AVI or MPEG, which format to burn??

[Darryn Carroll]

Good Morning professionals, today's question from a relative-newbie is which format to burn. can I fit more MPEG to a DVD than AVI? I shoot weddings, download tape from a deck and have routinely (I think simply because its the first option) save as an AVI, edit, then burn. When some finished weddings run a tad more than an hour, I need to use a DL DVD and I wondered if that's because I am using the AVI format. Would I suffer a noticeable difference in quality by using a smaller format?

Thanks all....

[Tom Hardwick]

Generally you compress your DV files to MPEG2 so that you can author DVDs, discs that will play happily in set top boxes, laptops, desktops and portables.

You'd burn avi files to a DVD blank just to use that as a retrieval storage system, but the disc would only be of use to those with a computer.

MPEG2 is a fierce but pretty efficient compression system. It's lossy, so that the more you compress (the lower the bit rate) the more you can fit on a DVD blank, but the more the losses will be apparent.

If you store 90 mins of avi files you'll need five DVDs, whereas 90 mins of MPEG2 will easily fit onto one disc.

tom.

[Darryn Carroll]

Thank you Tom, I think that's the answer I am looking for. I could transfer from tape to DV-AVI, edit and finish. Then export finished project to an MPEG file and burn, which should allow me up to 90 minutes. None of my finished projects are more than 90 minutes. A few times I kept everything as an AVI file I needed a DL disc in order to get 65-75 minutes of video.

[Bill Davis]

Darryn,

You're getting confused here.

You need to do more research. Particularly about the distinctions between COMPRESSION STANDARDS, FILE CONTAINER FORMATS, and actual CODECS.

Compression standards such as MPEG-1, MPEG-2, JPEG, etc. are complex sets of rules that a file needs to adhere to in order to be compatible with file structure standards expected by specific hardware and software systems. These "top level standards" set limitations and requirements so that all manufactures adhering to them can use the files in a cross-platform, software agnostic system.

File container formats, on the other hand, are a different set of standards that specific computer manufacturers either support or don't support relative to what kind of file systems need to see in order to be able to decode and operate on the information contained therein. QUICKTIME, AVI, WMV and others are CONTAINER FORMATS.

Then, at the heart of things are the actual CODEC or encoder/decoder scheme that the file has applied to it which determines elements like what type of compression is applied to an original data file make the file smaller or more efficient, what data rate or bit rate the file is transcoded into, and a number of other aspects applied to the original file in the encoding phase - and that MUST be applied to the file in the decoding phase in order to display, edit, or translate the underlying signal to a display or for an edit system to work with it.

Saying a file is a QUICKTIME file - (or an AVI file for that matter) tells one very little about the actual video stream on that file. It could be a HD raster with an H-264 compliant compression scheme applied - or a 120x240 raster with an MPEG-1 compression applied. BOTH could be in a QUICKTIME wrapper. And the small one might play perfectly while the big one chokes even a modern top of the line computer.

Same is true of two AVI files.

Until you get a description of the underlying CODEC - you have little idea of how that particular form of compression, bitrate, and/or compatibility will affect your ability to work with the file - or the losses the file might encounter in the encoding/decoding process.

This just isn't a simple "use this TYPE of compression and you're good to go" system.

Sorry.