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v4l2: Normalise control names in the same way as v4l2-ctl

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V4L2 kernel drivers allow configuration of the hardware settings via a
mechanism called controls.  These can be referred to by name such as
"Brightness" and "White Balance Temperature".  The user-space command line
client for setting these controls (v4l2-ctl) normalises these names such
that they only contain lower case alphanumeric characters and the
underscore '_'.  e.g:

    Kernel                     v4l2-ctl
    ----------------------------------------------------
    Brightness                 brightness
    White Balance Temperature  white_balance_temperature
    Focus (absolute)           focus_absolute

GStreamer seems to want to follow this pattern but failed for controls with
more than one consecutive non-alphanum character.  e.g. GStreamer would
produce "focus__absolute_" rather than "focus_absolute".

This commit fixes that issue.  Backwards compatibility is preserved by
normalising all control names before comparison.

https://bugzilla.gnome.org/show_bug.cgi?id=725632
This commit is contained in:
William Manley 2014-03-04 01:15:49 +00:00 committed by Nicolas Dufresne
parent ac83961033
commit d3bd3ecc3e
1 changed files with 46 additions and 8 deletions
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54
sys/v4l2/v4l2_calls.c
View file

@ -108,6 +108,29 @@ cap_failed:
}
}
/******************************************************
* The video4linux command line tool v4l2-ctrl
* normalises the names of the controls received from
* the kernel like:
*
* "Exposure (absolute)" -> "exposure_absolute"
*
* We follow their lead here. @name is modified
* in-place.
******************************************************/
static void
gst_v4l2_normalise_control_name (gchar * name)
{
int i, j;
for (i = 0, j = 0; name[j]; ++j) {
if (g_ascii_isalnum (name[j])) {
if (i > 0 && !g_ascii_isalnum (name[j - 1]))
name[i++] = '_';
name[i++] = g_ascii_tolower (name[j]);
}
}
name[i++] = '\0';
}
/******************************************************
* gst_v4l2_empty_lists() and gst_v4l2_fill_lists():
@ -326,14 +349,8 @@ gst_v4l2_fill_lists (GstV4l2Object * v4l2object)
case V4L2_CTRL_TYPE_BITMASK:
#endif
case V4L2_CTRL_TYPE_BUTTON:{
int i;
control.name[31] = '\0';
for (i = 0; control.name[i]; ++i) {
control.name[i] = g_ascii_tolower (control.name[i]);
if (!g_ascii_isalnum (control.name[i]))
control.name[i] = '_';
}
GST_INFO_OBJECT (e, "adding generic controls '%s'", control.name);
gst_v4l2_normalise_control_name ((gchar *) control.name);
g_datalist_id_set_data (&v4l2object->controls,
g_quark_from_string ((const gchar *) control.name),
GINT_TO_POINTER (n));
@ -1012,7 +1029,28 @@ static gboolean
set_contol (GQuark field_id, const GValue * value, gpointer user_data)
{
GstV4l2Object *v4l2object = user_data;
gpointer *d = g_datalist_id_get_data (&v4l2object->controls, field_id);
GQuark normalised_field_id;
gpointer *d;
/* 32 bytes is the maximum size for a control name according to v4l2 */
gchar name[32];
/* Backwards compatibility: in the past GStreamer would normalise strings in
a subtly different way to v4l2-ctl. e.g. the kernel's "Focus (absolute)"
would become "focus__absolute_" whereas now it becomes "focus_absolute".
Please remove the following in GStreamer 1.5 for 1.6 */
strncpy (name, g_quark_to_string (field_id), sizeof (name));
name[31] = '\0';
gst_v4l2_normalise_control_name (name);
normalised_field_id = g_quark_from_string (name);
if (normalised_field_id != field_id)
g_warning ("In GStreamer 1.4 the way V4L2 control names were normalised "
"changed. Instead of setting \"%s\" please use \"%s\". The former is "
"deprecated and will be removed in a future version of GStreamer",
g_quark_to_string (field_id), name);
field_id = normalised_field_id;
d = g_datalist_id_get_data (&v4l2object->controls, field_id);
if (!d) {
GST_WARNING_OBJECT (v4l2object,
"Control '%s' does not exist or has an unsupported type.",