Roedy Green said:
I wonder if anyone has any figures on approximately how much disk
space you need to store one hour of various audio and video formats.
For sound, you can vary the bit rate dramatically - with a corresponding
variation in sound quality.
I believe that digital telephones typically use around 44K bits per
second, before compression, to encode voice. What you get from
that sounds like, well, a telephone. After compression that might
be only around 4 Kbps.
The mp3 encoder used in Musicmatch Jukebox offers up to
320 Kbps _after_ compression to store high quality stereo audio.
You can also choose either fixed or variable rate compressions
with variable rate the same quality with a lower average bit rate, but
without being able to absolutely predict your file size from the
time of play.
Video is similar. You can choose a frame rate (number of frames
per second), a pixel count (width and height of the screen),
compression ratio, and encoding technology to optimize for size
or for quality, as desired. For example, my Canon S30 digital
camera stores 30 seconds of low quality 320x240 @ 15 frames
per second in about 5.2 MB. Or it can store 2 minutes of even
lower quality 160x120 video in the same space.
What you can achieve will depend on what encoder you use, and
what level of compression / degradation you can live with.
Alan