The Big AVI-Codec Mystery Topic

[Vertizor]

~5 minutes of uncompressed audio should be 50-70 MB-ish. Just look at the wav file after you extracted the track from an audio CD for example. Is audio in 48 kHz or 44 kHz? About MP3 encoding in Premiere, if it can't select the MP3 codec in Premiere then just encode the video stream, no audio, in Premiere and encode the audio into MP3 externally. Then get a multiplexer program to join the 2. It may fix your problem, plus it will speed up encoding times since you'll only be doing one stream at a time.

I've used VirtualDub and it has options to convert the frames into different color depths, such as 16, 24, or 32-bit depths. However, the avi codec might not like anything lower than 24 or 32. I don't know of Premiere's capabilities so you may have to look into that yourself. Obviously with a lower color depth each frame will require less memory, it's a matter of whether your software tools can encode it with lower color depths, and whether your movie can get away with that lower color depth.

Multi-pass encoding is a new feature many codecs support now-a-days. It effectively doubles your encoding time because the second pass goes through the whole stream again, but the second pass is a little more intelligent and may yeild smaller final file size.

720*576 is DVD resolutions, you shouldn't be surprised that the output file is so large. I have downloaded trailers and clips and rarely do I ever see a movie clip go over 500-pixel widths. Movie players can stretch the picture to fit a certain window size when people playback these movies, and the loss of quality from this stretching is NOT so bad. With smaller frame dimensions you can bump up the bitrate for better picture quality which will help the end result picture much more than having hi-res frames.

Also, when you're encoding the video are you using a variable bit-rate or constant bit-rate? Some codecs support both, you have to dig into the options and make sure variable is used. When it is used, the bit-rate you set is the max bit rate per frame. It would allow the codec to encode a frame below that bit rate if the frame does not require that much memory (for example is has large continuous areas of similar colors). Constant bit rate makes every frame use the same amount of memory, often that is a waste and bloats the file.

[Vertizor]

I might be a little inaccurate in regards to my description of variable vs. constant bit rate methods of encoding. At least with Divx, it chops each frame into little squares and encodes that region with a certain memory alllowance. I'm forgetting if constant bitrate means each tile gets the same amount of memory allowance or its allowed to vary - as in variable bit rate. So my confusion is between individual tiles or individual frames that are variable. The fact still remains that variable bit rate may be better in your case if you aren't already using it.

Furthermore, if the bit rate controls how much memory each frame gets, that bitrate is distributed over the whole frame. So take 2 frames of different dimensions (one smaller one larger) if they both were encoded with the same bit rate, the smaller one would end up being higher quality. Even though later on during playback, the smaller one will suffer more from "stretching." You just need to find a nice balance between all these parameters. I don't have specific settings to offer, just these basic ideas to help you decide.

[brzilian]

720x576 is definetly way too big for publishing to the web. I would probably go with half of that. Check your bitrate for audio - I wouldn't go above 128kbps and make sure you're working with 44.1kHz and not the DV standard of 48kHz. I don't have much experience with DivX or Xvid, but when I work with MPEG1 or Windows Media, I try to keep the video bitrate around 1000kbps. You may want to even bring that down to the 500-700kbps range.

Audio DOES significantly increase filesize. I was working on a 20 second animation today and the MPEG1 file size jumped from 2Mb to 8Mb once I added some background music.

[Lonely Pixel]

Aha, thanks so much for this help.

Vertizor; the DivX 5.1.2. codec I use only gives the option to choose an average bitrate, so I assume it's set to variable bitrate by default. I've first compressed it in the DVD res, which gave me an 18mb movie in average quality for exactly 60 seconds. I used 2000kbps bitrate.

I've just resampled the movie to a lower resolution, about 5..*450, but I pumped up the bitrate to 5500kbps, just to see what it'd do. For some reason it gave me a green screen for the entire length of the movie, although it was coded with the same DivX 5.1.2 codec as the first try. Anyway, I think I'm already heading the right direction, and finetweaking the balance between my needs and what the software has to offer should give me the exact settings that fit my needs.

Thanks very very much. If you or anyone else has any other tips, please feel free to stick em in here! It might also be usefull for other people who have an equal problem as me.

Thanks!

[glassefx]

Also remember that the content will to some extent dictate your codec choice.

Codecs and how they should be used (to the max) is a whole seperate volume of knowledge, and it's quite vast I might add.

You'll get into color depths, dithering methods, frame-rates, etc.

Good luck, I think trial and error while learning from others is the best method...Throw in a book or so every once in a while.

peace

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