Audio and Video Compression and it’s importance on the internet

AUDIO AND VIDEO COMPRESSION AND IT’S IMPORTANCEON THE INTERNETBrian DillingerMay 3, 2010

What is compression?

A reversible conversion of data that requires fewer bits using codecs

Audio and Video Codecs

A codec is a device or software that allows for COmpression and DECompression of video and audio

Common Audio Codecs

• MP3 (MPEG-1 Audio Layer 3)• FLAC (Free Lossless Audio Codec)• AAC (Advanced Audio Coding)• Ogg (Ogg Vorbis)

Common Video Codecs

• DivX (MPEG-4 Part 2)• XviD (MPEG-4 Part 2)• H.264/x264 (MPEG Part 10)• WMV (Windows Media Video)

Audio Standards MP3

MP3 file format is the most common With increased quality

comes increased file size CBR vs VBR ID3 tagging through

metadata

Switch

Target Kbit/s

Bitrate Range Kbit/s

320 320 320 CBR

V0 245 220-260 VBR

V1 225 190-250 VBR

192 192 192 CBR

V2 190 170-210 VBR

Audio Standards FLAC

FLAC file format is most commonly used for lossless compression

High bitrate 768 kBit/s Large file size

Song length of 4:31 MP3 V0 9.12MB FLAC 32.3MB

Audio Compression Software Exact Audio Copy (Powerful Accurate and

FREE) FLAC, WMV, MP3 and Ogg support MP3 ripping capable of both VBR and CBR

using Lame 3.98 Free CD lookup

iTunes MP3 and Apple Lossless Apple Lossless has limited

playback

VIDEO Standards XviD

Standard Definition standard Follows MPEG-4 part 2 standards Lossy encoding PAL video requires ~100GB per hour

Compressed at 200:1 XviD requires ~500MB per hour

Video Standards H.264/x264 Standard for High Definition video Follows MPEG-4 part 10 standards Allows for half the file size for the same

video as XviD standards

Video Compression Software bitRipper

Very simple way to convert DVD video using the XviD codec and avi container

Adobe Encore Expensive Professional Suite Extremely fast and efficient Voice to text for adding subtitles

Why use compression?

Disc space is increasing but not infinite Online streaming for both audio and video is a

growing trend Video conferencing and video chats

References

www.xvid.org www.hydrogenaudio.com www.id3.org www.flac.sourceforge.net www.matroska.org/