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Support 24bit audio

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SND_PCM_FORMAT_S24_LE and similar are for 24bit ints packed in 4-bytes each.
There is a similar family of formats for 3-bytes packed data (as stored in 24bit wave files).

This commit:
 - adds S24_3LE, S24_3BE, U24_3LE, U24_3BE PCM formats to the alsaaudio.c
 - updates documentation
 - updates playwav.py to correctly play typical 24Bit PCM wave files

Closes #38
This commit is contained in:
Michał Šrajer
2017-08-29 19:09:54 +02:00
parent 54e2712b7a
commit 40a1219dac
3 changed files with 13 additions and 5 deletions
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alsaaudio.c
+4
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@@ -2478,6 +2478,10 @@ 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/libalsaaudio.rst
+8 -4
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@@ -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)
========================= ===============
playwav.py
+1 -1
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@@ -24,7 +24,7 @@ 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: