mirrors/gstreamer
mirrors/gstreamer
1
1
Fork 0
mirror of https://gitlab.freedesktop.org/gstreamer/gstreamer.git synced 2025-01-23 07:38:16 +00:00
Code Issues 1 Projects Releases Wiki Activity

video-resampler: improve variable taps

Browse source 
Improve quality of variable taps on all methods by reusing the lanczos
parameters where possible.
This commit is contained in:
Wim Taymans 2014-11-25 10:32:02 +01:00
parent 721bbcad34
commit 1d55bde5bb
1 changed files with 40 additions and 65 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

105
gst-libs/gst/video/video-resampler.c
View file

@ -117,69 +117,48 @@ get_nearest_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
static gdouble
get_linear_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gdouble n_taps;
gdouble res, a;
gint xl = xi + l;
n_taps = (params->resampler->max_taps + 1) / 2;
a = fabs (x - xl) * params->fx;
a = fabs (x - xl);
if (a < n_taps)
res = (n_taps - a) / (gdouble) n_taps;
if (a < 1.0)
res = 1.0 - a;
else
res = 0.0;
return res;
}
static gdouble
bicubic (gdouble s, gdouble b, gdouble c)
{
gdouble s2, s3;
s = fabs (s);
s2 = s * s;
s3 = s2 * s;
if (s <= 1.0)
return ((12.0 - 9.0 * b - 6.0 * c) * s3 +
(-18.0 + 12.0 * b + 6.0 * c) * s2 + (6.0 - 2.0 * b)) / 6.0;
else if (s <= 2.0)
return ((-b - 6.0 * c) * s3 +
(6.0 * b + 30.0 * c) * s2 +
(-12.0 * b - 48.0 * c) * s + (8.0 * b + 24.0 * c)) / 6.0;
else
return 0.0;
}
static gdouble
get_cubic_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gdouble a, b, c, res;
gdouble a, a2, a3, b, c;
gint xl = xi + l;
a = x - (xi + 1);
a = fabs (x - xl) * params->fx;
a2 = a * a;
a3 = a2 * a;
b = params->b;
c = params->c;
if (l == 0)
res = bicubic (1.0 + a, b, c);
else if (l == 1)
res = bicubic (a, b, c);
else if (l == 2)
res = bicubic (1.0 - a, b, c);
if (a <= 1.0)
return ((12.0 - 9.0 * b - 6.0 * c) * a3 +
(-18.0 + 12.0 * b + 6.0 * c) * a2 + (6.0 - 2.0 * b)) / 6.0;
else if (a <= 2.0)
return ((-b - 6.0 * c) * a3 +
(6.0 * b + 30.0 * c) * a2 +
(-12.0 * b - 48.0 * c) * a + (8.0 * b + 24.0 * c)) / 6.0;
else
res = bicubic (2.0 - a, b, c);
return res;
return 0.0;
}
static gdouble
get_sinc_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gint xl = xi + l;
return sinc (x - xl);
return sinc ((x - xl) * params->fx);
}
static gdouble
@ -337,6 +316,7 @@ gst_video_resampler_init (GstVideoResampler * resampler,
{
ResamplerParams params;
gint max_taps;
gdouble scale_factor;
g_return_val_if_fail (in_size != 0, FALSE);
g_return_val_if_fail (out_size != 0, FALSE);
@ -353,6 +333,16 @@ gst_video_resampler_init (GstVideoResampler * resampler,
GST_DEBUG ("%d %u %u->%u", method, n_taps, in_size, out_size);
params.sharpness = GET_OPT_SHARPNESS (options);
params.sharpen = GET_OPT_SHARPEN (options);
scale_factor = in_size / (gdouble) out_size;
if (scale_factor > 1.0) {
params.fx = (1.0 / scale_factor) * params.sharpness;
} else {
params.fx = (1.0) * params.sharpness;
}
max_taps = GET_OPT_MAX_TAPS (options);
n_taps = CLAMP (n_taps, 0, max_taps);
@ -364,50 +354,35 @@ gst_video_resampler_init (GstVideoResampler * resampler,
break;
case GST_VIDEO_RESAMPLER_METHOD_LINEAR:
params.get_tap = get_linear_tap;
if (n_taps == 0)
n_taps = 2;
params.envelope = 1.0;
break;
case GST_VIDEO_RESAMPLER_METHOD_CUBIC:
params.b = GET_OPT_CUBIC_B (options);
params.c = GET_OPT_CUBIC_C (options);
n_taps = 4;
params.envelope = 2.0;
params.get_tap = get_cubic_tap;
break;
case GST_VIDEO_RESAMPLER_METHOD_SINC:
params.envelope = GET_OPT_ENVELOPE (options);
params.get_tap = get_sinc_tap;
if (n_taps == 0)
n_taps = 4;
break;
case GST_VIDEO_RESAMPLER_METHOD_LANCZOS:
{
params.envelope = GET_OPT_ENVELOPE (options);
params.sharpness = GET_OPT_SHARPNESS (options);
params.sharpen = GET_OPT_SHARPEN (options);
if (n_taps == 0) {
gdouble resample_inc = in_size / (gdouble) out_size;
if (resample_inc > 1.0) {
params.fx = (1.0 / resample_inc) * params.sharpness;
} else {
params.fx = (1.0) * params.sharpness;
}
params.ex = params.fx / params.envelope;
params.dx = ceil (params.envelope / params.fx);
n_taps = CLAMP (2 * params.dx, 0, max_taps);
}
params.fx = 2.0 * params.envelope / n_taps;
params.ex = 2.0 / n_taps;
params.get_tap = get_lanczos_tap;
break;
}
default:
break;
}
if (n_taps == 0) {
params.dx = ceil (2.0 * params.envelope / params.fx);
n_taps = CLAMP (params.dx, 0, max_taps);
}
params.fx = 2.0 * params.envelope / n_taps;
params.ex = 2.0 / n_taps;
g_print ("%d\n", n_taps);
if (n_taps > in_size)
n_taps = in_size;