Colour issue rendering to H.264

I am working with 3D (stereoscopic) material. After editing, I render the project to anaglyph 3D, i.e. green/magenta.
To do so, I apply the SOP/SAT effect to the clips for the left and right eye views and add an addition transition.
This results in a correct full colour anaglyph 3D video.

So here the issue:
If I save a frame from the monitor, I get a perfect PNG that looks exactly the same as when I do the whole procedure manually in Gimp.
If I render to DNxHD (custom render profile), I get the same nice quality when playing the video in i.e. VLC.
But if I render to H.264, quite some crosstalk/ghosting occurs, so I assume that there is some quality sacrifice impacting the colours that causes this.
This can be compensated with adjusting colours (saturation, ...) in VLC or other players to some extent, but the quality is never as good as with PNG or DNxHD.
I also tried other formats (MPEG2/4, ...) but it is either the same or even worse.

Finally my question:
Are there any ffmpeg/X264 parameters that could be related to this, that I could set to avoid this quality loss? I wouldn't mind if this would come with the price of larger files or so. I already played with some parameters but without success.

Forums:

Hi dode,
which were the render settings, you used already? I guess it will be easier to answer your question, when knowing which settings do not work. Which parameters did you play with?

Hello al25fps,

I used the default H.264, and I created my own simplified one which looks like this:

"f=mp4 hq=1 acodec=aac ab=%audiobitrate+'k' ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=%bitrate+'k' aspect=%dar pass=%passes"

But there wasn't any difference to the default H.264 profile.

I tried fmt=yuv422p, and I think it improves a litte. Can this be right or is it just imagination?

Anyway, I am being very picky. When looking at the rendered video without the anaglyph 3D glasses, the quality is very good and there is just a little decrease in sharpness. The colours look very much the same.
But when watching with glasses, there is quite some ghosting. It seems that the colour areas (the green and magenta) get some slightly dark edges (also only visible with the glasses), they are somehow less accurate. I'm sorry if I fail to describe it very well, if I could just provide some screenshots...

So I'd be very happy about suggestions what else I could try.

Hmmm... when using h.264 the default video bitrate is 12.000kbit. I wonder, if the dark edges come from compression. If so, a higher bitrate will be a solution. If that doesn't help, I'm currently out of ideas.

Thanks. It indeed does get better when increasing the bitrate to 18 mbit or even 25. But this rather toy-ish WD Elements Play media box has issues with such bitrates, so I have to stay with 12 for now.

Maybe there is some media box that can play 3D content from separate files like Bino does, this gives the best quality.

You dont mention final clip resolution and frame rate ... and speaking about bitrates only makes sense in context of these parameters. For instance, for 1080p 25fps a bitrate of 12kbit/s is already quite good and above "spec". If your video link bandwidth is limited then there is no sense in higher bitrates as they cannot be displayed and make your playback hardware much more expense ... so the manufacturer looses in a price-competitive market.

What kind of player do you use for playback? Did you check also? with a PC or Linux software player? Do you notice differences in playback between your media box and a PC?

It is 1080p and 25fps and I agree, 12mbit is already very good, the picture quality only increases slightly at higher bitrates.

I'm using different Linux players, like VLC and Bino, they all work very good, no problems even with very high bitrates. Just this WD Elements Play media box doesn't seem to be powerful enough for that, but the 12mbit videos play fine, so that's okay.
The quality of the video played by the media box (connected to the same screen as my notebook) is the same as with the Linux players.

Higher bitrates don't solve the "ghosting" issue anyway. It is not so bad, the 3D effect works great, overall picture quality is very good - I am just wondering where the ghosting might come from.
Accurate colour reproduction is very critical for anaglyph 3D, and it seems it suffers from lossy compression.

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