VIDEO FORMATS Prof Oakes

Compression

CODECS COMPRESSOR/DECOMPRESSOR A codec provides specific instructions on how to compress video to reduce its size, then decompress it to "full quality" for playback. All video is compressed, or else files would be huge. This is the trade-off. DV or HDV, is significantly compressed in a number of ways. Digi-Betacam is compressed less. H.261 and MPEG-4 compress for playback on the web.

Things to Consider The size of the compressed file The speed of compression The speed of decompression The quality of the final image Lossy Vs Lossless Codecs – Lossy “throws out” visual information – There is no perfect CoDec

Choosing a Co-Dec Select the codec that matches the format of the video you are editing. Thus, if you are shooting NTSC DV, the DV/DVCPRO - NTSC codec is the best one to choose. The second rule is if you are selecting a codec to integrate multiple video formats choose the codec that provides the highest quality. The third rule is to select your codec based upon your final output format. In general, image quality increases with file size. As file size increases, you need bigger and faster hard disks.

Notes The Highest quality video format is going to be the format you captured your video in. Always avoid compressing your original footage Always avoid re-compressing your footage The Highest quality video format is going to be the format you captured your video in. Always avoid compressing your original footage Always avoid re-compressing your footage

Containers and Codecs “Containers” are the video format Containers describe the structure of the file Some containers allow more than one compression type Think of the container as the file itself, think of the codec as its contents “Containers” are the video format Containers describe the structure of the file Some containers allow more than one compression type Think of the container as the file itself, think of the codec as its contents

Containers and Codecs CONTAINERS Audio Video Interleave (.AVI) QuickTime (.mov) Flash Video (.flv,.swf) CONTAINERS Audio Video Interleave (.AVI) QuickTime (.mov) Flash Video (.flv,.swf) CODECS Windows Media Video (.wmv) H.264 (mpeg 4) MPEG - 1 and 2 (These are codecs and containers) CODECS Windows Media Video (.wmv) H.264 (mpeg 4) MPEG - 1 and 2 (These are codecs and containers)

Questions to Ask What is the intended purpose? How will the file be projected/played? How fast is the processor/computer playing the file? What is the optimum balance between file size and image quality (loss)?

ASPECT RATIO Aspect Ratio = Width to Height 1:33 Aspect Ratio - Old Television 1:85 Aspect Ratio (Common in features) 16:9 HD- close to 1:85 2:35 Aspect Ratio (Widescreen/Letterbox)

Aspect Ratio

FPS Typical still cameras take one photo per shutter opening and closing (EXPOSURE) Movie cameras (24FPS) Video (29.97 FPS) HD usually 30 or 60 FPS, sometimes 24 PAL (Europe) is 25 FPS

Progressive or Interlaced Progressive or non-interlaced scanning is a method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence. – Line by Line This is in contrast to the Interlacing used in traditional television systems where only the odd lines, then the even lines of each frame (each image now called a field) are drawn alternately. – Alternating Rows

PIXELS and PROJECTION Projectors/Screens work in the opposite manner of digital cameras. Laptop LCD computer screens make up their images using pixels, although they are often much too small to see. In a television or computer screen, electronic equipment switches all these colored pixels on and off very quickly. Light from the screen travels out to your eyes and your brain is fooled into see a large, moving picture.

Screen Size and Definition

Questions to Ask What is the File Format? (size and type) What is the Aspect Ratio? (16:9, etc.) What is the Frames Per Second (24, 30, etc.) Progressive or Interlaced? (P or I)