Setup PCM device in constructor.

Currently, after recording audio using pyalsaaudio, the client is unable to close the device.

The reason is that PulseAudio client tries to drain the pipe to the PulseAudio server (presumably in order to prevent Broken Pipe error) on closing. That will never finish since new data will always arrive in the pipe.

Worse, the __del__ handler was auto-closing and thus auto-hanging.

Therefore, pause before de-allocating.

CHANGES

@@ -1,3 +1,32 @@
+Version 0.8.6:
+- Added four methods to the 'PCM' class to allow users to get detailed information about the device:
+
+  - 'getformats()' returns a dictionary of name / value pairs, one for each of the card's
+    supported formats - e.g. '{"U8": 1, "S16_LE": 2}',
+  - 'getchannels()' returns a list of the supported channel numbers, e.g. '[1, 2]',
+  - 'getrates()' returns supported sample rates for the device, e.g. '[48000]',
+  - 'getratebounds()' returns the device's official minimum and maximum supported 
+    sample rates as a tuple, e.g. '(4000, 48000)'.
+  
+  (#82 contributed by @jdstmporter)
+
+- Prevent hang on close after capturing audio (#80 contributed by @daym)
+
+Version 0.8.5:
+- Return an empty string/bytestring when 'read()' detects an 
+  overrun. Previously the returned data was undefined (contributed by @jcea)
+
+- Unlimited setperiod buffer size when reading frames (contributed by @jcea)
+
+Version 0.8.4:
+- Fix Python3 API usage broken in 0.8.3
+
+Version 0.8.3:
+- Add DSD sample formats (contributed by @lintweaker)
+- Add Mixer.handleevents() to acknowledge events identified by select.poll (contributed by @PaulSD)
+- Add functions for listing cards and their names (contributed by @chrisdiamand)
+- Add a method for setting enums (contributed by @chrisdiamand)
+
 Version 0.8.2:
 - fix #3 (we cannot get the revision from git for pip installs)
 

NOTES.md

@@ -0,0 +1,11 @@
+# Publishing the documentation
+
+ - Install Sphinx; `sudo pip install sphinx`
+ - Clone gh-pages branch: `cd doc; git clone -b gh-pages git@github.com:larsimmisch/pyalsaaudio.git gh-pages`
+ - `cd doc; make publish`
+
+# Release procedure
+
+ - Update version number in setup.py
+ - Create tag and push it, i.e. `git tag x.y.z; git push origin x.y.z`
+ - `python setup.py sdist upload -r pypi` 

alsaaudio.c

@@ -20,10 +20,74 @@
 #define PyLong_Check PyInt_Check
 #define PyLong_AS_LONG PyInt_AS_LONG
 #endif
+
+#if PY_MAJOR_VERSION < 3
+    #define PyLong_FromLong PyInt_FromLong
+#endif
+
 #include <alsa/asoundlib.h>
 #include <alsa/version.h>
 #include <stdio.h>
 
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof *(a))
+static const snd_pcm_format_t ALSAFormats[] = {
+    SND_PCM_FORMAT_S8,
+    SND_PCM_FORMAT_U8,
+    SND_PCM_FORMAT_S16_LE,
+    SND_PCM_FORMAT_S16_BE,
+    SND_PCM_FORMAT_U16_LE,
+    SND_PCM_FORMAT_U16_BE,
+    SND_PCM_FORMAT_S24_LE,
+    SND_PCM_FORMAT_S24_BE,
+    SND_PCM_FORMAT_U24_LE,
+    SND_PCM_FORMAT_U24_BE,
+    SND_PCM_FORMAT_S32_LE,
+    SND_PCM_FORMAT_S32_BE,
+    SND_PCM_FORMAT_U32_LE,
+    SND_PCM_FORMAT_U32_BE,
+    SND_PCM_FORMAT_FLOAT_LE,
+    SND_PCM_FORMAT_FLOAT_BE,
+    SND_PCM_FORMAT_FLOAT64_LE,
+    SND_PCM_FORMAT_FLOAT64_BE,
+    SND_PCM_FORMAT_IEC958_SUBFRAME_LE,
+    SND_PCM_FORMAT_IEC958_SUBFRAME_BE,
+    SND_PCM_FORMAT_MU_LAW,
+    SND_PCM_FORMAT_A_LAW,
+    SND_PCM_FORMAT_IMA_ADPCM,
+    SND_PCM_FORMAT_MPEG,
+    SND_PCM_FORMAT_GSM,
+    SND_PCM_FORMAT_SPECIAL,
+    SND_PCM_FORMAT_S24_3LE,
+    SND_PCM_FORMAT_S24_3BE,
+    SND_PCM_FORMAT_U24_3LE,
+    SND_PCM_FORMAT_U24_3BE,
+    SND_PCM_FORMAT_S20_3LE,
+    SND_PCM_FORMAT_S20_3BE,
+    SND_PCM_FORMAT_U20_3LE,
+    SND_PCM_FORMAT_U20_3BE,
+    SND_PCM_FORMAT_S18_3LE,
+    SND_PCM_FORMAT_S18_3BE,
+    SND_PCM_FORMAT_U18_3LE,
+    SND_PCM_FORMAT_U18_3BE
+};
+
+static const unsigned ALSARates[] = {
+    4000,
+    5512,
+    8000,
+    11025,
+    16000,
+    22050,
+    32000,
+    44100,
+    48000,
+    64000,
+    88200,
+    96000,
+    176400,
+    192000
+};
+
 PyDoc_STRVAR(alsaaudio_module_doc,
              "This modules provides support for the ALSA audio API.\n"
              "\n"
@@ -187,7 +251,7 @@ alsacard_list_indexes(PyObject *self, PyObject *args)
     for (rc = snd_card_next(&card); !rc && (card >= 0);
          rc = snd_card_next(&card))
     {
-        PyObject *item = PyInt_FromLong(card);
+        PyObject *item = PyLong_FromLong(card);
 
         PyList_Append(result, item);
         Py_DECREF(item);
@@ -294,74 +358,26 @@ PyDoc_STRVAR(pcms_doc,
 \n\
 List the available PCM devices");
 
-static int alsapcm_setup(alsapcm_t *self)
-{
-    int res,dir;
-    unsigned int val;
-    snd_pcm_format_t fmt;
-    snd_pcm_uframes_t frames;
-    snd_pcm_hw_params_t *hwparams;
-
-    /* Allocate a hwparam structure on the stack,
-       and fill it with configuration space */
-    snd_pcm_hw_params_alloca(&hwparams);
-    res = snd_pcm_hw_params_any(self->handle, hwparams);
-    if (res < 0)
-        return res;
-
-    /* Fill it with default values.
-
-       We don't care if any of this fails - we'll read the actual values
-       back out.
-     */
-    snd_pcm_hw_params_any(self->handle, hwparams);
-    snd_pcm_hw_params_set_access(self->handle, hwparams,
-                                 SND_PCM_ACCESS_RW_INTERLEAVED);
-    snd_pcm_hw_params_set_format(self->handle, hwparams, self->format);
-    snd_pcm_hw_params_set_channels(self->handle, hwparams,
-                                   self->channels);
-
-    dir = 0;
-    snd_pcm_hw_params_set_rate(self->handle, hwparams, self->rate, dir);
-    snd_pcm_hw_params_set_period_size(self->handle, hwparams,
-                                      self->periodsize, dir);
-    snd_pcm_hw_params_set_periods(self->handle, hwparams, 4, 0);
-
-    /* Write it to the device */
-    res = snd_pcm_hw_params(self->handle, hwparams);
-
-    /* Query current settings. These may differ from the requested values,
-       which should therefore be sync'ed with actual values */
-    snd_pcm_hw_params_current(self->handle, hwparams);
-
-    snd_pcm_hw_params_get_format(hwparams, &fmt); self->format = fmt;
-    snd_pcm_hw_params_get_channels(hwparams, &val); self->channels = val;
-    snd_pcm_hw_params_get_rate(hwparams, &val, &dir); self->rate = val;
-    snd_pcm_hw_params_get_period_size(hwparams, &frames, &dir);
-    self->periodsize = (int) frames;
-
-    self->framesize = self->channels * snd_pcm_hw_params_get_sbits(hwparams)/8;
-
-    return res;
-}
-
 static PyObject *
 alsapcm_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
-    int res;
     alsapcm_t *self;
     PyObject *pcmtypeobj = NULL;
     long pcmtype;
     int pcmmode = 0;
+    unsigned int rate = 48000;
+    unsigned int channels = 2;
+    snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;
     char *device = "default";
     char *card = NULL;
     int cardidx = -1;
     char hw_device[128];
-    char *kw[] = { "type", "mode", "device", "cardindex", "card", NULL };
-
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|Oisiz", kw,
+    int latency = 200;
+    char *kw[] = { "type", "mode", "device", "cardindex", "card", "format", "rate", "channels", "latency", NULL };
+    
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|Oisiziiii", kw,
                                      &pcmtypeobj, &pcmmode, &device,
-                                     &cardidx, &card))
+                                     &cardidx, &card, &rate, &format, &channels, &latency))
         return NULL;
 
     if (cardidx >= 0) {
@@ -394,29 +410,9 @@ alsapcm_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         return NULL;
     }
 
-    if (pcmmode < 0 || pcmmode > SND_PCM_ASYNC) {
-        PyErr_SetString(ALSAAudioError, "Invalid PCM mode");
-        return NULL;
-    }
-
-    if (!(self = (alsapcm_t *)PyObject_New(alsapcm_t, &ALSAPCMType)))
-        return NULL;
-
-    self->handle = 0;
-    self->pcmtype = pcmtype;
-    self->pcmmode = pcmmode;
-    self->channels = 2;
-    self->rate = 44100;
-    self->format = SND_PCM_FORMAT_S16_LE;
-    self->periodsize = 32;
-
     res = snd_pcm_open(&(self->handle), device, self->pcmtype,
                        self->pcmmode);
-
-    if (res >= 0) {
-        res = alsapcm_setup(self);
-    }
-    
+   
     if (res >= 0) {
         self->cardname = strdup(device);
     }
@@ -435,6 +431,7 @@ alsapcm_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 static void alsapcm_dealloc(alsapcm_t *self)
 {
     if (self->handle) {
+        snd_pcm_pause(self->handle, 1);
         snd_pcm_drain(self->handle);
         snd_pcm_close(self->handle);
     }
@@ -567,6 +564,184 @@ alsapcm_dumpinfo(alsapcm_t *self, PyObject *args)
     return Py_None;
 }
 
+// auxiliary function
+
+
+static PyObject *
+alsapcm_getformats(alsapcm_t *self, PyObject *args)
+{
+    snd_pcm_t *pcm = self->handle;
+    if (!pcm) {
+        PyErr_SetString(ALSAAudioError, "PCM device is closed");
+        return NULL;
+    }
+
+    snd_pcm_hw_params_t *params;
+    snd_pcm_hw_params_alloca(&params);
+    int err = snd_pcm_hw_params_any(pcm, params);
+    if (err < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get hardware parameters");
+        return NULL;
+    }
+
+    PyObject *fmts = PyDict_New();
+    for (size_t i = 0; i < ARRAY_SIZE(ALSAFormats); ++i) {
+        snd_pcm_format_t format = ALSAFormats[i];
+        if (!snd_pcm_hw_params_test_format(pcm, params, format)) {
+            const char *name = snd_pcm_format_name(format);
+            PyObject *pname=PyUnicode_FromString(name);
+            PyObject *value=PyLong_FromLong((long)format);
+            PyDict_SetItem(fmts,pname,value);
+        }
+    }
+    return fmts;
+}
+
+PyDoc_STRVAR(getformats_doc,
+"getformats() -> [str:int]\n\
+\n\
+Returns dictionary of supported format codes keyed by their standard ALSA names.");
+
+static PyObject *
+alsapcm_getratemaxmin(alsapcm_t *self, PyObject *args)
+{
+    snd_pcm_t *pcm = self->handle;
+    if (!pcm) {
+        PyErr_SetString(ALSAAudioError, "PCM device is closed");
+        return NULL;
+    }
+
+    snd_pcm_hw_params_t *params;
+    snd_pcm_hw_params_alloca(&params);
+    int err = snd_pcm_hw_params_any(pcm, params);
+    if (err < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get hardware parameters");
+        return NULL;
+    }
+
+    unsigned min,max;
+    if (snd_pcm_hw_params_get_rate_min(params, &min,NULL)<0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get minimum supported bitrate");
+        return NULL;
+    }
+    if (snd_pcm_hw_params_get_rate_max(params, &max,NULL)<0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get maximum supported bitrate");
+        return NULL;
+    }
+    
+    PyObject *minp=PyLong_FromLong(min);
+    PyObject *maxp=PyLong_FromLong(max);
+    return PyTuple_Pack(2, minp, maxp);
+}
+
+PyDoc_STRVAR(getratebounds_doc,
+"getratebounds() -> (int,int)\n\
+\n\
+Returns the card's minimum and maximum supported sample rates as a tuple.");
+
+static PyObject *
+alsapcm_getrates(alsapcm_t *self, PyObject *args)
+{
+    snd_pcm_t *pcm = self->handle;
+    if (!pcm) {
+        PyErr_SetString(ALSAAudioError, "PCM device is closed");
+        return NULL;
+    }
+
+    snd_pcm_hw_params_t *params;
+    snd_pcm_hw_params_alloca(&params);
+    int err = snd_pcm_hw_params_any(pcm, params);
+    if (err < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get hardware parameters");
+        return NULL;
+    }
+    
+    unsigned min, max;
+    if (snd_pcm_hw_params_get_rate_min(params, &min, NULL) <0 ) {
+        PyErr_SetString(ALSAAudioError, "Cannot get minimum supported bitrate");
+        return NULL;
+    }
+    if (snd_pcm_hw_params_get_rate_max(params, &max, NULL) < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get maximum supported bitrate");
+        return NULL;
+    }
+    
+    if (min == max) {
+        return PyLong_FromLong(min);
+    }
+    else if (!snd_pcm_hw_params_test_rate(pcm, params, min + 1, 0)) {
+        PyObject *minp=PyLong_FromLong(min);
+        PyObject *maxp=PyLong_FromLong(max);
+        return PyTuple_Pack(2,minp,maxp);
+    }
+    else {
+        PyObject *rates=PyList_New(0);
+        for (size_t i=0; i<ARRAY_SIZE(ALSARates); i++) {
+            unsigned rate = ALSARates[i];
+            if (!snd_pcm_hw_params_test_rate(pcm, params, rate, 0)) {
+                PyObject *prate=PyLong_FromLong(rate);
+                PyList_Append(rates,prate);
+            }
+        }
+        return rates;
+    }
+}
+
+PyDoc_STRVAR(getrates_doc,
+"getrates() -> obj\n\
+\n\
+Returns the sample rates supported by the device.\
+Returned value can be one of three types, depending on the card's properties.\
+There are three cases:\n\
+\n\
+- Card supports only a single rate: returns the rate\n\
+- Card supports a continuous range of rates: returns a tuple of the range's lower and upper bounds (inclusive)\n\
+- Card supports a collection of well-known rates: returns a list of the supported rates");
+
+static PyObject *
+alsapcm_getchannels(alsapcm_t *self,PyObject *args)
+{
+    snd_pcm_t *pcm = self->handle;
+    if (!pcm) {
+        PyErr_SetString(ALSAAudioError, "PCM device is closed");
+        return NULL;
+    }
+
+    snd_pcm_hw_params_t *params;
+    snd_pcm_hw_params_alloca(&params);
+    int err = snd_pcm_hw_params_any(pcm, params);
+    if (err < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get hardware parameters");
+        return NULL;
+    }
+
+    unsigned min, max;
+    if (snd_pcm_hw_params_get_channels_min(params, &min) < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get minimum supported number of channels");
+        return NULL;
+    }
+
+    if (snd_pcm_hw_params_get_channels_max(params, &max) < 0) {
+        PyErr_SetString(ALSAAudioError, "Cannot get maximum supported number of channels");
+        return NULL;
+    }
+
+    PyObject *out = PyList_New(0);
+    for (unsigned ch=min;ch<=max;++ch) {
+        if (!snd_pcm_hw_params_test_channels(pcm, params, ch)) {
+            PyObject *pch=PyLong_FromLong(ch);
+            PyList_Append(out,pch);
+        }
+    }
+    return out;
+}
+
+PyDoc_STRVAR(getchannels_doc,
+"getchannels() -> [int]\n\
+\n\
+Returns list of supported channel numbers.");
+
+
 static PyObject *
 alsapcm_pcmtype(alsapcm_t *self, PyObject *args)
 {
@@ -629,147 +804,13 @@ PyDoc_STRVAR(cardname_doc,
 \n\
 Returns the name of the sound card used by this PCM object.");
 
-
-static PyObject *
-alsapcm_setchannels(alsapcm_t *self, PyObject *args)
-{
-    int channels;
-    int res;
-    if (!PyArg_ParseTuple(args,"i:setchannels", &channels))
-        return NULL;
-
-    if (!self->handle) {
-        PyErr_SetString(ALSAAudioError, "PCM device is closed");
-        return NULL;
-    }
-
-    self->channels = channels;
-    res = alsapcm_setup(self);
-    if (res < 0)
-    {
-        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
-                     self->cardname);
-        return NULL;
-    }
-    return PyLong_FromLong(self->channels);
-}
-
-PyDoc_STRVAR(setchannels_doc,
-"setchannels(numchannels)\n\
-\n\
-Used to set the number of capture or playback channels. Common values\n\
-are: 1 = mono, 2 = stereo, and 6 = full 6 channel audio.\n\
-\n\
-Few sound cards support more than 2 channels.");
-
-
-static PyObject *
-alsapcm_setrate(alsapcm_t *self, PyObject *args)
-{
-    int rate;
-    int res;
-    if (!PyArg_ParseTuple(args,"i:setrate", &rate))
-        return NULL;
-
-    if (!self->handle)
-    {
-        PyErr_SetString(ALSAAudioError, "PCM device is closed");
-        return NULL;
-    }
-
-    self->rate = rate;
-    res = alsapcm_setup(self);
-    if (res < 0)
-    {
-        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
-                     self->cardname);
-        return NULL;
-    }
-    return PyLong_FromLong(self->rate);
-}
-
-PyDoc_STRVAR(setrate_doc,
-"setrate(rate)\n\
-\n\
-Set the sample rate in Hz for the device. Typical values are\n\
-8000 (telephony), 11025, 44100 (CD), 48000 (DVD audio) and 96000");
-
-
-static PyObject *
-alsapcm_setformat(alsapcm_t *self, PyObject *args)
-{
-    int format;
-    int res;
-    if (!PyArg_ParseTuple(args,"i:setformat", &format))
-        return NULL;
-
-    if (!self->handle)
-    {
-        PyErr_SetString(ALSAAudioError, "PCM device is closed");
-        return NULL;
-    }
-
-    self->format = format;
-    res = alsapcm_setup(self);
-    if (res < 0)
-    {
-        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
-                     self->cardname);
-        return NULL;
-    }
-    return PyLong_FromLong(self->format);
-}
-
-PyDoc_STRVAR(setformat_doc,
-"setformat(rate)\n");
-
-static PyObject *
-alsapcm_setperiodsize(alsapcm_t *self, PyObject *args)
-{
-    int periodsize;
-    int res;
-
-    if (!PyArg_ParseTuple(args,"i:setperiodsize", &periodsize))
-        return NULL;
-
-    if (!self->handle)
-    {
-        PyErr_SetString(ALSAAudioError, "PCM device is closed");
-        return NULL;
-    }
-
-    self->periodsize = periodsize;
-    res = alsapcm_setup(self);
-    if (res < 0)
-    {
-        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
-                     self->cardname);
-
-        return NULL;
-    }
-    return PyLong_FromLong(self->periodsize);
-}
-
-PyDoc_STRVAR(setperiodsize_doc,
-"setperiodsize(period) -> int\n\
-\n\
-Sets the actual period size in frames. Each write should consist of\n\
-exactly this number of frames, and each read will return this number of\n\
-frames (unless the device is in PCM_NONBLOCK mode, in which case it\n\
-may return nothing at all).");
-
 static PyObject *
 alsapcm_read(alsapcm_t *self, PyObject *args)
 {
     int res;
-    char buffer[8000];
-
-    if (self->framesize * self->periodsize > 8000) {
-
-        PyErr_SetString(ALSAAudioError,"Capture data too large. "
-                        "Try decreasing period size");
-        return NULL;
-    }
+    int size = self->framesize * self->periodsize;
+    PyObject *buffer_obj, *tuple_obj, *res_obj;
+    char *buffer;
 
     if (!PyArg_ParseTuple(args,":read"))
         return NULL;
@@ -786,6 +827,18 @@ alsapcm_read(alsapcm_t *self, PyObject *args)
         return NULL;
     }
 
+#if PY_MAJOR_VERSION < 3
+    buffer_obj = PyString_FromStringAndSize(NULL, size);
+    if (!buffer_obj)
+        return NULL;
+    buffer = PyString_AS_STRING(buffer_obj);
+#else
+    buffer_obj = PyBytes_FromStringAndSize(NULL, size);
+    if (!buffer_obj)
+        return NULL;
+    buffer = PyBytes_AS_STRING(buffer_obj);
+#endif
+
     Py_BEGIN_ALLOW_THREADS
     res = snd_pcm_readi(self->handle, buffer, self->periodsize);
     if (res == -EPIPE)
@@ -805,15 +858,39 @@ alsapcm_read(alsapcm_t *self, PyObject *args)
             PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
                          self->cardname);
 
+            Py_DECREF(buffer_obj);
             return NULL;
         }
     }
 
+    if (res <= 0) {
 #if PY_MAJOR_VERSION < 3
-    return Py_BuildValue("is#", res, buffer, res*self->framesize);
+        /* If the following fails, it will free the object */
+        if (_PyString_Resize(&buffer_obj, 0))
+            return NULL;
 #else
-    return Py_BuildValue("iy#", res, buffer, res*self->framesize);
+        /* If the following fails, it will free the object */
+        if (_PyBytes_Resize(&buffer_obj, 0))
+            return NULL;
 #endif
+    }
+
+    res_obj = PyLong_FromLong(res);
+    if (!res_obj) {
+        Py_DECREF(buffer_obj);
+        return NULL;
+    }
+    tuple_obj = PyTuple_New(2);
+    if (!tuple_obj) {
+        Py_DECREF(buffer_obj);
+        Py_DECREF(res_obj);
+        return NULL;
+    }
+    /* Steal reference counts */
+    PyTuple_SET_ITEM(tuple_obj, 0, res_obj);
+    PyTuple_SET_ITEM(tuple_obj, 1, buffer_obj);
+
+    return tuple_obj;
 }
 
 PyDoc_STRVAR(read_doc,
@@ -945,6 +1022,43 @@ PyDoc_STRVAR(pause_doc,
 If enable is 1, playback or capture is paused. If enable is 0,\n\
 playback/capture is resumed.");
 
+
+static PyObject *alsapcm_drop(alsapcm_t *self)
+{
+    int res;
+
+    if (!self->handle) {
+        PyErr_SetString(ALSAAudioError, "PCM device is closed");
+        return NULL;
+    }
+
+    res = snd_pcm_drop(self->handle);
+
+    if (res < 0)
+    {
+        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
+                     self->cardname);
+
+        return NULL;
+    }
+    
+    res = snd_pcm_prepare(self->handle);
+    if (res < 0)
+    {
+        PyErr_Format(ALSAAudioError, "%s [%s]", snd_strerror(res),
+                     self->cardname);
+
+        return NULL;
+    }
+    
+    return PyLong_FromLong(res);
+}
+
+PyDoc_STRVAR(drop_doc,
+"drop(enable=1)\n\
+\n\
+stop current read and drop residual packet");
+
 static PyObject *
 alsapcm_polldescriptors(alsapcm_t *self, PyObject *args)
 {
@@ -1008,16 +1122,15 @@ static PyMethodDef alsapcm_methods[] = {
     {"pcmtype", (PyCFunction)alsapcm_pcmtype, METH_VARARGS, pcmtype_doc},
     {"pcmmode", (PyCFunction)alsapcm_pcmmode, METH_VARARGS, pcmmode_doc},
     {"cardname", (PyCFunction)alsapcm_cardname, METH_VARARGS, cardname_doc},
-    {"setchannels", (PyCFunction)alsapcm_setchannels, METH_VARARGS,
-     setchannels_doc },
-    {"setrate", (PyCFunction)alsapcm_setrate, METH_VARARGS, setrate_doc},
-    {"setformat", (PyCFunction)alsapcm_setformat, METH_VARARGS, setformat_doc},
-    {"setperiodsize", (PyCFunction)alsapcm_setperiodsize, METH_VARARGS,
-     setperiodsize_doc},
     {"dumpinfo", (PyCFunction)alsapcm_dumpinfo, METH_VARARGS},
+    {"getformats", (PyCFunction)alsapcm_getformats, METH_VARARGS, getformats_doc},
+    {"getratebounds", (PyCFunction)alsapcm_getratemaxmin, METH_VARARGS, getratebounds_doc},
+    {"getrates", (PyCFunction)alsapcm_getrates, METH_VARARGS, getrates_doc},
+    {"getchannels", (PyCFunction)alsapcm_getchannels, METH_VARARGS, getchannels_doc},
     {"read", (PyCFunction)alsapcm_read, METH_VARARGS, read_doc},
     {"write", (PyCFunction)alsapcm_write, METH_VARARGS, write_doc},
     {"pause", (PyCFunction)alsapcm_pause, METH_VARARGS, pause_doc},
+    {"drop", (PyCFunction)alsapcm_drop, METH_VARARGS, drop_doc},
     {"close", (PyCFunction)alsapcm_close, METH_VARARGS, pcm_close_doc},
     {"polldescriptors", (PyCFunction)alsapcm_polldescriptors, METH_VARARGS,
      pcm_polldescriptors_doc},
@@ -1067,14 +1180,14 @@ static PyTypeObject ALSAPCMType = {
     0,                              /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT,             /* tp_flags */
     "ALSA PCM device.",             /* tp_doc */
-    0,					          /* tp_traverse */
-    0,					          /* tp_clear */
-    0,					          /* tp_richcompare */
-    0,					          /* tp_weaklistoffset */
-    0,					          /* tp_iter */
-    0,					          /* tp_iternext */
-    alsapcm_methods,		          /* tp_methods */
-    0,			                  /* tp_members */
+    0,                            /* tp_traverse */
+    0,                            /* tp_clear */
+    0,                            /* tp_richcompare */
+    0,                            /* tp_weaklistoffset */
+    0,                            /* tp_iter */
+    0,                            /* tp_iternext */
+    alsapcm_methods,                  /* tp_methods */
+    0,                            /* tp_members */
 };
 
 
@@ -2349,14 +2462,14 @@ static PyTypeObject ALSAMixerType = {
     0,                              /* tp_as_buffer*/
     Py_TPFLAGS_DEFAULT,             /* tp_flags */
     "ALSA Mixer Control.",          /* tp_doc */
-    0,					          /* tp_traverse */
-    0,					          /* tp_clear */
-    0,					          /* tp_richcompare */
-    0,					          /* tp_weaklistoffset */
-    0,					          /* tp_iter */
-    0,					          /* tp_iternext */
-    alsamixer_methods,		      /* tp_methods */
-    0,			                  /* tp_members */
+    0,                            /* tp_traverse */
+    0,                            /* tp_clear */
+    0,                            /* tp_richcompare */
+    0,                            /* tp_weaklistoffset */
+    0,                            /* tp_iter */
+    0,                            /* tp_iternext */
+    alsamixer_methods,            /* tp_methods */
+    0,                            /* tp_members */
 };
 
 
@@ -2473,6 +2586,10 @@ PyObject *PyInit_alsaaudio(void)
     _EXPORT_INT(m, "PCM_FORMAT_IMA_ADPCM",SND_PCM_FORMAT_IMA_ADPCM);
     _EXPORT_INT(m, "PCM_FORMAT_MPEG",SND_PCM_FORMAT_MPEG);
     _EXPORT_INT(m, "PCM_FORMAT_GSM",SND_PCM_FORMAT_GSM);
+    _EXPORT_INT(m, "PCM_FORMAT_S24_3LE",SND_PCM_FORMAT_S24_3LE);
+    _EXPORT_INT(m, "PCM_FORMAT_S24_3BE",SND_PCM_FORMAT_S24_3BE);
+    _EXPORT_INT(m, "PCM_FORMAT_U24_3LE",SND_PCM_FORMAT_U24_3LE);
+    _EXPORT_INT(m, "PCM_FORMAT_U24_3BE",SND_PCM_FORMAT_U24_3BE);
 
      /* DSD sample formats are included in ALSA 1.0.29 and higher
       * define OVERRIDE_DSD_COMPILE to include DSD sample support

doc/conf.py

@@ -1,182 +1,160 @@
 # -*- coding: utf-8 -*-
 #
-# alsaaudio documentation build configuration file, created by
-# sphinx-quickstart on Sat Nov 22 00:17:09 2008.
+# alsaaudio documentation documentation build configuration file, created by
+# sphinx-quickstart on Thu Mar 30 23:52:21 2017.
 #
-# This file is execfile()d with the current directory set to its containing dir.
+# This file is execfile()d with the current directory set to its
+# containing dir.
 #
-# The contents of this file are pickled, so don't put values in the namespace
-# that aren't pickleable (module imports are okay, they're removed automatically).
+# Note that not all possible configuration values are present in this
+# autogenerated file.
 #
-# All configuration values have a default value; values that are commented out
-# serve to show the default value.
+# All configuration values have a default; values that are commented out
+# serve to show the default.
 
-import sys, os
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#
+# import os
+# import sys
+# sys.path.insert(0, os.path.abspath('.'))
 
+import sys
 sys.path.insert(0, '..')
 from setup import pyalsa_version
 
-# If your extensions are in another directory, add it here. If the directory
-# is relative to the documentation root, use os.path.abspath to make it
-# absolute, like shown here.
-#sys.path.append(os.path.abspath('some/directory'))
 
-# General configuration
-# ---------------------
+# -- General configuration ------------------------------------------------
 
-# Add any Sphinx extension module names here, as strings. They can be extensions
-# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
+# If your documentation needs a minimal Sphinx version, state it here.
+#
+# needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
 extensions = []
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['.templates']
+templates_path = ['_templates']
 
-# The suffix of source filenames.
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+#
+# source_suffix = ['.rst', '.md']
 source_suffix = '.rst'
 
 # The master toctree document.
 master_doc = 'index'
 
-# General substitutions.
-project = u'alsaaudio'
-copyright = u'2008-20017, Casper Wilstrup, Lars Immisch'
+# General information about the project.
+project = u'alsaaudio documentation'
+copyright = u'2017, Lars Immisch & Casper Wilstrup'
+author = u'Lars Immisch & Casper Wilstrup'
 
-# The default replacements for |version| and |release|, also used in various
-# other places throughout the built documents.
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
 #
 # The short X.Y version.
 version = pyalsa_version
 # The full version, including alpha/beta/rc tags.
-release = pyalsa_version
+release = version
 
-# There are two options for replacing |today|: either, you set today to some
-# non-false value, then it is used:
-#today = ''
-# Else, today_fmt is used as the format for a strftime call.
-today_fmt = '%B %d, %Y'
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
 
-# List of documents that shouldn't be included in the build.
-#unused_docs = []
-
-# List of directories, relative to source directories, that shouldn't be searched
-# for source files.
-exclude_trees = ['.build']
-
-# The reST default role (used for this markup: `text`) to use for all documents.
-#default_role = None
-
-# If true, '()' will be appended to :func: etc. cross-reference text.
-#add_function_parentheses = True
-
-# If true, the current module name will be prepended to all description
-# unit titles (such as .. function::).
-#add_module_names = True
-
-# If true, sectionauthor and moduleauthor directives will be shown in the
-# output. They are ignored by default.
-#show_authors = False
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This patterns also effect to html_static_path and html_extra_path
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = 'sphinx'
 
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = False
 
-# Options for HTML output
-# -----------------------
 
-# The style sheet to use for HTML and HTML Help pages. A file of that name
-# must exist either in Sphinx' static/ path, or in one of the custom paths
-# given in html_static_path.
-html_style = 'default.css'
+# -- Options for HTML output ----------------------------------------------
 
-# The name for this set of Sphinx documents.  If None, it defaults to
-# "<project> v<release> documentation".
-#html_title = None
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#
+html_theme = 'alabaster'
 
-# A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
-
-# The name of an image file (relative to this directory) to place at the top
-# of the sidebar.
-#html_logo = None
-
-# The name of an image file (within the static path) to use as favicon of the
-# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
-# pixels large.
-#html_favicon = None
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#
+# html_theme_options = {}
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['static']
+html_static_path = ['_static']
 
-# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
-# using the given strftime format.
-html_last_updated_fmt = '%b %d, %Y'
 
-# If true, SmartyPants will be used to convert quotes and dashes to
-# typographically correct entities.
-#html_use_smartypants = True
-
-# Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
-
-# Additional templates that should be rendered to pages, maps page names to
-# template names.
-#html_additional_pages = {}
-
-# If false, no module index is generated.
-#html_use_modindex = True
-
-# If false, no index is generated.
-#html_use_index = True
-
-# If true, the index is split into individual pages for each letter.
-#html_split_index = False
-
-# If true, the reST sources are included in the HTML build as _sources/<name>.
-#html_copy_source = True
-
-# If true, an OpenSearch description file will be output, and all pages will
-# contain a <link> tag referring to it.  The value of this option must be the
-# base URL from which the finished HTML is served.
-#html_use_opensearch = ''
-
-# If nonempty, this is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = ''
+# -- Options for HTMLHelp output ------------------------------------------
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'alsaaudiodoc'
+htmlhelp_basename = 'alsaaudiodocumentationdoc'
 
 
-# Options for LaTeX output
-# ------------------------
+# -- Options for LaTeX output ---------------------------------------------
 
-# The paper size ('letter' or 'a4').
-#latex_paper_size = 'letter'
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    #
+    # 'papersize': 'letterpaper',
 
-# The font size ('10pt', '11pt' or '12pt').
-#latex_font_size = '10pt'
+    # The font size ('10pt', '11pt' or '12pt').
+    #
+    # 'pointsize': '10pt',
+
+    # Additional stuff for the LaTeX preamble.
+    #
+    # 'preamble': '',
+
+    # Latex figure (float) alignment
+    #
+    # 'figure_align': 'htbp',
+}
 
 # Grouping the document tree into LaTeX files. List of tuples
-# (source start file, target name, title, author, document class [howto/manual]).
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-  ('index', 'alsaaudio.tex', u'alsaaudio Documentation',
-   u'Casper Wilstrup, Lars Immisch', 'manual'),
+    (master_doc, 'alsaaudiodocumentation.tex', u'alsaaudio documentation Documentation',
+     u'Lars Immisch', 'manual'),
 ]
 
-# The name of an image file (relative to this directory) to place at the top of
-# the title page.
-#latex_logo = None
 
-# For "manual" documents, if this is true, then toplevel headings are parts,
-# not chapters.
-#latex_use_parts = False
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'alsaaudiodocumentation', u'alsaaudio documentation Documentation',
+     [author], 1)
+]
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (master_doc, 'alsaaudiodocumentation', u'alsaaudio documentation Documentation',
+     author, 'alsaaudiodocumentation', 'One line description of project.',
+     'Miscellaneous'),
+]
 
-# Additional stuff for the LaTeX preamble.
-#latex_preamble = ''
 
-# Documents to append as an appendix to all manuals.
-#latex_appendices = []
 
-# If false, no module index is generated.
-#latex_use_modindex = True

doc/index.rst

@@ -1,22 +1,32 @@
+.. alsaaudio documentation documentation master file, created by
+   sphinx-quickstart on Thu Mar 30 23:52:21 2017.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
 alsaaudio documentation
-=======================
+===================================================
 
 .. toctree::
    :maxdepth: 2
+   :caption: Contents:
 
    pyalsaaudio
    terminology
    libalsaaudio
 
+Download
+========
 
-Github pages
-=================
-
-* `Project page <https://github.com/larsimmisch/pyalsaaudio/>`_
 * `Download from pypi <https://pypi.python.org/pypi/pyalsaaudio>`_
+  
+      
+Github
+======
+
+* `Repository <https://github.com/larsimmisch/pyalsaaudio/>`_
 * `Bug tracker <https://github.com/larsimmisch/pyalsaaudio/issues>`_
 
-
+ 
 Indices and tables
 ==================
 
@@ -24,3 +34,5 @@ Indices and tables
 * :ref:`modindex`
 * :ref:`search`
 
+    
+  

doc/libalsaaudio.rst

@@ -193,10 +193,10 @@ PCM objects have the following methods:
    ``PCM_FORMAT_S16_BE``      Signed 16 bit samples for each channel (Big Endian byte order)
    ``PCM_FORMAT_U16_LE``      Unsigned 16 bit samples for each channel (Little Endian byte order)
    ``PCM_FORMAT_U16_BE``      Unsigned 16 bit samples for each channel (Big Endian byte order)
-   ``PCM_FORMAT_S24_LE``      Signed 24 bit samples for each channel (Little Endian byte order)
-   ``PCM_FORMAT_S24_BE``      Signed 24 bit samples for each channel (Big Endian byte order)}
-   ``PCM_FORMAT_U24_LE``      Unsigned 24 bit samples for each channel (Little Endian byte order)
-   ``PCM_FORMAT_U24_BE``      Unsigned 24 bit samples for each channel (Big Endian byte order)
+   ``PCM_FORMAT_S24_LE``      Signed 24 bit samples for each channel (Little Endian byte order in 4 bytes)
+   ``PCM_FORMAT_S24_BE``      Signed 24 bit samples for each channel (Big Endian byte order in 4 bytes)
+   ``PCM_FORMAT_U24_LE``      Unsigned 24 bit samples for each channel (Little Endian byte order in 4 bytes)
+   ``PCM_FORMAT_U24_BE``      Unsigned 24 bit samples for each channel (Big Endian byte order in 4 bytes)
    ``PCM_FORMAT_S32_LE``      Signed 32 bit samples for each channel (Little Endian byte order)
    ``PCM_FORMAT_S32_BE``      Signed 32 bit samples for each channel (Big Endian byte order)
    ``PCM_FORMAT_U32_LE``      Unsigned 32 bit samples for each channel (Little Endian byte order)
@@ -210,6 +210,10 @@ PCM objects have the following methods:
    ``PCM_FORMAT_IMA_ADPCM``   A 4:1 compressed format defined by the Interactive Multimedia Association.
    ``PCM_FORMAT_MPEG``        MPEG encoded audio?
    ``PCM_FORMAT_GSM``         9600 bits/s constant rate encoding for speech
+   ``PCM_FORMAT_S24_3LE``     Signed 24 bit samples for each channel (Little Endian byte order in 3 bytes)
+   ``PCM_FORMAT_S24_3BE``     Signed 24 bit samples for each channel (Big Endian byte order in 3 bytes)
+   ``PCM_FORMAT_U24_3LE``     Unsigned 24 bit samples for each channel (Little Endian byte order in 3 bytes)
+   ``PCM_FORMAT_U24_3BE``     Unsigned 24 bit samples for each channel (Big Endian byte order in 3 bytes)
    =========================  ===============
    
 
@@ -233,6 +237,9 @@ PCM objects have the following methods:
    ``(0,'')`` if no new period has become available since the last
    call to read.
 
+   In case of an overrun, this function will return a negative size: :const:`-EPIPE`.
+   This indicates that data was lost, even if the operation itself succeeded.
+   Try using a larger periodsize.
 
 .. method:: PCM.write(data)
 
@@ -256,6 +263,17 @@ PCM objects have the following methods:
    If *enable* is :const:`True`, playback or capture is paused.
    Otherwise, playback/capture is resumed.
 
+
+.. method:: PCM.polldescriptors()
+
+   Returns a tuple of *(file descriptor, eventmask)* that can be used to
+   wait for changes on the mixer with *select.poll*.
+
+   The *eventmask* value is compatible with `poll.register`__ in the Python 
+   :const:`select` module.
+
+__ poll_objects_
+
 **A few hints on using PCM devices for playback**
 
 The most common reason for problems with playback of PCM audio is that writes 
@@ -473,9 +491,14 @@ Mixer objects have the following methods:
 
 .. method:: Mixer.polldescriptors()
 
-   Returns a tuple of (file descriptor, eventmask) that can be used to
+   Returns a tuple of *(file descriptor, eventmask)* that can be used to
    wait for changes on the mixer with *select.poll*.
 
+   The *eventmask* value is compatible with `poll.register`__ in the Python 
+   :const:`select` module.
+
+__ poll_objects_
+
 .. method:: Mixer.handleevents()
 
    Acknowledge events on the *polldescriptors* file descriptors
@@ -620,3 +643,5 @@ argument::
 .. rubric:: Footnotes
 
 .. [#f1]   ALSA also allows ``PCM_ASYNC``, but this is not supported yet.
+
+.. _poll_objects: http://docs.python.org/library/select.html#poll-objects

doc/pyalsaaudio.rst

@@ -75,7 +75,7 @@ development at the time - and neither are very feature complete.
 I wrote PyAlsaAudio to fill this gap. My long term goal is to have the module
 included in the standard Python library, but that looks currently unlikely.
 
-PyAlsaAudio hass full support for sound capture, playback of sound, as well as
+PyAlsaAudio has full support for sound capture, playback of sound, as well as
 the ALSA Mixer API.
 
 MIDI support is not available, and since I don't own any MIDI hardware, it's
@@ -110,25 +110,32 @@ And then as root:  ---   ::
 Testing
 *******
 
-First of all, run::
-   
-   $ python test.py
+Make sure that :code:`aplay` plays a file through the soundcard you want, then
+try::
 
-This is a small test suite that mostly performs consistency tests. If
-it fails, please file a `bug report
-<https://github.com/larsimmisch/pyalsaaudio/issues>`_.
+  $ python playwav.py <filename.wav>
+
+If :code:`aplay` needs a device argument, like
+:code:`aplay -D hw:CARD=sndrpihifiberry,DEV=0`, use::
+
+   $ python playwav.py -d hw:CARD=sndrpihifiberry,DEV=0 <filename.wav>
 
 To test PCM recordings (on your default soundcard), verify your
 microphone works, then do::
 
-   $ python recordtest.py <filename>
+   $ python recordtest.py -d <device> <filename>
 
 Speak into the microphone, and interrupt the recording at any time
 with ``Ctl-C``.
 
 Play back the recording with::
 
-   $ python playbacktest.py <filename>
+   $ python playbacktest.py-d <device>  <filename>
 
+There is a minimal test suite in :code:`test.py`, but it is
+a bit dependent on the ALSA configuration and may fail without indicating
+a real problem.
 
+If you find bugs/problems, please file a `bug report
+<https://github.com/larsimmisch/pyalsaaudio/issues>`_.
 

doc/terminology.rst

@@ -46,7 +46,7 @@ Data rate
 
    At the other end of the scale, 96000 Hz, 6 channel sound with 64
    bit (8 bytes) samples has a data rate of 96000 \* 6 \* 8 = 4608
-   kb/s (almost 5 Mb sound data per second)
+   kb/s (almost 5 MB sound data per second)
 
 Period
    When the hardware processes data this is done in chunks of frames. The time

isine.py

@@ -6,30 +6,50 @@
 
 from __future__ import print_function
 
+import sys
 from threading import Thread
-from queue import Queue, Empty
+from multiprocessing import Queue
+
+if sys.version_info[0] < 3:
+    from Queue import Empty
+else:
+    from queue import Empty
+
 from math import pi, sin
 import struct
 import alsaaudio
 
-sampling_rate = 44100
+sampling_rate = 48000
+
 format = alsaaudio.PCM_FORMAT_S16_LE
 framesize = 2 # bytes per frame for the values above
+channels = 2
 
-def digitize(s):
-    if s > 1.0 or s < -1.0:
-        raise ValueError
-        
-    return struct.pack('h', int(s * 32767)) 
+def nearest_frequency(frequency):
+    # calculate the nearest frequency where the wave form fits into the buffer
+    # in other words, select f so that sampling_rate/f is an integer
+    return float(sampling_rate)/int(sampling_rate/frequency)
 
-def generate(frequency):
-    # generate a buffer with a sine wave of frequency
-    size = int(sampling_rate / frequency)
-    buffer = bytes()
-    for i in range(size):
-        buffer = buffer + digitize(sin(i/(2 * pi)))
+def generate(frequency, duration = 0.125):
+    # generate a buffer with a sine wave of `frequency`
+    # that is approximately `duration` seconds long
 
-    return buffer
+    # the buffersize we approximately want
+    target_size = int(sampling_rate * channels * duration)
+
+    # the length of a full sine wave at the frequency
+    cycle_size = int(sampling_rate / frequency)
+
+    # number of full cycles we can fit into target_size
+    factor = int(target_size / cycle_size)
+
+    size = max(int(cycle_size * factor), 1)
+    
+    sine = [ int(32767 * sin(2 * pi * frequency * i / sampling_rate)) \
+             for i in range(size)]
+             
+    return struct.pack('%dh' % size, *sine)
+                                                                                  
 
 class SinePlayer(Thread):
     
@@ -37,7 +57,7 @@ class SinePlayer(Thread):
         Thread.__init__(self)
         self.setDaemon(True)
         self.device = alsaaudio.PCM()
-        self.device.setchannels(1)
+        self.device.setchannels(channels)
         self.device.setformat(format)
         self.device.setrate(sampling_rate)
         self.queue = Queue()
@@ -47,19 +67,15 @@ class SinePlayer(Thread):
         '''This is called outside of the player thread'''
         # we generate the buffer in the calling thread for less
         # latency when switching frequencies
-        
 
-        # More than 100 writes/s are pushing it - play multiple buffers
-        # for higher frequencies
+        if frequency > sampling_rate / 2:
+            raise ValueError('maximum frequency is %d' % (sampling_rate / 2))
 
-        factor = int(frequency/100.0)
-        if factor == 0:
-            factor = 1
-        
-        buf = generate(frequency) * factor
-        print('factor: %d, frames: %d' % (factor, len(buf) / framesize))
+        f = nearest_frequency(frequency)
+        print('nearest frequency: %f' % f)
 
-        self.queue.put( buf)
+        buf = generate(f)
+        self.queue.put(buf)
                         
     def run(self):
         buffer = None

playwav.py

@@ -24,19 +24,21 @@ def play(device, f):
     elif f.getsampwidth() == 2:
         device.setformat(alsaaudio.PCM_FORMAT_S16_LE)
     elif f.getsampwidth() == 3:
-        device.setformat(alsaaudio.PCM_FORMAT_S24_LE)
+        device.setformat(alsaaudio.PCM_FORMAT_S24_3LE)
     elif f.getsampwidth() == 4:
         device.setformat(alsaaudio.PCM_FORMAT_S32_LE)
     else:
         raise ValueError('Unsupported format')
 
-    device.setperiodsize(320)
+    periodsize = f.getframerate() // 8
+
+    device.setperiodsize(periodsize)
     
-    data = f.readframes(320)
+    data = f.readframes(periodsize)
     while data:
         # Read data from stdin
         device.write(data)
-        data = f.readframes(320)
+        data = f.readframes(periodsize)
 
 
 def usage():

setup.py

@@ -8,7 +8,7 @@ from setuptools import setup
 from setuptools.extension import Extension
 from sys import version
 
-pyalsa_version = '0.8.3'
+pyalsa_version = '0.8.6'
 
 if __name__ == '__main__':
     setup(