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Virtual Tape Properties
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The format of the VTP (including image size, frame rate, SNR, MDR, QMF, Encoding, audio sampling and
audio form) is determined by the AV record settings ( Record menu pages 1 – 3) when the virtual tape is
created.
The remote edit controller controls the settings for individual edits. This includes the edit decisions for audio
and video in and out points for each edit.
Alternately, the
VTP Editor menu page can be used to edit virtual tapes and their assets from the front panel
GUI.
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The only audio settings that apply to virtual tapes are bit depth, sample rate and format. The number of audio
channels (tracks) does not apply because virtual tapes always have the maximum 16 channels available to
them at all times. In most cases, the number of audio channels supported by the editor controller determines
the number of audio channels that may be recorded into a virtual tape.
Unlike a collapsed clip, a virtual tape does not have a fixed number of audio tracks (channels). This is the
reason why the EDIT menu page does not show the number of audio channels for a VTP. The number of audio
tracks dubbed from the source material to a QuBit virtual tape may change on an edit-by-edit basis, as the
video editor chooses. Therefore, virtual tapes always have anywhere from 0 – 16 audio channels at any time. It
is up to the editor to determine which tracks receive audio, and how audio is routed, during the editing process.
Audio received on a specific channel during editing will play out on the same channel for playback.
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Virtual tapes run for the exact length of time specified when they are created. Unlike videotapes that typically
run slightly longer than their stated length, virtual tapes do not contain any “padding”. If your projects tend to
run long, it may be advisable to create a longer virtual tape than you think you’ll need.
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Editing virtual tapes can create “leftover” clips.
During the course of creating and editing a virtual tape you may decide to dub over an existing segment that
was previously recorded. This results in partial or total clips that remain the virtual tape directory but which are
not used in the final project. With videotape, recording over a section of the tape replaces the previous footage.
With a virtual tape, you are simply recording a new clip into the VTP directory, and the VTP project file (.vtp) is
keeping track of the fact that it replaces a previous clip that belonged there. The system does not automatically
remove unused segments, so you may wish to keep an eye on your disk usage if you make many changes.
Also, while unused segments do take up space on the disk array (volume), they do not take up time on the
virtual timeline since they are not an active part of the virtual tape project.
The VTP Clean utility (available from the Play Browser menu page under Tools ) is used to remove edits from a
virtual tape that point to assets that no longer exist. This enables a compromised virtual tape, where assets
may have been deleted, to be updated to only include edit that have physical assets assigned to them. This
same operation may be performed using the QShell
VTPMerge command and the –clean option.
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When you play a .vtp file from the GUI, you are in effect playing the virtual tape project (with all edits that have
been performed up to that point). You can monitor the timecode for the virtual tape by clicking on the
dashboard timecode display until it shows
TCV (Timecode Virtual).
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Select a video asset (“.v” file) in a virtual tape directory and press PLAY to play the clip without its original
audio tracks. Playing the video asset will only play the video.
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Select an audio asset (“.a”, “.wa” or “.a0x” file) in a virtual tape directory and press PLAY to play that audio file
separately from its video and audio siblings (the other file belonging to the same asset group).
QuVIS Acuity
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