The spikes are probably there even in playback, just less visible.
Try to increase the trace intensity and use line select to position yourself in the offending areas(hot spots, car headlights, fire, flames, etc.)
Then see if you can spot them at normal speed playback.
Another factor is interlacing. If the format recorded on tape is interlaced and the deck is set to display one field, it could make a difference when you're paused.
As a last trick, you can set trace persistence to infinity, let the tape run at normal speed, then come back and see the video level swing (both under and over shoot), then decide if you need to intervene.
BG
From: John Moore <bigfish@pacbell.net>
To: Avid L2 <Avid-L2@yahoogroups.com>
Sent: Saturday, February 8, 2014 12:03 PM
Subject: [Avid-L2] Video Levels jump in pause on Sony F-500 HDCam
Got a QC bounce for levels exceeding 720 millivolts. I have safe color limit set RGB 0 to 700 etc... plus an ensemble external legalizer also set 0 to 700mV. I am aware how both HDCam and to a lesser extent HDCamSr will exhibit specular/transient spikes on level due to their form of compression. What will run error free through my Tek WFM 7020 set to 0% gamut diamond error and Tek default alarm setting will light up like an Xmas tree playing the same sequence back from tape. In consulting with Tektronix setting the alarm area to 1% eliminates the unavoidable alarm triggers on tape playback.
Well today's QC of transient levels of 720mV is not on my Avid output only on the HDCam tape playback and it really only happens in pause. Playing through the flagged section is fine but once you hit pause the transient levels appear. Now pre digital I understood more about why in pause levels might shift, still frame chroma adjustment on a VPR-2 anyone ;-), but I'm curious why in a digital format the HDCam jacks the levels a bit in Pause/still. Given the levels are fine in play I told the QC Monkey to kindly pass the show, leaving out the part where I wanted to tell him/her to learn to use the scope properly and stop wasting my weekend time.
So can anyone enlighten me as to why in our HDCam F-500 transient levels appear in pause? The are little specular like excursion that pop up. It's not like the whole video signal level is jumping up overall. I figure it's the nature of the beast but why?
John Moore
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
__._,_.___
| Reply via web post | Reply to sender | Reply to group | Start a New Topic | Messages in this topic (2) |
.
__,_._,___
No comments:
Post a Comment