Re-rendering to DV... quality loss?
 

Just want to make sure..
i'm thinking of getting canopus express to help with encoding low-bitrate material. I'm using Vegas 4 as my editor. Can i be assured that there is *no* quality loss when importing DV files captured from a digital cam, edited, and re-rendered as DV?

Also, are there different "DV's"? I seem to remember reading about 2 different DV formats.
Thanks as always,
matt

There are actually more than 2, but these are all sort of 'nicknames'... There are several different 'formats' using the DV25 compression method. DV25 is the codec which compresses data when it is written to tape or a video file on a computer. Three different formats (MiniDV, DVCAM, and DVCPRO) all use the DV25 codec - the difference between them lies in how the data is physically recorded onto tape. The compression ratio is 5:1, 4:1:1 sampling, with a data rate of 25Mbps, hence the name DV25.

There is also DV50 - adopted to tame formats such as D-9 and DVCPRO50. The DV50 data stream has a 3.3:1 compression ratio and 4:2:2 sampling.

There is also DV100... which is still really under development and hasn't really been figured out how to use 100% in the market. It is an HD codec, uses 1.67:1 compression, 10-bit, and also supports 8 channels of audio.

If it's cuts only and the NLE supports it (Vegas does) and is set up properly, there'll be no quality loss. If there are fades, dissolves, text overlay, etc it will be recompressed to DV AVI.

If you want the best quality you can frameserve out to external encoders (I don't do it but someone might be able to tell you how) to avoid one recompression to DV, then another compression cycle to whatever web codec.

That said, you say you are looking at low bitrate stuff anyway, so one DV recompression cycle probably won't affect anything if you are highly compressing it.

I can't tell the difference between 1st and 2nd generation DV. I wouldn't sweat the difference.