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#1 Jerry Doran

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Posted 25 November 2006 - 10:21 PM

2 questions:

1. I was testing an SRW-1 set up to record 4:4:4 23.98 PSF from an HDC-950 and had a small Marshall monitor set up on-board the camera. Taking a feed to the Marshall from the HD-SDI Monitor Out on the back of the SRW-1, I noticed a small visual delay. Taking a feed from the SD-SDI Monitor Out, I noticed a larger delay. What is the exact time of these delays and can they be synced to real time?

2. In reading postings/web sites where people give numbers they tend to program into Cinealta cameras, they never mention whether or not these numbers are absolutes. For example, if someone says they typically start with their knee point at -25, does that mean they start with absolute zero so the absolute numbers read -25 across?
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#2 David Cox

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Posted 26 November 2006 - 04:25 PM

2 questions:

1. I was testing an SRW-1 set up to record 4:4:4 23.98 PSF from an HDC-950 and had a small Marshall monitor set up on-board the camera. Taking a feed to the Marshall from the HD-SDI Monitor Out on the back of the SRW-1, I noticed a small visual delay. Taking a feed from the SD-SDI Monitor Out, I noticed a larger delay. What is the exact time of these delays and can they be synced to real time?


Roughly how long were the delays?

I beleive there is a 1 frame delay to the output when the SRW-1 is recording. This is most likely just due to syncronisation but could also be because it is replaying what was just recorded to tape in order to provide "confidence" playback.

I'm thinking that there might also be a 1 frame delay from within the SRW-1 doing a 4:4:4 to 4:2:2 conversion for your HD-SDI out. Maybe another one downconverting this to SD. Did you have any aspect ratio conversion going on as this will also add a frame delay?

Also, does the Marshall monitor have any in-built delays as a lot of flat screen monitors do (although then of course your HD and SD feeds would both be late).

So that might all account for 1-3 frames of delay?
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#3 Jerry Doran

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Posted 26 November 2006 - 05:02 PM

Roughly how long were the delays?

I beleive there is a 1 frame delay to the output when the SRW-1 is recording. This is most likely just due to syncronisation but could also be because it is replaying what was just recorded to tape in order to provide "confidence" playback.

I'm thinking that there might also be a 1 frame delay from within the SRW-1 doing a 4:4:4 to 4:2:2 conversion for your HD-SDI out. Maybe another one downconverting this to SD. Did you have any aspect ratio conversion going on as this will also add a frame delay?

Also, does the Marshall monitor have any in-built delays as a lot of flat screen monitors do (although then of course your HD and SD feeds would both be late).

So that might all account for 1-3 frames of delay?


The HD out delay was small, no more than a few frames. The SD delay was longer, maybe 15 or so? No aspect ratio conversion. And I'm not sure about the Marshall...I'll look into it.

Edited by Jerry Doran, 26 November 2006 - 05:04 PM.

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