The ffmpeg program (www.ffmpeg.org) will convert most if not all supported formats. In addition it can automatically convert to 2 channels and to 44100hz. I currently use it to write discs from mono FLAC files and 22050 mono MP3 files which it automatically converts to the correct format. This would allow removal of the checks that prevent, for example, mono FLAC files from being added. If not, a feature allowing a user-specified converter with command line and %s/%t placeholders and a way to relax the checking of source files would be helpful.
cdrtfe already accepts any kind of mp3 files. They are automatically converted to 44.1kHz stereo using mpg123. flac.exe does not support such a conversion.
However, you can set a user-defined commandline for decoding compressed sound files. See section 'Audio CD' here: [inisettings].
cdrtfe now has an additional ini setting (for cdrtfe.ini and *.cfp project files) which allows to deactivate the check for 44.1kHz, stereo flac files.
[Audio-CD]
RelaxedFormatChecking=1
New test version:
http://home.arcor.de/kerberos002/download/cdrtfe-1.5.3.1-5.rar
Related
Wiki: inisettings