Audio resampling
[Encoding/Decoding Library]

Typedefs
typedef struct ReSampleContext	ReSampleContext
Functions
ReSampleContext *	av_audio_resample_init (int output_channels, int input_channels, int output_rate, int input_rate, enum AVSampleFormat sample_fmt_out, enum AVSampleFormat sample_fmt_in, int filter_length, int log2_phase_count, int linear, double cutoff)
	Initialize audio resampling context.
int	audio_resample (ReSampleContext *s, short *output, short *input, int nb_samples)
void	audio_resample_close (ReSampleContext *s)
	Free resample context.
struct AVResampleContext *	av_resample_init (int out_rate, int in_rate, int filter_length, int log2_phase_count, int linear, double cutoff)
	Initialize an audio resampler.
int	av_resample (struct AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx)
	Resample an array of samples using a previously configured context.
void	av_resample_compensate (struct AVResampleContext *c, int sample_delta, int compensation_distance)
	Compensate samplerate/timestamp drift.
void	av_resample_close (struct AVResampleContext *c)

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Typedef Documentation

typedef struct ReSampleContext ReSampleContext

Definition at line 4330 of file avcodec.h.

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Function Documentation

int audio_resample	(	ReSampleContext *	s,
		short *	output,
		short *	input,
		int	nb_samples
	)

Definition at line 282 of file resample.c.

void audio_resample_close

(

ReSampleContext *

s

)

Free resample context.

Parameters:

s

a non-NULL pointer to a resample context previously created with av_audio_resample_init()

Definition at line 420 of file resample.c.

ReSampleContext* av_audio_resample_init	(	int	output_channels,
		int	input_channels,
		int	output_rate,
		int	input_rate,
		enum AVSampleFormat	sample_fmt_out,
		enum AVSampleFormat	sample_fmt_in,
		int	filter_length,
		int	log2_phase_count,
		int	linear,
		double	cutoff
	)

Initialize audio resampling context.

Parameters:

	output_channels	number of output channels
	input_channels	number of input channels
	output_rate	output sample rate
	input_rate	input sample rate
	sample_fmt_out	requested output sample format
	sample_fmt_in	input sample format
	filter_length	length of each FIR filter in the filterbank relative to the cutoff frequency
	log2_phase_count	log2 of the number of entries in the polyphase filterbank
	linear	if 1 then the used FIR filter will be linearly interpolated between the 2 closest, if 0 the closest will be used
	cutoff	cutoff frequency, 1.0 corresponds to half the output sampling rate

Returns:

allocated ReSampleContext, NULL if error occurred

Definition at line 201 of file resample.c.

int av_resample	(	struct AVResampleContext *	c,
		short *	dst,
		short *	src,
		int *	consumed,
		int	src_size,
		int	dst_size,
		int	update_ctx
	)

Resample an array of samples using a previously configured context.

Parameters:

	src	an array of unconsumed samples
	consumed	the number of samples of src which have been consumed are returned here
	src_size	the number of unconsumed samples available
	dst_size	the amount of space in samples available in dst
	update_ctx	If this is 0 then the context will not be modified, that way several channels can be resampled with the same context.

Returns:

the number of samples written in dst or -1 if an error occurred

Definition at line 236 of file resample2.c.

Referenced by audio_resample().

void av_resample_close

(

struct AVResampleContext *

c

)

Definition at line 225 of file resample2.c.

Referenced by audio_resample_close().

void av_resample_compensate	(	struct AVResampleContext *	c,
		int	sample_delta,
		int	compensation_distance
	)

Compensate samplerate/timestamp drift.

The compensation is done by changing the resampler parameters, so no audible clicks or similar distortions occur

Parameters:

	compensation_distance	distance in output samples over which the compensation should be performed
	sample_delta	number of output samples which should be output less

example: av_resample_compensate(c, 10, 500) here instead of 510 samples only 500 samples would be output

note, due to rounding the actual compensation might be slightly different, especially if the compensation_distance is large and the in_rate used during init is small

Definition at line 230 of file resample2.c.

Referenced by av_resample(), and swri_resample_TMPL().

struct AVResampleContext* av_resample_init	(	int	out_rate,
		int	in_rate,
		int	filter_length,
		int	log2_phase_count,
		int	linear,
		double	cutoff
	)			[read]

Initialize an audio resampler.

Note, if either rate is not an integer then simply scale both rates up so they are.

Parameters:

	filter_length	length of each FIR filter in the filterbank relative to the cutoff freq
	log2_phase_count	log2 of the number of entries in the polyphase filterbank
	linear	If 1 then the used FIR filter will be linearly interpolated between the 2 closest, if 0 the closest will be used
	cutoff	cutoff frequency, 1.0 corresponds to half the output sampling rate

Definition at line 191 of file resample2.c.

Referenced by av_audio_resample_init().