Take a closer look at the dates.
Version 3.70 stable was released a month after 3.80 beta
Perhaps one of the LAME devs could elaborate a liitle more on the release strategy.
My guess is that ISO code removal justified an 0.1 version numer increase.
That's a long time ago btw, iirc I jumped on the LAME train somewhere around version 3.86 beta
QUOTE
LAME 3.81beta (CVS)
* LAME 3.81beta March 8 2000
* all ISO code removed!
* Takehiro Tominaga and Naoki Shibata: new MDCT routines.
* ISO 7680bit buffer limitation removed. It can be reactivated with "--strictly-enforce-ISO" Please report any trouble with high bitrate.
LAME 3.80beta March 6 2000
* Takehiro Tominaga: more efficient and faster huffman encoding!
* Takehiro Tominaga and Mark Taylor: much improved short block compression!
* Tomasz Motylewski and Mark Taylor: MPEG2.5 now supported!
* Mark Taylor: incorporated Takehiro's bitstream.c! bitstream.c used by default, but old ISO bitstream code can also be used.
* Scott Manley and Mark Taylor: good resampling routine finaly in LAME. uses a 19 point FIR filter with Blackman window. Very slow for non integer resampling ratios.
* Iwasa Kazmi: fixed SIGBUS error: VBR and id3 tags were using data after it was free()'d.
* Robert Hegemann: Improved VBR tuning. #define RH_QUALITY_CONTROL and #RH_SIDE_VBR now the defaults.
* Robert Hegemann: LAME version string now added to ancillary data.
* Kimmo Mustonen: VBR histogram support for Amiga.
* Casper Gripenberg: VBR stats (but not histogram) for DOS verson.
* Robert Hegemann: rare VBR overflow bug fixed.
* Zack: -F option strictly enforces the VBR min bitrate. Without -F, LAME will ignore the minimum bitrate when encoding analog silence.
* Shawn Riley: User can now specify a compression ratio (--comp <arg>) instead of a bit rate. Default settings based on a compression ratio of 11.0
* Mark Taylor: free format bitstreams can be created with --freeformat, and specify any integer bitrate from 8 to 320kbs with -b.
* Mark Taylor: lame be used as a decoder (output raw pcm only): lame --decode input.mp3 output.pcm
LAME 3.70 April 6 2000
* "LAME 3.69beta becomes LAME 3.70 "stable"