On Thu, Sep 20, 2018 at 2:42 PM John Moore bigfish@... [Editing-List] <Editing-List@yahoogroups.com> wrote:

 

I'm working on an HD project and all media and renders are ProResHQ.  I export a QT Ref from Avid and do a save as in QT Pro 7.  Everything looks fine at this point.  When I take the .mov into Adobe Media Encoder to compress for an H_264 screener set to 1.5 mbps target and max data rate there is severe blocking in the open title animation but the main show looks decent.  The open animation has a heavy chroma treatment with a wash over the footage going from magenta on the left to blueish on the right with a soft transition about mid frame.  This was done by an accomplished AE artist.  The chroma is heavy but not illegal on my Tek scope.

The resulting file has the blocking already mentioned in the open and also stuttery video in sections.  There is visible popping of the blocking size along the way.  Upping the data rate helps and going up to 10 mbps seems to make it pretty smooth.  I started playing with target vs. max data rate and seem to have found 1.5 mbps target and 5 mbps max data rate a good compromise.

My curiosity is that I understand heavy saturation and some hues more than others will tax an encoder but I'm surprised to see stuttering along with the blockyness.  Perhaps what appears to be stuttering is really strange shifts in the blockyness but it really looks like stuttering video.  This is only during the open animation.

Can anyone shed some light on practical application of setting a higher maximum data rate than the target bit rate in AME or other encoders.  Is it likely the hue wash saturation that is making the encoding wonky?  I assume so but the stuttery video is a surprising artifact to me.

 

John Moore Barking Trout Productions Studio City, CA bigfish@...