Video converting question

[mst]

I have a file that I need to convert to Xvid avi. I know it will lose some quality. How do I know what parameters to set in my converting software, so it will preserve as much as possible from the original quality and won't bloat the filesize uselessly (i.e. without any quality gain)?

[Baldrick]

Try use constant quality encoding. Try autogk.

[mst]

How can I select "constant quality"? My software has a "Same quality" box in Video Codec Preferences, is that it?

[manono]

If using AutoGK, tick 'Target Quality (in Percentage)'. The default 75% should give very good quality.

[mst]

I'm not searching for "very good" quality, but for a setting that gives the absolute Best quality that can be got, considering the inevitable loss of any conversion.

For example let's say footage X is quality 10. Upon conversion, let's say the quality that can be got depending on the settings, can be: 4, 5, 6, 7, 8 and 9. Not 10, as the conversion is lossy.

What I'm looking for, is the setting that gets me quality 9 (the best it can be after converting).
As I'm not using AutoGK, I need a more general answer. Is converting at all-out max settings the best idea for what I need, or is it something else?

[manono]

Since in three posts now you haven't said what program you are using, how can anyone answer? You say you want 9 quality, but you at the same time (in an earlier post) say you don't want to bloat the filesize needlessly. How do you define 'needlessly'? Only you can decide what filesize you're prepared to accept for the given quality you want. And since different movies compress differently, one 9 for one movie might be a much much larger size than a 9 for a different movie.

If you want a given quality, doing a target quality encode in AutoGK or a constant quant encode directly in VDub(Mod) will give you the quality you choose. But the filesizes will be all over the place. And the 'general answer' for which you're searching doesn't exist.

[mst]

I am using Total Video Converter.
What I meant by "needlessly" is: someone told me that you can set encoding parameters too high, so that from a certain value upwards, the destination file's quality stops increasing but the filesize continues growing- added filesize without correspondence in added quality, as it were.
So if someone were to type in the Bitrate field of a converter "25000" instead of "2500", the filesize would soar, without (from a certain bitrate value upwards) any quality gain.

[Cornucopia]

Well, many encoders allow 3 or 4 ways to determine the bitrate:
1. CBR - Constant Bitrate. Quality will vary depending on complexity, but the bitrate stays pretty much right at the level you set.
2. 1pass VBR - Variable Bitrate (focusing on the bitrate). "Semi-automatic" where you set the Average & Max and it TRIES to match it all at once.
3. 2pass VBR - Variable Bitrate (focusing on the bitrate). This one is more constrained & efficient than above because of the info gathered by the 1st pass being used on the 2nd pass.
4. Constant Q VBR - Variable Bitrate (focusing on the QUALITY). "Automatic" where you set the level of quality and the Avg. & Max are adjusted to suit your request.

What you're wanting is that 4th kind. Since you aren't setting the bitrate directly, and since the automatic choices created by the requirement of a certain level of quality, you aren't doing it "needlessly". It may "SOAR", but only in order to satisfy (if it can, there are limits) the quality expectation.

Total Video Converter? Don't know how that works, but I would venture to guess that there are other, better apps for doing what you want (and likely would be cheap/freeware, like AutoGK). However, many will require you to learn more about the workings of video that TVC does - it's VERY simplistic.
More homework for you, but MUCH better payoff. If you don't want to do the homework that's ok, but then I suggest you revise your quality expectations...

Scott