auracaster/sw_pyalsaaudio
3
0
Fork 0
forked from auracaster/pyalsaaudio
Code Pull Requests Activity

Add nominal_bits and physical_bits info

Browse Source 
Adds the information discussed in pull request #144
This commit is contained in:
Ville Viinikka
2024-02-20 19:31:53 +02:00
committed by Lars Immisch
parent eda913b203
commit 436c31f9fd
3 changed files with 74 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
alsaaudio.c
View File

@@ -598,6 +598,12 @@ alsapcm_dumpinfo(alsapcm_t *self, PyObject *args)
val = snd_pcm_hw_params_get_sbits(hwparams);
printf("significant bits = %d\n", val);
val = snd_pcm_format_width(self->format);
printf("nominal bits = %d\n", val);
val = snd_pcm_format_physical_width(self->format);
printf("physical bits = %d\n", val);
val = snd_pcm_hw_params_is_batch(hwparams);
printf("is batch = %d\n", val);
@@ -778,6 +784,16 @@ alsapcm_info(alsapcm_t *self, PyObject *args)
PyDict_SetItemString(info,"significant_bits", value);
Py_DECREF(value);
val = snd_pcm_format_width(self->format);
value=PyLong_FromUnsignedLong((unsigned long) val);
PyDict_SetItemString(info,"nominal_bits", value);
Py_DECREF(value);
val = snd_pcm_format_physical_width(self->format);
value=PyLong_FromUnsignedLong((unsigned long) val);
PyDict_SetItemString(info,"physical_bits", value);
Py_DECREF(value);
val = snd_pcm_hw_params_is_batch(hwparams);
value=PyBool_FromLong((unsigned long) val);
PyDict_SetItemString(info,"is_batch", value);

81
doc/libalsaaudio.rst
View File

@@ -205,44 +205,49 @@ PCM objects have the following methods:
the hardware, possibly depending on other properties. Those properties'
descriptions are prefixed with "hw:" below.
=========================== ============================= ==================================================================
Key Description (Reference) Type
=========================== ============================= ==================================================================
name PCM():device string
card_no *index of card* integer (negative indicates device not associable with a card)
device_no *index of PCM device* integer
subdevice_no *index of PCM subdevice* integer
state *name of PCM state* string
access_type *name of PCM access type* string
(call value) type PCM():type integer
(call value) type_name PCM():type string
(call value) mode PCM():mode integer
(call value) mode_name PCM():mode string
format PCM():format integer
format_name PCM():format string
format_description PCM():format string
subformat_name *name of PCM subformat* string
subformat_description *description of subformat* string
channels PCM():channels integer
rate PCM():rate integer (Hz)
period_time *period duration* integer (:math:`\mu s`)
period_size PCM():period_size integer (frames)
buffer_time *buffer time* integer (:math:`\mu s`) (negative indicates error)
buffer_size *buffer size* integer (frames) (negative indicates error)
get_periods *approx. periods in buffer* integer (negative indicates error)
rate_numden *numerator, denominator* tuple (integer (Hz), integer (Hz))
significant_bits *significant bits in sample* integer (negative indicates error)
is_batch *hw: double buffering* boolean (True: hardware supported)
is_block_transfer *hw: block transfer* boolean (True: hardware supported)
is_double *hw: double buffering* boolean (True: hardware supported)
is_half_duplex *hw: half-duplex* boolean (True: hardware supported)
is_joint_duplex *hw: joint-duplex* boolean (True: hardware supported)
can_overrange *hw: overrange detection* boolean (True: hardware supported)
can_mmap_sample_resolution *hw: sample-resol. mmap* boolean (True: hardware supported)
can_pause *hw: pause* boolean (True: hardware supported)
can_resume *hw: resume* boolean (True: hardware supported)
can_sync_start *hw: synchronized start* boolean (True: hardware supported)
=========================== ============================= ==================================================================
=========================== ==================================== ==================================================================
Key Description (Reference) Type
=========================== ==================================== ==================================================================
name PCM():device string
card_no *index of card* integer (negative indicates device not associable with a card)
device_no *index of PCM device* integer
subdevice_no *index of PCM subdevice* integer
state *name of PCM state* string
access_type *name of PCM access type* string
(call value) type PCM():type integer
(call value) type_name PCM():type string
(call value) mode PCM():mode integer
(call value) mode_name PCM():mode string
format PCM():format integer
format_name PCM():format string
format_description PCM():format string
subformat_name *name of PCM subformat* string
subformat_description *description of subformat* string
channels PCM():channels integer
rate PCM():rate integer (Hz)
period_time *period duration* integer (:math:`\mu s`)
period_size PCM():period_size integer (frames)
buffer_time *buffer time* integer (:math:`\mu s`) (negative indicates error)
buffer_size *buffer size* integer (frames) (negative indicates error)
get_periods *approx. periods in buffer* integer (negative indicates error)
rate_numden *numerator, denominator* tuple (integer (Hz), integer (Hz))
significant_bits *significant bits in sample* [#tss]_ integer (negative indicates error)
nominal_bits *nominal bits in sample* [#tss]_ integer (negative indicates error)
physical_bits *sample width in bits* [#tss]_ integer (negative indicates error)
is_batch *hw: double buffering* boolean (True: hardware supported)
is_block_transfer *hw: block transfer* boolean (True: hardware supported)
is_double *hw: double buffering* boolean (True: hardware supported)
is_half_duplex *hw: half-duplex* boolean (True: hardware supported)
is_joint_duplex *hw: joint-duplex* boolean (True: hardware supported)
can_overrange *hw: overrange detection* boolean (True: hardware supported)
can_mmap_sample_resolution *hw: sample-resol. mmap* boolean (True: hardware supported)
can_pause *hw: pause* boolean (True: hardware supported)
can_resume *hw: resume* boolean (True: hardware supported)
can_sync_start *hw: synchronized start* boolean (True: hardware supported)
=========================== ==================================== ==================================================================
.. [#tss] More information in the :ref:`terminology section for sample size <term-sample-size>`
..
The italicized descriptions give a summary of the "full" description
as can be found in the

15
doc/terminology.rst
View File

@@ -85,6 +85,21 @@ Period size
each write should contain exactly 32 frames of sound data, and each
read will return either 32 frames of data or nothing at all.
.. _term-sample-size:
Sample size
Each sample takes *physical_bits* of space. *nominal_bits* tells
how many least significant bits are used. This is the bit depth
in the format name and sometimes called just *sample bits* or
*format width*. *significant_bits* tells how many most significant
bits of the *nominal_bits* are used by the sample. This can be thought
of as the *sample resolution*. This is visualized as follows::
MSB |00000000 XXXXXXXX XXXXXXXX 00000000| LSB
|--significant--|
|---------nominal---------|
|-------------physical--------------|
Once you understand these concepts, you will be ready to use the PCM API. Read
on.