Video Compression Posted on June 15th
Video compression is an art as much as it is a science (and a lot of math). the rules change with each CODEC. this means the tweaks and setting that worked for Cinepak did not work with Sorenson won’t work at all for H.264. we’ve had to to reinvent our settings with each new technology.
rules of compression
GIGO or in other words always compress from the best source possible
don’t automatically make your settings BEST or LEAST
try the default settings first before making other changes
set minimum system requirement and stick with it.
better audio will help very compressed video “look better”
you have to test it and look for errors
it will always take a long time.
never point out compression mistakes to other people.
no whining about how bad it looks
it was to the compressionist to find the sweet settings for the specific content. and sometimes theses settings were counter intuitive. for example Cinepak worked better at higher data rates with virtually no keyframes Sorenson actually had improved image quality as compression increased (to a point) with software determined keyframes. compression tools often work differently when dealing with specific compressors. they may have settings that will help an image for one CODEC but not another. this was always true of previous version tools.
some things never change about compression. video that doesn’t change significantly from frame to frame will always look better compared to fast pans over grass. video that has lots of short cuts will look soft compared to long takes.
modern compression tools like HandBrake, FFmpeg, MPEGstreamclip, QuickTime Export, and Microsoft Media Encoder will do a remarkable job using default settings. in fact the tweak controls are hidden by default. you don’t get to change the temporal or visual compression settings. and maybe this is a good thing because it used to take days to dial in perfection.
video will always take a long time to compress. and maybe it will never get faster. compression complexity increases because CPUs can handle the job. meaning its still a good idea to setup automation for handling your compression. this forces you to use settings templates which in turn increases consistency. and it means you aren’t baby sitting a machine waiting to cue the next job.
hardware helpers can help speed your compression along. there has been a solution for every CODEC from Cinepak to MPEG1/ MPEG2. it’s a fact that you can never have it go faster enough. for H.264 the Elgato Turbo264HD can significantly speed up your work. it won’t be instant but it will be significant reduction in time. this is especially true for old hardware. in fact you would see similar performance if you compared notebooks 2006 with 2010 as the brains are in the dongle freeing the CPUs to do things like editing. of course there are tradeoffs. video that is compressed quickly may not look as good as video that is compressed more slowly because it has better scalers or uses multi-pass compression. but this has always been the tradeoff in doing compression work. and while we can recommend possible solutions it’s ultimately to you to discover if the workflow is a solution or a bug.
Andy Beach wrote a book called Real World Video Compression which covers all the tricks to get the best looking video that goes beyond selecting the Export to Web… function in QuickTime Pro. you can read the blog about it and you can buy it here.Trackback URL