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resampler: Generate normalized rows in calc_map_table()

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Remixing one channel map to another is (except for special cases) done
via a linear mapping between channels, whose corresponding matrix is
computed by calc_map_table(). The k-th row in this matrix corresponds to
the coefficients of the linear combination of the input channels that
result in the k-th output channel. In order to avoid clipping of samples
we require that the sum of these coefficients is (at most) 1. This
commit ensures this.

Prior to this commit tests/remix-test.c gives 52 of 132 matrices that
violate this property. For example:
'front-left,front-right,front-center,lfe' -> 'front-left,front-right'
           prior this commit                  after this commit
         I00   I01   I02   I03              I00   I01   I02   I03
      +------------------------          +------------------------
  O00 | 0.750 0.000 0.375 0.375      O00 | 0.533 0.000 0.267 0.200
  O01 | 0.000 0.750 0.375 0.375      O01 | 0.000 0.533 0.267 0.200

Building the matrix is done in several steps. However, only insufficient
measures are taken in order to preserve a row-sum of 1.0 (or leaves it
at 0.0) after each step. The current patch adds a post-processing step
in order check for each row whether the sum exceeds 1.0 and, if
necessary, normalizes this row. This allows for further simplifactions:
 - The insufficient normalizations after some steps are removed. Gains
   are adapted to (partially) resemble the old matrices.
 - Handling unconnected input channls becomes a lot simpler.
This commit is contained in:
Stefan Huber 2013-02-07 14:03:17 +01:00 • committed by Tanu Kaskinen
parent 1a40af9c3b
commit 930654a3af
1 changed files with 65 additions and 124 deletions
Download patch file Download diff file Expand all files Collapse all files

189
src/pulsecore/resampler.c
View file

@ -727,16 +727,17 @@ static void calc_map_table(pa_resampler *r) {
*
* 6) Make sure S:Left/S:Right is used: S:Left/S:Right: If not
* connected, mix into all D:left and all D:right channels. Gain is
* 0.1, the current left and right should be multiplied by 0.9.
* 1/9.
*
* 7) Make sure S:Center, S:LFE is used:
*
* S:Center, S:LFE: If not connected, mix into all D:left, all
* D:right, all D:center channels, gain is 0.375. The current (as
* result of 1..6) factors should be multiplied by 0.75. (Alt.
* suggestion: 0.25 vs. 0.5) If C-front is only mixed into
* L-front/R-front if available, otherwise into all L/R channels.
* Similarly for C-rear.
* D:right, all D:center channels. Gain is 0.5 for center and 0.375
* for LFE. C-front is only mixed into L-front/R-front if available,
* otherwise into all L/R channels. Similarly for C-rear.
*
* 8) Normalize each row in the matrix such that the sum for each row is
* not larger than 1.0 in order to avoid clipping.
*
* S: and D: shall relate to the source resp. destination channels.
*
@ -759,6 +760,7 @@ static void calc_map_table(pa_resampler *r) {
ic_unconnected_right = 0,
ic_unconnected_center = 0,
ic_unconnected_lfe = 0;
bool ic_unconnected_center_mixed_in = 0;
pa_assert(remix);
@ -885,117 +887,57 @@ static void calc_map_table(pa_resampler *r) {
ic_unconnected_lfe++;
}
if (ic_unconnected_left > 0) {
for (ic = 0; ic < n_ic; ic++) {
pa_channel_position_t a = r->i_cm.map[ic];
/* OK, so there are unconnected input channels on the left. Let's
* multiply all already connected channels on the left side by .9
* and add in our averaged unconnected channels multiplied by .1 */
if (ic_connected[ic])
continue;
for (oc = 0; oc < n_oc; oc++) {
pa_channel_position_t b = r->o_cm.map[oc];
if (!on_left(r->o_cm.map[oc]))
continue;
if (on_left(a) && on_left(b))
m->map_table_f[oc][ic] = (1.f/9.f) / (float) ic_unconnected_left;
for (ic = 0; ic < n_ic; ic++) {
else if (on_right(a) && on_right(b))
m->map_table_f[oc][ic] = (1.f/9.f) / (float) ic_unconnected_right;
if (ic_connected[ic]) {
m->map_table_f[oc][ic] *= .9f;
continue;
}
else if (on_center(a) && on_center(b)) {
m->map_table_f[oc][ic] = (1.f/9.f) / (float) ic_unconnected_center;
ic_unconnected_center_mixed_in = true;
if (on_left(r->i_cm.map[ic]))
m->map_table_f[oc][ic] = .1f / (float) ic_unconnected_left;
}
} else if (on_lfe(a) && !(r->flags & PA_RESAMPLER_NO_LFE))
m->map_table_f[oc][ic] = .375f / (float) ic_unconnected_lfe;
}
}
if (ic_unconnected_right > 0) {
if (ic_unconnected_center > 0 && !ic_unconnected_center_mixed_in) {
unsigned ncenter[PA_CHANNELS_MAX];
bool found_frs[PA_CHANNELS_MAX];
/* OK, so there are unconnected input channels on the right. Let's
* multiply all already connected channels on the right side by .9
* and add in our averaged unconnected channels multiplied by .1 */
memset(ncenter, 0, sizeof(ncenter));
memset(found_frs, 0, sizeof(found_frs));
for (oc = 0; oc < n_oc; oc++) {
/* Hmm, as it appears there was no center channel we
could mix our center channel in. In this case, mix it into
left and right. Using .5 as the factor. */
if (!on_right(r->o_cm.map[oc]))
for (ic = 0; ic < n_ic; ic++) {
if (ic_connected[ic])
continue;
for (ic = 0; ic < n_ic; ic++) {
if (ic_connected[ic]) {
m->map_table_f[oc][ic] *= .9f;
continue;
}
if (on_right(r->i_cm.map[ic]))
m->map_table_f[oc][ic] = .1f / (float) ic_unconnected_right;
}
}
}
if (ic_unconnected_center > 0) {
bool mixed_in = false;
/* OK, so there are unconnected input channels on the center. Let's
* multiply all already connected channels on the center side by .9
* and add in our averaged unconnected channels multiplied by .1 */
for (oc = 0; oc < n_oc; oc++) {
if (!on_center(r->o_cm.map[oc]))
if (!on_center(r->i_cm.map[ic]))
continue;
for (ic = 0; ic < n_ic; ic++) {
for (oc = 0; oc < n_oc; oc++) {
if (ic_connected[ic]) {
m->map_table_f[oc][ic] *= .9f;
continue;
}
if (on_center(r->i_cm.map[ic])) {
m->map_table_f[oc][ic] = .1f / (float) ic_unconnected_center;
mixed_in = true;
}
}
}
if (!mixed_in) {
unsigned ncenter[PA_CHANNELS_MAX];
bool found_frs[PA_CHANNELS_MAX];
memset(ncenter, 0, sizeof(ncenter));
memset(found_frs, 0, sizeof(found_frs));
/* Hmm, as it appears there was no center channel we
could mix our center channel in. In this case, mix it into
left and right. Using .375 and 0.75 as factors. */
for (ic = 0; ic < n_ic; ic++) {
if (ic_connected[ic])
if (!on_left(r->o_cm.map[oc]) && !on_right(r->o_cm.map[oc]))
continue;
if (!on_center(r->i_cm.map[ic]))
continue;
for (oc = 0; oc < n_oc; oc++) {
if (!on_left(r->o_cm.map[oc]) && !on_right(r->o_cm.map[oc]))
continue;
if (front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc])) {
found_frs[ic] = true;
break;
}
}
for (oc = 0; oc < n_oc; oc++) {
if (!on_left(r->o_cm.map[oc]) && !on_right(r->o_cm.map[oc]))
continue;
if (!found_frs[ic] || front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc]))
ncenter[oc]++;
if (front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc])) {
found_frs[ic] = true;
break;
}
}
@ -1004,40 +946,39 @@ static void calc_map_table(pa_resampler *r) {
if (!on_left(r->o_cm.map[oc]) && !on_right(r->o_cm.map[oc]))
continue;
if (ncenter[oc] <= 0)
if (!found_frs[ic] || front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc]))
ncenter[oc]++;
}
}
for (oc = 0; oc < n_oc; oc++) {
if (!on_left(r->o_cm.map[oc]) && !on_right(r->o_cm.map[oc]))
continue;
if (ncenter[oc] <= 0)
continue;
for (ic = 0; ic < n_ic; ic++) {
if (!on_center(r->i_cm.map[ic]))
continue;
for (ic = 0; ic < n_ic; ic++) {
if (ic_connected[ic]) {
m->map_table_f[oc][ic] *= .75f;
continue;
}
if (!on_center(r->i_cm.map[ic]))
continue;
if (!found_frs[ic] || front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc]))
m->map_table_f[oc][ic] = .375f / (float) ncenter[oc];
}
if (!found_frs[ic] || front_rear_side(r->i_cm.map[ic]) == front_rear_side(r->o_cm.map[oc]))
m->map_table_f[oc][ic] = .5f / (float) ncenter[oc];
}
}
}
}
if (ic_unconnected_lfe > 0 && !(r->flags & PA_RESAMPLER_NO_LFE)) {
for (oc = 0; oc < n_oc; oc++) {
float sum = 0.0f;
for (ic = 0; ic < n_ic; ic++)
sum += m->map_table_f[oc][ic];
/* OK, so there is an unconnected LFE channel. Let's mix it into
* all channels, with factor 0.375 */
for (ic = 0; ic < n_ic; ic++) {
if (!on_lfe(r->i_cm.map[ic]))
continue;
for (oc = 0; oc < n_oc; oc++)
m->map_table_f[oc][ic] = 0.375f / (float) ic_unconnected_lfe;
}
}
if (sum > 1.0f)
for (ic = 0; ic < n_ic; ic++)
m->map_table_f[oc][ic] /= sum;
}
/* make an 16:16 int version of the matrix */