[FFmpeg-devel] [PATCH] v4l2: allow to set device controls.
Nicolas George
nicolas.george at normalesup.org
Thu Apr 25 17:45:48 CEST 2013
Address trac ticket #2305.
Somme trickery is necessary to support gcc < 4.6
(used in Debian stable at the time of this commit)
and older versions of the v4l2 API without proper
version macros.
Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---
doc/indevs.texi | 4 ++
libavdevice/v4l2.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 146 insertions(+)
diff --git a/doc/indevs.texi b/doc/indevs.texi
index 5e8d215..2a51a73 100644
--- a/doc/indevs.texi
+++ b/doc/indevs.texi
@@ -699,6 +699,10 @@ Force conversion from monotonic to absolute timestamps.
@end table
Default value is @code{default}.
+
+ at item controls
+Set device controls. The argument is a list of @code{@var{key}=@var{value}}
+pairs separated by @code{:}.
@end table
@section vfwcap
diff --git a/libavdevice/v4l2.c b/libavdevice/v4l2.c
index 34e3d9c..553ea79 100644
--- a/libavdevice/v4l2.c
+++ b/libavdevice/v4l2.c
@@ -121,6 +121,7 @@ struct video_data {
int list_format; /**< Set by a private option. */
int list_standard; /**< Set by a private option. */
char *framerate; /**< Set by a private option. */
+ char *controls; /**< Set by a private option. */
};
struct buff_data {
@@ -707,6 +708,141 @@ static void mmap_close(struct video_data *s)
av_free(s->buf_len);
}
+static int add_control(struct v4l2_queryctrl **allctrls, unsigned *nb_ctrls,
+ struct v4l2_queryctrl *qctrl)
+{
+ char *name, *cur, *var;
+
+ (*nb_ctrls)++;
+ if (!(*nb_ctrls & (*nb_ctrls - 1))) {
+ *allctrls = av_realloc_f(*allctrls, sizeof(**allctrls),
+ (*nb_ctrls << 1) - 1);
+ if (!*allctrls)
+ return AVERROR(ENOMEM);
+ }
+ (*allctrls)[*nb_ctrls - 1] = *qctrl;
+ qctrl = &(*allctrls)[*nb_ctrls - 1];
+
+ /* "Control Name" -> "control_name", similar to name2var from v4l-utils */
+ for (name = cur = var = qctrl->name; *cur; cur++) {
+ unsigned c = *cur;
+ if ((c | 0x20) - 'a' < 26 || c - '0' < 10) {
+ *(var++) = av_tolower(*cur);
+ } else {
+ if (var > name && var[-1] != '_')
+ *(var++) = '_';
+ }
+ }
+ while (var > name && var[-1] == '_')
+ var--;
+ *var = 0;
+
+ return 0;
+}
+
+static int set_controls(AVFormatContext *s1)
+{
+ struct video_data *s = s1->priv_data;
+ struct v4l2_queryctrl qctrl, *allctrls = NULL;
+ struct v4l2_ext_control extctrl;
+ struct v4l2_ext_controls extctrls;
+ unsigned nb_ctrls = 0, i;
+ const char *opt = s->controls;
+ char *ctrl, *val, *tail;
+ long long vall;
+ int ret;
+
+ memset(&qctrl, 0, sizeof(qctrl));
+ qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
+ while (1) {
+ if (v4l2_ioctl(s->fd, VIDIOC_QUERYCTRL, &qctrl) < 0)
+ break;
+ if ((ret = add_control(&allctrls, &nb_ctrls, &qctrl)) < 0)
+ goto fail;
+ qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+ }
+
+ while (*opt) {
+ ret = av_opt_get_key_value(&opt, "=", ":", 0, &ctrl, &val);
+ if (ret < 0) {
+ av_log(s1, AV_LOG_ERROR, "Error in controls string near '%s': %s\n",
+ opt, av_err2str(ret));
+ goto fail;
+ }
+ for (i = 0; i < nb_ctrls; i++)
+ if (!strcmp(ctrl, allctrls[i].name))
+ break;
+ if (i >= nb_ctrls) {
+ av_log(s1, AV_LOG_ERROR, "Unknown control '%s'\n", ctrl);
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ av_log(s1, AV_LOG_VERBOSE, "Setting control %s to '%s'\n", ctrl, val);
+ memset(&extctrl, 0, sizeof(extctrl));
+ extctrl.id = allctrls[i].id;
+ switch (allctrls[i].type) {
+ case V4L2_CTRL_TYPE_INTEGER:
+ case V4L2_CTRL_TYPE_BOOLEAN:
+ case V4L2_CTRL_TYPE_MENU:
+ case V4L2_CTRL_TYPE_BUTTON:
+#ifdef V4L2_CTRL_CLASS_FLASH /* hack V4L2_CTRL_TYPE_BITMASK is an enum,
+ V4L2_CTRL_CLASS_FLASH was added just after */
+ case V4L2_CTRL_TYPE_BITMASK:
+#endif
+ case V4L2_CTRL_TYPE_INTEGER64:
+ vall = strtoll(val, &tail, 0);
+ if (*tail) {
+ av_log(s1, AV_LOG_ERROR, "Invalid numeric value '%s'\n", val);
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ if (allctrls[i].type == V4L2_CTRL_TYPE_INTEGER64)
+#if AV_GCC_VERSION_AT_LEAST(4,6)
+ extctrl.value64 = vall;
+#else
+ /* gcc < 4.6 does not support unnamed structures declared in
+ headers in c99 mode, access the field hackishly, hoping
+ the layout does not change soon */
+ *(__s64 *)(&extctrl.reserved2 + 1) = vall;
+#endif
+ else
+#if AV_GCC_VERSION_AT_LEAST(4,6)
+ extctrl.value = vall;
+#else
+ *(__s32 *)(&extctrl.reserved2 + 1) = vall;
+#endif
+ break;
+ case V4L2_CTRL_TYPE_STRING:
+ extctrl.size = strlen(val) + 1;
+ extctrl.string = val;
+ break;
+ default:
+ av_log(s1, AV_LOG_ERROR, "Unknown type for control '%s'\n", ctrl);
+ ret = AVERROR(EIO);
+ goto fail;
+ }
+ memset(&extctrls, 0, sizeof(extctrls));
+ extctrls.ctrl_class = 0;
+ extctrls.count = 1;
+ extctrls.controls = &extctrl;
+ if (v4l2_ioctl(s->fd, VIDIOC_S_EXT_CTRLS, &extctrls) < 0) {
+ ret = AVERROR(errno);
+ av_log(s1, AV_LOG_ERROR, "Error setting control %s to '%s': %s\n",
+ ctrl, val, av_err2str(ret));
+ goto fail;
+ }
+ av_freep(&ctrl);
+ av_freep(&val);
+ opt += !!*opt;
+ }
+
+fail:
+ av_freep(&ctrl);
+ av_freep(&val);
+ av_freep(&allctrls);
+ return ret;
+}
+
static int v4l2_set_parameters(AVFormatContext *s1)
{
struct video_data *s = s1->priv_data;
@@ -813,6 +949,10 @@ static int v4l2_set_parameters(AVFormatContext *s1)
s1->streams[0]->avg_frame_rate.den = tpf->numerator;
s1->streams[0]->r_frame_rate = s1->streams[0]->avg_frame_rate;
+ if (s->controls)
+ if ((ret = set_controls(s1)) < 0)
+ return ret;
+
return 0;
}
@@ -1072,6 +1212,8 @@ static const AVOption options[] = {
{ "abs", "use absolute timestamps (wall clock)", OFFSET(ts_mode), AV_OPT_TYPE_CONST, {.i64 = V4L_TS_ABS }, 0, 2, DEC, "timestamps" },
{ "mono2abs", "force conversion from monotonic to absolute timestamps", OFFSET(ts_mode), AV_OPT_TYPE_CONST, {.i64 = V4L_TS_MONO2ABS }, 0, 2, DEC, "timestamps" },
+ { "controls", "set device controls", OFFSET(controls), AV_OPT_TYPE_STRING, {.str = NULL }, 0, 0, DEC },
+
{ NULL },
};
--
1.7.10.4
More information about the ffmpeg-devel
mailing list