Tips for compressing video files for the internet?

July 30, 2004 1:45 PM

Compressing video files for the internet, either generally or specifically from Avid Xpress: do you have any tops tips or favourite software? How do you get the best results? Bonus points for advanced compression techniques for Super 8 to maintain the 'look'.
posted by gravelshoes to computers & internet (7 comments total)

Please do your part to control the proliferation of goofy "internet" video codecs and containers. Compress to MPEG-4/avi or MPEG-2. ffmpeg is a pretty damned fine encoder with which to do this. Please use multi-pass encoding.

Windows Media, Real, and QuickTime containers are to be avoided.
posted by majick at 3:37 PM on July 30, 2004

I've been using Quicktime Pro for this and have been pretty happy with the ease and product. I certainly see majick's point about avoiding proprietary formats, and Quicktime has a lot of different output options.
posted by shotsy at 3:59 PM on July 30, 2004

Actually, I spoke about this last week.

Semi-self link of the conference I spoke at

I did six sessions at that show. I chair tracks at NAB.

You're really talking about two things.

First "film look". You'll want to use the color corrector to add an "S" curve under the Master Curve to give a more filmic response - that is, if it's video.

Unfortunately- no compression software that I know of, can handle the reverse cadence of 8mm.

16 and 35mm are 24fps, transfered to video - 30fps (29.97 for your technical color freaks out there) and then, good compression software can do an inverse job on this. (This is called Telecine, and surprisingly, inverse telecine) returning the footage to 24fps.

In ANY form of compression - the greater the data rate per frame, the better each frame looks. Usually we talk about data rate as Kb/sec (that's kilobits per second). When there are less frames (ie. film) each frame gets more data. So, to be able to reverse this process, improves the quality of the picture.

Key elements - who is your target audience - what format, computer needs are you delivering to?

If it's DVD, and since we can't really restore the 18fps cadence of Super-8....

Let's at least keep our compression decent.

Use 2 pass VBR on whatever codec you use.

Items like ffmpeg, TMPGenc, and sorenson squeeze are all good tools - for MPEG-2 (squeeze does much more)

If you can encode the audio at AC-3 rates, you can improve the video (I'm speaking about MPEG-2 here). You can go in at a VBR rate of 7.5 to 8Mb/sec and get tremendous results - even if if you haven't converted back to film cadence.

------
Oops.

Just re-read what your question is. Are you going to a download? Or a streaming file.

Downloads look better (higher data rate). Today, right now, on a PC - Windows Media Player (try their free encoder) makes excellent video. I'm a big fan of apple's new MPG-4 encoder - but not today.

WMP-9 info -
Windows Media Download center

Key items from above are still true - 2 pass VBR is best. Higher data rates are best. Since it's coming from video, much above 320x240 (or whatever their preset is) would be a good choice - higher data rates are great.

I'd use Sorenson Squeeze - it should have come with Xpress Pro (if you just have an express, I have other ideas); this way you can export a Quicktime Reference (no extra space on your drives) and have Squeeze make it a WMP-9

More on squeeze. I'd make sure I used a noise filter on the video (higher if it's DV, lower if it's 2:1, you only get two choices in squeeze), and I'd adjust the contrast up a couple of notches to restore 0-255 space from video's range of 16-235.

Gravel, you're welcome to contact me directly if you have direct questions on this subject.

Oh, and I"m a Mac guy, love QT; but for this option the best quality will be proprietary - such as a free encoder like WMP-9 or using it with sorenson. Yes, it's proprietary (and majick is right - proprietary codecs are frustrating for the future, they are not a "standard"). Lower data rates (as you said, you want to post it on the net), WMP-9 shines at;

Especially if you're using Xpress pro - you got Sorenson free. If you are really using an Xpress, well....that's a little different.

It's different in acquisition (compression) and (possibly) platform.

So, what do you have (Xpress or Xpress pro) and did they throw any free software into the mix (cleaner or Squeeze?)
posted by filmgeek at 4:38 PM on July 30, 2004

Sorry that was so long.
posted by filmgeek at 4:38 PM on July 30, 2004

Please don't apologise - great answer. Thanks very much. It seems I have hit the jackpot for Avid related compression questions

I'll reply here because I your advice is probably appreciated by more than me reading this.

I've got Xpress at home, and Pro at work. I haven't checked Pro for Sorenson - will do so on Monday.

My situation is probably fairly typical for people who make films but don't have much internet expertise. I've been thinking about putting some personal projects on the web for a while (for download, not streaming, and for a general audience whose connections I can't assume to be fast), but every time I start prepping the material in Xpress at home (no free software - there only seem to Xpress's own conversion tools in the Export options, although it will export to pretty much all formats), the files always seem end up far too large and the quality far to bad, and after a few of hours fiddling I end up getting fed up and forget about the whole thing for another couple of months.

but I see great results on the web from well-sized files all the time...

Would be very good to hear your ideas for Xpress without Squeeze.

many thanks
posted by gravelshoes at 6:07 AM on July 31, 2004

oh, and I'm on a PC.
posted by gravelshoes at 6:09 AM on July 31, 2004

Contacting you directly. :D
posted by filmgeek at 7:16 PM on July 31, 2004