ullanta
Veteran
Video "Streaming" protocols, like the previously ubiquitous video tape formats, send data in realtime at a fixed rate. Think of it this way - tape mechanisms can't easily or accurately change speed to record/playback video recorded with different amounts of data each second. So, a DVCProHD stream from the HVX must be 100Mbps. Further, the streams determine the number of frames per second, and the size of each frame, so DVCProHD is either 60 progressive frames or 30 interlaced frames.
So, recording at 30p, uou have to put SOMETHING in the extra frames to fill out the stream. You could put in blank frames, or random noise, but when played back on DVCProHD stream-handling equipment, it would sure look weird! So they put in duplicate frames, which allow the stream to be viewed or played in the most reasonable way.
If you're asking, "why not pack 'extra original' frames into the stream?", the answer is, where would they come from? The camera captures in real-time... In general, at 30fps the shutter is held open twice as long as at 60fps; for 10fps it would be six times as long. So there's no way of just "grabbing more frames"... so at 30fps, the camera is only capturing 30 frames each second, and can't "pack the future" into the stream.
However, from what I understand, you don't care about any of this... you want the highest frame rate you can get for most detail of the actions/expressions of your subjects... so you'd shoot at 60fps, which fills the stream completely and needs no frame duplication. Right?
So, recording at 30p, uou have to put SOMETHING in the extra frames to fill out the stream. You could put in blank frames, or random noise, but when played back on DVCProHD stream-handling equipment, it would sure look weird! So they put in duplicate frames, which allow the stream to be viewed or played in the most reasonable way.
If you're asking, "why not pack 'extra original' frames into the stream?", the answer is, where would they come from? The camera captures in real-time... In general, at 30fps the shutter is held open twice as long as at 60fps; for 10fps it would be six times as long. So there's no way of just "grabbing more frames"... so at 30fps, the camera is only capturing 30 frames each second, and can't "pack the future" into the stream.
However, from what I understand, you don't care about any of this... you want the highest frame rate you can get for most detail of the actions/expressions of your subjects... so you'd shoot at 60fps, which fills the stream completely and needs no frame duplication. Right?
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