SF patch #489989 (Charles G Waldman) linuxaudiodev.c - fix initialization

gvanrossum · gvanrossum · commit 7745218c0517 · 2001-12-08T17:13:45.000Z
The OSS Programmer's Reference (www.4front-tech.com) states: *Setting Sampling Parameters There are three parameters which affect the sound quality (and therefore memory and bandwidth requirements) of sampled audio data. These are: ** sample format (sometimes called number of bits) ** number of channels (mono or stereo), and ** sampling rate (speed) NOTE: It is important to always set these parameters in the above order. Setting sampling rate before the number of channels doesn't work with all devices.
diff --git a/Modules/linuxaudiodev.c b/Modules/linuxaudiodev.c
@@ -258,15 +258,6 @@ lad_setparameters(lad_t *self, PyObject *args)
 	return NULL;
     }
 
-    if (ioctl(self->x_fd, SNDCTL_DSP_SPEED, &rate) == -1) {
-        PyErr_SetFromErrno(LinuxAudioError);
-        return NULL;
-    }
-    if (ioctl(self->x_fd, SNDCTL_DSP_CHANNELS, &nchannels) == -1) {
-        PyErr_SetFromErrno(LinuxAudioError);
-        return NULL;
-    }
-
     for (n = 0; n < n_audio_types; n++)
         if (fmt == audio_types[n].a_fmt)
             break;
@@ -294,6 +285,14 @@ lad_setparameters(lad_t *self, PyObject *args)
         PyErr_SetFromErrno(LinuxAudioError);
         return NULL;
     }
+    if (ioctl(self->x_fd, SNDCTL_DSP_CHANNELS, &nchannels) == -1) {
+        PyErr_SetFromErrno(LinuxAudioError);
+        return NULL;
+    }
+    if (ioctl(self->x_fd, SNDCTL_DSP_SPEED, &rate) == -1) {
+        PyErr_SetFromErrno(LinuxAudioError);
+        return NULL;
+    }
 
     Py_INCREF(Py_None);
     return Py_None;
