Capturing HDV- jerky preview with only 40% CPU util.

[Andretti]

I have 2 questions.

FIRST:
I understand that sometimes the preview function when capturing is assigned a low priority to allow for no dropped frames. But how come that my device control (Sony HC1) and preview is lacking at best, when my CPU is taxed with less that half of its capacity?

My current editing platform is a Sony Vaio notebook, which would represent a low end solution under these circumstances but still...

I have a Pentium M 2.GHz+ CPU (corresponding to 3.0 GHz P4), and like I said it isn't sweating during this part of capturing.

My clips do turn out fine, but it's a nuisance to control the tape in small increments during preview/capture.

SECOND:
In absence of scene detect I tend to use batch capture. Often when MSP8 is starting this process it will rewind the tape at 1x speed between clips instead of just fast forwarding to the next clip in sequence. Since the speed is only 1x it means that it takes more than 80 min of dead time just to go from a clip indexed at 40 minutes into the tape to the next one indexed at, let's say 42 minutes and 2 seconds. This has to be a bug. Am I the only one?

It might have to do with CPU util. jumping to close to 100% when MSP8 is 'controling' the camcorder (just fast forwarding- not previewing).

Appreciate any input

thanks

a

[Devil]

"Capturing" is not what you think it is, when your starting point is already in a digital format. Theoretically, it needn't use any CPU power at all, other than a tiny amount for system management. Your signal stream goes to a part of the memory which acts as a buffer and from there it goes to hard disk, bypassing the CPU through DMA (direct memory access). Some of is "stolen" by the CPU to process into the display and sound etc. This is done by sampling at a frequency which will ensure that there is no risk that the CPU will give it priority over the all-important system management.

Put it this way, with arbitrary figures. Say 10% average of the CPU is used for system management and 40% altogether is used during capturing, with the sound being continuous (half of the loading) and the video showing 1 frame in, say, 20 (the other half). That means 15% is used for displaying the video. Increase the display rate to 20/20 frames and your CPU usage will rise to a whopping 300%, causing you problems.

OK, this is a very simplistic explanation, but you get the picture? (Or should I say you capture the picture? )

So be happy that you get what you get!

Why don't you simply transfer (note I don't say "capture"!) the whole tape and then use the split by scene feature in VE?

[Andretti]

Thanks for taking the time to reply.

I like your tip at the very end. Can you confirm that this is possible with HDV? Because capturing with scene detect is a feature I miss from some of the other softwares I've tried.
If it really is possible to capture the whole tape and then split by scene afterwards, that is most likely going to be my preferred method.

When you say transfer, I guess you still mean with the capture tool, right?

I'm new to MSP8, trying to read up on it in my spare time....

[Terry Stetler]

As Devil said the term "capture" when used in the context of DV and HDV video is a loosely defined one. They're actually data transfers, much as if the camera were an old-style tape drive and you were copying its contents to a hard drivel.

As for split by scene; this can be done on the timeline, in the Storyboard or in a Media Library by selecting the file and selecting "Split by Scene" from the context menu.

With this fucnction DV is split by timecode (pause/stop) scene markers and MPEG-2 by the scenes content. This can also be done in the Insert Video dialog when you load a captured file from the HDD by clicking the "Scenes" button, then in the next dialog clicking the "Scan" button.

Of course when splitting by scene content sometimes you'll get more "scenes" than are really there, but the "extra" ones can be "Joined" to others to fine tune the split.

Another option is to select the Multi-Trim tool from the same Storyboard/Media Library context menu. Multi-Trim allows you to mark long captures into sections for splitting. Here's the UI;