VDIFStreamWriter

class baseband.vdif.base.VDIFStreamWriter(fh_raw, header0=None, sample_rate=None, nthread=1, squeeze=True)

Bases: VDIFStreamBase, StreamWriterBase

VLBI VDIF format writer.

Encodes and writes sequences of samples to file.

Parameters:

fh_rawfilehandle

Which will write filled sets of frames to storage.

header0VDIFHeader

Header for the first frame, holding time information, etc.

sample_rateQuantity

Number of complete samples per second, i.e. the rate at which each channel in each thread is sampled. For EDV 1 and 3, can alternatively set sample_rate within the header.

nthreadint, optional

Number of threads (e.g., 2 for 2 polarisations). Default: 1.

squeezebool, optional

If True (default), write accepts squeezed arrays as input, and adds any dimensions of length unity.

Attributes Summary

bps	Bits per elementary sample.
complex_data	Whether the data are complex.
header0	First header of the file.
sample_rate	Number of complete samples per second.
sample_shape	Shape of a complete sample (possibly subset or squeezed).
samples_per_frame	Number of complete samples per frame.
squeeze	Whether data arrays have dimensions with length unity removed.
start_time	Start time of the file.
time	Time of the sample pointer's current offset in file.

Methods Summary

close()
tell([unit])	Current offset in the file.
write(data[, valid])	Write data, buffering by frames as needed.

Attributes Documentation

bps

Bits per elementary sample.

complex_data

Whether the data are complex.

header0

First header of the file.

sample_rate

Number of complete samples per second.

sample_shape

Shape of a complete sample (possibly subset or squeezed).

samples_per_frame

Number of complete samples per frame.

squeeze

Whether data arrays have dimensions with length unity removed.

If True, data read out has such dimensions removed, and data passed in for writing has them inserted.

start_time

Start time of the file.

See also time for the time of the sample pointer’s current offset.

time

Time of the sample pointer’s current offset in file.

See also start_time for the start time of the file.

Methods Documentation

close()

tell(unit=None)

Current offset in the file.

Parameters:

unitUnit or str, optional

Time unit the offset should be returned in. By default, no unit is used, i.e., an integer enumerating samples is returned. For the special string ‘time’, the absolute time is calculated.

Returns:

offsetint, Quantity, or Time

Offset in current file (or time at current position).

write(data, valid=True)

Write data, buffering by frames as needed.

Parameters:

datandarray

Piece of data to be written, with sample dimensions as given by sample_shape. This should be properly scaled to make best use of the dynamic range delivered by the encoding.

validbool, optional

Whether the current data are valid. Default: True.