Problem enumerating devices based on Pa_GetHostApiInfo()

[Tim Pattinson]

Hi all,

I am encountering a problem which could be a bug in PortAudio, or could be my misunderstanding.

I am attempting to enumerate the audio devices made available by each host API.

The logic is: Call Pa_GetHostApiInfo() to get the number of devices, then call Pa_HostApiDeviceIndextoDeviceIndex() to get the global index of it.

(I am aware that I could enumerate directly, but it seemed useful to do it this way to make a list of what is available in each host API)

The issue I am having is that  Pa_HostApiDeviceIndextoDeviceIndex() returns the error paInvalidDevice when queried with a device index which is less that what is returned by  Pa_GetHostApiInfo()->deviceCount

My expectation was that I can query Pa_HostApiDeviceIndextoDeviceIndex() with 0 to deviceCount-1 and get a valid index. This is based on the comments in the PaHostApiInfo struct.

Stepping inside the function, it seems to compare my index with a different value for the maximum number of devices, and returns the error code.

I have attached a short program which reproduces this issue.

My system is Windows 11 25H2 but I am using the latest MSYS2 MinGW toolchain.

The output is: 

tim@TIMSPC UCRT64 ~
$ ./a.exe
PortAudio initialised
enumerating 5 APIs.
PA API: MME
        has 7 devices, default input device: 1
Trying device 0 on api 0 (index: 14)
        PA device (API idx 0): Realtek ASIO
        Input Channels: 2
                defaultLowOutputLatency: 0.023220
                defaultHighInputLatency: 0.023220
                defaultSampleRate 44100.000000
Trying device 1 on api 0 (index: -9996)
Segmentation fault         ./a.exe

I seperately compiled the example "pa_devs.c" and that seems to work fine, although it doesn't enumerate devices in the same way.

I'd appreciate someone pointing out my error or reproducing on their system.

Thanks