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6f68f89498
see e967f81f6a.
note, this does **not** affect cat-based module selection items
(of which there are just three in use by the core), since that
mechanism uses subcats not cats.
94 lines
3.2 KiB
C
94 lines
3.2 KiB
C
/*****************************************************************************
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* center.c : Central channel filter
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*****************************************************************************
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* Copyright © 2020 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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static block_t *Process ( filter_t *filter, block_t *in_buf )
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{
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#define NB_CHANNELS 3
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(void) filter;
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float *in = (float*)in_buf->p_buffer;
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size_t i_nb_samples = in_buf->i_nb_samples;
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block_t *out_buf = block_Alloc(sizeof(float) * i_nb_samples * NB_CHANNELS);
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if ( !out_buf )
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{
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block_Release(in_buf);
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return out_buf;
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}
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float * p_out = (float*)out_buf->p_buffer;
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out_buf->i_nb_samples = i_nb_samples;
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out_buf->i_dts = in_buf->i_dts;
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out_buf->i_pts = in_buf->i_pts;
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out_buf->i_length = sizeof(float) * i_nb_samples;
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const float factor = .70710678;
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for ( size_t i = 0 ; i < i_nb_samples ; ++i)
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{
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float left = in[i*2];
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float right = in[i*2+1];
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float center = ( left + right ) * factor / 2;
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p_out[i * NB_CHANNELS ] = left;
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p_out[i * NB_CHANNELS + 1 ] = right;
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p_out[i * NB_CHANNELS + 2 ] = center;
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}
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block_Release(in_buf);
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return out_buf;
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}
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static int Open (vlc_object_t *in)
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{
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filter_t *filter = (filter_t *)in;
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if (filter->fmt_in.audio.i_physical_channels != AOUT_CHANS_STEREO)
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return VLC_EGENERIC;
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static_assert(AOUT_CHANIDX_CENTER > AOUT_CHANIDX_RIGHT &&
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AOUT_CHANIDX_RIGHT > AOUT_CHANIDX_LEFT, "Change in channel order.");
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filter->fmt_out.audio.i_format = VLC_CODEC_FL32;
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filter->fmt_in.audio.i_format = VLC_CODEC_FL32;
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filter->fmt_out.audio.i_physical_channels = AOUT_CHANS_STEREO | AOUT_CHAN_CENTER;
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filter->fmt_out.audio.i_rate = filter->fmt_in.audio.i_rate;
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aout_FormatPrepare(&filter->fmt_in.audio);
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aout_FormatPrepare(&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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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_("Center"))
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set_description (N_("Create a central channel"))
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set_subcategory (SUBCAT_AUDIO_AFILTER)
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set_capability ("audio filter",0)
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set_callback (Open)
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vlc_module_end ()
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