High Def 25Psf video

More than a decade ago when Mr Sony was developing what would become HDCam (with some small contribution from the previous 1" open-reel HDVRS analogue & digital formats) they realised that progressive video was the future but existing HD equipment (typically the BVM-D series monitors) couldn't lock to such a slow framerate (24/25/29.97 as opposed to 48/50/59.98 fields). The answer for progressively-sourced pictures was the Psf standard which makes progressive frames look like interlaced video. So as to make film people think that this was better than video they have a new name for a field - the segment. In fact Psf is interlaced video (but there is no movement between the fields) - it just shows that good old interlaced video is able to faithfully reproduce progressive pictures (but the reverse is not true as progressive video with the same frame-rate has only half the motion rendition as interlaced video).

So - let's dismiss a couple of misconceptions;

• There is no difference between a Psf signal and an interlaced signal from a technical standpoint
  
• Sending 1080 pictures via Psf doesn't degrade them in the slightest - in fact if you're laying off 1080 to HDCamSR then anything below a 5800 (in 50/60P mode @880mBits) is recording Psf!

Now then - below are screen-grabs from my trusty WFM7120. The first shows the output from a Symphony NitrisDX BOB. The footage had come from a Sony EX3 cameras recorded at 35mBits 1080/25P onto Memory Stick and imported straight into a progressive timeline. The Avid plays back Psf which the Tek shows as 1080i (for the reasons discussed above). Laying this off to HDCamSR (a 5500 deck) gives a 25Psf recording on tape. The second screen shot is the Quicktime sample movie imported into a new 25P timeline - it just serves to comfirm that the BOB output is always Psf.



This last picture is the down-convert output of a Leitch X75 which is a great little get you out of trouble box (basically does everything->everything with a few extra tricks thrown in - profanity delay etc.) but it's not a multi-frame broadcast standards converter (like a Snell & Wilcox Ukon).

Although you can't see it from this screen-grab the SD output has had it's field-dominance changed and the quality of the video ain't great. This wouldn't be an issue for VHS/DVD review copy or if it was the pre-processed feed for web-conversion but it's not suitable for SD delivery.
For that the best option (short of a £20k Ukon!) is to use the SD-downconvert from the HDCamSR machine.

Flashing STOP button in Sony VTRs

If (on a DigiBeta DVW-A500 or similair) you enable menu item 105 - Ref Alarm - the stop lamp will flash under several conditions;

• The reference signal is solid and the input video is locked but there is more than 43 video lines offset between them - the a longer period than the VTR's pre-read system will tolerate,


• The reference signal is solid and the input video is unlocked.


• The reference signal is solid and there is no input video and the deck is locked to video rather than ref


• There is no reference

Most folks assume it's down to a loss of reference - that's only the case in a minority of situations. I've been back and forth to one particular facility where they fail to understand this it's getting tedious!

Adrienne Electronics

Do you remember a BBC2 late-night show called Diners - back in 2002 anything that had the reality label attached to it got commissioned (although admittedly on very late in the evening). If you Google for it now there is scant evidence of it! I did find a John Walsh article from The Independent. Anyhow - one of the problems I had to solve for that show was using cheap Avids (software-only versions - ExpressDV back then) to capture or log live feeds with timecode. Of course the studio or OB sends you audio timecode (the kind that sounds like a fax and comes down a twisted pair cable) but all hardware-less edit stations assumed the timecode comes down the RS422 line as part of the machine control.
Adrienne Electronics do a range of really useful boxes to address these kind of problems - the AEC-Box-2 takes in audio code and has a 9-pin connector. It emulates a VTR but (being a solid box) doesn't actually play or rewind tape - it just tells the Avid it is doing so (in this case it's an Avid MCSoft with SDi Mojo). The really cool thing is that when the Avid asks for timecode down the RS422 the box returns what it is receiving on it's input. It's the ideal solution for using cheap workstations to log or capture proper studio or OB type material.
Now I'd been puzzling about this for ages last night (got home late from the studio where I was working) and it was only over my tea that I remembered solving the problem five years before - kinda like how everyone has forgotten Diners!