Lurking inside the V4HD is an extremely powerful processor that provides real-time, broadcast quality video conversions.
The V4HD's hardware accelerated video processing distinguishes it from the HDX-SDI, which relies entirely on the host computer for all video conversions and processing. The V4HD takes on some of the heavy lifting required to process video (especially HD) in real time, freeing the computer's CPU for other important processing tasks during real-time capture and playback.
Up-conversion and down-conversion
When you feed an SD signal into the V4HD, it automatically converts the signal in real time to the currently chosen HD format. This allows the HD outputs to produce signal, even when an SD signal is being captured. It also allows you to capture the SD signal in the HD format of your choice, in real time, during capture, saving you the time it would take to convert the clip off line afterwards.
Conversely, when you feed an HD signal into the V4HD, it automatically converts it in real time to SD, so that all SD outputs are active, even when an HD signal is being captured. Because the down-conversion is being handled by the V4HD, you can also choose to capture the HD signal as SD on the computer, if you like.
Pulldown insertion and removal
Pull-down is a process used to convert 23.976 fps film footage to 29.97 interlaced video.
Reverse pull-down, or pull-down removal, can be used to restore the original film frame rate.
These processes involve the addition or removal of interlaced video fields. If you feed a signal running at 23.976 or 24 fps into the V4HD, and then send it to an output running at a different frame rate (29.97, 30, 59.94 or 60), the V4HD hardware processor inserts extra frames to reconcile the two formats.
You can even choose the cadence for pull-down insertion: either 2:3 or 2:3:3:2. These cadences prevent artifacts or "glitching" in the resulting footage.