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v4l2src: Consider framerate during caps selection

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This simplifies the way it picks the closest caps to preference and take into
consideration the framerate to avoid picking high resolution at 5fps or so.
Simply calculate a "distance" of caps A and B from the preference and put
closest first, sorting by framerate first.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5956>
This commit is contained in:
Xavier Claessens 2023-12-06 20:42:32 -08:00 committed by Tim-Philipp Müller
parent 533b28cd6a
commit 0ce3a2782c
1 changed files with 21 additions and 48 deletions
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69
subprojects/gst-plugins-good/sys/v4l2/gstv4l2src.c
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@ -438,68 +438,41 @@ gst_v4l2_src_parse_fixed_struct (GstStructure * s,
gst_structure_get_fraction (s, "framerate", fps_n, fps_d);
}
/* TODO Consider framerate */
static gint
gst_v4l2src_fixed_caps_compare (GstCaps * caps_a, GstCaps * caps_b,
struct PreferredCapsInfo *pref)
{
GstStructure *a, *b;
gint aw = G_MAXINT, ah = G_MAXINT, ad = G_MAXINT;
gint bw = G_MAXINT, bh = G_MAXINT, bd = G_MAXINT;
gint ret;
gint aw = G_MAXINT, ah = G_MAXINT;
gint bw = G_MAXINT, bh = G_MAXINT;
gint a_fps_n = G_MAXINT, a_fps_d = 1;
gint b_fps_n = G_MAXINT, b_fps_d = 1;
gint a_distance, b_distance;
a = gst_caps_get_structure (caps_a, 0);
b = gst_caps_get_structure (caps_b, 0);
gst_v4l2_src_parse_fixed_struct (a, &aw, &ah, NULL, NULL);
gst_v4l2_src_parse_fixed_struct (b, &bw, &bh, NULL, NULL);
gst_v4l2_src_parse_fixed_struct (a, &aw, &ah, &a_fps_n, &a_fps_d);
gst_v4l2_src_parse_fixed_struct (b, &bw, &bh, &b_fps_n, &b_fps_d);
/* When both are smaller then pref, just append to the end */
if ((bw < pref->width || bh < pref->height)
&& (aw < pref->width || ah < pref->height)) {
ret = 1;
goto done;
}
// Sort first the one with closest framerate to preference. Note that any
// framerate lower then 1 frame per second will be considered the same. In
// practice this should be fine considering that these framerate only exists
// for still picture, in which case the resolution is most likely the key.
a_distance = ABS ((a_fps_n / a_fps_d) - (pref->fps_n / pref->fps_d));
b_distance = ABS ((b_fps_n / b_fps_d) - (pref->fps_n / pref->fps_d));
if (a_distance != b_distance)
return a_distance - b_distance;
/* If a is smaller then pref and not b, then a goes after b */
if (aw < pref->width || ah < pref->height) {
ret = 1;
goto done;
}
// If same framerate, sort first the one with closest resolution to preference
a_distance = ABS (aw * ah - pref->width * pref->height);
b_distance = ABS (bw * bh - pref->width * pref->height);
/* If b is smaller then pref and not a, then a goes before b */
if (bw < pref->width || bh < pref->height) {
ret = -1;
goto done;
}
gint ret = a_distance - b_distance;
/* Both are larger or equal to the preference, prefer the smallest */
ad = MAX (1, aw - pref->width) * MAX (1, ah - pref->height);
bd = MAX (1, bw - pref->width) * MAX (1, bh - pref->height);
GST_TRACE ("Placing %" GST_PTR_FORMAT " %s %" GST_PTR_FORMAT,
caps_a, ret > 0 ? "after" : "before", caps_b);
/* Adjust slightly in case width/height matched the preference */
if (aw == pref->width)
ad -= 1;
if (ah == pref->height)
ad -= 1;
if (bw == pref->width)
bd -= 1;
if (bh == pref->height)
bd -= 1;
/* If the choices are equivalent, maintain the order */
if (ad == bd)
ret = 1;
else
ret = ad - bd;
done:
GST_TRACE ("Placing %ix%i (%s) %s %ix%i (%s)", aw, ah,
gst_structure_get_string (a, "format"), ret > 0 ? "after" : "before", bw,
bh, gst_structure_get_string (b, "format"));
return ret;
}