[MEncoder-users] issues for time-lapse video encoding

[Hugh Secker-Walker]

Hi Folks,

I'm creating and processing time-lapse movies of outdoor scenes using
mencoder (or ffmpeg) to do the capture from a webcam, and then
mencoder to process into a playable video.  I'm using an Ubuntu server
setup, and the initial video comes in from a USB webcam in
video4linux2 format.  I'm capturing 1280x1024 frames at 0.1 frame per
second, i.e. 6 frames per minute.  The intended playback is 30 fps.

I have two questions:

1) Since I want to use two-pass processing of the captured video, I
   need to do the initial capture with as little degredation as
   possible.  I'd like e.g. 3000 frames to go into about 1gB in the
   oringial captured video.  Is there a recommended codec/setting for
   this?  I've tried rawvideo and ffv1, but these generate too much
   data.  So I need some compression.  Given that the size of the
   compressed video at this point isn't a big issue, which codec will
   degrade the images the least or have the simplest behavior/results?
   BTW, I'm currently using the mjpeg codec, but there's no control
   that I can see (ffmpeg) for the compression that it's doing....

2) I want to do some filtering of the resulting video.  In particular,
   it would be nice to remove all the objects, e.g. birds, that appear
   in only a single frame.  I can imagine that some sort of median
   filter would do the job (e.g. median for each pixel across 7
   frames).  What should I be looking at for this kind of filtering?
   It's a kind of denoising, but the extent of the noisy object can be
   quite large, but always only for a single frame.  

   Relatedly, is there a codec that would be best suited to the
   time-lapse material?  I've toyed with wmv2, mpeg4, and x264 -- but
   experimenting with just the set of controls that I've seen
   mentioned in FAQs is daunting, and I haven't yet seen anything that
   specifically addresses the nature of time-lapse video of outdoor
   scenes.  So, I'd also appreciate any pointers to information about
   the encoding issues for time-lapse video.

Thanks in advance,
-Hugh