5: Backup this golden setting - in regedit go to "File -> Export" and save it. In case you accidentally edit the codecs audio settings just double-click the saved .reg file and voila surround is back

Afterwards you get it to work do not change "Audio Decoder Settings" in "MP Config -> Directshow Filter Control -> WinDVD 7 Decoder Filters" as this will void the registry setting you just made. (necessitating the .reg-file you of course made in step 5).


Bit-perfect stereo playback
As extra icing on the cake here's how to get that bit-perfect stereo audio reproduction avoiding Windows' Kernel Mixer.

1: Install Symphys ASIO plugin (This may be embedded in the MP code some time?)
2: In Mediaportal Configuration go to "Plugins -> PureAudio" and right-click and select "Configuration". Under "ASIO Device" select "ASIO 2.0 - ProDigy 7.1 HiFi" and click "OK"
3: Click OK in Config window and start up MediaPortal
4: Play an MP3 or .flac and enjoy the increased sound quality.