View Full Version : I-Frame indicator??


Brian T. Young
July 13th, 2012, 04:38 PM
Greetings -
New NanoFlash owner here, so forgive if this is stupid.

I am looking to use the NF in a couple of ways: to replicate P2 AVC-Intra recording by putting the NF on a PDW-F800 and record in I-frame - and to replicate XDCAM 422 Long-GOP when using it on an HPX2700 Varicam and recording in Long-GOP. In basic words, to make an xdcam a p2 cam and vice versa.

My question is - in performing test recordings on the F-800 with the NF set to I-frame/100mb/1080/30p, and then playing back in both QuickTime Player 7 and FCP 7, I always see (under "format): Apple XDCAM HD422 50 Mb/s CBR when analyzing the clip.

is my mac/fcp/QT doing something to this upon playback??

thank you!
Brian

Jack Zhang
July 13th, 2012, 05:25 PM
First off: MPEG-2 I-frame is less efficient than AVC-Intra so it requires more bitrate to be relatively equal. 220+Mbps I-frame MPEG-2 should be relatively equal to or superior to AVC-Intra at 100Mbps.

It is normal for QT to read 50Mbps as the codec. Your actual data rate shows in Movie Inspector as MB/s.

Brian T. Young
July 13th, 2012, 05:35 PM
Jack,

Understood on I-frame/Intra efficiencies - thank you.

Strange for QT to incorrectly show the codec, isn't it?

Thanks again,
b

Billy Steinberg
July 15th, 2012, 09:20 PM
The Apple XDCAM HD422 Quicktime codec can play any bitrate the nano can record, but the Quicktime codec can only encode to 50Mb. It's "title" includes the 50Mb part.