how much to compress

[namiefan]

I am new to video editing. I know that avi's are suppose to compress better than mpg, but i want to know how much i can compress without loosing quality.
For example, if i have an mpg (700mb, 1000kbps bitrate, 352x240 res) , how much can i compress that file without loosing quality using divx codec? and what bitrate would i set it at?

Is there any other factor that should be considered?

[atifsh]

every person has its own meaning of quality u hav to see ur self what u think is actually loosing quality.

say the orignal file is of 4000 kbits and u reencode it to 3500 u may not see the difference but quality loss is present even in that.

[tigerman8u]

avi (mpeg4) can handle a lower bitrate than mpeg 1/2 and maintain the quality of the video. The higher the resolution the higher the bitrate has to be to maintain the quality. ie with 1/2 DVD (352x480) you can use a lower bitrate. 352x240 (vcd) uses a bitrate of 1150kbps. I've seen alot of avi videos with a bitrate between 700kbps-1000kbps with a higher resolution than 352x240. Use Virtual dub or one of it's variants and cut out a couple of minutes of the video and re-encode with different settings and see what you like. After you find what you like then re-encode the whole movie.
ps. if your source is 352x240 you won't benefit by gone to a higher resolutin.

[namiefan]

Originally posted by tigerman8u
avi (mpeg4) can handle a lower bitrate than mpeg 1/2 and maintain the quality of the video. The higher the resolution the higher the bitrate has to be to maintain the quality. ie with 1/2 DVD (352x480) you can use a lower bitrate. 352x240 (vcd) uses a bitrate of 1150kbps. I've seen alot of avi videos with a bitrate between 700kbps-1000kbps with a higher resolution than 352x240. Use Virtual dub or one of it's variants and cut out a couple of minutes of the video and re-encode with different settings and see what you like. After you find what you like then re-encode the whole movie.
ps. if your source is 352x240 you won't benefit by gone to a higher resolutin.

Thanks, that's what i was looking for. But i was hoping for soemthing standard like a general guideline or something. I guess there's no such thing. Hehe, thanks again.

But now i have another problem. I have an avi encoded in divx. I added subtitles to it using the subtitler plugin for virtualdub and the ssa file. I simply reencoded using the same settings from the original (same video and audio bitrate, same resolution size, etc). The problem is that the resulting video, which is the same mb size as the original, is much worse quality than the original. What did i do wrong? Please help.

[tigerman8u]

Any time you re-encode you will lose some quality. If done right you shouldn't see much difference. Make sure you keep the interlacing of the file the same. Check on this site and also at www.dvdrhelp.com for good guides.

[namiefan]

"Make sure you keep the interlacing of the file the same. "

How do i do that? And how do i check the interlacing of the original. I'm using vdub 1.5.7 and i looked under "file information". It didn't list such info.

I've been reading a lot of sites about video editing, but nothing seemed to help. I only know the basics to encode videos. Can you give me a more specific link to an article relating to this problem? Thanks.

[tigerman8u]

I'm using Vdub mpeg2. This is a modification of Vdub that allows you to use mpeg2 files also. Good reason to upgrade and it's free. You should be able to d/l it here if not go to the tools section here www.dvdrhelp.com.
open your file in Vdub or one of it's variants
under the video tab choose compression
highlight your divx codec
click on configure
when the divx codec properties window comes up click on the video tab
bottom left it says source interlace
I use progressive
I forgot and used deinterlace one time and got stairsteps and macroblocks and garbage in my re-encode
will try to find a complete guide for you and post link
between here, dvdrhelp and doom9.org you should be able to find just about anything
ps check here for some good guides and read knowing your video source www.lordsmurf.com
good luck and let me know how you make out