samplerate.lowlevel – Lowlevel wrappers around libsamplerate

Lowlevel wrappers around libsamplerate.

The docstrings of the src_* functions are adapted from the libsamplerate header file.

samplerate.lowlevel.src_callback_new(callback, converter_type, channels)

Initialisation for the callback based API.

Parameters:

• callback (function) – Called whenever new frames are to be read. Must return a NumPy array of shape (num_frames, channels).
• converter_type (int) – Converter to be used.
• channels (int) – Number of channels.

Returns:

• state – An anonymous pointer to the internal state of the converter.
• handle – A CFFI handle to the callback data.
• error (int) – Error code.

samplerate.lowlevel.src_callback_read(state, ratio, frames, data)

Read up to frames worth of data using the callback API.

Returns:frames – Number of frames read or -1 on error. Return type:int

samplerate.lowlevel.src_delete(state)

Release state.

Cleanup all internal allocations.

samplerate.lowlevel.src_error(state)

Return an error number.

samplerate.lowlevel.src_get_description(converter_type)

Return the description of the converter given by converter_type.

samplerate.lowlevel.src_get_name(converter_type)

Return the name of the converter given by converter_type.

samplerate.lowlevel.src_get_version()

Return the version string of libsamplerate.

samplerate.lowlevel.src_is_valid_ratio(ratio)

Return True if ratio is a valid conversion ratio, False otherwise.

samplerate.lowlevel.src_new(converter_type, channels)

Initialise a new sample rate converter.

Parameters:

• converter_type (int) – Converter to be used.
• channels (int) – Number of channels.

Returns:

• state – An anonymous pointer to the internal state of the converter.
• error (int) – Error code.

samplerate.lowlevel.src_process(state, input_data, output_data, ratio, end_of_input=0)

Standard processing function.

Returns non zero on error.

samplerate.lowlevel.src_reset(state)

Reset the internal SRC state.

Does not modify the quality settings. Does not free any memory allocations. Returns non zero on error.

samplerate.lowlevel.src_set_ratio(state, new_ratio)

Set a new SRC ratio.

This allows step responses in the conversion ratio. Returns non zero on error.

samplerate.lowlevel.src_simple(input_data, output_data, ratio, converter_type, channels)

Perform a single conversion from an input buffer to an output buffer.

Simple interface for performing a single conversion from input buffer to output buffer at a fixed conversion ratio. Simple interface does not require initialisation as it can only operate on a single buffer worth of audio.

samplerate.lowlevel.src_strerror(error)

Convert the error number into a string.