You’re going to lose quality whenever you transcode, unless you are going to an uncompressed format. That’s why you often transcode in the first place, to reduce the file size so it’s more manageable during the edit or for final output.
You can think of codecs like file types. In Photoshop you can make jpegs, tiffs, pngs, gifs, psds, etc. A tiff, psd, or png is lossless, meaning it is uncompressed and unaltered. These files can be big. Whereas a jpeg will create a very small file by performing an algorithm to simplify the visual data; I believe it averages clusters of pixels and reduces the number of colors. In video, the ‘animation’ codec and ‘png sequence’ codec is a lossless codec. No compression is taking place and the files tend to be big. A QT h264 file on the other hand is very compressed and creates smaller files which tend to work well for computer playback and streaming.
I agree that Quicktime Pro 7 is the best $35 you’ll spend. If you need to make a .wmv for PC, you can buy Flip4Mac that works seamlessly with Quicktime Pro 7. Flip4Mac is more expensive but is necessary (and thank god it exists) if you need to make PC compatible files.
I tend to favor Quicktime Pro 7 over Adobe Media Converter for transcoding. I find I get better results for unknown reasons to me.
Best regards,
Kevin Camin