gstreamer/sys/v4l2/v4l2_calls.c
Ronald S. Bultje 3aa3407ca8 Let's use g_strerror() instead of strerror()
Original commit message from CVS:
Let's use g_strerror() instead of strerror()
2002-10-26 09:40:55 +00:00

853 lines
24 KiB
C

/* G-Streamer generic V4L2 element - generic V4L2 calls handling
* Copyright (C) 2002 Ronald Bultje <rbultje@ronald.bitfreak.net>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <string.h>
#include <errno.h>
#include "v4l2_calls.h"
#define DEBUG(format, args...) \
GST_DEBUG_ELEMENT(GST_CAT_PLUGIN_INFO, \
GST_ELEMENT(v4l2element), \
"V4L2: " format, ##args)
/******************************************************
* gst_v4l2_get_capabilities():
* get the device's capturing capabilities
* return value: TRUE on success, FALSE on error
******************************************************/
static gboolean
gst_v4l2_get_capabilities (GstV4l2Element *v4l2element)
{
DEBUG("getting capabilities");
GST_V4L2_CHECK_OPEN(v4l2element);
if (ioctl(v4l2element->video_fd, VIDIOC_QUERYCAP, &(v4l2element->vcap)) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Error getting %s capabilities: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}
/******************************************************
* gst_v4l2_empty_lists() and gst_v4l2_fill_lists():
* fill/empty the lists of enumerations
* return value: TRUE on success, FALSE on error
******************************************************/
static gboolean
gst_v4l2_fill_lists (GstV4l2Element *v4l2element)
{
gint n;
DEBUG("getting enumerations");
GST_V4L2_CHECK_OPEN(v4l2element);
/* create enumeration lists - let's start with format enumeration */
for (n=0;;n++) {
struct v4l2_fmtdesc format, *fmtptr;
format.index = n;
if (ioctl(v4l2element->video_fd, VIDIOC_ENUM_PIXFMT, &format) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in pixelformat enumeration for %s: %s",
n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
fmtptr = g_malloc(sizeof(format));
memcpy(fmtptr, &format, sizeof(format));
v4l2element->formats = g_list_append(v4l2element->formats, fmtptr);
}
/* and now, the inputs */
for (n=0;;n++) {
struct v4l2_input input, *inpptr;
input.index = n;
if (ioctl(v4l2element->video_fd, VIDIOC_ENUMINPUT, &input) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in input enumeration for %s: %s",
n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
inpptr = g_malloc(sizeof(input));
memcpy(inpptr, &input, sizeof(input));
v4l2element->inputs = g_list_append(v4l2element->inputs, inpptr);
}
/* outputs */
for (n=0;;n++) {
struct v4l2_output output, *outptr;
output.index = n;
if (ioctl(v4l2element->video_fd, VIDIOC_ENUMOUTPUT, &output) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in output enumeration for %s: %s",
n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
outptr = g_malloc(sizeof(output));
memcpy(outptr, &output, sizeof(output));
v4l2element->outputs = g_list_append(v4l2element->outputs, outptr);
}
/* norms... */
for (n=0;;n++) {
struct v4l2_enumstd standard, *stdptr;
standard.index = n;
if (ioctl(v4l2element->video_fd, VIDIOC_ENUMSTD, &standard) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in norm enumeration for %s: %s",
n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
stdptr = g_malloc(sizeof(standard));
memcpy(stdptr, &standard, sizeof(standard));
v4l2element->norms = g_list_append(v4l2element->norms, stdptr);
}
/* and lastly, controls+menus (if appropriate) */
for (n=0;;n++) {
struct v4l2_queryctrl control, *ctrlptr;
GList *menus = NULL;
control.id = n;
if (ioctl(v4l2element->video_fd, VIDIOC_QUERYCTRL, &control) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in control enumeration for %s: %s",
n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
ctrlptr = g_malloc(sizeof(control));
memcpy(ctrlptr, &control, sizeof(control));
v4l2element->controls = g_list_append(v4l2element->controls, ctrlptr);
if (control.type == V4L2_CTRL_TYPE_MENU) {
struct v4l2_querymenu menu, *mptr;
int i;
menu.id = n;
for (i=0;;i++) {
menu.index = i;
if (ioctl(v4l2element->video_fd, VIDIOC_QUERYMENU, &menu) < 0) {
if (errno == EINVAL)
break; /* end of enumeration */
else {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get no. %d in menu %d enumeration for %s: %s",
i, n, v4l2element->device, g_strerror(errno));
return FALSE;
}
}
mptr = g_malloc(sizeof(menu));
memcpy(mptr, &menu, sizeof(menu));
menus = g_list_append(menus, mptr);
}
}
v4l2element->menus = g_list_append(v4l2element->menus, menus);
}
return TRUE;
}
static void
gst_v4l2_empty_lists (GstV4l2Element *v4l2element)
{
DEBUG("deleting enumerations");
/* empty lists */
while (g_list_length(v4l2element->inputs) > 0) {
gpointer data = g_list_nth_data(v4l2element->inputs, 0);
v4l2element->inputs = g_list_remove(v4l2element->inputs, data);
g_free(data);
}
while (g_list_length(v4l2element->outputs) > 0) {
gpointer data = g_list_nth_data(v4l2element->outputs, 0);
v4l2element->outputs = g_list_remove(v4l2element->outputs, data);
g_free(data);
}
while (g_list_length(v4l2element->norms) > 0) {
gpointer data = g_list_nth_data(v4l2element->norms, 0);
v4l2element->norms = g_list_remove(v4l2element->norms, data);
g_free(data);
}
while (g_list_length(v4l2element->formats) > 0) {
gpointer data = g_list_nth_data(v4l2element->formats, 0);
v4l2element->formats = g_list_remove(v4l2element->formats, data);
g_free(data);
}
while (g_list_length(v4l2element->controls) > 0) {
gpointer data = g_list_nth_data(v4l2element->controls, 0);
v4l2element->controls = g_list_remove(v4l2element->controls, data);
g_free(data);
}
v4l2element->menus = g_list_remove_all(v4l2element->menus, NULL);
while (g_list_length(v4l2element->menus) > 0) {
GList *items = (GList *) g_list_nth_data(v4l2element->menus, 0);
v4l2element->inputs = g_list_remove(v4l2element->inputs, items);
while (g_list_length(items) > 0) {
gpointer data = g_list_nth_data(v4l2element->menus, 0);
items = g_list_remove(items, data);
g_free(data);
}
}
}
/******************************************************
* gst_v4l2_open():
* open the video device (v4l2element->device)
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_open (GstV4l2Element *v4l2element)
{
DEBUG("Trying to open device %s", v4l2element->device);
GST_V4L2_CHECK_NOT_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
/* be sure we have a device */
if (!v4l2element->device)
v4l2element->device = g_strdup("/dev/video");
/* open the device */
v4l2element->video_fd = open(v4l2element->device, O_RDWR);
if (!GST_V4L2_IS_OPEN(v4l2element)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to open device %s: %s",
v4l2element->device, g_strerror(errno));
goto error;
}
/* get capabilities */
if (!gst_v4l2_get_capabilities(v4l2element)) {
goto error;
}
/* create enumerations */
if (!gst_v4l2_fill_lists(v4l2element))
goto error;
gst_info("Opened device '%s' (%s) successfully\n",
v4l2element->vcap.name, v4l2element->device);
return TRUE;
error:
if (GST_V4L2_IS_OPEN(v4l2element)) {
/* close device */
close(v4l2element->video_fd);
v4l2element->video_fd = -1;
}
/* empty lists */
gst_v4l2_empty_lists(v4l2element);
return FALSE;
}
/******************************************************
* gst_v4l2_close():
* close the video device (v4l2element->video_fd)
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_close (GstV4l2Element *v4l2element)
{
DEBUG("Trying to close %s", v4l2element->device);
GST_V4L2_CHECK_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
/* close device */
close(v4l2element->video_fd);
v4l2element->video_fd = -1;
/* empty lists */
gst_v4l2_empty_lists(v4l2element);
return TRUE;
}
/******************************************************
* gst_v4l2_get_norm()
* Get the norm of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_get_norm (GstV4l2Element *v4l2element,
gint *norm)
{
struct v4l2_standard standard;
gint n;
DEBUG("getting norm");
GST_V4L2_CHECK_OPEN(v4l2element);
if (ioctl(v4l2element->video_fd, VIDIOC_G_STD, &standard) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get the current norm for device %s: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
/* try to find out what norm number this actually is */
for (n=0;n<g_list_length(v4l2element->norms);n++) {
struct v4l2_enumstd *stdptr = (struct v4l2_enumstd *) g_list_nth_data(v4l2element->norms, n);
if (!strcmp(stdptr->std.name, standard.name)) {
*norm = n;
return TRUE;
}
}
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to find norm '%s' in our list of available norms for device %s",
standard.name, v4l2element->device);
return FALSE;
}
/******************************************************
* gst_v4l2_set_norm()
* Set the norm of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_set_norm (GstV4l2Element *v4l2element,
gint norm)
{
struct v4l2_enumstd *standard;
DEBUG("trying to set norm to %d", norm);
GST_V4L2_CHECK_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
if (norm < 0 || norm >= g_list_length(v4l2element->norms)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Invalid norm number %d (%d-%d)",
norm, 0, g_list_length(v4l2element->norms));
return FALSE;
}
standard = (struct v4l2_enumstd *) g_list_nth_data(v4l2element->norms, norm);
if (ioctl(v4l2element->video_fd, VIDIOC_S_STD, &standard->std) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set norm '%s' (%d) for device %s: %s",
standard->std.name, norm, v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}
/******************************************************
* gst_v4l2_get_norm_names()
* Get the list of available norms
* return value: the list
******************************************************/
GList *
gst_v4l2_get_norm_names (GstV4l2Element *v4l2element)
{
GList *names = NULL;
gint n;
DEBUG("getting a list of norm names");
for (n=0;n<g_list_length(v4l2element->norms);n++) {
struct v4l2_enumstd *standard = (struct v4l2_enumstd *) g_list_nth_data(v4l2element->norms, n);
names = g_list_append(names, g_strdup(standard->std.name));
}
return names;
}
/******************************************************
* gst_v4l2_get_input()
* Get the input of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_get_input (GstV4l2Element *v4l2element,
gint *input)
{
gint n;
DEBUG("trying to get input");
GST_V4L2_CHECK_OPEN(v4l2element);
if (ioctl(v4l2element->video_fd, VIDIOC_G_INPUT, &n) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get current input on device %s: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
*input = n;
return TRUE;
}
/******************************************************
* gst_v4l2_set_input()
* Set the input of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_set_input (GstV4l2Element *v4l2element,
gint input)
{
DEBUG("trying to set input to %d", input);
GST_V4L2_CHECK_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
if (input < 0 || input >= g_list_length(v4l2element->inputs)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Invalid input number %d (%d-%d)",
input, 0, g_list_length(v4l2element->inputs));
return FALSE;
}
if (ioctl(v4l2element->video_fd, VIDIOC_S_INPUT, &input) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set input %d on device %s: %s",
input, v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}
/******************************************************
* gst_v4l2_get_input_names()
* Get the list of available input channels
* return value: the list
******************************************************/
GList *
gst_v4l2_get_input_names (GstV4l2Element *v4l2element)
{
GList *names = NULL;
gint n;
DEBUG("getting a list of input names");
for (n=0;n<g_list_length(v4l2element->inputs);n++) {
struct v4l2_input *input = (struct v4l2_input *) g_list_nth_data(v4l2element->inputs, n);
names = g_list_append(names, g_strdup(input->name));
}
return names;
}
/******************************************************
* gst_v4l2_get_output()
* Get the output of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_get_output (GstV4l2Element *v4l2element,
gint *output)
{
gint n;
DEBUG("trying to get output");
GST_V4L2_CHECK_OPEN(v4l2element);
if (ioctl(v4l2element->video_fd, VIDIOC_G_OUTPUT, &n) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get current output on device %s: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
*output = n;
return TRUE;
}
/******************************************************
* gst_v4l2_set_output()
* Set the output of the current device
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_set_output (GstV4l2Element *v4l2element,
gint output)
{
DEBUG("trying to set output to %d", output);
GST_V4L2_CHECK_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
if (output < 0 || output >= g_list_length(v4l2element->outputs)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Invalid output number %d (%d-%d)",
output, 0, g_list_length(v4l2element->outputs));
return FALSE;
}
if (ioctl(v4l2element->video_fd, VIDIOC_S_OUTPUT, &output) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set output %d on device %s: %s",
output, v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}
/******************************************************
* gst_v4l2_get_output_names()
* Get the list of available output channels
* return value: the list, or NULL on error
******************************************************/
GList *
gst_v4l2_get_output_names (GstV4l2Element *v4l2element)
{
GList *names = NULL;
gint n;
DEBUG("getting a list of output names");
for (n=0;n<g_list_length(v4l2element->outputs);n++) {
struct v4l2_output *output = (struct v4l2_output *) g_list_nth_data(v4l2element->outputs, n);
names = g_list_append(names, g_strdup(output->name));
}
return names;
}
/******************************************************
* gst_v4l_has_tuner():
* Check whether the device has a tuner
* return value: TRUE if it has a tuner, else FALSE
******************************************************/
gboolean
gst_v4l2_has_tuner (GstV4l2Element *v4l2element)
{
gint input_num;
struct v4l2_input *input;
DEBUG("detecting whether device has a tuner");
GST_V4L2_CHECK_OPEN(v4l2element);
if (!gst_v4l2_get_input(v4l2element, &input_num))
return FALSE;
input = (struct v4l2_input *) g_list_nth_data(v4l2element->inputs, input_num);
return (input->type == V4L2_INPUT_TYPE_TUNER &&
v4l2element->vcap.flags & V4L2_FLAG_TUNER);
}
/******************************************************
* gst_v4l_get_frequency():
* get the current frequency
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_get_frequency (GstV4l2Element *v4l2element,
gulong *frequency)
{
gint n;
DEBUG("getting current tuner frequency");
GST_V4L2_CHECK_OPEN(v4l2element);
if (!gst_v4l2_has_tuner(v4l2element))
return FALSE;
if (ioctl(v4l2element->video_fd, VIDIOC_G_FREQ, &n) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get current tuner frequency for device %s: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
*frequency = n;
return TRUE;
}
/******************************************************
* gst_v4l_set_frequency():
* set frequency
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_set_frequency (GstV4l2Element *v4l2element,
gulong frequency)
{
gint n = frequency;
DEBUG("setting current tuner frequency to %lu", frequency);
GST_V4L2_CHECK_OPEN(v4l2element);
GST_V4L2_CHECK_NOT_ACTIVE(v4l2element);
if (!gst_v4l2_has_tuner(v4l2element))
return FALSE;
if (ioctl(v4l2element->video_fd, VIDIOC_G_FREQ, &n) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set tuner frequency to %lu for device %s: %s",
frequency, v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}
/******************************************************
* gst_v4l_signal_strength():
* get the strength of the signal on the current input
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_signal_strength (GstV4l2Element *v4l2element,
gulong *signal_strength)
{
struct v4l2_tuner tuner;
DEBUG("trying to get signal strength");
GST_V4L2_CHECK_OPEN(v4l2element);
if (ioctl(v4l2element->video_fd, VIDIOC_G_TUNER, &tuner) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set signal strength for device %s: %s",
v4l2element->device, g_strerror(errno));
return FALSE;
}
*signal_strength = tuner.signal;
return TRUE;
}
/******************************************************
* gst_v4l_has_audio():
* Check whether the device has audio capabilities
* return value: TRUE if it has a tuner, else FALSE
******************************************************/
gboolean
gst_v4l2_has_audio (GstV4l2Element *v4l2element)
{
gint input_num;
struct v4l2_input *input;
DEBUG("detecting whether device has audio");
GST_V4L2_CHECK_OPEN(v4l2element);
if (!gst_v4l2_get_input(v4l2element, &input_num))
return FALSE;
input = (struct v4l2_input *) g_list_nth_data(v4l2element->inputs, input_num);
return (input->capability & V4L2_INPUT_CAP_AUDIO);
}
/******************************************************
* gst_v4l_get_attributes():
* get a list of attributes available on this device
* return value: the list
******************************************************/
GList *
gst_v4l2_get_attributes (GstV4l2Element *v4l2element)
{
gint i;
GList *list = NULL;
DEBUG("getting a list of available attributes");
for (i=0;i<g_list_length(v4l2element->controls);i++) {
struct v4l2_queryctrl *control = (struct v4l2_queryctrl *) g_list_nth_data(v4l2element->controls, i);
GstV4l2Attribute* attribute = g_malloc(sizeof(GstV4l2Attribute));
attribute->name = g_strdup(control->name);
attribute->index = i;
attribute->list_items = NULL;
switch (control->type) {
case V4L2_CTRL_TYPE_INTEGER:
attribute->val_type = GST_V4L2_ATTRIBUTE_VALUE_TYPE_INT;
break;
case V4L2_CTRL_TYPE_BOOLEAN:
attribute->val_type = GST_V4L2_ATTRIBUTE_VALUE_TYPE_BOOLEAN;
break;
case V4L2_CTRL_TYPE_MENU: {
/* list items */
gint n;
GList *menus = (GList *) g_list_nth_data(v4l2element->menus, i);
for (n=0;n<g_list_length(menus);n++) {
struct v4l2_querymenu *menu = g_list_nth_data(menus, n);
attribute->list_items = g_list_append(attribute->list_items, g_strdup(menu->name));
}
attribute->val_type = GST_V4L2_ATTRIBUTE_VALUE_TYPE_LIST;
break; }
case V4L2_CTRL_TYPE_BUTTON:
attribute->val_type = GST_V4L2_ATTRIBUTE_VALUE_TYPE_BUTTON;
break;
}
switch (control->category) {
case V4L2_CTRL_CAT_VIDEO:
attribute->type = GST_V4L2_ATTRIBUTE_TYPE_VIDEO;
break;
case V4L2_CTRL_CAT_AUDIO:
attribute->type = GST_V4L2_ATTRIBUTE_TYPE_AUDIO;
break;
case V4L2_CTRL_CAT_EFFECT:
attribute->type = GST_V4L2_ATTRIBUTE_TYPE_EFFECT;
break;
}
gst_v4l2_get_attribute(v4l2element, i, &attribute->value);
attribute->min = control->minimum;
attribute->max = control->maximum;
}
return list;
}
/******************************************************
* gst_v4l_get_attribute():
* try to get the value of one specific attribute
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_get_attribute (GstV4l2Element *v4l2element,
gint attribute_num,
gint *value)
{
struct v4l2_control control;
DEBUG("getting value of attribute %d", attribute_num);
GST_V4L2_CHECK_OPEN(v4l2element);
if (attribute_num < 0 || attribute_num >= g_list_length(v4l2element->controls)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Invalid control ID %d", attribute_num);
return FALSE;
}
control.id = attribute_num;
if (ioctl(v4l2element->video_fd, VIDIOC_G_CTRL, &control) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to get value for control %d on device %s: %s",
attribute_num, v4l2element->device, g_strerror(errno));
return FALSE;
}
*value = control.value;
return TRUE;
}
/******************************************************
* gst_v4l_set_attribute():
* try to set the value of one specific attribute
* return value: TRUE on success, FALSE on error
******************************************************/
gboolean
gst_v4l2_set_attribute (GstV4l2Element *v4l2element,
gint attribute_num,
gint value)
{
struct v4l2_control control;
DEBUG("setting value of attribute %d to %d", attribute_num, value);
GST_V4L2_CHECK_OPEN(v4l2element);
if (attribute_num < 0 || attribute_num >= g_list_length(v4l2element->controls)) {
gst_element_error(GST_ELEMENT(v4l2element),
"Invalid control ID %d", attribute_num);
return FALSE;
}
control.id = attribute_num;
control.value = value;
if (ioctl(v4l2element->video_fd, VIDIOC_S_CTRL, &control) < 0) {
gst_element_error(GST_ELEMENT(v4l2element),
"Failed to set value %d for control %d on device %s: %s",
value, attribute_num, v4l2element->device, g_strerror(errno));
return FALSE;
}
return TRUE;
}