H264 Export

[Michael Phillips]

Are you exporting out as REC601/709 or RGB? That will make s difference on export, as it does on import.

Michael

Michael Phillips

[Job Ter burg]

I hear and read a lot about gamma issues with H264.
Here’s someone how explains how he could fix it my modifying the QT file in QT Pro:
https://forums.cgsociety.org/archive/index.php/t-327725.html

How to fix an H.264 video conversion ‘wash out’ issue
By: ccedit (https://www.macosxhints.com/users.php?mode=profile&uid=1047792) on Thu, Jan 4 ’07 at 3:54PM PST
I have also searched high and low for a solution to the “washed out” look. After an almost sleepless night I came across the fix without having to mess around with color profiles. I’m working from a PC so some of the commands might be slightly different.

After you create the QuickTime/h.264 file, open it up in QuickTime and select “Show Movie Properties.” Highlight the video track then click on the “Visual Settings” tab. Towards the bottom left you should see “Transparency” with a drop-down box next to it. Select “Blend” from the menu then move the “Transparency Level” slider to 100%. Right after that, choose “Straight Alpha” from the same drop-down and close the properties window. AND finally, “Save.”

[David Braswell]

Yeah if you’re exporting from a PC the gamma goes screwy. You can tweak it on export though. First, export using “RGB” setting. Next, go into the Quicktime panel’s custom settings (not the Avid exporter’s settings) and in the “filter” section change the brightness and contrast. Try “-6” for brightness and “+4” for contrast to start with. Render a short section and compare it to the video in your record window. Adjust as necessary. It’s a kludge but it works and doesn’t seem to affect export quality.

[Bill Ravens]

Hans,
I’ve never been able to successfully export the proper gamma from Avid into H.264. Personally, if you’re working on a PC, my workflow is to export the timeline as a Quicktime Reference, then use the QTref as input to MPEG_STREAMCLIP, which is freeware. Within MPEG_STREAMLIP you can setup a template as follows:
Limit Datarate: 8 Mbps
Check:Frameblending
Check: Better Downscaling
Check: Deinterlace Video (trust me on this one)

I think you’ll find the output better than any other encoder.

[Hans Sieber]

Hi Folks,
big thanks to all of you for your fast replies. What I actually do is exporting my clips to QT using H264 and RGB checked in the Avid export settings(working on Avid PC). I know the way of altering the “washed out look” using QT Pro (Blend). But as far as I`ve understood this only changes the appearence of the QT movie on your computer screen. But what I`m encountering is the actual altering of pixel values, not just their appearence on screen. After reimporting such a QT h264 export RGB Import RGB also is gamma shift of 0.7 in the Avid. So therefore I`m thinking that Avid does something else than just altering the appearence. As mentioned in my first mail right now I`m using QT Animation or Avid codecs on export and then reconvert to H264 using QT Pro. These files brought back into Avid just look fine(in regards to gamma). Therefore Avid must be doing something I don`t understand on export. Anyone got a clue?
Thanks to all for listening and I wish you all a merry christmas!!!

Yours sincerely
Hans

[Job Ter burg]

I still think it is a bug in the H264 codec. When you do H264 straight from Avid, your source is 16-235 when it enters the H264 encoder. When you first do the export in Animation 0-255, then the H264 encoder in QT Pro gets a 0-255 source to begin with.

As far as I understand, the Avid export module simply uses the QT exporters, nothing else.

You could test this. Export same-as-source with 601/709 levels. Then encode in QT Pro to H264, then reimport into Avid. Does the same gamma shift occur?

[Hans Sieber]

Hi Job,
thanks for your input. Right now I`m doing the export the way you describe it. Export via QT same as source then reencode to H264 using QT Pro. When I reimport the file back into Avid there is no gamma shift. What seems strange to me is that not only in the H264 codec but also e.g. in MJPEG A this gamma shift happens. I frankly don`t know what engine the Avid application uses for encoding QT files. I exported the same file on machine which only has the QT viewer not Pro and got the same result (gamma shift). How does Avid encode a QT when QT pro is not installed on the system? Does the application itself contain a QT Pro?
Alas for the brave new file based world we`re living in. I hope the condec jungle we`re wading through right now will lighten up a bit in the future!
Yours sincerely
Hans

[Job Ter burg]

I’m pretty sure that the Avid uses the QT engine and the QT codecs it has access to. QT Pro is just a set of unlocked features in QT player, AFAIK.

[Hans Sieber]

Hi Job,
thanks for your relpy. Well I think I just got to stick witch the workaround by using QT ref export to encocde working QT files.
Wish you a happy new year!
And keep up the spirit!!

Yours sincerely
Hans