how to control the time in ffmpeg?

[petrum]

I try to convert a aac file to MP3 format (using ffmpeg).
There is a disconnect btw. the input Duration and the output time. The duration is 51 sec., the output time is 102 sec (please see below).

Duration: 00:00:51.1, start: 0.000000, bitrate: 32 kb/s

size= 399kB time=102.2 bitrate= 32.0kbits/s

The output's time is double, and the sound is distorted (slower).
I've tried to change the '-ar', '-ab' parameters, but the duration/time are not affected.

How can I control the output time?
Where the problem could come from?

Regards,
Petru
P.S. The input file comes from an online radio station
It is playable with both WinAmp and mplayer.

bash-3.1$ ffmpeg.exe -y -i sr_program_2006_08_06_07_27_58.aac -acodec mp3 -ab 32 output.mp3
//...
Input #0, aac, from 'sr_program_2006_08_06_07_27_58.aac':
Duration: 00:00:51.1, start: 0.000000, bitrate: 32 kb/s
Stream #0.0: Audio: aac, 22050 Hz, stereo, 32 kb/s
Output #0, mp3, to 'output.mp3':
Stream #0.0: Audio: mp3, 22050 Hz, stereo, 32 kb/s
//...
size= 399kB time=102.2 bitrate= 32.0kbits/s
video:0kB audio:399kB global headers:0kB muxing overhead 0.000000%

[Baldrick]

one similiar topic is enough, just reply to add new information or bump it.
https://forum.videohelp.com/viewtopic.php?t=305818&highlight=