--- /dev/null
+/*****************************************************************************
+ * 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;
+}
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