AmmosReader 0.314 documentation
"""I provide a specialized Ammos Reader for audio data."""
import logging
from ammosreader.AbstractAmmosReader import AbstractAmmosReader
from ammosreader.AmmosGlobalFrameBody import AmmosGlobalFrameBody
from ammosreader.AmmosAudioDataHeader import AmmosAudioDataHeader
from ammosreader.AmmosExtendedAudioDataHeader import AmmosExtendedAudioDataHeader
from ammosreader.AmmosAudioDataBody import AmmosAudioDataBody
[docs]class AmmosAudioReader(AbstractAmmosReader):
"""I read the audio data embedded in an R&S AMMOS recording."""
def __init__(self, file_name):
"""
I return an instance of AmmosAudioReader initialized with a given file name.
:param file_name: the file to read from
:type file_name: str
"""
super().__init__(file_name)
[docs] def read_next_global_frame_body_data_header(self):
"""
I return the next global frame body data header from current position in file.
:param data_header_size: the number of bytes to read
:type data_header_size: int
:return: the next Ammos Audio Data header or None if incomplete
:rtype: AmmosAudioDataHeader
"""
header_size = AmmosAudioDataHeader.HEADER_SIZE
bytes = self.ammos_file.read(header_size)
logging.info("\nReading global frame body standard data header\n")
if ((not bytes) or (len(bytes) < header_size)):
logging.debug("Can not read all %s bytes of global frame body data header", header_size)
return None
return AmmosAudioDataHeader.from_bytes(bytes)
[docs] def read_next_global_frame_body_extended_data_header(self):
"""
I return the next global frame body extended data header from current position in file.
:return: the next Ammos Audio Extended Data header or None if incomplete
:rtype: AmmosExtendedAudioDataHeader
"""
header_size = AmmosExtendedAudioDataHeader.HEADER_SIZE
bytes = self.ammos_file.read(header_size)
if ((not bytes) or (len(bytes) < header_size)):
logging.debug("Can not read all %s bytes of global frame extended data header", header_size)
return None
return AmmosExtendedAudioDataHeader.from_bytes(bytes)
[docs] def read_next_audio_data_body(self, number_of_samples, number_of_channels, sample_size):
"""
I return the next audio data read from current position in file.
:param number_of_samples: the number of samples per channel inside data body
:type number_of_samples: int
:param number_of_channels: number of channels (e.g. mono, stereo or even more)
:type number_of_channels: int
:param sample_size: sample size in bytes (1, 2 or 4 bytes)
:type sample_size: int
:return: the next audio data or None if incomplete
:rtype: bytes
"""
total = number_of_samples*number_of_channels*sample_size
byte_string = self.ammos_file.read(total)
if len(byte_string) != total:
logging.debug("Can not read all %s bytes of data body", total)
return None
return AmmosAudioDataBody(byte_string, number_of_channels, number_of_samples, sample_size)
[docs] def read_next_global_frame_body(self, data_header_length):
"""
I return the next global frame body read from current position in file.
:param global_frame_header:
"""
audio_data_header = None
if data_header_length == AmmosAudioDataHeader.HEADER_SIZE:
logging.info("Read standard data header")
audio_data_header = self.read_next_global_frame_body_data_header()
logging.info("Data header length %s", data_header_length)
if data_header_length == AmmosExtendedAudioDataHeader.HEADER_SIZE:
logging.info("Read extended data header")
audio_data_header = self.read_next_global_frame_body_extended_data_header()
if audio_data_header is None:
logging.debug("Data header missing or format unknown")
return None
audio_data_body = self.read_next_audio_data_body(audio_data_header.number_of_samples,
audio_data_header.number_of_channels,
audio_data_header.sample_size)
if audio_data_body is None:
logging.debug("Data body missing")
return None
return AmmosGlobalFrameBody(audio_data_header, audio_data_body)
[docs] def pcm_for_channel(self, a_channel):
"""
I return the raw pcm audio data for a given channel.
:param a_channel: the channel I have to extract
:type a_channel: int
:rtype: bytes
"""
return b"".join([each.global_frame_body.data_body.pcm_for_channel(a_channel) for each in self.container.global_frames])