>I’ve been posting a lot at Adobe Forums: After Effects lately, after I unexpectedly was asked to become an Adobe Community Expert. I just thought I’d share a reply I just made to a question about how to avoid quality reduction while rendering and moving video between applications. Perhaps I’ll make a small table listing the codec options and their advantages/disadvantages, if you post a couple of nice comments!
Both AVIs and QuickTimes can be “uncompressed” but the file sizes are huge! In the case of AVIs, the only advantage is that “uncompressed” is the old AVI format that supports an alpha channel.
Better is to use lossless codecs such as QuickTime Animation: Best and QuickTime PNG: Best which have so called “RLE” compression just like ZIP files, which has no quality-loss whatsoever, but still manages to shrink the file sizes considerably. Both these codecs also support alpha channel, but only QT PNG supports 16-bit.
There are several third-party QuickTimes codecs such as the BlackMagic Design‘s codec that also have similiar options, but they need to be installed separately on every machine.
For really small but almost lossless renderings, I normally use QuickTime PhotoJPEG: Best which is a standard 8-bit QT codec that has been around for a long time. At 100% quality very few pixel values are changed at all, making it virtually lossless.
The other alternative is to render to file sequences such as TIFF, SGI or TGA. This has several advantages, but unfortunately file sizes is not one of them. However, they are great for multi-machine renderings and if you need to re-render parts of your video it’s easy just to replace just those frames. Also, it’s easier to split up large renderings across DVDs, CDs and portable disks since you don’t have to split up a huge video file, you can just copy all the frames that fit on to every disk. Network transfer speeds are lower for file sequences because every file has more over-head and many network protocols start out by only sending small chunks and only increase the packet size if the initial transfer was OK. Remember that if you have sound, you’ll need to render that separately to an audio file if you use file sequences.
One file sequence format to avoid (unfortunately) is PNG since it has cross-plattform and cross-application problems with gamma-shifting. The options in the PNG file format let applications enter gamma values into the file, which are only read by some other apps, resulting in shifts, so you should unfortunately avoid PNG sequences.