Monochannel and multichannel audio frame converter

Mono - multi-channels audio conversion. More...

Macros
#define	PJMEDIA_STEREO_MIX   PJ_TRUE

Enumerations
enum	pjmedia_stereo_port_options { PJMEDIA_STEREO_DONT_DESTROY_DN = 4 }

Functions
pj_status_t	pjmedia_convert_channel_nto1 (pj_int16_t mono[], const pj_int16_t multi[], unsigned channel_count, unsigned samples_per_frame, pj_bool_t mix, unsigned channel_src)
pj_status_t	pjmedia_convert_channel_1ton (pj_int16_t multi[], const pj_int16_t mono[], unsigned channel_count, unsigned samples_per_frame, unsigned options)
pj_status_t	pjmedia_stereo_port_create (pj_pool_t *pool, pjmedia_port *dn_port, unsigned channel_count, unsigned options, pjmedia_port **p_port)

Detailed Description

Macro Definition Documentation

PJMEDIA_STEREO_MIX

#define PJMEDIA_STEREO_MIX   PJ_TRUE

Multichannel to monochannel conversion mixes samples from all channels into the monochannel.

Enumeration Type Documentation

pjmedia_stereo_port_options

enum pjmedia_stereo_port_options

Options for channel converter port.

Enumerator
PJMEDIA_STEREO_DONT_DESTROY_DN	Specifies whether this port should not destroy downstream port when this port is destroyed.

Function Documentation

pjmedia_convert_channel_nto1()

pj_status_t pjmedia_convert_channel_nto1	(	pj_int16_t	mono[],
		const pj_int16_t	multi[],
		unsigned	channel_count,
		unsigned	samples_per_frame,
		pj_bool_t	mix,
		unsigned	channel_src
	)

Multichannel to monochannel conversion. This function can work safely using the same buffer (in place conversion).

Parameters

mono	Output buffer to store the mono frame extracted from the multichannels frame.
multi	Input frame containing multichannels audio.
channel_count	Number of channels in the input frame.
samples_per_frame	Number of samples in the input frame.
mix	If the value is PJ_TRUE then the input channels will be mixed to produce output frame, otherwise only frame from channel_src will be copied to the output frame.
channel_src	When mixing is disabled, the mono output frame will be copied from this channel number.

Returns

PJ_SUCCESS on success;

References PJ_ASSERT_RETURN, PJ_EINVAL, PJ_FALSE, PJ_INLINE, and PJ_SUCCESS.

pjmedia_convert_channel_1ton()

pj_status_t pjmedia_convert_channel_1ton	(	pj_int16_t	multi[],
		const pj_int16_t	mono[],
		unsigned	channel_count,
		unsigned	samples_per_frame,
		unsigned	options
	)

Monochannel to multichannel conversion, it will just duplicate the samples from monochannel frame to all channels in the multichannel frame. This function can work safely using the same buffer (in place conversion) as long as the buffer is big enough for the multichannel samples.

Parameters

multi	Output buffer to store the multichannels frame mixed from the mono frame.
mono	The input monochannel audio frame.
channel_count	Desired number of channels in the output frame.
samples_per_frame	Number of samples in the input frame.
options	Options for conversion, currently must be zero.

Returns

PJ_SUCCESS on success;

References PJ_ASSERT_RETURN, PJ_EINVAL, PJ_INLINE, PJ_SUCCESS, and PJ_UNUSED_ARG.

pjmedia_stereo_port_create()

pj_status_t pjmedia_stereo_port_create	(	pj_pool_t *	pool,
		pjmedia_port *	dn_port,
		unsigned	channel_count,
		unsigned	options,
		pjmedia_port **	p_port
	)

Create a mono-multi channel converter port. This creates a converter session, which will adjust the samples of audio frame to a different channel count when the port's get_frame() and put_frame() is called.

When the port's get_frame() is called, this port will get a frame from the downstream port and convert the frame to the target channel count before returning it to the caller.

When the port's put_frame() is called, this port will convert the frame to the downstream port's channel count before giving the frame to the downstream port.

Parameters

pool	Pool to allocate the structure and buffers.
dn_port	The downstream port, which channel count is to be converted to the target channel count.
channel_count	This port channel count.
options	Bitmask flags from pjmedia_stereo_port_options and also application may add PJMEDIA_STEREO_MIX to mix channels. When this flag is zero, the default behavior is to use simple N-to-1 channel converter and to destroy downstream port when this port is destroyed.
p_port	Pointer to receive the stereo port instance.

Returns

PJ_SUCCESS on success.

References PJ_END_DECL.