Opus always encoded at 48 kHz?

[Jeff Fortin Tam]

Running SoundConverter 4.0.3 on Fedora 37, converting some .wav files that Nautilus says are 44100 Hz (and Audacity says they are "stereo 44100Hz 32-bit float"), with SoundConverter set to not resample anything, SoundConverter's output when using the Opus encoder is always 48000 Hz (according to Nautilus' file properties dialog, and Audacity), whereas for other codecs (such as FLAC) it correctly remains at 44100 Hz.

It also happens if transcoding from 44.1 kHz FLAC files to Opus, the resulting Opus files are 48 kHz.

(I haven't tested encoding to MP3, AAC or Speex)

[sezanzeb (sezanzeb)]

Hi. It seems this is a restriction of the opus format: https://en.wikipedia.org/wiki/Opus_(audio_format)#Bandwidth_and_sampling_rate

[sezanzeb (sezanzeb)]

The available sample rates should probably be dynamic depending on the selected output format.

Currently they are hard-coded in liststore_resample in the soundconverter.glade file.

It would probably be possible to change the contents of the liststore in the on_output_mime_type_changed function.

Gtk.ListStore.remove and .insert could modify it. https://lazka.github.io/pgi-docs/#Gtk-3.0/classes/ListStore.html

Unfortunately quite a few other projects have higher priority for me right now, so I probably won't do the research of the possible sample rates for all the different formats, and the implementation, any time soon.

[GautierPortet (kassoulet)]

Hi. If the sample is fixed when converting to Opus, we could just disable the sample-rate selector when Opus is selected.

Does it sound right to you?

Or can just ignore the issue, as this is due to the format itself.