H264 Codec

[Frank Kruse]

Originally Posted by minister

I took an 89 MB H264 and cross converted it to DNxHD 36 same aspect and frame rate and the file is now 819 MB and looks very desaturated (worse). I did this using MPEG Streamclip (setting at 100%).

I assume that larger file size and washing out the colors is not what everyone is raving about.... What am I missing?

Did you use the RGB or 709 color-space setting? Or did you keep it as the original? I just did the same (H264 to DNxHD and had no color-shift (709 setting, 709 is the standard HDTV color-space. RGB leads to color re-mapping which could explain the wash-out).

And I just did the opposite. 1 reel of DNxHD36 (4GB) to H264 (maximum quality, every key-frame). H264 is more than 8GB after conversion but looks the same and took about 1 hour via QTpro on my MacPro (specs below)

Frank.

[minister]

Originally Posted by Frank Kruse

Did you use the RGB or 709 color-space setting? Or did you keep it as the original? I just did the same (H264 to DNxHD and had no color-shift (709 setting, 709 is the standard HDTV color-space. RGB leads to color re-mapping which could explain the wash-out).

And I just did the opposite. 1 reel of DNxHD36 (4GB) to H264 (maximum quality, every key-frame). H264 is more than 8GB after conversion but looks the same and took about 1 hour via QTpro on my MacPro (specs below)

Frank.

Hmmm... I did 709. I am sure, because it defaults to it. Alpha: None. I did it twice. I'll try it in QT Pro.

I don't have any DNxHD movies to start from, I receive H264 ALL the time -- even if I ask for something different....

[Chief Technician]

Originally Posted by minister

Hmmm... I did 709. I am sure, because it defaults to it. Alpha: None. I did it twice. I'll try it in QT Pro.

Alpha would not affect the process or create the washed out appearance.

Do you have a waveform monitor? It would show you what is going on.

709 color levels go from 16 (black) to white (235). My guess is that you had content that was 16-235 (Rec 709) and it was converted to 0-255 (not Rec 709) and that is why it looks washed out.

Bouncing out QuickTime movies when working with Mojo SDI would result in washed out movies, and it's been years since I researched the issue, but its definitely related to one range being mapped to the other. Either 16-235 was expanded to 0-255 (more likely) or 0-255 was clipped on the bottom and crushed on the top to 16-235 (less likely).

[mike connelly]

Thanks for the tip on Mpeg Streamclip. Any recommendations for a good codec for smaller pixel dimensions? Looks like the DNx only does 1080 or 720 and I use smaller files often. Thanks.