Skip to content

Fix grab-compute-capping-fps latency regression in zedsrc #97

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
adujardin wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Fix grab-compute-capping-fps latency regression in zedsrc #97

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
25 changes: 21 additions & 4 deletions gst-zed-src/gstzedsrc.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1856,6 +1856,7 @@ static void gst_zedsrc_reset(GstZedSrc *src) {

src->out_framesize = 0;
src->is_started = FALSE;
src->effective_fps = 0;

src->last_frame_count = 0;
src->total_dropped_frames = 0;
Expand Down Expand Up @@ -2946,6 +2947,19 @@ static gboolean gst_zedsrc_calculate_caps(GstZedSrc *src) {

fps = static_cast<gint>(cam_info.camera_configuration.fps);

// When grab_compute_capping_fps is active and lower than camera FPS,
// use it as the effective output framerate so downstream elements
// (queues, muxers, sinks) schedule correctly and don't add latency.
if (src->grab_compute_capping_fps > 0.0f &&
src->grab_compute_capping_fps < static_cast<float>(fps)) {
GST_INFO_OBJECT(src,
"grab_compute_capping_fps (%.1f) < camera FPS (%d), "
"using capped rate as effective output FPS",
src->grab_compute_capping_fps, fps);
fps = static_cast<gint>(src->grab_compute_capping_fps);
}
src->effective_fps = fps;

if (format != GST_VIDEO_FORMAT_UNKNOWN) {
gst_video_info_init(&vinfo);
gst_video_info_set_format(&vinfo, format, width, height);
Expand Down Expand Up @@ -3555,10 +3569,10 @@ static gboolean gst_zedsrc_query(GstBaseSrc *bsrc, GstQuery *query) {
return FALSE;
}

// Calculate latency based on configured FPS
// Latency is approximately one frame duration
if (src->camera_fps > 0) {
min_latency = gst_util_uint64_scale_int(GST_SECOND, 1, src->camera_fps);
// Calculate latency based on effective output FPS
// (accounts for grab_compute_capping_fps when active)
if (src->effective_fps > 0) {
min_latency = gst_util_uint64_scale_int(GST_SECOND, 1, src->effective_fps);
max_latency = min_latency * 2; // Allow some buffer for processing
} else {
// Fallback to 30 FPS assumption
Expand Down Expand Up @@ -3930,6 +3944,9 @@ static void gst_zedsrc_attach_metadata(GstZedSrc *src, GstBuffer *buf, GstClockT
GST_BUFFER_TIMESTAMP(buf) =
GST_CLOCK_DIFF(gst_element_get_base_time(GST_ELEMENT(src)), clock_time);
GST_BUFFER_DTS(buf) = GST_BUFFER_TIMESTAMP(buf);
if (src->effective_fps > 0) {
GST_BUFFER_DURATION(buf) = gst_util_uint64_scale_int(GST_SECOND, 1, src->effective_fps);
}
GST_BUFFER_OFFSET(buf) = src->buffer_index++;
// <---- Timestamp meta-data

Expand Down
2 changes: 2 additions & 0 deletions gst-zed-src/gstzedsrc.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,8 @@ struct _GstZedSrc {
guint32 total_dropped_frames;
guint64 buffer_index; // Frame counter for buffer offset

gint effective_fps; // Effective output FPS (accounts for grab_compute_capping_fps)

GstCaps *caps;
guint out_framesize;

Expand Down