First part of a new mono for audio filter 2. You can select the channel you...

First part of a new mono for audio filter 2. You can select the channel you want to hear all other channels are silenced.

TODO:
- stereo_to_mono downmix

modules/audio_filter/converter/Modules.am

@@ -15,3 +15,4 @@ SOURCES_s8tofloat32 = s8tofloat32.c
 SOURCES_u8tofixed32 = u8tofixed32.c
 SOURCES_u8tofloat32 = u8tofloat32.c
 SOURCES_mpgatofixed32 = mpgatofixed32.c
+SOURCES_mono = mono.c

modules/audio_filter/converter/mono.c

+/*****************************************************************************
+ * mono.c : stereo2mono downmixsimple channel mixer plug-in
+ *****************************************************************************
+ * Copyright (C) 2006 M2X
+ * $Id$
+ *
+ * Authors: Jean-Paul Saman <jpsaman at m2x dot nl>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <stdlib.h>                                      /* malloc(), free() */
+#include <string.h>
+
+#ifdef HAVE_STDINT_H
+#   include <stdint.h>                                         /* int16_t .. */
+#elif HAVE_INTTYPES_H
+#   include <inttypes.h>                                       /* int16_t .. */
+#endif
+
+#ifdef HAVE_UNISTD_H
+#   include <unistd.h>
+#endif
+
+#include <vlc/vlc.h>
+#include <vlc_es.h>
+#include <vlc_block.h>
+#include <vlc_filter.h>
+#include <audio_output.h>
+#include <aout_internal.h>
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static int  OpenFilter    ( vlc_object_t * );
+static void CloseFilter   ( vlc_object_t * );
+
+static block_t *Convert( filter_t *p_filter, block_t *p_block );
+static void stereo_mono_downmix( aout_instance_t *, aout_filter_t *,
+                                 aout_buffer_t *, aout_buffer_t * );
+static unsigned int stereo_to_mono( int16_t *, int16_t *, unsigned int );
+
+static void silence_channel( aout_instance_t *, aout_filter_t *,
+                             aout_buffer_t *, aout_buffer_t * );
+
+/*****************************************************************************
+ * Local structures
+ *****************************************************************************/
+struct filter_sys_t
+{
+    vlc_bool_t b_block_channel;
+    int i_nb_channels; /* number of float32 per sample */
+    unsigned int i_channel_selected;
+    int i_bitspersample;
+};
+
+#define MONO_CHANNEL_TEXT ("Select channel to keep")
+#define MONO_CHANNEL_LONGTEXT ("This option silcences all other channels " \
+    "except the selected channel. Choose one from (0=left, 1=right " \
+    "2=rear left, 3=rear right, 4=center, 5=left front")
+
+static int pi_pos_values[] = { 0, 1, 2, 4, 8, 5 };
+static char *ppsz_pos_descriptions[] =
+{ N_("Left"), N_("Right"), N_("Left rear"), N_("Right rear"), N_("Center"),
+  N_("Left front") };
+
+/* our internal channel order (WG-4 order) */
+static const uint32_t pi_channels_out[] =
+{ AOUT_CHAN_LEFT, AOUT_CHAN_RIGHT, AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT,
+  AOUT_CHAN_CENTER, AOUT_CHAN_LFE, 0 };
+
+#define MONO_CFG "sout-"
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+vlc_module_begin();
+    set_description( _("Audio filter for stereo to mono conversion") );
+    set_capability( "audio filter2", 5 );
+
+    add_integer( MONO_CFG "mono-channel", 0, NULL, MONO_CHANNEL_TEXT, MONO_CHANNEL_LONGTEXT, VLC_FALSE );
+        change_integer_list( pi_pos_values, ppsz_pos_descriptions, 0 );
+
+    set_category( CAT_AUDIO );
+    set_subcategory( SUBCAT_AUDIO_MISC );
+    set_callbacks( OpenFilter, CloseFilter );
+    set_shortname( "Mono" );
+vlc_module_end();
+
+/*****************************************************************************
+ * OpenFilter
+ *****************************************************************************/
+static int OpenFilter( vlc_object_t *p_this )
+{
+    filter_t * p_filter = (filter_t *)p_this;
+    filter_sys_t *p_sys = NULL;
+
+    if( aout_FormatNbChannels( &(p_filter->fmt_in.audio) ) == 1 )
+    {
+        msg_Dbg( p_filter, "filter discarded (incompatible format)" );
+        return VLC_EGENERIC;
+    }
+
+    if( (p_filter->fmt_in.i_codec != AOUT_FMT_S16_NE) ||
+        (p_filter->fmt_out.i_codec != AOUT_FMT_S16_NE) )
+    {
+        msg_Err( p_this, "invalid format" );
+        return -1;
+    }
+
+    if( (p_filter->fmt_in.audio.i_format != p_filter->fmt_out.audio.i_format) &&
+        (p_filter->fmt_in.audio.i_rate != p_filter->fmt_out.audio.i_rate) &&
+        (p_filter->fmt_in.audio.i_format != AOUT_FMT_S16_NE) &&
+        (p_filter->fmt_out.audio.i_format != AOUT_FMT_S16_NE) )
+    {
+        msg_Err( p_this, "couldn't load mono filter" );
+        return VLC_EGENERIC;
+    }
+
+    /* Allocate the memory needed to store the module's structure */
+    p_sys = p_filter->p_sys = malloc( sizeof(filter_sys_t) );
+    if( p_sys == NULL )
+    {
+        msg_Err( p_filter, "out of memory" );
+        return VLC_EGENERIC;
+    }
+
+    var_Create( p_this, MONO_CFG "mono-channel",
+                VLC_VAR_INTEGER | VLC_VAR_DOINHERIT );
+    p_sys->i_channel_selected =
+            (unsigned int) var_GetInteger( p_this, MONO_CFG "mono-channel" );
+
+    /* temporarily force channel silence */
+    p_sys->b_block_channel = VLC_TRUE;
+    if( p_sys->b_block_channel )
+    {
+        p_filter->fmt_out.audio.i_physical_channels =
+                            (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT);
+    }
+    else
+        p_filter->fmt_out.audio.i_physical_channels = AOUT_CHAN_CENTER;
+
+    p_filter->pf_audio_filter = Convert;
+    p_filter->fmt_out.audio.i_rate = p_filter->fmt_in.audio.i_rate;
+    p_filter->fmt_out.audio.i_format = p_filter->fmt_out.i_codec;
+
+    p_sys->i_nb_channels = aout_FormatNbChannels( &(p_filter->fmt_out.audio) );
+    p_sys->i_bitspersample = p_filter->fmt_out.audio.i_bitspersample;
+
+    msg_Dbg( p_this, "%4.4s->%4.4s, channels %d->%d, bits per sample: %i->%i",
+             (char *)&p_filter->fmt_in.i_codec,
+             (char *)&p_filter->fmt_out.i_codec,
+             p_filter->fmt_in.audio.i_physical_channels,
+             p_filter->fmt_out.audio.i_physical_channels,
+             p_filter->fmt_in.audio.i_bitspersample,
+             p_filter->fmt_out.audio.i_bitspersample );
+
+    return VLC_SUCCESS;
+}
+
+/*****************************************************************************
+ * CloseFilter
+ *****************************************************************************/
+static void CloseFilter( vlc_object_t *p_this)
+{
+    filter_t *p_filter = (filter_t *) p_this;
+    filter_sys_t *p_sys = p_filter->p_sys;
+
+    var_Destroy( p_this, MONO_CFG "mono-channel" );
+    free( p_sys );
+}
+
+/*****************************************************************************
+ * Convert
+ *****************************************************************************/
+static block_t *Convert( filter_t *p_filter, block_t *p_block )
+{
+    aout_filter_t aout_filter;
+    aout_buffer_t in_buf, out_buf;
+    block_t *p_out = NULL;
+    int i_out_size;
+
+    if( !p_block || !p_block->i_samples )
+    {
+        if( p_block )
+            p_block->pf_release( p_block );
+        return NULL;
+    }
+
+    i_out_size = p_block->i_samples * p_filter->p_sys->i_bitspersample/8 *
+                 p_filter->p_sys->i_nb_channels;
+
+    p_out = p_filter->pf_audio_buffer_new( p_filter, i_out_size );
+    if( !p_out )
+    {
+        msg_Warn( p_filter, "can't get output buffer" );
+        p_block->pf_release( p_block );
+        return NULL;
+    }
+
+    p_out->i_samples = p_block->i_samples;
+    p_out->i_dts = p_block->i_dts;
+    p_out->i_pts = p_block->i_pts;
+    p_out->i_length = p_block->i_length;
+
+    aout_filter.p_sys = (struct aout_filter_sys_t *)p_filter->p_sys;
+    aout_filter.input = p_filter->fmt_in.audio;
+    aout_filter.input.i_format = p_filter->fmt_in.i_codec;
+    aout_filter.output = p_filter->fmt_out.audio;
+    aout_filter.output.i_format = p_filter->fmt_out.i_codec;
+
+    in_buf.p_buffer = p_block->p_buffer;
+    in_buf.i_nb_bytes = p_block->i_buffer;
+    in_buf.i_nb_samples = p_block->i_samples;
+
+#if 0
+    if( in_buf.i_nb_bytes != (p_filter->p_sys->i_bitspersample/8) * in_buf.i_nb_samples )
+    {
+        msg_Err( p_filter, "input buffer is not alligned" );
+/*        if( in_buf.i_nb_bytes > (p_filter->p_sys->i_bitspersample/8) * in_buf.i_nb_samples)
+            in_buf.i_nb_bytes = (p_filter->p_sys->i_bitspersample/8) * in_buf.i_nb_samples;
+        else
+            //in_buf*/
+    }
+#endif
+
+    out_buf.p_buffer = p_out->p_buffer;
+    out_buf.i_nb_bytes = p_out->i_buffer;
+    out_buf.i_nb_samples = p_out->i_samples;
+
+    stereo_mono_downmix( (aout_instance_t *)p_filter, &aout_filter, &in_buf, &out_buf );
+
+    p_out->i_buffer = out_buf.i_nb_bytes;
+    p_out->i_samples = out_buf.i_nb_samples;
+
+    p_block->pf_release( p_block );
+    return p_out;
+}
+
+static void stereo_mono_downmix( aout_instance_t * p_aout, aout_filter_t * p_filter,
+                                 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
+{
+    filter_sys_t *p_sys = (filter_sys_t *)p_filter->p_sys;
+
+    if( p_sys->b_block_channel )
+    {
+        silence_channel( p_aout, p_filter, p_out_buf, p_in_buf );
+    }
+    else
+    {
+        unsigned int i_samples;
+
+        i_samples = stereo_to_mono( (int16_t *)p_out_buf->p_buffer, (int16_t *)p_in_buf->p_buffer,
+                                    p_out_buf->i_nb_samples );
+    }
+
+    p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
+}
+
+/* silence_channel - play silence on all channels except the selected one.
+ */
+static void silence_channel( aout_instance_t * p_aout, aout_filter_t * p_filter,
+                             aout_buffer_t *p_out_buf, aout_buffer_t *p_in_buf )
+{
+    filter_sys_t *p_sys = (filter_sys_t *)p_filter->p_sys;
+    unsigned int n = 0;
+    int16_t *p_in, *p_out;
+
+    p_in = (int16_t *)p_in_buf->p_buffer;
+    p_out = (int16_t *)p_out_buf->p_buffer;
+
+    for( n = 0; n < p_in_buf->i_nb_samples * p_sys->i_nb_channels; n++ )
+    {
+        if( (n%p_sys->i_nb_channels) == p_sys->i_channel_selected )
+        {
+            p_out[n] = p_in[n];
+        }
+        else
+        {
+            p_out[n] = 0x0;
+        }
+    }
+}
+
+/* stereo_to_mono() function is from ffmpeg file libavcodec/resample.c 
+ * Copyright (c) 2000 Fabrice Bellard.
+ */
+static unsigned int stereo_to_mono( int16_t *p_output, int16_t *p_input,
+                                    unsigned int i_samples )
+{
+    int16_t *p, *q;
+    unsigned int n = i_samples;
+
+    p = p_input;
+    q = p_output;
+
+    while (n >= 4) {
+        q[0] = (p[0] + p[1]) >> 1;
+        q[1] = (p[2] + p[3]) >> 1;
+        q[2] = (p[4] + p[5]) >> 1;
+        q[3] = (p[6] + p[7]) >> 1;
+        q += 4;
+        p += 8;
+        n -= 4;
+    }
+    while (n > 0) {
+        q[0] = (p[0] + p[1]) >> 1;
+        q++;
+        p += 2;
+        n--;
+    }
+    return n;
+}