Preserving Audiovisual Materials (LIS 198-Digital Preservation)
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Transcript of Preserving Audiovisual Materials (LIS 198-Digital Preservation)
preserving
materials
what are
materials?
audiovisual
are surrogate
history
2’’ Quad (1956)
TCR 100 Quad (1969)
UV 340 (1964)
Panasonic video
cartridge (1969)
Philips video
recorder (1970)
U-Matic(1971)
V-Cord (1972)
Betamax(1975)
VHS (1976)
D-2 (1988)Hi8 (1989) Digital betacam(1993)
Digital –S (1995)
-2 (1988) Hi8 (1989) Digital betacam(1993)
-2 (1988) 1992
-2 (1988) 1997 : RM
-2 (1988)VOBASF
2001-present
OCG MP4FLV MOVMKV 3GP
in
digital
signal
recording of a signal onto a carrier
digitization
digital preservation of the digitized signal
via
you
computer playback device
video cassette recorder
LEFT: The Avid Dazzle Video Creator Plus HD ($89/P4500) captures video. RIGHT: Pinnacle’s Studio MovieBox HD ($100/P5000) is a similar capture device.
LEFT: The Avid Dazzle Video Creator Plus HD ($89/P4500) captures video. RIGHT: Pinnacle’s Studio MovieBox HD ($100/P5000) is a similar capture device.
LEFT: The Avid Dazzle Video Creator Plus HD ($89/P4500) captures video. RIGHT: Pinnacle’s Studio MovieBox HD ($100/P5000) is a similar capture device.
LEFT: The Avid Dazzle Video Creator Plus HD ($89/P4500) captures video. RIGHT: Pinnacle’s Studio MovieBox HD ($100/P5000) is a similar capture device.
LEFT: The Avid Dazzle Video Creator Plus HD ($89/P4500) captures video. RIGHT: Pinnacle’s Studio MovieBox HD ($100/P5000) is a similar capture device.
properties
resolution-number of pixels present in the images of the
video-determines whether your video is standard
definition or high def.
size-pixel dimension of the frame
aspect ratio-Ratio of width to height
frame rates-speed at which the frames are captured and
intended for playback
bit rate-or data rate-amount of data used to describe the video portion of the file
bit rate-typically measured in per second units then in KB,MB,GB-higher bit rate, better quality (in general)
codec
properties
sampling rate-how often the audio is sampled when converted
from analog to digital
number of channels
Either coming from single (mono) or multiple channels (stereo)
codec
what is a
container VS codec
Describes structure of the file
Short for coder/decoderCompressor or decompressor
-Way of encoding video into a stream of bytes-Chief determinator of quality
…
Container as the file itself.Codec as its contents.
Impt. to realize:-most good container formats can hold many codecs
Describe both!
Example:MOV file containing H.264 data
Problem:
Common use of terms Confusion and imprecision
Even more confusing:-both describes codec and container
Example:“mpeg-4”
Windows media video
-can be streamed across the internet-when WM server: viewed before entire file-windows media player-internet streaming server
Audio video interleave
-Windows Player (ex. WMP)-uncompressed: high quality video-internet: entire file must be downloaded-stored on local hard disk or CDROM
Apple Quicktime Movie
-Apple Quicktime Movie Player-viewed before entire file-streamed across internet-depends on compression
Motion Picture Experts Group
-provide VHS quality movies or better-MPEG player-entire file must be downloaded
-Mpeg1 = VHSMpeg2better than VHS; used for DVDMpeg4best quality
Real Media
-RealPlayer-viewed before the file-high compression but at a cost to quality
-makes a file smaller-decoded file is unaltered after decompression has taken place-by using a scheme known as “run length encoding”
Example:
-Animation codec (which is typically used for archiving or transferring files), have a low compression ratio
-Usually, it’s no more than 2:1.
-you lose some image, video, or audio information. -bit tricky because good lossy compression is a balancing act between quality, data rate/file size, color depth, and fluid motion-Almost every video compression scheme is lossy
-Lossy compression schemes like H.264 (used on Canon video DSLRs) can have compression ratios of more than 100:1.
-With video workflows, compression can be applied (or removed) at several stages.