DV Info Net

DV Info Net (https://www.dvinfo.net/forum/)
-   Canon EOS Crop Sensor for HD (https://www.dvinfo.net/forum/canon-eos-crop-sensor-hd/)
-   -   Blockiness and codec choice (https://www.dvinfo.net/forum/canon-eos-crop-sensor-hd/473812-blockiness-codec-choice.html)

Declan Smith February 28th, 2010 03:53 PM

Blockiness and codec choice
 
2 Attachment(s)
I recently took a pick up shot across a river coming into sun set, sun in front and to left of frame with the 7D. As the shot is to be a composited in background, and I haven't seen the foreground yet, I took a few versions at different exposures, from slightly blown out - balanced - highcontrast dark shot.

This last shot when played through quicktimeX has noticeable (and distracting) blockiness in the top right hand corner, where the picture is gray. Tonal range across this frame goes from white to black and obviously some bit in between.

If the same file is played in Quicktime 7 pro, no blockiness is seen.

It's difficult to compare in FCP, as it struggles to play h.264 clips at full speed.

So, as normal, I convert the H.264 into Prores 422 (LT). Blockiness is still apparent in Quicktime X. I then tried Prores 422 (HQ) and the blockiness is not there in QuicktimeX.

Is this an issue with QuicktimeX or the 7D compressed clips and / or I am I better off transcoding to prores 422 (HQ) ? If I Transcode to 422 (HQ) then transcode that clip to prores 422 (LT) the blockiness returns (in quicktimeX).

I have attached two photos, Sunset-Block.jpg (H.264), and Sunset-422.jpg (Prores 422(HQ)). Both are screen grabs from QuicktimeX.

Thanks in advance

David Chapman February 28th, 2010 04:17 PM

There used to be a setting in Quicktime 7 (and below) to play the clip at full quality (not on be default?). Window > Show Movie Properties... then select the video track and check the box "High Quality" in the bottom right.

ProRes LT might be compressing it too much? I don't have Studio 3 at the moment to conform. I only have ProRes and HQ and regular ProRes works fine for me.

Declan Smith April 5th, 2010 06:35 PM

I managed to reduce the blockiness by using magic bullet looks, however I now get banding where the colour changes ( which I can use the reduce banding filter to remove).

Is there something I can do whilst shooting to avoid this either using picture style or maybe iso settings. Not all clips suffer from this. This particular clip is high contrast so not sure whether this is a factor or not? Clearly the h264 compression is probably responsible, so any tips on how to expose the shot for maximum quality from a h264 point of view would be useful.

Bill Pryor April 6th, 2010 07:34 PM

I convert everything to ProRes 422 for editing, no problems. Some shots may play jerky in FCP, but when the project is completed and I make a master, there's no problem.


All times are GMT -6. The time now is 10:15 PM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2024 The Digital Video Information Network