I have a problem. I have set default sample rate and project sample rate to 44100Hz and 16 bit sample format. I have taken a .wav file with these characteristics (sample rate to 44100Hz and 16 bit sample format) but when I convert it to .mp3 it becomes 24000Hz and 32-bit. I have set in preferences the defaults in “quality” and “file format” tabs to be 44100Hz and 16 bit but it still creates an mp3 with 24000Hz and 32 bit. What’s going wrong?
Normally it is best to leave Audacity at the default Quality setting of 44100 Hz 32 bit float.
Is there a special reason why you need to set the Quality at 16 bit? (note that the bit depth setting in “Quality” does not affect the bit depth of the exported file).
When you import an MP3 file, Audacity copies the audio data from the file into the Audacity project. The data in the track is not the same data as the file - it is a copy.
The reason for this is that only very limited editing can be done on compressed audio data (such as MP3 files), so Audacity automatically copies the audio into an uncompressed form so that you can do wild and wonderful things to it. What this means is that the numbers shown on the left side of the track do not relate directly to the the format of the file that you imported. Those numbers relate to the copy of the data that is in the Audacity Project.
The best way to check the exact format of an audio file is to use a program such as MediaInfo (open source freeware) that can analyse the file. MediaInfo
If you are using Audacity 1.3.12, select 44100 as the Project rate (bottom left corner of the main Audacity window) before you Export.
Then select MP3 as the export format, and click on the “Options” button to set the compression amount to 64 kbps (in the “Constant bit rate” settings).
Bit depth does not apply to mp3 files, the only parameters for mp3 are sample rate (e.g. 44100Hz), bit rate (e.g. 64kbps), and the type of encoding, (e.g. constant, variable). Bit depth would be relevant for WAV type files.
Audacity can produce a stereo mp3 with a sample rate of 44100Hz and a bit rate of 64Kbps*, without forcing a downgrade in the sample rate to 24000Hz, e.g. attached with it’s media info, (note no mention of “bit depth” in media info, only “bit rate”).
I did the above, (placed also the project rate at 44100) and it still didn’t work. Then I uninstalled audacity and reinstalled the beta version which it says its better for vista and it worked!! I now have 44100 Hz and 64 kbps .mp3 file.
The site specifications are 44100Hz, 64kbps and 16 bit . It is an internet radio (radiobubble.gr) in which you can upload broadcasts - unfortunately it’s only in greek.
When stating “16 bit” perhaps they are trying to reduce the file size of the submitted mp3 by first reducing the bit depth of the WAV that the mp3 is derived from, (which could be a 32 or 24 bit depth WAV). I’ve tried that and reducing the bit depth of the WAV doesn’t reduce the size of the mp3 derived from it , (at least not when using Audacity with LAMEv3.98.2).
The sound quality of a 64 kbps file will be fairly poor if you start with a stereo track in Audacity (as this will produce a stereo MP3, so the bit rate of each channel will be a lot less than 64 kbps). However, if you have a mono track in Audacity, this will produce a mono MP3 and the sound quality will be significantly better.
In Audacity 1.3.12, stereo tracks can be converted to mono from “Tracks menu > Stereo Track To Mono”