dlls/include/mmsystem.h:#define MAXPNAMELEN 32 /* max product name length (including NULL) */
I wanted to know what the reason was for bounding this string to only 32 bytes (actually 31 + null). We have a situation with identical devices and need to add some differentiating text to that string when multiple identical devices exist so that applications can choose the correct device.
Our device product string is "USB PnP Sound Device" (20 chars). mmdevdrv.c:static WCHAR *construct_device_id() then prefixs with either "In: " (4 chars) or "Out: " (5 chars) and concatenates " - USB" (6 chars).
In: USB PnP Sound Device - USB Out: USB PnP Sound Device - USB
Total string length is 30 or 31 characters. Any additional text added at the end will get truncated and a prefix will cause the existing string to be truncated.
-Doug-
That's just how it is in Windows.
That's just what it was defined as.
- Joshie 🐸✨
On 1/29/21 2:02 AM, Doug Kingston wrote:
dlls/include/mmsystem.h:#define MAXPNAMELEN 32 /* max product name length (including NULL) */
I wanted to know what the reason was for bounding this string to only 32 bytes (actually 31 + null). We have a situation with identical devices and need to add some differentiating text to that string when multiple identical devices exist so that applications can choose the correct device.
Our device product string is "USB PnP Sound Device" (20 chars). mmdevdrv.c:static WCHAR *construct_device_id() then prefixs with either "In: " (4 chars) or "Out: " (5 chars) and concatenates " - USB" (6 chars).
In: USB PnP Sound Device - USB Out: USB PnP Sound Device - USBTotal string length is 30 or 31 characters. Any additional text added at the end will get truncated and a prefix will cause the existing string to be truncated.
-Doug-
Hello Doug,
On 1/28/21 8:02 PM, Doug Kingston wrote:
dlls/include/mmsystem.h:#define MAXPNAMELEN 32 /* max product name length (including NULL) */
I wanted to know what the reason was for bounding this string to only 32 bytes (actually 31 + null). We have a situation with identical devices and need to add some differentiating text to that string when multiple identical devices exist so that applications can choose the correct device.
Our device product string is "USB PnP Sound Device" (20 chars). mmdevdrv.c:static WCHAR *construct_device_id() then prefixs with either "In: " (4 chars) or "Out: " (5 chars) and concatenates " - USB" (6 chars).
In: USB PnP Sound Device - USB Out: USB PnP Sound Device - USBTotal string length is 30 or 31 characters. Any additional text added at the end will get truncated and a prefix will cause the existing string to be truncated.
The limit here is imposed by Microsoft, and is necessary for ABI and API compatibility.
Note however that it only applies to the old WinMM subsystem, and that no such limit is enforced in WASAPI (aka mmdevapi) or DirectSound. I don't know about XAudio, but I'd be surprised if it has such a limit either. Of course, if you're dealing with MIDI devices, WinMM is (I believe) the only extant API, and there's not really anything that can be done in that case.
-Doug-
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Doug Kingston -
Joshua Ashton -
Zebediah Figura (she/her)