DVD-Playback AC-3/DTS under MME | Alesis Hammerfall DSP System

12.2 DVD-Playback (AC-3/DTS) under MME

AC-3 / DTS

When using popular DVD software player like WinDVD and PowerDVD, their audio data stream can be sent to any AC-3/DTS capable receiver via the HDSP MADI. For this to work an output wave device has to be selected in >Control Panel/ Sounds and Multimedia/ Audio<. Also check 'use preferred device only'.

You will notice that the DVD software's audio properties now allow to use 'SPDIF Out', 'Use SPDIF' or to 'activate SPDIF output'. When selecting these, the software will transfer the non- decoded digital multichannel data stream to the HDSP. Naturally a successful decoding also requires a MADI to AES converter like the RME ADI-642, converting the playback signals to stereo AES3 or SPDIF.

Note: This 'SPDIF' signal sounds like chopped noise at highest level.

Multichannel

PowerDVD can also operate as software decoder, sending a DVD's multichannel data stream directly to the analog outputs of the HDSP MADI. Supported are all modes, from 2 to 8 chan- nels, at 16 bit resolution and 48 kHz sample rate.

For this to work an output wave device of the HDSP has to be selected in >Control Panel/ Sounds and Multimedia/ Audio<. Also check 'use preferred device only'. PowerDVD's audio properties now lists several multichannel modes. If one of these is selected, PowerDVD sends the decoded analog multichannel data to the HDSP MADI.

The device selected as Preferred Playback Device defines the first playback channel. Choosing ADAT 3/4 and 6-channel mode, playback will happen on channels 3 to 8. Choosing MADI 3/4 and 6-channel mode, playback will happen on channels 3 to 8.

The channel assignment using PowerDVD is:

1 (first chosen playback channel) - Left

2 - Right

3 - Center

4 - LFE (Low Frequency Effects)

5 - SR (Surround Right)

6 - SL (Surround Left)

Note 1: Setting the card to be used as system playback device is against common sense, as professional cards are not specialized to play back system sounds, and shouldn't be disturbed by system events. To prevent this, be sure to re-assign this setting after usage, or to disable any system sounds (tab Sounds, scheme 'No audio').

Note 2: The DVD player will be synced backwards from the HDSP card. So when using Auto- Sync and/or word clock, the playback speed and pitch follows the incoming clock signal.

Note 3: PowerDVD 5 no longer supports a starting channel other than channel 1. Use TotalMix to send audio to any aother output port if necessary.

Note 4: In WinDVD 5 and 6, a channel-separated 5.1 playback using the HDSP requires a change in the registry. Start regedit, go to >HKEY_CURRENT_USER / Software / InterVideo / DVD5 / AUDIOCHAN<, and set its value to 4 (hexadecimal). Additionally select 'Waveout' as Audio Renderer in the Audio configuration dialog. Warning: Changes to the registry are done at your own risk. Danger of complete data loss!