thecoalman - 10:11 am on Nov 27, 2007 (gmt 0)

For direct download via link:

1. MPEG1 , this will play on practically any OS out of the box. Downside is it requires 4x to 5x the filesize for comparable quality for files using codecs like wmv or divx.
2. WMV , this will play on any windows machine, even the 9.X codecs are compatible back to something like windows player 6.4. so technically you can get it to play on Win95 but chances are a win95 machine isn't going to have the CPU required to display anything with larger resolutions.

For embedding in a page:

1. Flash, don't use it myself but it appears to be the way to go as it removes many of the cross browser and cross OS problems, try embedding a WMV with valid markup... just about impossible. The only downside is they need the plug-in but that appears to be less and less an issue.

2. WMV, again this is compatible with all windows machines and can be made to work on some other OS's.

Converting from one lossy-compression format to another is almost always going to result is a poorer quality.

Any reencoding of video will result in the loss of quality however the loss is minimal when working with certain formats. DV was mentioned by another poster and this can be re-compressed numerous times into a another DV stream with negligible loss in quality because it uses a very light compression method and each frame is individually stored. You may ask why you would want to do this? If for example you adjust the brightness, hue or add some filters that affect every frame this requires the entire length of the video be re-compressed. In instances where you are just adding transitions any decent editor will only re-compress frames where such changes have occurred. DV has a standard bitrate and resolution so one DV stream will have the identical properties of another, the only place they may differ is whether they are NTSC or PAL which use different resolution and framerates.

This can also be done with MPEG using the appropriate software and settings under the right circumstances. Ulead Video Studio, Womble or for simple cutting there's tool called cuttermaran that is free. These will only re-encode the necessary frames such as where you have made changes like transitions. One thing to be aware of is the properties of any clips you wish to join must exactly match to do this, i.e. resolution, bitrate, etc. If you're working with material from the same device this is quite easy to do.

As far as tools for doing this with WMV or Divx I'm not aware of any but I'm sure they exist. I've never had the reason to research them so I really don't know.

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Ideally you want to use a high quality source like DV, either export as DV from an editor to import into the encoder or if your editor supports it encode directly to the desired format. If you need multiple formats or the same format with different properties always go back to your DV file as a source or whatever you have as the most original source. To maintain quality you should do as little as possible to video, minor filtering aside for restoration work you can only make it worse each time you do anything to it.