QtMultimedia not recognizing my sound card
I have written a Qt application for recording MP3 files. It works on Windows (XP/7/10). It works on my Linux netbooks (32 bit Debian 8), and it works on my Linux desktop (64 bit Linux Mint). I recently installed Ubuntu 64 bit Linux on an RCA Cambio (a cheap convertible tablet/laptop using the Intel Atom Baytrail chipset). I cannot get my recording application to work on this machine. First of all, Linux does not support the internal sound card on this hardware. But I have an external USB sound card that works fine. The USB sound card appears in the Pulse Audio mixer as both an input and output device. I can play music through the sound card. But QtMultimedia refuses to recognize the USB sound card. QAudioDeviceInfo::availableDevices returns an empty list for available input devices. QAudioDeviceInfo::defaultInputDevice returns a device with a blank name, and empty lists for supportedChanelCounts and supportedSampleRates.
Why is QtMultimedia not recognizing my USB sound card, even though Pulse Audio is seeing the card just fine?
I solved the problem. I needed to install the library libqt5multimedia5-plugins with sudo apt-get install libqt5multimedia5-plugins. That library was not installed by default even after I installed qtmultimedia5-dev. Getting everything you need installed for QtMultimedia on Linux is a little tricky.