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# COPYRIGHT(c) 2018 STMicroelectronics #
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# IMPORT
from blue_st_sdk.feature import Feature
from blue_st_sdk.feature import Sample
from blue_st_sdk.feature import ExtractedData
from blue_st_sdk.features.field import Field
from blue_st_sdk.features.field import FieldType
from blue_st_sdk.features.audio.adpcm.bv_audio_sync_manager import BVAudioSyncManager
from blue_st_sdk.utils.number_conversion import LittleEndian
from blue_st_sdk.utils.blue_st_exceptions import BlueSTInvalidDataException
# CLASSES
[docs]class FeatureAudioADPCM(Feature):
"""The feature handles the compressed audio data acquired from a microphone.
Data is a twenty bytes array.
"""
FEATURE_NAME = "ADPCM Audio"
FEATURE_UNIT = None
FEATURE_DATA_NAME = "Audio"
DATA_MAX = 0
DATA_MIN = 256
FEATURE_FIELDS = Field(
FEATURE_DATA_NAME,
FEATURE_UNIT,
FieldType.ByteArray,
DATA_MAX,
DATA_MIN)
DATA_LENGTH_BYTES = 20
AUDIO_PACKAGE_SIZE = 40
bv_sync_manager = None
engine_adpcm = None
[docs] def __init__(self, node):
"""Constructor.
Args:
node (:class:`blue_st_sdk.node.Node`): Node that will send data to
this feature.
"""
global bv_sync_manager
super(FeatureAudioADPCM, self).__init__(
self.FEATURE_NAME, node, [self.FEATURE_FIELDS])
FeatureAudioADPCM.bv_sync_manager = BVAudioSyncManager()
FeatureAudioADPCM.engine_adpcm = ADPCMEngine()
return ExtractedData(sample, self.DATA_LENGTH_BYTES)
[docs] @classmethod
def get_audio(self, sample):
"""Get the audio data from a sample.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Sample data.
Returns:
short[]: audio values if the data array is valid, None[]
otherwise.
"""
audioPckt = []
if sample is not None:
if sample._data:
if sample._data[0] is not None:
length = len(sample._data)
audioPckt = [None] * length
for i in range(0,length):
if sample.data[i] != None:
audioPckt[i] = LittleEndian.bytes_to_int16(sample._data[i], (2*i))
return audioPckt
return audioPckt
[docs] def set_audio_sync_parameters(self, sample):
"""Set the object synchronization parameters necessary to the
decompression process.
Args:
sample (:class:`blue_st_sdk.feature.Sample`): Extracted sample which
contains the synchronization parameters.
"""
self.bv_sync_manager.set_synchronization_parameters(sample)
[docs]class ADPCMEngine(object):
"""DPCM Engine class.
It contains all the operations and parameters necessary to decompress the
received audio.
"""
[docs] def __init__(self):
"""Constructor."""
# Quantizer step size lookup table .
self._step_size_table=[7,8,9,10,11,12,13,14,16,17,
19,21,23,25,28,31,34,37,41,45,
50,55,60,66,73,80,88,97,107,118,
130,143,157,173,190,209,230,253,279,307,
337,371,408,449,494,544,598,658,724,796,
876,963,1060,1166,1282,1411,1552,1707,1878,2066,
2272,2499,2749,3024,3327,3660,4026,4428,4871,5358,
5894,6484,7132,7845,8630,9493,10442,11487,12635,13899,
15289,16818,18500,20350,22385,24623,27086,29794,32767]
# Table of index changes.
self._index_table = [-1,-1,-1,-1,2,4,6,8,-1,-1,-1,-1,2,4,6,8]
self._index = 0
self._pred_sample = 0
[docs] def decode(self, code, sync_manager):
"""ADPCM_Decode.
Args:
code (byte): It contains a 4-bit ADPCM sample.
Returns:
int: A 16-bit ADPCM sample.
"""
# 1. get sample
if (sync_manager is not None and sync_manager.is_intra()):
self._index = sync_manager.get_index_in()
self._pred_sample = sync_manager.get_pred_sample_in()
sync_manager.initialize_reset_flag()
step = self._step_size_table[self._index]
# 2. inverse code into diff
diffq = step>> 3
if ((code&4)!=0):
diffq += step
if ((code&2)!=0):
diffq += step>>1
if ((code&1)!=0):
diffq += step>>2
# 3. add diff to predicted sample
if ((code&8)!=0):
self._pred_sample -= diffq
else:
self._pred_sample += diffq
# check for overflow
if (self._pred_sample > 32767):
self._pred_sample = 32767
elif (self._pred_sample < -32768):
self._pred_sample = -32768
# 4. find new quantizer step size
self._index += self._index_table [code]
#check for overflow
if (self._index < 0):
self._index = 0
if (self._index > 88):
self._index = 88
# 5. save predict sample and index for next iteration
# done! static variables
# 6. return speech sample
return self._pred_sample