Comp Sci - Lecture 10.docx

4 Pages
Unlock Document

Western University
Computer Science
Computer Science 1033A/B
Vivi Tryphonopolous

"" - Lecture10 Editing a Video • Before digital video Copy from one tape to another Load up takes on a machine to copy Lossof quality after each copy made • Now can easily move clips around no loss of quality slight compression occurs in the camcorder when video is captured Data Rate • Amount of video processed per second • Average data rate = file size/length Compression Strategies 1. Lower frame size of the video 2. Lower frame rate of the video 3. Pick a codec that does higher compression A codec is a piece of code that compresses the video or audio as it is created (exported from the editin g software) and then decompresses the video or audio when displayed to the user Dalso stands for coder/decoder There are lots of coders ,you have to use the same one to decompress that was used to compress the video Most common coders are: o Sorenson Spark o H.264 o DIV-X Compression Strategies Cont'd 4. Picka codec that does higher compression 5. Lower the picture quality of the video 6. Lower the colour depth 7. Play with the audio Compression Concepts • Spatial Compression Compresses each frame individually Uses same techniques as JPGcompression Codecs that do spatial compression Danimation ,planar RGB • Temporal Compression Only saves info on selected frames (called keyframes) All other frames just have differences from the previous keyframe Good when the difference between current frame and keyframe is small • Lossyvs.LosslessCompression Depending on the codec LosslessDlooks for large blocks of pixels that are the same RLE(run length encoding} LossyDlowers video quality but gets better file size& data rate **Terms You Need to Know** • Container file format A file format that stores both the data (the frames) and how to play the data (which codec to use) Somecommon containers are: o .avi - sometimes hasuncompressed video o .mov o .fla o .mkv - newest & open source,allows you to store unlim
More Less

Related notes for Computer Science 1033A/B

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.