Conversions to AVI---file sizes

sean@oregonsound.com wrote on 7/6/2004, 12:14 PM
Hi all. I'm confused as to why the AVI files I create from MOV files are consistently so much larger than the original file. A 2.7 meg MOV directly converted to NTSC DV jumps to 111 meg with similar quality. A Cinepak conversion to multimedia size jumps to nearly 20 meg, with noticeable loss of quality. Is there some inherent reason the conversions gain so much size? Or are there some secret settings that will maintain quality without exorbitant size during the conversion? Any help appreciated.

Comments

Spot|DSE wrote on 7/6/2004, 12:37 PM
Depends on the .mov file compression scheme, and what avi compression scheme you are going to. For instance, if you are rendering a DV avi from a Sorenson 3 .mov that is compressed to 1.5Mbps, then you'll see file sizes grow exponentially because you are moving to a different compression format. Expect to lose or rather not gain any quality transcoding from a .mov to an .avi file format. why transcode? What is the purpose for this upsample?
sean@oregonsound.com wrote on 7/6/2004, 1:39 PM
Thanks for the info. I use SAWStudio for most audio projects, and it unfortunately doesn't include codecs for anything other than AVI files. So I guess the next question would be whether or not there is a particular type and spec of compression I can request from all my FCP editors that would still allow their files to be of a manageable size for internet exchange, of reasonable quality, and not grow to enormous proportions when converted to AVI. I have on occasion been given AVI files, but most of them hate to do that because, I'm told, the FCP/Quicktime process of rendering or converting to AVI is painfully slow by comparison.

Other than this unusual situation, isn't there ever any other reason to go with AVI over MOV?
Chienworks wrote on 7/6/2004, 1:51 PM
NTSC DV .avi files are approximately 225MB/minute. That's a fixed rate and can't be changed. These files are probably the best format for use with Vegas as it's the format Vegas works with natively. If you convert whatever you get to this format then the editing and rendering will be about as fast and streamlined as possible. However, since you mention 111MB, i'm assuming that the clips you are working with are probably short. In this case, the extra time involved in using non-DV .avi files on the timeline probably isn't a critical issue. Simply place the .mov file on the timeline and use it. There's no need to convert it first. You won't gain any quality by doing so. The editing time savings will probably be minimal, and won't even begin to offset the time you would have spent converting the file.

When you need to export audio to SAWStudio you can render only the audio track to a new .wav file (approximately 10MB/minute for CD quality stereo), edit this in SAWStudio, and then bring the newly edited version back into Vegas to replace the original audio. Even simpler yet, tell Vegas to use SAWStudio as your external audio editor and Vegas will handle passing and retrieving the audio automatically; no need to do any manual conversion at all.

What does SAWStudio do for you that Vegas doesn't do? We might be able to get you to the point where you're doing the whole thing in Vegas.
sean@oregonsound.com wrote on 7/7/2004, 8:07 AM
Thanks for the info. Yes, most of my video work is on 30" TV commercials, so your 225MB/min formula is right on. File sizes aren't an issue on these short projects, but I occasionally work on longer form post production and that's where it becomes a concern. And as I mentioned, SAWStudio can only display AVI files and can only render AVI DV files to external FireWire.

Although Vegas' audio engine works well and has improved (I'll be upgrading to V5 later this year), it's still a video program with an audio mixer. SAWStudio is a program that was designed from day one to do nothing but audio, and in spite of its quirks, is lightning fast for assembly work. And if nothing else, Vegas' current lack of VST implementation rules it out for serious audio work for me.

I'm not a video editor, and I got Vegas for DVD authoring of surround projects. But of course I've found it to be highly useful in many other situations and have dived into it further than originally intended. It's a great program that I will continue to use, but just as I use Logic Audio for composing, I'm comfortable with using multiple programs for their individual strengths.
Spot|DSE wrote on 7/7/2004, 8:39 AM
Sean,
I used to use SAW, and it's now an antiquated tool, particularly when compared to Vegas. Vegas originated as an audio tool. The ONLY thing SAW brings to the table that Vegas doesn't do is broadcast wav files. Vegas does everything else SAW does and a whale of a lot more.
Logic is better than SAW, IMO as well, so maybe that tells you where I'm coming from. The fact that Apple killed Logic for Windows when they bought Emagic really tweaked me.
Vegas works fine with VST using a wrapper, and I find that using the FXPansion wrapper is faster than using a straight line to VST. Sonar works the same way. I've been told a dozen reasons why it's this way, but I only care that it works.
sean@oregonsound.com wrote on 7/7/2004, 9:37 AM
Yes, software is very subjective and personal, isn't it? I had forgotten that Vegas started out as an audio program. All the SAW products through SAWPro are antiquated by comparison, but it sounds like you haven't used SAWStudio. I'm not on a Bob Lentini crusade, but in everything from metering to workspace layout flexibility to automation fluidity, I've seen very little in Vegas that can rival it. Vegas is by far the superior Swiss army knife in terms of file formats, etc., has plenty of power available and, like SAWStudio, seems extremely stable. But I'm reasonably certain that no matter how much time I put into it, I would never be able to work as quickly and efficiently with it.