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A Compression Question....

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With all that I am trying to understand and retain about compression, there are still some things that I can't seem to find answers for. I have a pretty good tutorial, but these questions are not answered

How do I know if what I have compressed is compressed enough?

What is a big compressed file? What is a small compressed file?

The two work samples that I want to put up are 20 to 30 mb according to a friend of mine. Is that big? What is a normal sized compression?

what is the difference between a Quicktime compression, a .mov file compression and a MPEG-4 compression?

I would like to put my samples on my website (yes! it is almost ready for launch!) but I don't know what the different 'formats'(?) are or what makes them different.

I would like to get these online no later that Monday, but I am shooting for Friday to get my site online, I think I can do that :D Help, you guys!

-- spinner :cool:
 
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MPEG 1 and 2 can be viewed on Windows/Mac/Linux. High quality, large files.

Personally, I like Quicktime's MPEG4 H.264 for quality (256kb video, 64kb AAC audio @ 320x240). It makes a small file and it looks great. Windows/Mac only.

Windows WMV format is the most popular because Microsoft added 'Movie Maker' in WXP for free. The files are roughly the same size, but the quality is very lossy. Windows only.

As for the Real format, I don't know ANYONE using this. They're compression application is expensive (hundreds of dollars) but they do have a native Win/Mac/Linux player.

Play around. Encode in everything and judge for yourself what you like.
 
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spinner said:
How do I know if what I have compressed is compressed enough?
Click to expand...
I start with a nominally low bit-rate and work my way up until the quality is acceptable to me.
spinner said:
What is a big compressed file? What is a small compressed file?

The two work samples that I want to put up are 20 to 30 mb according to a friend of mine. Is that big? What is a normal sized compression?
Click to expand...
That depends on the length of the clip. 1MB/minute would be very small. 5MB/minute is about normal for 320x240 or 360x180 formats. You can user lower frame rates if you don't have a lot of motion.

spinner said:
what is the difference between a Quicktime compression, a .mov file compression and a MPEG-4 compression?

I would like to put my samples on my website (yes! it is almost ready for launch!) but I don't know what the different 'formats'(?) are or what makes them different.
Click to expand...
As the Loud Orange Cat already said, H.264 gives excellent quality at pretty low bit-rates (file size). Also, with H.264 (Quicktime) or MP4, you can use AAC compression on your audio, which also gives decent quality at low bit-rates. Entire books have been written on compression. There are no stock answers, because compression varies with content. You can select your file type and compressor based on the audience you are trying to reach, then you have to work out the bit-rate that gives you the quality you want in the frame size and frame rate you select.
 
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oakstreetphotovideo said:
I start with a nominally low bit-rate and work my way up until the quality is acceptable to me.
Click to expand...

...how would I go about changing the bit-rate? My mac tutorial doesn't really tell you how to do this, can you offer some parameters?

That depends on the length of the clip. 1MB/minute would be very small. 5MB/minute is about normal for 320x240 or 360x180 formats. You can user lower frame rates if you don't have a lot of motion.
Click to expand...

...both clips are about 5:30 give or take, so I guess that means it should be about 30MB, what do I do if it is higher? I guess that means, how do I change the bit-rate again. As for movement, there are no special effects or anything like that, just normal video transitions for the most part....


As the Loud Orange Cat already said, H.264 gives excellent quality at pretty low bit-rates (file size). Also, with H.264 (Quicktime) or MP4, you can use AAC compression on your audio, which also gives decent quality at low bit-rates. Entire books have been written on compression. There are no stock answers, because compression varies with content. You can select your file type and compressor based on the audience you are trying to reach, then you have to work out the bit-rate that gives you the quality you want in the frame size and frame rate you select.
Click to expand...

...okay, one more question:
I would like to make the samples play-able for both Quicktime and Windows Media Player. Do I have to do anything different to make that happen?

-- spinner :cool:
 
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Microsoft does not interoperate. They were actually on the MPEG4 technology group, but after MPEG4 became the industry standard, they promptly dropped MPEG4 support in WMP. Go figure.

Therefore, if you want to play in WMP and Quicktime, you must do two different encodings. MPEG4 will play in Quicktime or RealPlayer 10+. To play everywhere, you'd need to back off to MPEG1 or MPEG2. Personally, I don't think those are good options for high quality web delivery.

Regarding bit rate setting, you have to tell me what application you are using for doing your compression. If it is Quicktime Pro, you will want to go into options and settings for the codec (coder-decoder). Each codec is a little different. Also different applications, although they use the same encoders, give you different options on the front end. Also, is your video 4x3 or 16x9 format? Are you encoding at 320x240 (360x180) size? Can you lower your frame rate to 15 fps and get away with it? At least lower your frame rate to 25fps.

As I said before, no two videos are the same, so you have to make some decisions based on how much quality reduction you can live with, and who is your audience. I guess you want a wide audience, so H.264 is probably out; unless you do H.264 *AND* a Windows media (WMV) version. That's not a bad way to go, if you want the best possible quality, with a wide viewership.
 
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There is a program called flip4mac that's out now that converts windows media files into Quicktime files. However, it's not set up to use on the new intel macs and you'd have to have a link to the download for mac users. I'm sure a lot of people don't have it yet.

Anyway, at our company, we generally just use Flash video on our website. Flash is a program that's pretty widely available and used by both mac and pc users. We compress our full rez video files to H.264 quicktime files, then a guy that works in our office compresses the H.264 file to a Flash file. It ends up pretty nice. To Check them out, go to www.fulvew.com and click on the projects page. You'll notice our website requires at least Flash 8 to be installed just to view it.

The H.264 bit rates, frame sizes, frame rate and keyframes are infinite. Just mess with them until you get the best possible file at the file size you want. Or, if you're going to go to a Flash compression from there, crank everything up. The beauty with Flash is, again, that it works with both mac and pc. Don't ask me why the H.264 step helps, it just does. We messed with compressions for a while and that's what we came up with.

And to answer an earlier question, I beleive a .mov file is just a basic Quicktime file. An MPEG-4 is a much more compressed Quicktime file, which H.264 is a varriation of. MPEG-4 is a better choice for web video than MPEG-1, 2 or a Windows Media File. If pc users can't figure out how to download a free Quicktime player, they don't deserve to see your video.
 
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I completely forgot about Flash. Flash does pretty decent compression. The downside to Flash is that you need to buy the Flash encoder. I'm not aware of a free version.

Regarding mov (Quicktime) and mpeg4. You can use MPEG4 compression in a mov file. The Quicktime file format is just a container format. It doesn't specify any particular compression. It can contain any number of video and/or audio tracks, text tracks, etc. Don't confuse the Quicktime movie format with any particular media or compression.

You can use Quicktime to make an actual .mp4 file, but if you want the H.264 encoding, I think you use the Quicktime file format, if you're using Apple's Quicktime tools.

Quicktime is a very powerful format, and people using PCs can play Quicktime movies if they install the free player. Someone can correct me, if I'm wrong, but Flash requires a $commercial$ Flash encoding tool. If you have a Flash encoder, it's definitely a viable option.
 
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I got the Flash Video encoder with Macromedia's Flash Professional 8 product. If you're not doing Flash authoring, that would be a pricey option. Maybe someone knows of another tool that will encode Flash video.
 
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