[libcamera-devel] [PATCH v6 2/2] gstreamer: Provide framerate support for libcamerasrc
Umang Jain
umang.jain at ideasonboard.com
Wed Nov 2 15:13:13 CET 2022
Hello,
On 11/2/22 7:26 PM, Umang Jain wrote:
> From: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
>
> Control the framerate by passing the controls::FrameDurationLimits
> during Camera::start(). Framerate in gstreamer is expressed as
> GST_TYPE_FRACTION so we maximise on maintaining it as a fraction
> throughout and only do arithematic computations as and when required
> (to compute frame-duration and vice-versa).
>
> To weed out abritrary framerate as input, place the clamping via the
> controls::FrameDurationLimits provided after camera::configure() phase.
> This is handled by a helper function
> gst_libcamera_clamp_and_set_frameduration().
>
> Set the bound checked framerate (done in the above mentioned helper)
> into the caps and pass the ControlList containing the frame-duration
> to Camera::start(ctrls).
>
> Signed-off-by: Rishikesh Donadkar <rishikeshdonadkar at gmail.com>
> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> Tested-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
> src/gstreamer/gstlibcamera-utils.cpp | 78 ++++++++++++++++++++++++++++
> src/gstreamer/gstlibcamera-utils.h | 6 +++
> src/gstreamer/gstlibcamerasrc.cpp | 15 +++++-
> 3 files changed, 98 insertions(+), 1 deletion(-)
>
> diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
> index 244a4a79..c14f72ec 100644
> --- a/src/gstreamer/gstlibcamera-utils.cpp
> +++ b/src/gstreamer/gstlibcamera-utils.cpp
> @@ -8,6 +8,7 @@
>
> #include "gstlibcamera-utils.h"
>
> +#include <libcamera/control_ids.h>
> #include <libcamera/formats.h>
>
> using namespace libcamera;
> @@ -407,6 +408,83 @@ gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
> }
> }
>
> +void gst_libcamera_get_framerate_from_caps(GstCaps *caps,
> + GstStructure *container)
> +{
> + GstStructure *s = gst_caps_get_structure(caps, 0);
> + /*
> + * Default to 30 fps. If the "framerate" fraction is invalid below,
> + * libcamerasrc will set 30fps as the framerate.
> + */
> + gint fps_n = 30, fps_d = 1;
> +
> + if (gst_structure_has_field_typed(s, "framerate", GST_TYPE_FRACTION)) {
> + if (!gst_structure_get_fraction(s, "framerate", &fps_n, &fps_d))
> + GST_WARNING("Invalid framerate in the caps");
> + }
> +
> + gst_structure_set(container, "framerate", GST_TYPE_FRACTION,
> + fps_n, fps_d, nullptr);
> +}
> +
> +void gst_libcamera_clamp_and_set_frameduration(ControlList &initCtrls,
> + const ControlInfoMap &cam_ctrls,
> + GstStructure *container)
> +{
> + gboolean in_bounds = false;
> + gint fps_caps_n, fps_caps_d;
> +
> + if (!gst_structure_has_field_typed(container, "framerate", GST_TYPE_FRACTION))
> + return;
> +
> + auto iterFrameDuration = cam_ctrls.find(controls::FrameDurationLimits.id());
> + if (iterFrameDuration == cam_ctrls.end()) {
> + GST_WARNING("FrameDurationLimits not found in camera controls.");
> + return;
> + }
> +
> + const GValue *framerate = gst_structure_get_value(container, "framerate");
> +
> + fps_caps_n = gst_value_get_fraction_numerator(framerate);
> + fps_caps_d = gst_value_get_fraction_denominator(framerate);
> +
> + int64_t frame_duration = (fps_caps_d * 1000000.0) / fps_caps_n;
> + int64_t min_frame_duration = iterFrameDuration->second.min().get<int64_t>();
> + int64_t max_frame_duration = iterFrameDuration->second.max().get<int64_t>();
> +
> + if (frame_duration < min_frame_duration) {
> + frame_duration = min_frame_duration;
> + } else if (frame_duration > max_frame_duration) {
> + frame_duration = max_frame_duration;
> + } else {
> + in_bounds = true;
> + }
> +
> + if (!in_bounds) {
> + gint framerate_clamped = 1000000 / frame_duration;
> +
> + /* Update the framerate which then will be exposed in caps. */
> + gst_structure_set(container, "framerate", GST_TYPE_FRACTION,
> + framerate_clamped, 1, nullptr);
So the logic here is that, if the input is too high/low fps - it will be
bound to min/max FrameDuration and exposed it caps.
It doesn't mean, the camera will go on to stream ... it means that
bound-limit will be exposed in caps but the negotiation will probably
fail (representing that the fps requested was too high/low and not
supported by the camera)
For e.g.
Input: framerate=100/1
[[capped to framerate=43/1 by this patch on OV5647 ]]
Exposed in caps : framerate=43/1
[[negotation failed]]
Expected framerate=100/1 but got framerate=43/1
It seems to me this is expected. But I am not 100% sure here.
Can the expectation be to stream the camera somehow (not sure how to
surpass negotitaiton in caps) with the bound-limit set? Probably worth
exploring other gstreamer plugins specific to framerate handling...
> + }
> +
> + initCtrls.set(controls::FrameDurationLimits,
> + { frame_duration, frame_duration });
> +}
> +
> +void gst_libcamera_framerate_to_caps(GstCaps *caps, const GValue *container)
> +{
> + if (!GST_VALUE_HOLDS_FRACTION(container))
> + return;
> +
> + GstStructure *s = gst_caps_get_structure(caps, 0);
> + gint fps_caps_n, fps_caps_d;
> +
> + fps_caps_n = gst_value_get_fraction_numerator(container);
> + fps_caps_d = gst_value_get_fraction_denominator(container);
> + gst_structure_set(s, "framerate", GST_TYPE_FRACTION, fps_caps_n, fps_caps_d, nullptr);
> +}
> +
> #if !GST_CHECK_VERSION(1, 17, 1)
> gboolean
> gst_task_resume(GstTask *task)
> diff --git a/src/gstreamer/gstlibcamera-utils.h b/src/gstreamer/gstlibcamera-utils.h
> index 164189a2..3d217fcf 100644
> --- a/src/gstreamer/gstlibcamera-utils.h
> +++ b/src/gstreamer/gstlibcamera-utils.h
> @@ -9,6 +9,7 @@
> #pragma once
>
> #include <libcamera/camera_manager.h>
> +#include <libcamera/controls.h>
> #include <libcamera/stream.h>
>
> #include <gst/gst.h>
> @@ -18,6 +19,11 @@ GstCaps *gst_libcamera_stream_formats_to_caps(const libcamera::StreamFormats &fo
> GstCaps *gst_libcamera_stream_configuration_to_caps(const libcamera::StreamConfiguration &stream_cfg);
> void gst_libcamera_configure_stream_from_caps(libcamera::StreamConfiguration &stream_cfg,
> GstCaps *caps);
> +void gst_libcamera_get_framerate_from_caps(GstCaps *caps, GstStructure *container);
> +void gst_libcamera_clamp_and_set_frameduration(libcamera::ControlList &controls,
> + const libcamera::ControlInfoMap &camera_controls, GstStructure *container);
> +void gst_libcamera_framerate_to_caps(GstCaps *caps, const GValue *container);
> +
> #if !GST_CHECK_VERSION(1, 17, 1)
> gboolean gst_task_resume(GstTask *task);
> #endif
> diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
> index 60032236..955d6eac 100644
> --- a/src/gstreamer/gstlibcamerasrc.cpp
> +++ b/src/gstreamer/gstlibcamerasrc.cpp
> @@ -131,6 +131,7 @@ struct GstLibcameraSrcState {
> std::queue<std::unique_ptr<RequestWrap>> completedRequests_
> LIBCAMERA_TSA_GUARDED_BY(lock_);
>
> + ControlList initControls_;
> guint group_id_;
>
> int queueRequest();
> @@ -462,6 +463,8 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> GstFlowReturn flow_ret = GST_FLOW_OK;
> gint ret;
>
> + GstStructure *container = gst_structure_new_empty("container");
> +
> GST_DEBUG_OBJECT(self, "Streaming thread has started");
>
> gint stream_id_num = 0;
> @@ -504,6 +507,7 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> /* Fixate caps and configure the stream. */
> caps = gst_caps_make_writable(caps);
> gst_libcamera_configure_stream_from_caps(stream_cfg, caps);
> + gst_libcamera_get_framerate_from_caps(caps, container);
> }
>
> if (flow_ret != GST_FLOW_OK)
> @@ -525,6 +529,10 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> goto done;
> }
>
> + /* Check frame duration bounds within controls::FrameDurationLimits */
> + gst_libcamera_clamp_and_set_frameduration(state->initControls_,
> + state->cam_->controls(), container);
> +
> /*
> * Regardless if it has been modified, create clean caps and push the
> * caps event. Downstream will decide if the caps are acceptable.
> @@ -532,8 +540,11 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> for (gsize i = 0; i < state->srcpads_.size(); i++) {
> GstPad *srcpad = state->srcpads_[i];
> const StreamConfiguration &stream_cfg = state->config_->at(i);
> + const GValue *framerate = gst_structure_get_value(container, "framerate");
>
> g_autoptr(GstCaps) caps = gst_libcamera_stream_configuration_to_caps(stream_cfg);
> + gst_libcamera_framerate_to_caps(caps, framerate);
> +
> if (!gst_pad_push_event(srcpad, gst_event_new_caps(caps))) {
> flow_ret = GST_FLOW_NOT_NEGOTIATED;
> break;
> @@ -567,7 +578,7 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> gst_flow_combiner_add_pad(self->flow_combiner, srcpad);
> }
>
> - ret = state->cam_->start();
> + ret = state->cam_->start(&state->initControls_);
> if (ret) {
> GST_ELEMENT_ERROR(self, RESOURCE, SETTINGS,
> ("Failed to start the camera: %s", g_strerror(-ret)),
> @@ -577,6 +588,8 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> }
>
> done:
> + state->initControls_.clear();
> + g_free(container);
> switch (flow_ret) {
> case GST_FLOW_NOT_NEGOTIATED:
> GST_ELEMENT_FLOW_ERROR(self, flow_ret);
More information about the libcamera-devel
mailing list