[libcamera-devel] [PATCH v5 2/2] gstreamer: Provide framerate support for libcamerasrc.
Umang Jain
umang.jain at ideasonboard.com
Wed Nov 2 13:13:28 CET 2022
Hi Rishi,
Thank you for the patch.
On 9/15/22 5:17 PM, Rishikesh Donadkar wrote:
> Control the framerate by setting the controls::FrameDurationLimits
> in an ControlList and passing the control list at camera::start(). This
> requires converting the framerate which of the type
> GST_TYPE_FRACTION into FrameDuration which of the type int64_t. This
> conversion causes loss of precision and the precise framerate cannot be
> obtained by Inverting the control::FrameDurationLimits value.
>
> Example -
>
> * Suppose the framerate requested is 35/1. The framerate is read form
> the caps in the from of fraction that has a numerator and
> denominator.
>
> * Converting to FrameDuration (in microseconds)
> (1 * 10^6) / 35 = 28571.4286
> int64_t frame_duration = 28571
> (the precision here is lost.)
> * To expose the framerate in caps, Inverting the frame_duration to get
> back the framerate and converting to Seconds.
> double framerate = 10^6 / 28571
> and
> 10^6/28571 which is close but not equal to 35/1 will fail the negotiation.
I would summarise this, stating that now we preserve the fraction in a
GstContainer and expose it similarly in the caps.
>
> Get the framerate from the caps and convert it to FrameDuration.
>
> Clamp the frame_duration between the min/max FrameDuration supported
> by the camera. Set the FrameDurationLimits control in the initControls_.
> Store the clamped/unclamped framerate in the container to be retrieved later.
>
> Set the bound checked framerate from the container into the caps.
>
> Pass the ControlList initControls_ at camera->start().
>
> Signed-off-by: Rishikesh Donadkar<rishikeshdonadkar at gmail.com>
> ---
> src/gstreamer/gstlibcamera-utils.cpp | 70 ++++++++++++++++++++++++++++
> src/gstreamer/gstlibcamera-utils.h | 6 +++
> src/gstreamer/gstlibcamerasrc.cpp | 16 ++++++-
> 3 files changed, 91 insertions(+), 1 deletion(-)
>
> diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
> index 244a4a79..89f116ba 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 +408,75 @@ gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
> }
> }
>
> +void gst_libcamera_get_framerate_from_caps([[maybe_unused]] GstCaps *caps,
no need for [[maybe_unused]]
> + GstStructure *container)
> +{
> + GstStructure *s = gst_caps_get_structure(caps, 0);
> + gint fps_n = 0, fps_d = 1;
this is problematic. If you set fps_n = 0, it will be divide by 0 for
frame_duration calculation in
gst_libcamera_clamp_and_set_frameduration() as an edge case.
Instead, I would treat this as a default value (set in case there is a
error below and set the framerate as 30/1 hence,
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_structure_set(container, "framerate", GST_TYPE_FRACTION, fps_n, fps_d, nullptr);
> + else
> + GST_WARNING("invalid framerate in the caps.");
> + }
this can better be reworked as :
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 &controls, const ControlInfoMap &camera_controls,
Would shorten names
s/controls/ctrls
s/camera_controls/cam_ctrls
and reflow
> + GstStructure *container)
> +{
> + gboolean in_bounds = false;
> + gint fps_caps_n, fps_caps_d, fps_n, fps_d;
> +
> + if (!gst_structure_has_field_typed(container, "framerate", GST_TYPE_FRACTION))
> + return;
> +
> + auto iterFrameDuration = camera_controls.find(controls::FrameDurationLimits.id());
> + if (iterFrameDuration == camera_controls.end()) {
> + GST_WARNING("Valid bounds for FrameDuration not found");
> + 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) {
> + double framerate_clamped = 1000000.0 / frame_duration;
> + gst_util_double_to_fraction(framerate_clamped, &fps_n, &fps_d);
> + gst_structure_set(container, "framerate", GST_TYPE_FRACTION, fps_n, fps_d, nullptr);
> + }
> +
> + controls.set(controls::FrameDurationLimits,
> + Span<const int64_t, 2>({ 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..37f07676 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;
> @@ -496,6 +499,7 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
> /* Retrieve the supported caps. */
> g_autoptr(GstCaps) filter = gst_libcamera_stream_formats_to_caps(stream_cfg.formats());
> g_autoptr(GstCaps) caps = gst_pad_peer_query_caps(srcpad, filter);
> +
unwanted
These changes are already addressed on my branch. So no need to follow
up on these.
I added a few comments as well, which you can see in v6 (will be posted
shortly)
> if (gst_caps_is_empty(caps)) {
> flow_ret = GST_FLOW_NOT_NEGOTIATED;
> break;
> @@ -504,6 +508,7 @@ 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 +530,10 @@ 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 +541,11 @@ 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 +579,7 @@ 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 +589,8 @@ 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);
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