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); val = snd_pcm_hw_params_get_sbits(hwparams);
printf("significant bits = %d\n", val); 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); val = snd_pcm_hw_params_is_batch(hwparams);
printf("is batch = %d\n", val); printf("is batch = %d\n", val);
@@ -778,6 +784,16 @@ alsapcm_info(alsapcm_t *self, PyObject *args)
PyDict_SetItemString(info,"significant_bits", value); PyDict_SetItemString(info,"significant_bits", value);
Py_DECREF(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); val = snd_pcm_hw_params_is_batch(hwparams);
value=PyBool_FromLong((unsigned long) val); value=PyBool_FromLong((unsigned long) val);
PyDict_SetItemString(info,"is_batch", value); 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' the hardware, possibly depending on other properties. Those properties'
descriptions are prefixed with "hw:" below. descriptions are prefixed with "hw:" below.
=========================== ============================= ================================================================== =========================== ==================================== ==================================================================
Key Description (Reference) Type Key Description (Reference) Type
=========================== ============================= ================================================================== =========================== ==================================== ==================================================================
name PCM():device string name PCM():device string
card_no *index of card* integer (negative indicates device not associable with a card) card_no *index of card* integer (negative indicates device not associable with a card)
device_no *index of PCM device* integer device_no *index of PCM device* integer
subdevice_no *index of PCM subdevice* integer subdevice_no *index of PCM subdevice* integer
state *name of PCM state* string state *name of PCM state* string
access_type *name of PCM access type* string access_type *name of PCM access type* string
(call value) type PCM():type integer (call value) type PCM():type integer
(call value) type_name PCM():type string (call value) type_name PCM():type string
(call value) mode PCM():mode integer (call value) mode PCM():mode integer
(call value) mode_name PCM():mode string (call value) mode_name PCM():mode string
format PCM():format integer format PCM():format integer
format_name PCM():format string format_name PCM():format string
format_description PCM():format string format_description PCM():format string
subformat_name *name of PCM subformat* string subformat_name *name of PCM subformat* string
subformat_description *description of subformat* string subformat_description *description of subformat* string
channels PCM():channels integer channels PCM():channels integer
rate PCM():rate integer (Hz) rate PCM():rate integer (Hz)
period_time *period duration* integer (:math:`\mu s`) period_time *period duration* integer (:math:`\mu s`)
period_size PCM():period_size integer (frames) period_size PCM():period_size integer (frames)
buffer_time *buffer time* integer (:math:`\mu s`) (negative indicates error) buffer_time *buffer time* integer (:math:`\mu s`) (negative indicates error)
buffer_size *buffer size* integer (frames) (negative indicates error) buffer_size *buffer size* integer (frames) (negative indicates error)
get_periods *approx. periods in buffer* integer (negative indicates error) get_periods *approx. periods in buffer* integer (negative indicates error)
rate_numden *numerator, denominator* tuple (integer (Hz), integer (Hz)) rate_numden *numerator, denominator* tuple (integer (Hz), integer (Hz))
significant_bits *significant bits in sample* integer (negative indicates error) significant_bits *significant bits in sample* [#tss]_ integer (negative indicates error)
is_batch *hw: double buffering* boolean (True: hardware supported) nominal_bits *nominal bits in sample* [#tss]_ integer (negative indicates error)
is_block_transfer *hw: block transfer* boolean (True: hardware supported) physical_bits *sample width in bits* [#tss]_ integer (negative indicates error)
is_double *hw: double buffering* boolean (True: hardware supported) is_batch *hw: double buffering* boolean (True: hardware supported)
is_half_duplex *hw: half-duplex* boolean (True: hardware supported) is_block_transfer *hw: block transfer* boolean (True: hardware supported)
is_joint_duplex *hw: joint-duplex* boolean (True: hardware supported) is_double *hw: double buffering* boolean (True: hardware supported)
can_overrange *hw: overrange detection* boolean (True: hardware supported) is_half_duplex *hw: half-duplex* boolean (True: hardware supported)
can_mmap_sample_resolution *hw: sample-resol. mmap* boolean (True: hardware supported) is_joint_duplex *hw: joint-duplex* boolean (True: hardware supported)
can_pause *hw: pause* boolean (True: hardware supported) can_overrange *hw: overrange detection* boolean (True: hardware supported)
can_resume *hw: resume* boolean (True: hardware supported) can_mmap_sample_resolution *hw: sample-resol. mmap* boolean (True: hardware supported)
can_sync_start *hw: synchronized start* 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 The italicized descriptions give a summary of the "full" description
as can be found in the 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 each write should contain exactly 32 frames of sound data, and each
read will return either 32 frames of data or nothing at all. 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 Once you understand these concepts, you will be ready to use the PCM API. Read
on. on.