mpg123 volume and equalizer

Collaboration diagram for mpg123 volume and equalizer:

Modules
	mpg123 status and information

Enumerations
enum	mpg123_channels { MPG123_LEFT =0x1 , MPG123_RIGHT =0x2 , MPG123_LR =0x3 }

Functions
MPG123_EXPORT int	mpg123_eq (mpg123_handle *mh, enum mpg123_channels channel, int band, double val)
MPG123_EXPORT double	mpg123_geteq (mpg123_handle *mh, enum mpg123_channels channel, int band)
MPG123_EXPORT int	mpg123_reset_eq (mpg123_handle *mh)
MPG123_EXPORT int	mpg123_volume (mpg123_handle *mh, double vol)
MPG123_EXPORT int	mpg123_volume_change (mpg123_handle *mh, double change)
MPG123_EXPORT int	mpg123_getvolume (mpg123_handle *mh, double *base, double *really, double *rva_db)

Detailed Description

Enumeration Type Documentation

mpg123_channels

enum mpg123_channels

another channel enumeration, for left/right choice

Enumerator
MPG123_LEFT	The Left Channel.
MPG123_RIGHT	The Right Channel.
MPG123_LR	Both left and right channel; same as MPG123_LEFT|MPG123_RIGHT

Definition at line 936 of file mpg123.h.

{
     MPG123_LEFT=0x1    
    ,MPG123_RIGHT=0x2   
    ,MPG123_LR=0x3  
};

Function Documentation

mpg123_eq()

MPG123_EXPORT int mpg123_eq	(	mpg123_handle *	mh,
		enum mpg123_channels	channel,
		int	band,
		double	val
	)

Set the 32 Band Audio Equalizer settings.

Parameters

mh	handle
channel	Can be MPG123_LEFT, MPG123_RIGHT or MPG123_LEFT|MPG123_RIGHT for both.
band	The equaliser band to change (from 0 to 31)
val	The (linear) adjustment factor.

Returns

MPG123_OK on success

Definition at line 416 of file libmpg123.c.

{
#ifndef NO_EQUALIZER
    if(mh == NULL) return MPG123_BAD_HANDLE;
    if(band < 0 || band > 31){ mh->err = MPG123_BAD_BAND; return MPG123_ERR; }
    switch(channel)
    {
        case MPG123_LEFT|MPG123_RIGHT:
            mh->equalizer[0][band] = mh->equalizer[1][band] = DOUBLE_TO_REAL(val);
        break;
        case MPG123_LEFT:  mh->equalizer[0][band] = DOUBLE_TO_REAL(val); break;
        case MPG123_RIGHT: mh->equalizer[1][band] = DOUBLE_TO_REAL(val); break;
        default:
            mh->err=MPG123_BAD_CHANNEL;
            return MPG123_ERR;
    }
    mh->have_eq_settings = TRUE;
#endif
    return MPG123_OK;
}

mpg123_geteq()

MPG123_EXPORT double mpg123_geteq	(	mpg123_handle *	mh,
		enum mpg123_channels	channel,
		int	band
	)

Get the 32 Band Audio Equalizer settings.

Parameters

mh	handle
channel	Can be MPG123_LEFT, MPG123_RIGHT or MPG123_LEFT|MPG123_RIGHT for (arithmetic mean of) both.
band	The equaliser band to change (from 0 to 31)

Returns

The (linear) adjustment factor (zero for pad parameters)

Definition at line 437 of file libmpg123.c.

{
    double ret = 0.;
#ifndef NO_EQUALIZER
 
    /* Handle this gracefully. When there is no band, it has no volume. */
    if(mh != NULL && band > -1 && band < 32)
    switch(channel)
    {
        case MPG123_LEFT|MPG123_RIGHT:
            ret = 0.5*(REAL_TO_DOUBLE(mh->equalizer[0][band])+REAL_TO_DOUBLE(mh->equalizer[1][band]));
        break;
        case MPG123_LEFT:  ret = REAL_TO_DOUBLE(mh->equalizer[0][band]); break;
        case MPG123_RIGHT: ret = REAL_TO_DOUBLE(mh->equalizer[1][band]); break;
        /* Default case is already handled: ret = 0 */
    }
#endif
    return ret;
}

mpg123_getvolume()

MPG123_EXPORT int mpg123_getvolume	(	mpg123_handle *	mh,
		double *	base,
		double *	really,
		double *	rva_db
	)

Return current volume setting, the actual value due to RVA, and the RVA adjustment itself. It's all as double float value to abstract the sample format. The volume values are linear factors / amplitudes (not percent) and the RVA value is in decibels.

Parameters

mh	handle
base	return address for base volume (linear factor)
really	return address for actual volume (linear factor)
rva_db	return address for RVA value (decibels)

Returns

MPG123_OK on success

Definition at line 1045 of file frame.c.

{
    if(mh == NULL) return MPG123_ERR;
    if(base)   *base   = mh->p.outscale;
    if(really) *really = mh->lastscale;
    get_rva(mh, NULL, rva_db);
    return MPG123_OK;
}

mpg123_reset_eq()

MPG123_EXPORT int mpg123_reset_eq

(

mpg123_handle *

mh

)

Reset the 32 Band Audio Equalizer settings to flat

Parameters

mh

handle

Returns

MPG123_OK on success

Definition at line 172 of file frame.c.

{
    int i;
    if(mh == NULL) return MPG123_BAD_HANDLE;
#ifndef NO_EQUALIZER
    mh->have_eq_settings = 0;
    for(i=0; i < 32; ++i) mh->equalizer[0][i] = mh->equalizer[1][i] = DOUBLE_TO_REAL(1.0);
#endif
    return MPG123_OK;
}

Referenced by frame_init_par().

mpg123_volume()

MPG123_EXPORT int mpg123_volume	(	mpg123_handle *	mh,
		double	vol
	)

Set the absolute output volume including the RVA setting, vol<0 just applies (a possibly changed) RVA setting.

Parameters

mh	handle
vol	volume value (linear factor)

Returns

MPG123_OK on success

Definition at line 980 of file frame.c.

{
    if(mh == NULL) return MPG123_ERR;
 
    if(vol >= 0) mh->p.outscale = vol;
    else mh->p.outscale = 0.;
 
    do_rva(mh);
    return MPG123_OK;
}

Referenced by mpg123_volume_change().

mpg123_volume_change()

MPG123_EXPORT int mpg123_volume_change	(	mpg123_handle *	mh,
		double	change
	)

Adjust output volume including the RVA setting by chosen amount

Parameters

mh	handle
change	volume value (linear factor increment)

Returns

MPG123_OK on success

Definition at line 974 of file frame.c.

{
    if(mh == NULL) return MPG123_ERR;
    return mpg123_volume(mh, change + (double) mh->p.outscale);
}