[vorbis] APPLAUD.WAV problems

[Greg Wooledge]

Ed Sweetman (ed.sweetman at wmich.edu) wrote:

> can you explain why there are no low bitrates for audio sections that
> require very little information to be encoded to have the quality that
> is designated. 

Because the sections that you're encoding are not as simple as you
think they are.  A very quiet but non-zero signal is just as hard to
encode as a really loud signal.  Those 6 seconds of "silence" before a
song starts up are full of background noise from the recording studio,
not digital silence.

Digital silence looks something like this:

$ dd if=/dev/zero bs=1024 count=512 | oggenc -r -o silence.ogg -
Encoding standard input to 
         "silence.ogg" at quality 3.00
Encoding with VBR
        Encoding [ 0m03s so far] \512+0 records in
512+0 records out

<p>Done encoding file "silence.ogg"

        File length:  0m 02.0s
        Elapsed time: 0m 04.0s
        Rate:         0.7461
        Average bitrate: 7.9 kb/s

$ ls -l silence.ogg 
-rw-rw-r--    1 greg     greg         2949 Feb 17 18:27 silence.ogg


-- 
Greg Wooledge                  |   "Truth belongs to everybody."
greg at wooledge.org              |    - The Red Hot Chili Peppers
http://wooledge.org/~greg/     |


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