Reducing file size of enormous avi files?

[shira]

In the past, someone here mentioned it's possible to reduce an avi file's size by changing some of its settings. Can anyone recommend a tool to do it and steer me to what kind of changes I should make to the file's settings?

Is it possible to reduce an avi file with 1 hour of material to a small enough size to fit on a 4.7-gig burned disk? Currently this avi file is 11 gigabytes in size for an hour of footage.

[jimmalenko]

Bitrate / Codec / Virtualdub / Guides section.

[thecoalman]

Depends on what you want to do with the file aftwerwards? just burn to data disc for archiving, author a DVD?

[shira]

Hi Coalman! I would plan to burn a DVD from that avi file, so maintaining high quality would be important to me. That's why I don't want to convert it to MPEG. But neither do I want it to take up my whole hard disk. So I want to archive it in a format that will preserve the quality and can serve as a good original for future DVD authoring. Once the DVD has been burned, I would keep the original AVI for archiving purposes, since it is likely that in the future I might want to use pieces from it in other projects and I'd rather go back to the avi original than use an mpeg from the DVD I'm planning now.

I have 18 of these files, each chewing up 10-12 gigabytes of my hard disk, so I'm very motivated to reduce them to a more frugal format!

[wwjd]

Did these files come from a miniDV camcorder? If so, the 'Best' archival solution is to leave the DV avi on the miniDV tape. DVDs are not necessarily the best media for archiving. If you do use DVD then use high quality, no labels and them in a dry temperature controlled area. Make duplicates of each one as well.

Reducing the file size from 11-12Gb down to around 4Gb can only be done by re-encoding. Once you do that you lose quality.

If you no longer have the original souce material then your pretty much stuck. Either buy another HDD or re-encode to a smaller file size. If you do re-encode I recommend using mpeg2 using around 6mb CBR bit rate. Be sure to use a good mpeg encoder like Pro Coder, CCE Basic or Main Concept. Again, in my opinion, stay away from DivX, Xvid or WMV.

Are the files of one continuous subject or are they like family videos, where there are a number of different subjects? If there are a number different subjects then you should be able to cut/split the DV avi files into smaller chunks which can then be put on DVD. This approach would require a fair amount of work and quite a few DVDs. However, DVDs these days are cheap. But remember to make at least one copy of each DVD.

[shira]

wwjd, thanks much for your feedback on which mpeg coders you think are best versus which you don't think are as good. I usually use Adobe Premier for my mpeg encoding, which comes with MainConcept as its mpeg encoder.

The files in question are of a dance show, and there are logical breaking points between the dances. So it would be theoretically possible for me to split the avi's at break points after one dance ends and the next is ready to begin. There is dead time on the stage at these points which would be edited out in the final DVD anyway.

I see your point about keeping the original 18 tapes for archiving. They are mini-DV's. I think my primary hesitation about relying on that approach is that tape formats have changed so many times in even the last 5 years, and I've known folks who have their old tapes but no longer have working camcorders that can play them back. The dancer whom I'm helping with this project certainly can keep the tapes, but the camcorder was borrowed and will need to be returned to its owner after I capture all the tapes for her. But I don't want my entire hard disk occupied by someone else's video files for perpetuity, which is why, once I've captured them into computer-friendly form, I want to put them out on DVD's where I can hand them over to her.

I'm aware that the longevity of burned CD's and DVD's is unknown & untested, and therefore not reliable. Your point is well taken, and it's always good to be reminded. I'll have to make sure I impress that on her when I return the tapes and the DVD's to her.

From what I'm seeing here, it's starting to sound like reducing the size of individual avi's to a small enough size to fit on a DVD by re-encoding is not necessarily a good idea....

[yoda313]

From what I'm seeing here, it's starting to sound like reducing the size of individual avi's to a small enough size to fit on a DVD by re-encoding is not necessarily a good idea....

But if the end result is going to be a dvd for viewing on a regular player you have to reencode it to mpeg 2 to meet the specifications of that player.

The only other option to preserve the footage in digital format without converting would be to have the person buy a large capacity external harddrive and backup the original avi to it. Then it would be preserved intact.

But you'll still have to convert it to mpeg2 for dvd viewing - or divx on dvd if they have a divx capable standalone player.

[thecoalman]

From what I'm seeing here, it's starting to sound like reducing the size of individual avi's to a small enough size to fit on a DVD by re-encoding is not necessarily a good idea....

Not necessarily, it depends on the source. If you have a really ggod source like one from a prosumer cam your going to get some quality loss. If it's a consumer cam the loss will be negligble.

Personally I archive to tape and DVD in DV-AVI format, that requires about 4 DVD's per hour of footage..... Just split them and burn in pieces, you can always rejoinf them later. When a DVD fails it generally fails at the end, I try and keep it to about 16-17 minutes per clip.

[gll99]

If I wanted to store the dv avi I would split each hour file in 3 roughly 4 gig files and burn each sectioned avi to a disc. I plan to do this with my own family videos.

If you have 18 tapes that will take 54 DVD discs at .30c to .40c each disc.
Just for safety you can backup each disc and double your cost.

Total money spent less than $45 including backups.

When you are ready to process to dvd at some point you will have the DV data in it's original form on discs. Each 1 hour of video will make a nice high bitrate authored DVD someday.

Your friend can keep his tapes as an extra backup. Cutting the videos can be done very easily in virtualdub. You may need a DV codec like the free Panasonic which you can reference in the tools section on this site. In vdub make sure that you use direct stream copy and not full processing mode when you make your cuts. There will be no re-encoding and it will only take a few minutes per cut.