Does anyone find a real need for using the 2 Pass option? I don't know much about authoring DVDs with VirtualDub or G-Knot, so I wouldn't be surprised if it was used with those programs. I use both XviD and DivX a fair amount, but always in converting to AVI from another format. Everything that I encode using either of the two codecs looks great using 1 pass. I have to say that my compression ratios are not so hot, but MPEG-4 files are so much smaller than MPEG-2 files, that compression really isn't an issue for me. It's not a total nobrainer, however, as I have tested the limits just to see how far I could go, and when you configure either codec to encode too fast then you do reach a point where the quality really drops off. Having said that, I still find that for all reasonable settings, I get remarkably good quality, to my eyes even better than DVD, using just 1 pass.
If you care about filesize then you should use 2 passes. If you don't care about filesize then you won't gain any quality over a 1 pass constant quant encode. If you are encoding for a standalone though then quant encoding may lead to bitrate spikes. A two pass encode will give you proper VBV to avoid such spikes.
Hello celtic_d, Thanks for the info. I have noticed that when encoding in batch mode that a couple of times a session the bitrate will become a little erratic before settling back down to around the average.
In the world of Home Theatre, the topic is bass. Lots of bass is good :^) And it's easy to get good bass - all you need is 100KG speakers. The challenge, of course, is to get good bass from small speakers! Likewise, if bitrate is not important you can get very good 1-pass XviD encode. To get good quality in a small package though, you use 2-pass to maximize efficiency. And like celtic_d says, there are other reasons (apart from final filesize) to use 2-pass, ie. bitrate consistency. L8R
To be brutally honest, I really have been getting away with murder, that is, from a storage media point of view. I set my quant at 2.5, which is probably a bit low, in an attempt to generate some additional bits in hope of getting good quality. The quality is surprisingly good for a novice like myself, but it's sort of embarrasing to say but, a couple of days ago using WMV files as I/P my XviD O/P files were on average around 20% larger after encoding. I'm just lucky in that I am doing the opposite of what a lot of folks are doing. I am burning files from my H/D to DVD for viewing on a JVC DivX-capable DVD player. This has allowed me to become much too lazy in my encoding. I have decided to actually do the math. Being as I always use 1 pass as I do, I really never had to calculate the bitrate for the 2nd pass. Now I think that it would probably be a good thing to start doing, as opposed to always going by estimation. I should have been doing this all along. I really am trying to increase my knowledge so that I can increase my skills in the FourCC department. It really would be nice to be able to lend someone else a hand, one of these days. I think that I will get started with a batch a little later this evening. Thanks to everyone for your kind assistance. I didn't mean to be so verbose. Thank goodness AD doesn't charge by the word or I would have been bankrupt at least a month ago! <|
