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Old September 29th, 2009, 07:08 PM   #1
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Time-Lapse and Pre-Buffer Recording

Just a quick note that the time-lapse recording is coming along faster than I had expected. I saw the first files this afternoon with a 1 frame per second and 1 frame per minute interval. The video looked great, with the clouds moving over Pikes Peak and the cars streaming by on the interstate.

Just for clarification, time-lapse recording is done in I-Frame only mode, since the changes from one frame to another can be significant. Since the actual data-rate to the CF cards is greatly reduced (compared to full-motion video), we are recommding that everyone use the 220 Mbps I-Frame only CODEC, which gives fantatsic video quality. We are modifying the firmware to allow all qualified CF cards (even the 133X cards) to be used at the 220Mbps rate (in time-lapse mode only).

Also, the pre-record buffer has been greatly expanded. Previous the pre-record buffer was fixed at 4.5 seconds for all bit-rates. The new firmware will now provide the following:
1) 4.5 seconds for 140/160 Mbps rate
2) 7.0 seconds for 100 Mbps rate
3) 11.0 seconds for 50Mbps (and lower) rates

The new firmware is scheduled for release in Oct, the exact date is pending reliability tests.

Best-
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Old September 29th, 2009, 08:48 PM   #2
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That great news Mike.
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Old September 29th, 2009, 09:52 PM   #3
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Hi Mike:
What exactly are the are the interval settings ? One frame at what interval spreads have CD programmed ? This is really great news to learn you have this feature working. Do you have this feature working on a Flash XDR as well ?
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Old September 29th, 2009, 11:07 PM   #4
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Dear Mark,

For our Time-Lapse feature, we have a lower limit of one second.

(Below one second will be handled by our upcoming over and under-cranking feature.)

Our Time-Lapse feature is extremely flexible.

You can specify any value for the time-lapse interval in the form of:

HH:MM:SS (I do not know if we have days, as in DD:HH:MM:SS)

Thus one can specify any number of hours, minutes and second for the delay interval.

This is far more flexible than most implementations which allow you to use a pull down menu to select from a limited number of options.

You can specify the exact Hours, Minutes, or Seconds that you want for the interval.

I do not know if we limited the hours to a maximum of 99 hours or allowed for longer intervals.

I think it is highly unlikely one needs to have a time-interval of longer than one frame per day. We think the most common time intervals will be far less than this, typically one frame per second, or one frame per minute.

One real important feature of our implementation is that you can obtain 220 Mbps I-Frame Only quality, using any one of our recommended CompactFlash cards, even the slowest recommended 133x cards.

Mike reports that the images look great.

Also, note that your camera or HD-SDI signal source does not need to have time-lapse capability. We do need for the camera to remain on during the duration of you time-lapse recording session.
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Old September 30th, 2009, 05:37 AM   #5
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I think the Time-lapse option and requirement are OK.
I agree with Allister Chapman about the time-lapse for sunsets and other natural scenes:
1 frame per second.
I guess that using Intraframe some how can be less power consuming than GOPs.
Not sure.
The Stock Footage companies prefers time-lapse from still cameras. With I-Frame 220Mbps I don't think they will complain much.
The expansion in the pre-buffer simply rocks.
rafael
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Old September 30th, 2009, 07:10 AM   #6
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Dear Rafael,

Yes, the one frame a second looks very nice.

There are technical reasons why we are using I-Frame Only (Intraframe) instead of Long-GOP for our Time-Lapse feature.

If the time-lapse period is short, there may be only minor changes from one recorded frame to another. But, if the time-lapse period is longer, there could be major changes.

In any case, our I-Frame Only Time-Lapse feature appears to be working very well.


We were very happy to be able to increase our Pre-Record Buffer times.
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Old September 30th, 2009, 09:51 AM   #7
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Quote:
Originally Posted by Dan Keaton View Post
Dear Mark,

For our Time-Lapse feature, we have a lower limit of one second.

(Below one second will be handled by our upcoming over and under-cranking feature.)

Our Time-Lapse feature is extremely flexible.

You can specify any value for the time-lapse interval in the form of:

HH:MM:SS (I do not know if we have days, as in DD:HH:MM:SS)

Thus one can specify any number of hours, minutes and second for the delay interval.

This is far more flexible than most implementations which allow you to use a pull down menu to select from a limited number of options.

You can specify the exact Hours, Minutes, or Seconds that you want for the interval.

I do not know if we limited the hours to a maximum of 99 hours or allowed for longer intervals.

I think it is highly unlikely one needs to have a time-interval of longer than one frame per day. We think the most common time intervals will be far less than this, typically one frame per second, or one frame per minute.

One real important feature of our implementation is that you can obtain 220 Mbps I-Frame Only quality, using any one of our recommended CompactFlash cards, even the slowest recommended 133x cards.

Mike reports that the images look great.

Also, note that your camera or HD-SDI signal source does not need to have time-lapse capability. We do need for the camera to remain on during the duration of you time-lapse recording session.
...Hi Dan. Well this is totally amazing ! What about the other sort of timelapse where you have the intervals as you mentioned, but it's stop shutter open, stop shutter open ? Would it be possible for a camera like the XL H1 to take several *scans* during the I-Frame recording proceedure in order to totalize exposure of a subject ?

An example of this would be to catch low light scenes, such as, the Night sky and constellations, moonlit landscapes, etc.
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Old September 30th, 2009, 10:14 AM   #8
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Dear Mark,

Sorry, we do not support "Frame Accumulate".

Personally, as one interested in astronomy, I would like such a feature, but this is a very specialized application.
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Old September 30th, 2009, 10:36 AM   #9
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Quote:
Originally Posted by Dan Keaton View Post
Dear Mark,

Sorry, we do not support "Frame Accumulate".

Personally, as one interested in astronomy, I would like such a feature, but this is a very specialized application.
...Darn ! I would very much like to put the XL H1 on an equatorial mount with the XDR and do interval frame accumulate recording. I don't think anything would change with your code as far as you have written your basic time count intervals, but if you could turn on the firewire interface, then you folks *might* be able to get HDV camcorders (Like the XL H1) to *clock* the CCD's to accumulate scans to frame exposure. I must admit this is pretty darn fancy stuff, but it's theoretically possible. The FireWire interface might only give you 4:2:0 color space as well, which would not be ideal, but would be a reasonable compromise, unless their is yet another way to clock the CCD's via the HD-SDI interface.
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