specifying a lower minimum bitrate for -aps

2003-04-29 13:06:57

Per the bitrate range of --alt-preset standard: I recently encoded Chuck Berry's "anthology" double-disc, and initially used -aps but found that for most files, 99% of the frames were going to 128 kbps (-aps has a lower limit of -b 128 automatically).  So I overrode that lower limit by specifying
--alt-preset standard -b 112, and on most of the files around 20% of the frames (if I remember correctly) went to 112 kbps.  There are a few tracks tht nearly all of the frames went to 112, so the average bitrate of the vbr file is at 112.3.  Most of the songs average in at around 128 kbps.  It makes sense that some old music is easy to encode, just b/c the resolution isn't there.  But tell me if there's any problem with specifying a lower minimum bitrate.  Thanks.

specifying a lower minimum bitrate for -aps

Reply #1 – 2003-04-29 13:23:26

Check out this recent thread:

http://www.hydrogenaudio.org/forums/index....=ST&f=16&t=8794

If a great deal of frames are encoded at 128 kbps, there is a probability that the source file is mono, and in that case the best choice is to encode in mono too. A mono commandline approximately equal to stereo --alt-preset standard which has been suggested once, and which I use myself is:

--alt-preset standard -mm -b 80

Why then -b 80 and not -b 64? As I've understood it the resulting bitrate in mono is not half the stereo bitrate, but a little greater, because no bits are longer saved by the use of joint stereo - thus the need for a higher -b value.

EDIT: You'd better do a search in the archives for mono encoding, because there are some issues that should be considered when encoding in mono, particularly regarding downmixing "fake stereo" to mono.

specifying a lower minimum bitrate for -aps

Reply #2 – 2003-04-29 14:03:46

timcupery > take a look at the 3.94 alpha codec (and preset). The new floor is set to 96 kbps, and bitrate distribution is totally different.