Hi,
because it´s not easy to change my (good) old Car-Radio to a new one which can play
mp3´s from USB or SDcard, I get one of these MP3 Car cigarette Lighter FM Transmitter.
The transmitting power is sufficient, but the sound was dull/muffled because of the reasons we all know .... missing FM preemphasis.
I try and use the Commandline version 3.53 + Lame to process my mp3 songs (mostly not normalized but good coded >160kbit/s) and was very satisfied.
(I need only the preemphasis, a little loudness and compression, and smaller filesizes because of the lowpass)
For easy click/process and copy I´ve automated it with a little self-written Frontend-
Program that creates the needed .STS and .Bat files.
(haven´t found an easier way to process a great number of files and play around with the stereo-tool settings)
Thats my short .STS file, leaving all other parameters at default:
[Common]
Pre amplifier=1.0
Extra loudness=1.2
Hard limit output=1
Mode=Advanced
[Multiband Compressor]
Enabled=1
Difference=0
Very high quality enabled=1
Maximum volume - Band -1=9000 .....\
Maximum volume - Band 0=8000 ...... Don´t want to kill the bass
Maximum volume - Band 1=7300 ..... /
[Output Filter]
Enabled=1
Lowpass filter=15000
[FM Transmitter]
Enabled=1
Pre-emphasize=1
Pre-emphasis time=50
Output is pre-emphasized=1
Stereo encoder enabled=0
Batchfile:
lame --decode -S %1 - | stereo_tool353 - - c:\fmwork\STS.sts | lame --preset standard -S - %2
*** Now we come to the interesting part (Bug?) ***
Only playing around with the Lowpass filter to recode a test-source (simple top10-pop 320kbit/s) I get the following filesizes:
Music_12khz.mp3 3306465 bytes
Music_13khz.mp3
5110075 bytes
Music_14khz.mp3 3550746 bytes
Music_15khz.mp3 3650746 bytes
Music_noFilt.mp3 4037351 bytes
Any idea from the expert(s) why the peak at 13khz ?
Regards