Advice needed on using MovieMaker

loripo · #1 (**permalink**) 01-11-2009, 02:40 PM

I use Windows Movie Maker to edit and assemble my video clips for publishing to PC and writing to DVD. The site that I upload to is for Schools use, but like Youtube is restricted to 100mb files. The first I did runs for 5mins and was an assemblage of about 6 previously edited clips. I find that if I run a completed video,(ie with titles/subtitles etc) through Movie maker again , with no amendments it produces a smaller file. I know that like photo images, they are actually instructions to produce an image and repeated open/save can lose quality. Does this happen in videos? I can’t see any difference in the before/after and have used this to get a smaller file. Most I only get a run of 2-3 mins. And I don’t use all the special effects just fade in/out. Any suggestions?

Jason Green · #2 (**permalink**) 01-11-2009, 02:58 PM

Hi Steven Spielberg, sorry I mean Lori

Yes, video quality can degrade - but only when you re-save with a different level of compression or another file extension. Most standard videos including TV programmes are filmed at 24 fps - that is to say, the video is made up of 24 individual, slightly different photos that are displayed and advancing each second - 24 frames per second. A standard 5min video will contain 7,200 seperate images, therefor each picture is of a lower quality than a JPG straight off a camera. If you choose to lower the saving quality to reduce the file size you will reduce the quality of each image - but only marginally as the reduction in Mb will be spread over the entire 7,200 pictures, with each being changed only slightly - hence you not noticing. It would notice far more on an individual photograph straight from a camera as the reduction would affect the 1 single image. This is my reasoning, others may know more on the subject!

What size are your videos? Those I take are 320x240 for YouTube are run at 24fps. Of course, uploading to a video-sharing site will automatically incur their filesize-reducing software too to save on their bandwidth as far as I know - YT does this.

When you re-save to get a different filesize - are you using the same file extension (...I like .AVI ) and save compression? If not, this may account for it.

Hope this helps!

Take care,

Jason

loripo · #3 (**permalink**) 01-11-2009, 03:57 PM

My camera produces .AVI files 640X480. After publishing in MM they are still AVI and 768X576. The full screen version on that site doesnt show very well but if you click on 'download' it then shows in your media player and quite good quality. I usually select 'best quality for playback on my computer' as I
don't know about the compression options etc.