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WVTV I frame interval

Started by techboy, Friday Oct 01, 2010, 11:23:22 PM

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techboy

Anybody else notice that WVTV has increased the I frame interval from 15 frames to 45 frames?  2/3 less I frames results in about a 1 mb reduction of the stream data rate, but it makes finding an I frame to edit on ( cut out the non program material ) a lot more difficult.  Whats the technical point of 1-1/2 seconds between I frames?
Retired Broadcast TV / Radio Engineer WTMJ. ( 35 Yrs )

Jimboy

Quote from: techboy;56329Anybody else notice that WVTV has increased the I frame interval from 15 frames to 45 frames?  2/3 less I frames results in about a 1 mb reduction of the stream data rate, but it makes finding an I frame to edit on ( cut out the non program material ) a lot more difficult.  Whats the technical point of 1-1/2 seconds between I frames?

No I didn't notice.......
Didn't change anything. It should still be set to 15.
I'll check on Monday.

techboy

Recorded Smallville 10/08 and still getting 45 frame I frame interval except for hard I frames at scene cuts.   While I can make an edit on B or P frames, it's better for my decoder if I keep to I frames.  What's changed?  I had 15 frame interval for the recordings I made last season.
Retired Broadcast TV / Radio Engineer WTMJ. ( 35 Yrs )

Jimboy

Quote from: techboy;56365Recorded Smallville 10/08 and still getting 45 frame I frame interval except for hard I frames at scene cuts.   While I can make an edit on B or P frames, it's better for my decoder if I keep to I frames.  What's changed?  I had 15 frame interval for the recordings I made last season.

New Encoders. Installed 7/23/10.
They offer up to 25% better picture quality over the older units we were using. They also work much better than the units damaged by the flood.

tencom

The data saved by using  45 I frame instead of 15 frame intervals could be applied towards providing additional picture detail. Must be using a improved motion Algorithm that requires less refreshing