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Downmix stereo to mono channel and choose with --sout-mono-channel <n> the destination channel.

This commit is contained in:
Jean-Paul Saman 2006-08-22 14:31:40 +00:00
parent 63fa138598
commit 10e3212ea5
1 changed files with 30 additions and 83 deletions
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113
modules/audio_filter/converter/mono.c
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@ -51,19 +51,15 @@ 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 * );
static unsigned int stereo_to_mono( 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;
@ -118,7 +114,7 @@ static int OpenFilter( vlc_object_t *p_this )
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" );
msg_Err( p_this, "filter discarded (invalid format)" );
return -1;
}
@ -144,23 +140,20 @@ static int OpenFilter( vlc_object_t *p_this )
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 =
#if 0
p_filter->fmt_out.audio.i_physical_channels = AOUT_CHAN_CENTER;
#endif
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_nb_channels = aout_FormatNbChannels( &(p_filter->fmt_in.audio) );
p_sys->i_bitspersample = p_filter->fmt_out.audio.i_bitspersample;
p_filter->pf_audio_filter = Convert;
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,
@ -193,6 +186,7 @@ static block_t *Convert( filter_t *p_filter, block_t *p_block )
aout_buffer_t in_buf, out_buf;
block_t *p_out = NULL;
int i_out_size;
unsigned int i_samples;
if( !p_block || !p_block->i_samples )
{
@ -202,7 +196,7 @@ static block_t *Convert( filter_t *p_filter, block_t *p_block )
}
i_out_size = p_block->i_samples * p_filter->p_sys->i_bitspersample/8 *
p_filter->p_sys->i_nb_channels;
aout_FormatNbChannels( &(p_filter->fmt_out.audio) );
p_out = p_filter->pf_audio_buffer_new( p_filter, i_out_size );
if( !p_out )
@ -212,7 +206,8 @@ static block_t *Convert( filter_t *p_filter, block_t *p_block )
return NULL;
}
p_out->i_samples = p_block->i_samples;
p_out->i_samples = (p_block->i_samples / p_filter->p_sys->i_nb_channels) *
aout_FormatNbChannels( &(p_filter->fmt_out.audio) );
p_out->i_dts = p_block->i_dts;
p_out->i_pts = p_block->i_pts;
p_out->i_length = p_block->i_length;
@ -228,13 +223,12 @@ static block_t *Convert( filter_t *p_filter, block_t *p_block )
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 )
unsigned int i_in_size = in_buf.i_nb_samples * (p_filter->p_sys->i_bitspersample/8) *
aout_FormatNbChannels( &(p_filter->fmt_in.audio) );
if( (in_buf.i_nb_bytes != i_in_size) && ((i_in_size % 32) != 0) ) /* is it word aligned?? */
{
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*/
msg_Err( p_filter, "input buffer is not word aligned" );
/* Fix output buffer to be word aligned */
}
#endif
@ -242,7 +236,8 @@ static block_t *Convert( filter_t *p_filter, block_t *p_block )
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 );
i_samples = stereo_to_mono( (aout_instance_t *)p_filter, &aout_filter,
&out_buf, &in_buf );
p_out->i_buffer = out_buf.i_nb_bytes;
p_out->i_samples = out_buf.i_nb_samples;
@ -251,77 +246,29 @@ static block_t *Convert( filter_t *p_filter, block_t *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.
/* stereo_to_mono - mix 2 channels (left,right) into one and play silence on
* all other channels.
*/
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 )
static unsigned int stereo_to_mono( aout_instance_t * p_aout, aout_filter_t *p_filter,
aout_buffer_t *p_output, aout_buffer_t *p_input )
{
filter_sys_t *p_sys = (filter_sys_t *)p_filter->p_sys;
unsigned int n = 0;
int16_t *p_in, *p_out;
unsigned int n;
p_in = (int16_t *)p_in_buf->p_buffer;
p_out = (int16_t *)p_out_buf->p_buffer;
p_in = (int16_t *) p_input->p_buffer;
p_out = (int16_t *) p_output->p_buffer;
for( n = 0; n < p_in_buf->i_nb_samples * p_sys->i_nb_channels; n++ )
for( n = 0; n < (p_input->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];
p_out[n] = (p_in[n] + p_in[n+1]) >> 1;
}
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;
}