On Friday 12 March 2004 16:16, James Hatridge wrote:

I have an 8-bit mono wav file. When I compress it using lame into an mp3 file the mp3 file sounds like Micky Mouse on speed. What am I doing wrong? Ahh yes, been there, done that. Don't worry, no comical response here... well, at least I will give you the useful info first.

When specifying commandline options in lame, MAKE SURE you specify mono mode: -m m [-m is mode and the final "m" is "mono"] If that still produces the same, or indeed the opposite effect, use sox to convert your mono file to a stereo, and then use lame with the -m m option :) You can have (from the man page): (s)tereo In this mode, the encoder makes no use of potentially existing correlations between the two input channels. It can, however, negotiate the bit demand between both channel, i.e. give one channel more bits if the other contains silence or needs less bits because of a lower complexity. (j)oint stereo In this mode, the encoder will make use of a correlation between both channels. The signal will be matrixed into a sum ("mid"), computed by L+R, and difference ("side") signal, computed by L-R, and more bits are allocated to the mid channel. This will effectively increase the bandwidth if the signal does not have too much stereo separation, thus giving a significant gain in encoding quality. Using mid/side stereo inappropriately can result in audible compression artifacts. To much switching between mid/side and regular stereo can also sound bad. To determine when to switch to mid/side stereo, LAME uses a much more sophisticated algorithm than that described in the ISO documentation, and thus is safe to use in joint stereo mode. (f)orced joint stereo This mode will force MS joint stereo on all frames. It is slightly faster than joint stereo, but it should be used only if you are sure that every frame of the input file has very little stereo separation. (d)ual channels In this mode, the 2 channels will be totally indenpendently encoded. Each channel will have exactly half of the bitrate. This mode is designed for applications like dual languages encoding (for example: English in one channel and French in the other). Using this encoding mode for regular stereo files will result in a lower quality encoding. (m)ono The input will be encoded as a mono signal. If it was a stereo signal, it will be downsampled to mono. The downmix is calculated as the sum of the left and right channel, attenuated by 6 dB.

The Friday 2004-03-12 at 17:16 +0100, James Hatridge wrote:

I have an 8-bit mono wav file. When I compress it using lame into an mp3 file the mp3 file sounds like Micky Mouse on speed. What am I doing wrong?

Maybe you have to manually specify the sampling rate. -- Cheers, Carlos Robinson