* modules/audio_filter/channel_mixer/simple.c: very simple channel mixer for 7/7.1/5/5.1 -> Stereo.

configure.ac

@@ -949,7 +949,7 @@ VLC_ADD_PLUGINS([cvdsub svcdsub spudec subsdec dvbsub mpeg_audio lpcm a52 dts ci
 VLC_ADD_PLUGINS([deinterlace invert adjust wall transform distort clone crop motionblur])
 VLC_ADD_PLUGINS([float32tos16 float32tos8 float32tou16 float32tou8 a52tospdif dtstospdif fixed32tofloat32 fixed32tos16 s16tofixed32 s16tofloat32 s16tofloat32swab s8tofloat32 u8tofixed32 u8tofloat32 audio_format])
 VLC_ADD_PLUGINS([trivial_resampler ugly_resampler linear_resampler bandlimited_resampler])
-VLC_ADD_PLUGINS([trivial_channel_mixer headphone_channel_mixer])
+VLC_ADD_PLUGINS([trivial_channel_mixer simple_channel_mixer headphone_channel_mixer])
 VLC_ADD_PLUGINS([trivial_mixer spdif_mixer float32_mixer])
 VLC_ADD_PLUGINS([aout_file equalizer])
 VLC_ADD_PLUGINS([i420_rgb i420_yuy2 i422_yuy2 i420_ymga])

modules/audio_filter/channel_mixer/Modules.am

 SOURCES_trivial_channel_mixer = trivial.c
+SOURCES_simple_channel_mixer = simple.c
 SOURCES_headphone_channel_mixer = headphone.c

modules/audio_filter/channel_mixer/simple.c

+/*****************************************************************************
+ * simple.c : simple channel mixer plug-in (only 7/7.1/5/5.1 -> Stereo for now)
+ *****************************************************************************
+ * Copyright (C) 2002 VideoLAN
+ * $Id$
+ *
+ * Authors: Gildas Bazin <gbazin@videolan.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <stdlib.h>                                      /* malloc(), free() */
+#include <string.h>
+
+#include <vlc/vlc.h>
+#include "audio_output.h"
+#include "aout_internal.h"
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static int  Create    ( vlc_object_t * );
+
+static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
+                        aout_buffer_t * );
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+vlc_module_begin();
+    set_description( _("audio filter for simple channel mixing") );
+    set_capability( "audio filter", 10 );
+    set_callbacks( Create, NULL );
+vlc_module_end();
+
+/*****************************************************************************
+ * Create: allocate trivial channel mixer
+ *****************************************************************************/
+static int Create( vlc_object_t *p_this )
+{
+    aout_filter_t * p_filter = (aout_filter_t *)p_this;
+
+    if ( (p_filter->input.i_physical_channels
+           == p_filter->output.i_physical_channels
+           && p_filter->input.i_original_channels
+               == p_filter->output.i_original_channels)
+          || p_filter->input.i_format != p_filter->output.i_format
+          || p_filter->input.i_rate != p_filter->output.i_rate
+          || p_filter->input.i_format != VLC_FOURCC('f','l','3','2') )
+    {
+        return -1;
+    }
+
+    msg_Err( p_this, aout_FormatPrintChannels( &p_filter->input ) );
+
+    /* Only conversion to Stereo right now */
+    if( p_filter->output.i_physical_channels !=
+        (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) ) return -1;
+
+    /* Only from 7/7.1/5/5.1 */
+    if( (p_filter->input.i_physical_channels & ~AOUT_CHAN_LFE) !=
+        (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER |
+         AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT) &&
+        (p_filter->input.i_physical_channels & ~AOUT_CHAN_LFE) !=
+        (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER |
+         AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT |
+         AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT) )
+    {
+        return -1;
+    }
+
+    p_filter->pf_do_work = DoWork;
+    p_filter->b_in_place = 0;
+
+    return 0;
+}
+
+/*****************************************************************************
+ * DoWork: convert a buffer
+ *****************************************************************************/
+static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
+                    aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
+{
+    int i_input_nb = aout_FormatNbChannels( &p_filter->input );
+    int i_output_nb = aout_FormatNbChannels( &p_filter->output );
+    float *p_dest = (float *)p_out_buf->p_buffer;
+    float *p_src = (float *)p_in_buf->p_buffer;
+    int i;
+
+    p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
+    p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
+
+    if( p_filter->input.i_physical_channels & AOUT_CHAN_MIDDLELEFT )
+    for( i = p_in_buf->i_nb_samples; i--; )
+    {
+        *p_dest = p_src[6] + 0.5 * p_src[0] + p_src[2] / 4 + p_src[4] / 4;
+        p_dest++;
+        *p_dest = p_src[6] + 0.5 * p_src[1] + p_src[3] / 4 + p_src[5] / 4;
+        p_dest++;
+
+        p_src += 7;
+
+        if( p_filter->input.i_physical_channels & AOUT_CHAN_LFE ) p_src++;
+    }
+    else
+    for( i = p_in_buf->i_nb_samples; i--; )
+    {
+        *p_dest = p_src[4] + 0.5 * p_src[0] + 0.33 * p_src[2];
+        p_dest++;
+        *p_dest = p_src[4] + 0.5 * p_src[1] + 0.33 * p_src[3];
+        p_dest++;
+
+        p_src += 5;
+
+        if( p_filter->input.i_physical_channels & AOUT_CHAN_LFE ) p_src++;
+    }
+}