Known Pro Tools HD/TDM Issues

Note: AAX plug-ins and Pro Tools HD 10.3 and 11

We strongly recommend updating to 3.8, as AAX plug-ins do not exhibit the behaviour discussed below.

RTAS plug-ins and Pro Tools HD

RTAS plug-ins in Pro Tools HD 7-10 may exhibit the following behaviour:

• When the transport is not in playback or record, the RTAS engine may stop processing and you will not hear your connection partner. Putting the transport into play will refresh this.
• Remote Transport Sync may fail to respond when using RTAS plug-ins.

To resolve many issues we ultimately recommend that you use Source-Connect Pro as a Standalone application (version 3.8) and use the optical I/O where possible. See Appendix I in the User Guide for advice or contact our support team.

Where this is not possible you can try to minimize the issues. Please set the following in your HD sessions.

1. In your Setup->Playback menu to your RTAS processors to 1
2. Set your HW buffer in the Playback settings to 512 or 1024
3. Set your DSP voices to 48, 32 or lower (try 32, if you get CPU errors you can raise this, but we have found that 32 or lower is more stable).

If you do not set the above you may experience issues when going into record (the audio connection may drop completely or stutter), and your RTS functionality may be disrupted.

Recommendation for Pro Tools HD Users:

It is recommended to use the external I/O method instead of using plug-ins.

Using external I/O with Source-Connect

Note that there are no known issues with Pro Tools LE or M-Powered, or with Pro Tools 6 HD.

Some questions about Pro Tools HD are explained below.

Why do I sometimes not send or receive audio in PT HD during my Source-Connect session?

With Pro Tools 7 HD, Digidesign no longer supported HTDM plug-ins. RTAS plug-ins are controlled by a different clock than TDM, and this RTAS host processing is not given the same priority as TDM processing. Because The TDM and Host RTAS process need to be synchronized, Digidesign periodically stops and restarts the RTAS processing. Simply put there are unpredictable times when PT7 will sometimes simply stop providing RTAS plug-ins with audio. We try to detect this and alert you via an IM message in SC. The only known way to continue processing is to activate the playback, which essentially 'restarts' the RTAS processing engine. This issue can also affect use of Remote Transport Sync, though this is far more rare as the system is being put into playback and thus the RTAS engine should restart itself.

Why isn't Source-Connect a TDM plug-in?

TDM plug-ins cannot give audio to the host (your computer's CPU), and while it is possible for us to process the audio on the DSP chip there is no way to access the resulting data to send over the network. Source-Connect is an HTDM plug-in for Pro Tools 6.4-6.9 TDM systems, and as such does not exhibit the same issues experienced in Pro Tools HD 7/8 (where it runs as an HTDM plug-in, because it adheres to the TDM clock and thus does not stop processing).

Does Pro Tools LE have these issues?

Not at all. Source-Connect runs flawlessly in Pro Tools Native, LE and M-Powered. (assuming your system is properly configured according to Digidesign specifications and you have suitable bandwidth and network conditions). Other known issues:

The implementation of RTAS on TDM also creates other inconveniences to the user.

1. RTAS plug-ins on Aux and Master channels creates a latency equal to the Hardware buffer. For this reason we suggest that TDM users of Source-Live place the plug-in on an separate Auxillary track receiving a copy of the the master channel's audio but not directly monitored in the control room or headphones of the local system.
2. When the RTAS engine restarts, it starts as much as half a second after the TDM engine starts. For this reason when using Source-Connect you will find you have not recorded the first half-second of the receiving audio and or may not send the first half second of audio that is heard in the control room. To resolve this please ensure you start playback or record a second or so before the actual time you wish to start.
3. Some users may experience issues with both Source-Connect and Source-Live where send/receive does not work, or the RTAS engine never processes audio. The workaround for this seems to be lowering the number of DSP voices you are using.