Good stream to use for 1st pass when doing multiple encodes

[benwaggoner]

Assuming one is encoding a bunch of different 2nd pass encodes at different bitrates and frame sizes, using a single 1st pass log file.

What's a good stream to pick as the reference stream? Highest frame size? Highest peak bits per pixel? Highest bitrate?

Since the 1st pass doesn't need to map to any particular output, could one mock up some settings that would maximum the effectiveness of the first pass? E.g., leave VBV and peak bitrate off the analysis pass even if all the output streams will have those contraints?

[benwaggoner]

Also, how much does similarity to the original .stats file matter? If a .stats is generated based on a 10 Mbps 1920x1080 stream, is it not going to be a great basis for a 512x288 200 Kbps encode of the same source?

I'm thinking it might be best to use --pass 1 on the top bitrate, and then use --pass 3 on the rest of the streams in bitrate order, refining the log file throughout.

Man, do I hate .bat files...

[Blue_MiSfit]

I did some testing on this a couple years ago... Here's what I determined:

http://www.mediafire.com/view/?wf3rn7upg1gctus

In short, I got the best results (in terms of PSNR) doing --pass 1 at the top bitrate and working down with --pass 3

No guarantees this is still the case, but the difference should be pretty small no matter how you slice it.

http://i.imgur.com/xZnGY3a.png