At 23:10 22/06/00 +1200, you wrote:
>It was Acy Stapp not Mark T that had a look at doing it but apparently the
>Windows
>ACM doesn't support VBR and I think it was abandoned. I'm not sure where the
>problem is because I'm fairly sure that the Fraunhofer ACM does play VBR
>MP3 WAV
>files.
Hello,
The real problem is that ACM codecs only know how deal with CBR file
formats, this is not a problem in playback (without seeking) because you
simply go forward in the stream. If you perform a seek over a VBR file
without Xing header (Or something like that) you can get a aproximate
position but not occurate and sometimes something totally wrong (Think in
1000 frames at 256 Kbit and 1000 frames at 32 kbit, if you seek 50% you
will be positioned in the 4% of the song :-?¿?¿?)
The other main problem is the configuration in the compressor, ACM only
have one field for configuration that represent in ASCII format all
possible combinations, applying this to lame (3.80) you have:
18 different bitrates
4 panning modes (mono, stereo, joint and dual)
6 freqs.
This means 432 combinations (:-?) for CBR mode.
If you add VBR this number simply explodes:
2 modes (VBR and CBR)
18 different Max bitrate
18 different Min bitrate
10 VBR quality levels
Ummm!!!... where is my calculator... oh! here... well... 2.799.360
combinations.
Think in a drop combobox with 2 million entries... and you need the last
one!!! :-) and thinking in text mode :-) 2 million using around 20 chars.
by line means that you need 50 megabytes of RAM to configure partially your
LAME-ACM codec.
I think that the only one solution is create an ACM codec that is a subset
of Lame options:
bitrates like:
256, 192, 160,128,32
Mono and joint stereo
VBR Quality High, medium and low (1 MinaxBit=128/256,4 96/192,9=128/32) +/-
22050 and 44100 freq.
This give us 60 combinations that are something reasonable.
ACM support quality high and low, it could be high lame and low lame
qualities or high and normal.
Note: Othe solution for the ACM bitrates is a "setup" program for the ACM
codec and store the desired bitrates in the windows registry.
--
MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
