Possible indiv frames sent wrong order

Compression Techniques

Possible indiv frames sent wrong order

Posted by Emanuel Ach on July 13, 2011 at 5:08 pm

Hi,

I received a complain and I hope you guys will be able to make it clear for me.

“It appears to me that there is a problem with the method the video is being encoded. From what I can observe, the video signal seems to be de-interlaced into frames, but that the individual frames are being sent in the wrong order. This makes any motion in the video appear really jerky and tiring to the eyes.”

Is he talking about the structure of GOP? Any tips?

Thanks,

Craig Seeman replied 14 years, 10 months ago 2 Members · 6 Replies
6 Replies

Craig Seeman
July 13, 2011 at 5:20 pm

Field order being reversed maybe.
Emanuel Ach
July 13, 2011 at 5:28 pm

it makes sense… what you are saying

DV straight from tape, how do I find out which is the original?

Thanks,
Emanuel Ach
July 13, 2011 at 5:52 pm

the dv footage imported in FCP7 – sequence settings – field dominance – it says “lower” (even) and in my compression settings (in compressor) it says for field dominance – “top first”.

So apparently this is the problem right?
Which way do I go? Do I change the settings for sequence in FCP or the compression settings? Also how does it come straight from camera, top or bottom?
Craig Seeman
July 13, 2011 at 6:04 pm

How you fix depends on the encoding software you use but it’s a common problem. I generally use Episode. I’d have to check how this would be done in Compressor if that’s what you’re using. What are you encoding to? You don’t mention your Compressor settings beyond top field.
Emanuel Ach
July 13, 2011 at 6:07 pm

My full compression settings for broadcast:

Name: ntsc
Description: MPEG-2 Program Stream with MPEG audio at 48kHz. Settings based off the source resolution and frame-rate.
File Extension: mpeg
Estimated size: 2.87 GB/hour of source
Type: MPEG-2 program stream
Video Encoder
Format: M2V
Width: 720
Height: 480
Pixel aspect ratio: NTSC CCIR 601/DV
Crop: None
Padding: None
Frame rate: (100% of source)
Frame Controls: Off
Start timecode from source
Aspect ratio: 4:3
Field dominance: Top first
Average bit rate: 6 (Mbps)
Best motion estimation
Closed GOP Size: 1/2 second, Structure: IBBP
Audio Encoder
Format: MPEG
Sample Rate: 48.000kHz
Channels: 2
Bits Per Sample: 16
Craig Seeman
July 13, 2011 at 6:24 pm

Thanks for that.

As a test try using Compressor’s MPEG-2 Program Stream setting unaltered and see what the results look like. This can give you a clue whether there’s a setting you modified that’s having an unintended consequence. I notice their setting for Field Dominance is Automatic. Test their setting and see what happens.

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