MultiCam In Blender 2.5

So, I was wondering how to switch between multiple cameras in a blender scene when rendering to video. There are several tutorials that suggest making marks on the timeline and binding them to camera switches. eg:
http://www.youtube.com/watch?v=kq0wtgekSyA
This seamed rather cumbersome and inflexible. I found that one can achieve the same effect in a more intuitive manner in the video sequence editor (VSE) by using multiple scene tracks with different camera overrides set. You can then use soft cuts in the tracks to open holes in the higher tacks to achieve cuts to and from lower track cameras. This makes for a much more visual and intuitive editing system as you can see what camera is in action at each frame etc.

On the flexibility front one can use hard cuts to create time jumps, repeats or other effects.

I use the rather tempremental cinelerra-cv for my video editing.
cinelerra-cv has problems with many video containers, but apparently less so with mov.

I also wanted to de interlace and scale the video for youTube.
The following command takes a video and does the above:

mencoder -ovc lavc -oac lavc -of lavf -lavcopts vcodec=mpeg4:vrc_buf_size=1835:vrc_maxrate=10000:vbitrate=8000:vqmin=1:keyint=25:aspect=16/9:abitrate=224:acodec=mp2:vstrict=0:dc=10:trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=-10:predia=-10:cbp -lavfopts format=mov -vf yadif,hqdn3d,harddup,scale=1280:720 -ofps 25 -o output.mov input.mpg

I got most of the command from:
http://www.coswellproductions.com/wordpress/2007/05/16/more-cinelerra-and-mencoder-fun/

Replace Spaces in Filenames

As noted in the previous post spaces in file names break many scripts so here is a quick script to replace all spaces in file names with an _

#!/bin/bash
find | while read FN;do mv "$FN" "`echo $FN | sed -e 's/ /_/g'`";done

Audio Conversion with ffmpeg

I was looking to convert a set of arbitrary audio files to mp3 so I could play them on my mp3 player. My first thought was mencoder but unfortunately I could find no way to encode from an audio stream without a container, mplayer kept saying video was required.

After some searching ffmpeg was suggested:

ffmpeg -i name_file.aac -vn -acodec libmp3lame name_file.mp3
ffmpeg -i name_file.aac -vn -acodec libmp3lame -aq 6 name_file.mp3
ffmpeg -i name_file.aac -vn -acodec libmp3lame -ar 44100 -ac 2 -ab 128000 name_file.mp3

This results in the following script to convert all files in the current directory with the given extension to mp3:

#!/bin/bash
for i in *.$1; do ffmpeg -i $i -vn -acodec libmp3lame $i.mp3  done;

Note that the file names cannot contain spaces or the script will break.