filesize of mpeg to AVI conversion?

[andyr74]

I have a hauppauge TV card which I use to record TV shows. If I want to put it on a DVD I select a bitrate so I use most of the DVD fot the best quality.
But sometimes I just want to keep the tv show as a avi file. I then record the show with a constant maximum bitrate of 12 Mbit before I convert it to AVI. I use VDUB en xvid codec for the conversion. But what filesize should i aim at?

If I look at the downloadable popular TV-shows (on bittorrent or other sites), the filesize for a +-40 min show is half a CD. Why is this? Is this the best quality/size?

Is there a noticable difference in quality between a half-CD size or full-CD size conversion for such a TV-show?

[Baldrick]

You have to test and see what looks okey for you. It also depends what frame size/resolution you want. Do some short encoding test and compare. If your source is interlaced you must deinterlace if you want to use higher resolutions than 352x240 or use AutoGK(it has everything built in, just set the output size and convert).

[jagabo]

Half the size of a CD is chosen simply so that two episodes will fit on a CD.

One thing you'll have to consider: many of those files are DVD rips. DVD is probably a much cleaner signal than the analog source you're recording from. The cleaner the signal, the lower the bitrate you can use and still maintain quality. So you may have to use higher bitrates or smaller frame sizes if you want that size.

If you don't need a specific file size consider using single pass, constant quantizer mode in Xvid. Pick the quality (quantizer) you want and encode in a single pass.

[andyr74]

I record from TV. So quality isn't like DVD.
Up until now I used a resolution of 640x480 and I tried to fit a 40 min show on a cd-size.
Sometimes I tried it on a half-Cd size.