// Copyright 2019, Collabora, Ltd. // SPDX-License-Identifier: BSL-1.0 /*! * @file * @brief V4L2 frameserver implementation * @author Pete Black * @author Jakob Bornecrantz * @ingroup drv_v4l2 */ #include "util/u_misc.h" #include "util/u_debug.h" #include "util/u_format.h" #include "xrt/xrt_frameserver.h" #include "v4l2_interface.h" #include #include #include #include #include #include #include #include #include /* * * Defines. * */ #define V_SPEW(p, ...) \ do { \ if (p->print_spew) { \ fprintf(stderr, "%s - ", __func__); \ fprintf(stderr, __VA_ARGS__); \ fprintf(stderr, "\n"); \ } \ } while (false) #define V_DEBUG(p, ...) \ do { \ if (p->print_debug) { \ fprintf(stderr, "%s - ", __func__); \ fprintf(stderr, __VA_ARGS__); \ fprintf(stderr, "\n"); \ } \ } while (false) #define V_ERROR(p, ...) \ do { \ fprintf(stderr, "%s - ", __func__); \ fprintf(stderr, __VA_ARGS__); \ fprintf(stderr, "\n"); \ } while (false) #define V_CONTROL_GET(VID, CONTROL) \ do { \ int _value = 0; \ if (v4l2_control_get(VID, V4L2_CID_##CONTROL, &_value) != 0) { \ V_ERROR(VID, "failed to get V4L2_CID_" #CONTROL); \ } else { \ V_DEBUG(VID, "V4L2_CID_" #CONTROL " = %i", _value); \ } \ } while (false); #define V_CONTROL_SET(VID, CONTROL, VALUE) \ do { \ if (v4l2_control_set(VID, V4L2_CID_##CONTROL, VALUE) != 0) { \ V_ERROR(VID, "failed to set V4L2_CID_" #CONTROL); \ } \ } while (false); DEBUG_GET_ONCE_BOOL_OPTION(v4l2_options, "V4L2_PRINT_OPTIONS", false) DEBUG_GET_ONCE_BOOL_OPTION(v4l2_spew, "V4L2_PRINT_SPEW", false) DEBUG_GET_ONCE_BOOL_OPTION(v4l2_debug, "V4L2_PRINT_DEBUG", false) DEBUG_GET_ONCE_NUM_OPTION(v4l2_exposure_absolute, "V4L2_EXPOSURE_ABSOLUTE", 15) #define NUM_V4L2_BUFFERS 8 /* * * Structs * */ /*! * A single open v4l2 capture device, starts it's own thread and waits on it. */ struct v4l2_fs { struct xrt_fs base; int fd; struct { bool extended_format; bool timeperframe; } has; struct { bool ps4_cam; bool set_auto_exposure; bool set_exposure_absolute; int value_exposure_absolute; int value_auto_exposure; } quirks; struct { void *mem[NUM_V4L2_BUFFERS]; bool mmap; bool userptr; } capture; struct xrt_fs_sink *sink; pthread_t stream_thread; struct v4l2_source_descriptor *descriptors; uint32_t num_descriptors; uint32_t selected; struct xrt_fs_capture_parameters capture_params; bool is_configured; bool is_running; bool print_spew; bool print_debug; }; /*! * Streaming thread entrypoint */ static void * v4l2_fs_stream_run(void *ptr); /*! * Cast to derived type. */ static inline struct v4l2_fs * v4l2_fs(struct xrt_fs *xfs) { return (struct v4l2_fs *)xfs; } static void dump_controls(struct v4l2_fs *vid); /* * * Misc helper functions * */ XRT_MAYBE_UNUSED static int v4l2_control_get(struct v4l2_fs *vid, uint32_t id, int *out_value) { struct v4l2_control control = {0}; int ret; control.id = id; ret = ioctl(vid->fd, VIDIOC_G_CTRL, &control); if (ret != 0) { return ret; } *out_value = control.value; return 0; } static int v4l2_control_set(struct v4l2_fs *vid, uint32_t id, int value) { struct v4l2_control control = {0}; int ret; control.id = id; control.value = value; ret = ioctl(vid->fd, VIDIOC_S_CTRL, &control); if (ret != 0) { return ret; } return 0; } static int v4l2_query_cap_and_validate(struct v4l2_fs *vid) { int ret; /* * Regular caps. */ struct v4l2_capability cap; ret = ioctl(vid->fd, VIDIOC_QUERYCAP, &cap); if (ret != 0) { V_ERROR(vid, "error: Failed to get v4l2 cap."); return ret; } if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) { // not a video device V_ERROR(vid, "error: Is not a capture device."); return -1; } if (!(cap.capabilities & V4L2_CAP_STREAMING)) { // cannot stream V_ERROR(vid, "error: Can not stream!"); return -1; } if (cap.capabilities & V4L2_CAP_EXT_PIX_FORMAT) { // need to query for extended format info vid->has.extended_format = true; } /* * Stream capture caps. */ struct v4l2_streamparm stream = {0}; stream.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ret = ioctl(vid->fd, VIDIOC_G_PARM, &stream); if (ret != 0) { V_ERROR(vid, "error: Failed to get v4l2 stream param."); return ret; } if (stream.parm.capture.capability & V4L2_CAP_TIMEPERFRAME) { // Does this device support setting the timeperframe interval. vid->has.timeperframe = true; } else { V_DEBUG(vid, "warning: No V4L2_CAP_TIMEPERFRAME"); } // Dump controls. if (debug_get_bool_option_v4l2_options()) { dump_controls(vid); } /* * Find quirks */ char *card = (char *)cap.card; vid->quirks.ps4_cam = strcmp(card, "USB Camera-OV580: USB Camera-OV") == 0; if (vid->quirks.ps4_cam) { // The experimented best controls to best track things. vid->quirks.set_auto_exposure = true; vid->quirks.value_auto_exposure = 2; vid->quirks.set_exposure_absolute = true; vid->quirks.value_exposure_absolute = debug_get_num_option_v4l2_exposure_absolute(); } // Done return 0; } static int v4l2_try_userptr(struct v4l2_fs *vid, struct v4l2_requestbuffers *v_bufrequest) { v_bufrequest->memory = V4L2_MEMORY_USERPTR; if (ioctl(vid->fd, VIDIOC_REQBUFS, v_bufrequest) == 0) { vid->capture.userptr = true; return 0; } V_DEBUG(vid, "info: Driver does not handle userptr buffers."); return -1; } static int v4l2_try_mmap(struct v4l2_fs *vid, struct v4l2_requestbuffers *v_bufrequest) { v_bufrequest->memory = V4L2_MEMORY_MMAP; if (ioctl(vid->fd, VIDIOC_REQBUFS, v_bufrequest) == 0) { vid->capture.mmap = true; return 0; } V_DEBUG(vid, "info: Driver does not mmap userptr buffers."); return -1; } static int v4l2_setup_mmap_buffer(struct v4l2_fs *vid, int index, struct v4l2_buffer *v_buf) { void *ptr = mmap(0, v_buf->length, PROT_READ, MAP_SHARED, vid->fd, v_buf->m.offset); if (ptr == MAP_FAILED) { V_ERROR(vid, "error: Call to mmap failed!"); return -1; } vid->capture.mem[index] = ptr; return 0; } static int v4l2_setup_userptr_buffer(struct v4l2_fs *vid, int index, struct v4l2_buffer *v_buf) { // align this to a memory page, v4l2 likes it that way void *ptr = aligned_alloc(getpagesize(), v_buf->length); if (ptr == NULL) { V_ERROR(vid, "error: Could not alloc page-aligned memory!"); return -1; } vid->capture.mem[index] = ptr; v_buf->m.userptr = (intptr_t)ptr; return 0; } /* * * Mode adding functions. * */ static void v4l2_quirk_apply_ps4(struct v4l2_fs *vid, struct v4l2_source_descriptor *desc) { desc->offset = 32 + 64; desc->base.stereo_format = XRT_FS_STEREO_SBS; switch (desc->stream.width) { case 3448: desc->base.width = 1280 * 2; desc->base.height = 800; break; case 1748: desc->base.width = 640 * 2; desc->base.height = 400; break; case 898: desc->base.width = 320 * 2; desc->base.height = 192; break; default: break; } } static struct v4l2_source_descriptor * v4l2_add_descriptor(struct v4l2_fs *vid) { uint32_t index = vid->num_descriptors++; size_t new_size = vid->num_descriptors * sizeof(struct v4l2_source_descriptor); vid->descriptors = realloc(vid->descriptors, new_size); struct v4l2_source_descriptor *desc = &vid->descriptors[index]; memset(desc, 0, sizeof(*desc)); return desc; } static void v4l2_list_modes_interval(struct v4l2_fs *vid, const struct v4l2_fmtdesc *fmt, const struct v4l2_frmsizeenum *size, const struct v4l2_frmivalenum *interval) { if (interval->discrete.denominator % interval->discrete.numerator == 0) { int fps = interval->discrete.denominator / interval->discrete.numerator; V_DEBUG(vid, "#%i %dx%d@%i", vid->num_descriptors, interval->width, interval->height, fps); } else { double fps = (double)interval->discrete.denominator / (double)interval->discrete.numerator; V_DEBUG(vid, "#%i %dx%d@%f", vid->num_descriptors, interval->width, interval->height, fps); } } static void v4l2_list_modes_size(struct v4l2_fs *vid, const struct v4l2_fmtdesc *fmt, const struct v4l2_frmsizeenum *size) { if (size->type != V4L2_FRMSIZE_TYPE_DISCRETE) { V_DEBUG(vid, "warning: Skipping non discrete frame size."); return; } struct v4l2_frmivalenum interval; U_ZERO(&interval); interval.pixel_format = size->pixel_format; interval.width = size->discrete.width; interval.height = size->discrete.height; // Since we don't keep track of the interval // we only make sure there is at least one. while (ioctl(vid->fd, VIDIOC_ENUM_FRAMEINTERVALS, &interval) == 0) { v4l2_list_modes_interval(vid, fmt, size, &interval); interval.index++; } // We didn't find any frame intervals. if (interval.index == 0) { return; } enum xrt_format format = 0; switch (interval.pixel_format) { case V4L2_PIX_FMT_YUYV: format = XRT_FORMAT_YUV422; break; case V4L2_PIX_FMT_MJPEG: format = XRT_FORMAT_MJPEG; break; default: V_ERROR(vid, "error: Format not supported."); return; } // Allocate new descriptor. struct v4l2_source_descriptor *desc = v4l2_add_descriptor(vid); // Fill out the stream variables. desc->stream.width = interval.width; desc->stream.height = interval.height; desc->stream.format = interval.pixel_format; snprintf(desc->format_name, sizeof(desc->format_name), "%s", fmt->description); if (u_format_is_blocks(format)) { u_format_size_for_dimensions( format, interval.width, interval.height, &desc->stream.stride, &desc->stream.size); } // Fill out the out sink variables. desc->base.stereo_format = XRT_FS_STEREO_NONE; desc->base.format = format; desc->base.width = desc->stream.width; desc->base.height = desc->stream.height; /* * Apply any quirks to the modes. */ if (vid->quirks.ps4_cam) { v4l2_quirk_apply_ps4(vid, desc); } } static void v4l2_list_modes_fmt(struct v4l2_fs *vid, const struct v4l2_fmtdesc *fmt) { V_DEBUG(vid, "format: %s %08x %d", fmt->description, fmt->pixelformat, fmt->type); switch (fmt->pixelformat) { case V4L2_PIX_FMT_YUYV: break; case V4L2_PIX_FMT_MJPEG: break; default: V_ERROR(vid, "error: Unknown pixelformat '%s'", fmt->description); return; } struct v4l2_frmsizeenum size = {0}; size.pixel_format = fmt->pixelformat; while (ioctl(vid->fd, VIDIOC_ENUM_FRAMESIZES, &size) == 0) { v4l2_list_modes_size(vid, fmt, &size); size.index++; } } static void v4l2_list_modes(struct v4l2_fs *vid) { struct v4l2_fmtdesc desc; U_ZERO(&desc); desc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; while (ioctl(vid->fd, VIDIOC_ENUM_FMT, &desc) == 0) { v4l2_list_modes_fmt(vid, &desc); desc.index++; } } /* * * Exported functions. * */ static bool v4l2_fs_enumerate_modes(struct xrt_fs *xfs, struct xrt_fs_mode **out_modes, uint32_t *out_count) { struct v4l2_fs *vid = v4l2_fs(xfs); if (vid->num_descriptors == 0) { return false; } struct xrt_fs_mode *modes = U_TYPED_ARRAY_CALLOC(struct xrt_fs_mode, vid->num_descriptors); if (modes == NULL) { return false; } for (uint32_t i = 0; i < vid->num_descriptors; i++) { modes[i] = vid->descriptors[i].base; } *out_modes = modes; *out_count = vid->num_descriptors; return true; } static bool v4l2_fs_configure_capture(struct xrt_fs *xfs, struct xrt_fs_capture_parameters *cp) { // struct v4l2_fs *vid = v4l2_fs(xfs); //! @todo return false; } static bool v4l2_fs_stream_start(struct xrt_fs *xfs, uint32_t descriptor_index) { struct v4l2_fs *vid = v4l2_fs(xfs); if (descriptor_index >= vid->num_descriptors) { V_ERROR(vid, "error Invalid descriptor_index (%i >= %i)", descriptor_index, vid->num_descriptors); return false; } vid->selected = descriptor_index; vid->is_running = true; if (pthread_create(&vid->stream_thread, NULL, v4l2_fs_stream_run, xfs)) { vid->is_running = false; V_ERROR(vid, "error: Could not create thread"); return false; } V_SPEW(vid, "info: Started!\n"); // we're off to the races! return true; } static bool v4l2_fs_stream_stop(struct xrt_fs *xfs) { struct v4l2_fs *vid = v4l2_fs(xfs); if (!vid->is_running) { return true; } vid->is_running = false; pthread_join(vid->stream_thread, NULL); return true; } static bool v4l2_fs_is_running(struct xrt_fs *xfs) { struct v4l2_fs *vid = v4l2_fs(xfs); return vid->is_running; } static void v4l2_fs_destroy(struct xrt_fs *xfs) { struct v4l2_fs *vid = v4l2_fs(xfs); // Make sure that the stream is stopped. v4l2_fs_stream_stop(xfs); if (vid->descriptors != NULL) { free(vid->descriptors); vid->descriptors = NULL; vid->num_descriptors = 0; } vid->capture.mmap = false; if (vid->capture.userptr) { vid->capture.userptr = false; for (uint32_t i = 0; i < NUM_V4L2_BUFFERS; i++) { free(vid->capture.mem[i]); vid->capture.mem[i] = NULL; } } if (vid->fd >= 0) { close(vid->fd); vid->fd = -1; } free(vid); } struct xrt_fs * v4l2_fs_create(const char *path, struct xrt_fs_sink *sink) { struct v4l2_fs *vid = U_TYPED_CALLOC(struct v4l2_fs); vid->base.enumerate_modes = v4l2_fs_enumerate_modes; vid->base.configure_capture = v4l2_fs_configure_capture; vid->base.stream_start = v4l2_fs_stream_start; vid->base.stream_stop = v4l2_fs_stream_stop; vid->base.is_running = v4l2_fs_is_running; vid->base.destroy = v4l2_fs_destroy; vid->print_spew = debug_get_bool_option_v4l2_spew(); vid->print_debug = debug_get_bool_option_v4l2_debug(); vid->sink = sink; vid->fd = -1; int fd = open(path, O_RDWR, 0); if (fd < 0) { V_ERROR(vid, "Can not open '%s'\n", path); free(vid); return NULL; } vid->fd = fd; int ret = v4l2_query_cap_and_validate(vid); if (ret != 0) { v4l2_fs_destroy(&vid->base); vid = NULL; return NULL; } v4l2_list_modes(vid); return &(vid->base); } void * v4l2_fs_stream_run(void *ptr) { struct xrt_fs *xfs = (struct xrt_fs *)ptr; struct v4l2_fs *vid = v4l2_fs(xfs); V_DEBUG(vid, "info: Thread enter!"); if (vid->fd == -1) { V_ERROR(vid, "error: Device not opened!"); return NULL; } // set up our capture format struct v4l2_source_descriptor *desc = &vid->descriptors[vid->selected]; struct v4l2_format v_format; U_ZERO(&v_format); v_format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; v_format.fmt.pix.width = desc->stream.width; v_format.fmt.pix.height = desc->stream.height; v_format.fmt.pix.pixelformat = desc->stream.format; v_format.fmt.pix.field = V4L2_FIELD_ANY; if (vid->has.extended_format) { v_format.fmt.pix.priv = V4L2_PIX_FMT_PRIV_MAGIC; } if (ioctl(vid->fd, VIDIOC_S_FMT, &v_format) < 0) { V_ERROR(vid, "could not set up format\n"); return NULL; } // set up our buffers - prefer userptr (client alloc) vs mmap (kernel // alloc) // TODO: using buffer caps may be better than 'fallthrough to mmap' struct v4l2_requestbuffers v_bufrequest; U_ZERO(&v_bufrequest); v_bufrequest.count = NUM_V4L2_BUFFERS; v_bufrequest.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (v4l2_try_userptr(vid, &v_bufrequest) != 0 && v4l2_try_mmap(vid, &v_bufrequest) != 0) { V_ERROR(vid, "error: Driver does not support mmap or userptr."); return NULL; } // set up our buffers struct v4l2_buffer v_buf = {0}; for (uint32_t i = 0; i < NUM_V4L2_BUFFERS; i++) { v_buf.index = i; v_buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; v_buf.memory = v_bufrequest.memory; if (ioctl(vid->fd, VIDIOC_QUERYBUF, &v_buf) < 0) { V_ERROR(vid, "error: Could not query buffers!"); return NULL; } if (vid->capture.userptr && v4l2_setup_userptr_buffer(vid, i, &v_buf) != 0) { return NULL; } if (vid->capture.mmap && v4l2_setup_mmap_buffer(vid, i, &v_buf) != 0) { return NULL; } // Silence valgrind. memset(vid->capture.mem[i], 0, v_buf.length); // Queue this buffer if (ioctl(vid->fd, VIDIOC_QBUF, &v_buf) < 0) { V_ERROR(vid, "error: queueing buffer failed!"); return NULL; } } int start_capture = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (ioctl(vid->fd, VIDIOC_STREAMON, &start_capture) < 0) { V_ERROR(vid, "error: Could not start capture!"); return NULL; } /* * Need to set these after we have started the stream. */ if (vid->quirks.set_auto_exposure) { V_CONTROL_SET(vid, EXPOSURE_AUTO, vid->quirks.value_auto_exposure); } if (vid->quirks.set_exposure_absolute) { V_CONTROL_SET(vid, EXPOSURE_ABSOLUTE, vid->quirks.value_exposure_absolute); } struct xrt_fs_frame f = {0}; while (vid->is_running) { if (ioctl(vid->fd, VIDIOC_DQBUF, &v_buf) < 0) { V_ERROR(vid, "error: Dequeue failed!"); vid->is_running = false; break; } V_SPEW(vid, "Got frame %i", v_buf.index); uint8_t *data = vid->capture.mem[v_buf.index]; //! @todo Sequense number and timestamp. f.width = desc->base.width; f.height = desc->base.height; f.format = desc->base.format; f.stereo_format = desc->base.stereo_format; f.data = data + desc->offset; f.stride = desc->stream.stride; f.size = v_buf.bytesused - desc->offset; f.source_id = vid->base.source_id; vid->sink->push_frame(vid->sink, &f); if (ioctl(vid->fd, VIDIOC_QBUF, &v_buf) < 0) { V_ERROR(vid, "error: Requeue failed!"); vid->is_running = false; break; } } V_DEBUG(vid, "info: Thread leave!"); return NULL; } /* * * Helper debug functions. * */ static void dump_menu(struct v4l2_fs *vid, uint32_t id, uint32_t min, uint32_t max) { fprintf(stderr, " Menu items:\n"); struct v4l2_querymenu querymenu = {0}; querymenu.id = id; for (querymenu.index = min; querymenu.index <= max; querymenu.index++) { if (0 != ioctl(vid->fd, VIDIOC_QUERYMENU, &querymenu)) { fprintf(stderr, " %i\n", querymenu.index); continue; } fprintf(stderr, " %i: %s\n", querymenu.index, querymenu.name); } } static void dump_contron_name(uint32_t id) { const char *str = "ERROR"; switch (id) { #define CASE(CONTROL) \ case V4L2_CID_##CONTROL: str = "V4L2_CID_" #CONTROL; break CASE(BRIGHTNESS); CASE(CONTRAST); CASE(SATURATION); CASE(HUE); CASE(AUDIO_VOLUME); CASE(AUDIO_BALANCE); CASE(AUDIO_BASS); CASE(AUDIO_TREBLE); CASE(AUDIO_MUTE); CASE(AUDIO_LOUDNESS); CASE(BLACK_LEVEL); CASE(AUTO_WHITE_BALANCE); CASE(DO_WHITE_BALANCE); CASE(RED_BALANCE); CASE(BLUE_BALANCE); CASE(GAMMA); CASE(EXPOSURE); CASE(AUTOGAIN); CASE(GAIN); CASE(DIGITAL_GAIN); CASE(ANALOGUE_GAIN); CASE(HFLIP); CASE(VFLIP); CASE(POWER_LINE_FREQUENCY); CASE(POWER_LINE_FREQUENCY_DISABLED); CASE(POWER_LINE_FREQUENCY_50HZ); CASE(POWER_LINE_FREQUENCY_60HZ); CASE(POWER_LINE_FREQUENCY_AUTO); CASE(HUE_AUTO); CASE(WHITE_BALANCE_TEMPERATURE); CASE(SHARPNESS); CASE(BACKLIGHT_COMPENSATION); CASE(CHROMA_AGC); CASE(CHROMA_GAIN); CASE(COLOR_KILLER); CASE(COLORFX); CASE(COLORFX_CBCR); CASE(AUTOBRIGHTNESS); CASE(ROTATE); CASE(BG_COLOR); CASE(ILLUMINATORS_1); CASE(ILLUMINATORS_2); CASE(MIN_BUFFERS_FOR_CAPTURE); CASE(MIN_BUFFERS_FOR_OUTPUT); CASE(ALPHA_COMPONENT); // Camera controls CASE(EXPOSURE_AUTO); CASE(EXPOSURE_ABSOLUTE); CASE(EXPOSURE_AUTO_PRIORITY); CASE(AUTO_EXPOSURE_BIAS); CASE(PAN_RELATIVE); CASE(TILT_RELATIVE); CASE(PAN_RESET); CASE(TILT_RESET); CASE(PAN_ABSOLUTE); CASE(TILT_ABSOLUTE); CASE(FOCUS_ABSOLUTE); CASE(FOCUS_RELATIVE); CASE(FOCUS_AUTO); CASE(ZOOM_ABSOLUTE); CASE(ZOOM_RELATIVE); CASE(ZOOM_CONTINUOUS); CASE(PRIVACY); CASE(IRIS_ABSOLUTE); CASE(IRIS_RELATIVE); #undef CASE default: fprintf(stderr, "0x%08x", id); return; } fprintf(stderr, "%s", str); } static void dump_controls(struct v4l2_fs *vid) { struct v4l2_queryctrl queryctrl = {0}; queryctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL; while (0 == ioctl(vid->fd, VIDIOC_QUERYCTRL, &queryctrl)) { fprintf(stderr, "Control "); dump_contron_name(queryctrl.id); fprintf(stderr, " '%s'", queryctrl.name); #define V_CHECK(FLAG) \ do { \ if (queryctrl.flags & V4L2_CTRL_FLAG_##FLAG) { \ fprintf(stderr, ", " #FLAG); \ } \ } while (false) V_CHECK(DISABLED); V_CHECK(GRABBED); V_CHECK(READ_ONLY); V_CHECK(UPDATE); V_CHECK(INACTIVE); V_CHECK(SLIDER); V_CHECK(WRITE_ONLY); V_CHECK(VOLATILE); V_CHECK(HAS_PAYLOAD); V_CHECK(EXECUTE_ON_WRITE); V_CHECK(MODIFY_LAYOUT); #undef V_CHECK fprintf(stderr, "\n"); if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) { continue; } if (queryctrl.type == V4L2_CTRL_TYPE_MENU) { dump_menu(vid, queryctrl.id, queryctrl.minimum, queryctrl.maximum); } queryctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; } }