Record Preferences

This page is a comprehensive description of what each specific preference in VirtualVTR and VirtualVTR Pro will do. It does not offer overall guidance on particular setups.

Restore Video Settings
When VirtualVTR enters E-E or record mode, it will use the default parameters set up in QuickTime to determine which Video device, input, codec, frame rate, audio input, sample rate etc to use. This is all defined in the 'Video Settings' and 'Audio Settings' available in record-ready (E-E mode). Often it is useful to have these parameters saved from session to session, to avoid the need to re-enter them for each recording. This preference requests setup data from the current video device after recording, and saves this with the VirtualVTR preferences. It later retrieves this data, next time you prepare to record and passes this back to the video device. Note that VirtualVTR has no specific understanding of the contents of this data - it is merelt stored and retrieved. All creation and interpretation of this data is handled by the Video card device driver. In most cases, this pref behaves as you would expect. However in some cases the video device driver mis-manages the data, and this can result in problems when entering or leaving the record state. If this occurs, delete the VirtualVTR preferences, disable this preference and contact the vendor of your Video device driver.

Preview During Capture
This is a generic QuickTime preference flag passed onto the Video device driver you use to record. Its purpose is defined by the driver, but in some cases it controls whether the video driver will attempt to 'present' the incoming video on the mac capture window, as well as at its video output. This can have an effect on the performance of the system during capture. Note that some video devices will ignore the status of this preference.

Include TC track text display when recording
All video in VirtualVTR inherently must have a timecode track. This can optionally be represented by a text area above or below the movie (only on a VGA monitor, not video out). This is actually an additional 'Text track' in the QuickTime movie. Whether this track is *displayed* is controlled in the 'Reset Timecode Reference' dialog, but in some cases, merely having the track existing in the movie can be problematic. In particular, when recording movies in VirtualVTR for editing in Final Cut Pro, sometimes the text track becomes permanently turned on and rendered into the Video in Final Cut. To avoid this situation, unchecking this preference supresses creation of the text track in recorded movies.

MTC overrides Video Hardware timestamp
All video in VirtualVTR inherently must have a timecode track. Sometimes this timestamp comes from a timecode feed supplied *during* the recording, and other times it is manually entered after recording. During record the timecode can come from 1 of 2 sources.
- 1) Via MTC through Midi, from an external LTC feed
- 2) From the video device driver itself, alongside the Video.
The second case applies when the Video hardware has the capability to communicate timecode, for example with a DV bridge where the timecode is embedded in the DV stream via Firewire. Also, devices like the Aurora Igniter can communicate timecode from its hardware LTC and VITC readers on the component interface.
By default, the timecode from the device driver will take precidence over MTC, but in some cases you want it the other way around. In particular, with DV, often the timecode always starts from zero (at the start of every tape for mini-DV, or when the interface was switched on for some bridges). In these cases, you probably want to feed real LTC from a deck via MTC to create the timestamp, overriding the embedded video hardware timestamp.

Build Video Overviews
The VirtualVTR bin has the ability to display miniature 'film strips' showing a sequence of picons drawn from the video sequence. When this pref is checked this film strip is calculated and stored inside the movie file when the movie is first added to VirtualVTR. However, in some cases, this is not possible, for example with 'locked' movies like some internet movie trailers, and when you do not have write access to the movie file (for example, on a shared storage network). In this case, you should disable this pref. If you experience any problems when adding movies, or when first opening VirtualVTR (loading the default bin), then you should delete the VirtualVTR Prefs file, and default bin, and uncheck this preference.

Force Lock To Sound Timebase
This pref enables a new function which ensures that Quicktime uses the timebase from the selected sound hardware during capture. This is important for certain hardware to ensure good audio/video sync. This pref should be ON unless it appears to cause problems with your hardware.

Limit Capture To :
This preference allows VirtualVTR to automatically stop recording after a pre-set time. This is useful for unattended loading of long sections of video. For example, perhaps you want to load in 30 minutes of video whilst you go for an extended lunch. Set this preference to 32 minutes, then set it recording. After your well earned 2 hour lunch, you return to 32 minutes of recorded video, rather than 30 minutes, and then 1.5 hours of black eating up your disk space.

Capture TC Correction mSecs :
When timestamping movies during capture, by reading MTC, various fixed latencies in the video subsystem cause offsets between the timecode arriving via USB and MTC, vs the Video arriving through the video card. This preference allows you to correct for this latency to ensure that your timestamp on the captured movie is frame accurate to the picture. The best way to set this up is by recording window-burned picture, alongside coherent timecode. Adjust this preference until the timestamp applied to recorded movies matches the window burn. The latency should be a fixed value for any given hardware setup.

©2003 Gallery