mirror of https://code.videolan.org/videolan/vlc
121 lines
4.0 KiB
C
121 lines
4.0 KiB
C
/*****************************************************************************
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* stereo_pan.c : Stereo panning filter
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*****************************************************************************
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* Copyright © 2021 VLC authors and VideoLAN
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*
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* Authors: Vedanta Nayak <vedantnayak2@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <vlc_common.h>
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#include <vlc_aout.h>
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#include <vlc_filter.h>
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#include <vlc_plugin.h>
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#include <stdatomic.h>
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#define PAN_CONTROL_TEXT N_("Pan control")
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#define PAN_CONTROL_LONGTEXT N_(\
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"Set pan control between 0 (left) and 1 (right). Default: 0.5")
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typedef struct
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{
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_Atomic float f_pan;
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}filter_sys_t;
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static block_t *Process ( filter_t *p_filter, block_t *p_in_buf )
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{
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filter_sys_t *p_sys = p_filter->p_sys;
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float *p_in = (float *)p_in_buf->p_buffer;
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size_t i_nb_samples = p_in_buf->i_nb_samples;
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size_t i_nb_channels = aout_FormatNbChannels( &p_filter->fmt_in.audio );
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float f_pan = atomic_load( &p_sys->f_pan );
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for ( size_t i = 0 ; i < i_nb_samples ; ++i )
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{
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float f_left = p_in[ i * i_nb_channels ];
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float f_right = p_in[ i * i_nb_channels + 1 ];
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p_in[ i * i_nb_channels ] = f_left * (1 - f_pan);
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p_in[ i * i_nb_channels + 1 ] = f_right * f_pan;
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}
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return p_in_buf;
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}
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static int paramCallback( vlc_object_t *p_this, char const *psz_var,
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vlc_value_t oldval, vlc_value_t newval,
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void *p_data)
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{
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filter_sys_t *p_sys = p_data;
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VLC_UNUSED(oldval);
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VLC_UNUSED(p_this);
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VLC_UNUSED(psz_var);
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atomic_store( &p_sys->f_pan, newval.f_float);
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return VLC_SUCCESS;
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}
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static void Close (vlc_object_t *p_in)
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{
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filter_t *p_filter = (filter_t *)p_in;
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filter_sys_t *p_sys = p_filter->p_sys;
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vlc_object_t *p_aout = vlc_object_parent(p_filter);
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var_DelCallback( p_aout, "pan-control", paramCallback, p_sys );
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var_Destroy( p_aout, "pan-control" );
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free(p_sys);
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}
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static int Open (filter_t *p_filter)
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{
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if (p_filter->fmt_out.audio.i_channels < 2) {
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msg_Err( p_filter, "At least 2 audio channels are required" );
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return VLC_EGENERIC;
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}
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vlc_object_t *p_aout = vlc_object_parent(p_filter);
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filter_sys_t *p_sys = p_filter->p_sys = malloc( sizeof(*p_sys) );
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if (unlikely(!p_sys))
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return VLC_ENOMEM;
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atomic_init( &p_sys->f_pan,
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var_CreateGetFloat( p_aout, "pan-control" ) );
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var_AddCallback( p_aout, "pan-control", paramCallback, p_sys );
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p_filter->fmt_out.audio.i_format = VLC_CODEC_FL32;
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p_filter->fmt_in.audio.i_format = VLC_CODEC_FL32;
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aout_FormatPrepare( &p_filter->fmt_in.audio );
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aout_FormatPrepare( &p_filter->fmt_out.audio );
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static const struct vlc_filter_operations filter_ops =
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{
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.filter_audio = Process,
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};
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p_filter->ops = &filter_ops;
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return VLC_SUCCESS;
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}
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vlc_module_begin()
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set_shortname ( N_("Stereo Pan") )
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set_description ( N_("Perform Stereo Panning") )
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set_subcategory ( SUBCAT_AUDIO_AFILTER )
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add_float_with_range( "pan-control", 0.5, 0, 1,
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PAN_CONTROL_TEXT, PAN_CONTROL_LONGTEXT )
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set_capability ( "audio filter", 0 )
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set_callbacks ( Open, Close )
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vlc_module_end ()
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