How to record opus audio programatically?

roundedrectangle · 13 October 2025 19:18

I use C++ QAudioRecorder to record audio. I know that it’s possible to set the codec and container by making an instance of QAudioEncoderSettings, using its method setCodec and then applying it to an audio recorder with QAudioRecorder::setEncodingSettings. The list of supported encodings can be queried from Qt using the QAudioRecorder::supportedAudioCodecs method. On my device, it includes these codecs: “audio/vorbis”, “audio/speex”, “audio/PCM”, “audio/FLAC”.

I also read here that QtMultimedia uses GStreamer internally. So, I installed gstreamer1.0-tools package and tried running gst-inspect-1.0. It showed that I have the opusenc codec installed. To test it, I ran this command: gst-launch-1.0 pulsesrc ! audioconvert ! opusenc ! oggmux ! filesink location=output.opus. It worked without any issues.

But still, the list from supportedAudioCodecs doesn’t include the opus codec, even though it works fine using GStreamer command line tools. So, why can’t I use the opus codec from Qt, and how can I workaround this?

Mister_Magister · 13 October 2025 19:53

github.com/Michal-Szczepaniak/Yottagram

Yottagram/src/components/audiorecorder.cpp

master

/*

This file is part of Yottagram.
Copyright 2020, Michał Szczepaniak <m.szczepaniak.000@gmail.com>

Yottagram is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Yottagram is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Yottagram. If not, see <http://www.gnu.org/licenses/>.

*/

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Mister_Magister · 13 October 2025 19:55

If you want specifically opus in ogg, instead of vorbis in ogg then you probably would have to somehow employ encoder or like, look into recording audio from pulseaudio, or you could employ gstreamer pipeline to do it

roundedrectangle · 14 October 2025 07:11

Thank you but that does not help. You showed me how to record vorbis-encoded audio, and I am asking why Qt can see and use flac, vorbis, and other encoders but not opus, even though it functions correctly using GStreamer command line tools.

Mister_Magister · 14 October 2025 07:19

I’d say black magic and/or witches but i doubt that helps either sorry

poetaster · 14 October 2025 08:51

The obvious answer is that the gstreamer tools are more modern than the version of QAudioEncoderSettings we have with our ancient QT. That's just a guess, mind.

roundedrectangle · 14 October 2025 10:32

Supported codecs information seems to be hard-coded in Qt 5.6, here. That is why it doesn’t work and codec names are different from ones found using GStreamer tools. A better implementation is present in Qt 5.6 and can be found here. I am not sure why it is not used in the GStreamer plugin.