AVCHD and Xvid Proxies for Chroma Keying

[blazer003]

Alright, quick sitrep. I have a Panasonic GH1 that records in AVCHD. My current thought on editing method is to make proxies by AVISynthing those clips into virtualdub and saving AVIs.

Ultimately these proxies will obviously be replaced in the Premiere Pro CS3 Timeline by the originals as AVISynth scripts.

Now I'm trying to find the best intermediate codec for my purposes. It has to edit fast and it has to retain an acceptable enough amount of detail that I can set up a chroma key on it and get a good idea of how the AVCHD footage will react.

So, I'm in the Mpeg4 area because I was told by a friend that using XVid in "virtually lossless" mode would be a good option. Now my experience with Xvid hasn't exactly been that it is a fast codec to edit, especially at 1920x1080, however he said that in the settings you are taking away the interframe compression so it's a lot faster.

So my questions are:

What quantizer, bitrate, quality (etc) settings do I use to get the highest quality image possible and no interframe compression (is this actually possible?)

I'll test this myself as well, but do you think this will be a stable and quick editing solution? My friend was convinced that there is no interframe compression with the right settings. Is this the case and does it make the decompresser not work as hard on the timeline?

If you have any, what would be other options for codecsyou'd recommend?

[dilpill]

You can make Xvid intra-only by setting the motion search to 0, off. For the best quality, use MPEG quantization, turn adaptive quantization off, and encode at constant quantization 1. This will give you a visually lossless (99% of the time) result.

Decoding should be a lot faster since your editing program will only need to decode one frame each time you seek. The file size will be pretty large though, at 1080p probably something like 40000 kbit/s.

[henryho_hk]

According to the top sticky "XviD presets" thread, the "Editing-only" preset is:

ME precision=6, VHQ=1, no b-frames, chroma ME, Sharktooth's EQM V3EHR, 1-pass only @ constant quantizer = 2, Trellis, chroma optimizer .

IMO, u can turn off chroma optimizer.

[Dark Shikari]

You can make Xvid intra-only by setting the motion search to 0, off.I'm pretty sure you have to set max keyint to 1. I recall motion search on 0 just uses 0,0 vectors only (or maybe fullpel only?).

[infoeater]

I'm pretty sure you have to set max keyint to 1. I recall motion search on 0 just uses 0,0 vectors only (or maybe fullpel only?).

Both methods work. Xvid would not use P, or B frames, when "Motion search precision" is set to "0 - none". I was surprised too, because using 0,0 vectors should save same (or a lot for example in recording screenshots) bitrate at static scenes without any motion search. "Motion search precision" "1 - Very Low" does some real search, so AFAIK it is impossible to get 0,0 vectors only in P frames in Xvid.

[Motenai Yoda]

lagarith work fully lossless and do a null-frame compression, multithreading, 32/64bit, and supports yv12 yuy2 and rgb

[Blue_MiSfit]

Lossless may very well be too large :) The I/O hit from using lossless when editing is also substantial!

I think Xvid is a good idea, but you might look into H.264 in AVI. *ducks*

I know it sounds ugly, but you might get great results encoding to ~50mbps intra only x264 (basically an 8 bit half bred AVC-Intra http://en.wikipedia.org/wiki/AVC-Intra).

Also, everyone's hatred of H.264 in AVI should be easily sidestepped, since you're using no B-Frames, and no complex audio (PCM, right?)

~MiSfit