Decimating resampler. More...

#include <decimation_resampler.h>

Inheritance diagram for roc::audio::DecimationResampler:

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Collaboration diagram for roc::audio::DecimationResampler:

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Public Member Functions
	DecimationResampler (const core::SharedPtr< IResampler > &inner_resampler, core::IArena &arena, FrameFactory &frame_factory, const SampleSpec &in_spec, const SampleSpec &out_spec)
	Initialize. More...

virtual bool	is_valid () const
	Check if object is successfully constructed. More...

virtual bool	set_scaling (size_t input_rate, size_t output_rate, float multiplier)
	Set new resample factor. More...

virtual const core::Slice< sample_t > &	begin_push_input ()
	Get buffer to be filled with input data. More...

virtual void	end_push_input ()
	Commit buffer with input data. More...

virtual size_t	pop_output (sample_t *out_data, size_t out_size)
	Read samples from input frame and fill output frame. More...

virtual float	n_left_to_process () const
	How many samples were pushed but not processed yet. More...

Public Member Functions inherited from roc::audio::IResampler
	IResampler (core::IArena &arena)
	Initialization. More...

virtual	~IResampler ()
	Deinitialization. More...

Public Member Functions inherited from roc::core::RefCounted< IResampler, core::ArenaAllocation >
	RefCounted ()
	Initialize. More...

	RefCounted (const core::ArenaAllocation &policy)
	Initialize. More...

int	getref () const
	Get reference counter. More...

void	incref () const
	Increment reference counter. More...

void	decref () const
	Decrement reference counter. More...

Additional Inherited Members
Protected Member Functions inherited from roc::core::ArenaAllocation
IArena &	arena () const
	Get arena. More...

	ArenaAllocation (IArena &arena)
	Initialize. More...

template<class T >
void	destroy (T &object)
	Destroy object and return memory to arena. More...

Detailed Description

Decimating resampler.

Acts as decorator for another resampler instance.

Performs resampling in two stages:

first, uses underlying resampler to apply constant part of scaling factor based on input and output rates; if these rates are equal, first stage is skipped
then, uses decimation or duplication to apply dynamic part of scaling factor, a.k.a. multiplier, by dropping or duplicating samples

When input and output rates are the same, this backend implements fastest possible resampling algorithm working almost at the speed of memcpy().

Although decimation usually degrades quality a lot, it's not so dramatic in this specific case because we use it only for dynamic part of scaling factor, which in practice is very close to 1.0, and typically we remove or insert up to 20 samples per second or so on 48kHz, which corresponds to ~ 0.4ms/second.

When input and output rates are different, this backend uses another, underlying resampler, but only for converting between input and output rates. It still uses decimation or duplication for applying dynamic part of scaling factor.

Definition at line 50 of file decimation_resampler.h.

Constructor & Destructor Documentation

◆ DecimationResampler()

roc::audio::DecimationResampler::DecimationResampler	(	const core::SharedPtr< IResampler > &	inner_resampler,
		core::IArena &	arena,
		FrameFactory &	frame_factory,
		const SampleSpec &	in_spec,
		const SampleSpec &	out_spec
	)