mirror of
https://code.videolan.org/videolan/vlc
synced 2024-10-03 01:31:53 +02:00
188 lines
6.6 KiB
C
188 lines
6.6 KiB
C
/*****************************************************************************
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* float32.c : precise float32 audio mixer implementation
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*****************************************************************************
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* Copyright (C) 2002 the VideoLAN team
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* $Id$
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*
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* Authors: Christophe Massiot <massiot@via.ecp.fr>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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/*****************************************************************************
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* Preamble
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*****************************************************************************/
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#include <stdlib.h> /* malloc(), free() */
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#include <string.h>
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#include <vlc/vlc.h>
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#include "audio_output.h"
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#include "aout_internal.h"
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/*****************************************************************************
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* Local prototypes
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*****************************************************************************/
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static int Create ( vlc_object_t * );
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static void DoWork ( aout_instance_t *, aout_buffer_t * );
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/*****************************************************************************
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* Module descriptor
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*****************************************************************************/
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vlc_module_begin();
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set_category( CAT_AUDIO );
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set_subcategory( SUBCAT_AUDIO_MISC );
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set_description( _("Float32 audio mixer") );
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set_capability( "audio mixer", 10 );
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set_callbacks( Create, NULL );
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vlc_module_end();
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/*****************************************************************************
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* Create: allocate mixer
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*****************************************************************************/
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static int Create( vlc_object_t *p_this )
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{
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aout_instance_t * p_aout = (aout_instance_t *)p_this;
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if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
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{
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return -1;
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}
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if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
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{
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/* Tell the trivial mixer to go for it. */
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return -1;
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}
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p_aout->mixer.pf_do_work = DoWork;
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return 0;
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}
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/*****************************************************************************
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* ScaleWords: prepare input words for averaging
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*****************************************************************************/
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static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
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int i_nb_inputs, float f_multiplier )
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{
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int i;
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f_multiplier /= i_nb_inputs;
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for ( i = i_nb_words; i--; )
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{
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*p_out++ = *p_in++ * f_multiplier;
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}
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}
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/*****************************************************************************
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* MeanWords: average input words
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*****************************************************************************/
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static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
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int i_nb_inputs, float f_multiplier )
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{
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int i;
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f_multiplier /= i_nb_inputs;
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for ( i = i_nb_words; i--; )
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{
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*p_out++ += *p_in++ * f_multiplier;
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}
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}
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/*****************************************************************************
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* DoWork: mix a new output buffer
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*****************************************************************************
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* Terminology : in this function a word designates a single float32, eg.
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* a stereo sample is consituted of two words.
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*****************************************************************************/
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static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
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{
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int i_nb_inputs = p_aout->i_nb_inputs;
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float f_multiplier = p_aout->mixer.f_multiplier;
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int i_input;
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int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
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for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
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{
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int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
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aout_input_t * p_input = p_aout->pp_inputs[i_input];
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float * p_out = (float *)p_buffer->p_buffer;
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float * p_in = (float *)p_input->p_first_byte_to_mix;
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if ( p_input->b_error ) continue;
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for ( ; ; )
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{
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ptrdiff_t i_available_words = (
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(float *)p_input->fifo.p_first->p_buffer - p_in)
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+ p_input->fifo.p_first->i_nb_samples
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* i_nb_channels;
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if ( i_available_words < i_nb_words )
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{
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aout_buffer_t * p_old_buffer;
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if ( i_available_words > 0 )
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{
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if ( !i_input )
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{
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ScaleWords( p_out, p_in, i_available_words,
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i_nb_inputs, f_multiplier );
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}
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else
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{
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MeanWords( p_out, p_in, i_available_words,
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i_nb_inputs, f_multiplier );
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}
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}
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i_nb_words -= i_available_words;
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p_out += i_available_words;
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/* Next buffer */
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p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
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aout_BufferFree( p_old_buffer );
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if ( p_input->fifo.p_first == NULL )
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{
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msg_Err( p_aout, "internal amix error" );
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return;
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}
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p_in = (float *)p_input->fifo.p_first->p_buffer;
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}
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else
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{
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if ( i_nb_words > 0 )
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{
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if ( !i_input )
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{
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ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
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f_multiplier );
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}
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else
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{
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MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
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f_multiplier );
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}
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}
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p_input->p_first_byte_to_mix = (void *)(p_in
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+ i_nb_words);
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break;
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}
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}
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}
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}
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