Add a pipeline config parameter "return_newest_frames" to always use the
most recently captured Unicam frame when processing a request. This effectively
stops the pipeline handler from queuing Unicam buffers and processing requests
using the buffer at the front of the queue.
Note that setting this parameter might incur unnecessary frame drops during
times of high transient CPU loads where the application might not be able to
provide requests quick enough.
Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
---
.../pipeline/raspberrypi/data/default.json | 7 +++++-
.../pipeline/raspberrypi/raspberrypi.cpp | 23 +++++++++++++++++++
2 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/src/libcamera/pipeline/raspberrypi/data/default.json b/src/libcamera/pipeline/raspberrypi/data/default.json
index 707414bcc5c5..eda053258c67 100644
--- a/src/libcamera/pipeline/raspberrypi/data/default.json
+++ b/src/libcamera/pipeline/raspberrypi/data/default.json
@@ -18,6 +18,11 @@
"num_output0_buffers": 1,
# Override any request from the IPA to drop a number of startup frames.
- "disable_startup_frame_drops": false
+ "disable_startup_frame_drops": false,
+
+ # Always process a pending request with the last captured sensor frame.
+ # Note that this might lead to avoidable frame drops during periods
+ # of transient heavy CPU loading.
+ "return_newest_frames": false
}
}
diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index ef49d32037af..a369fbd2a528 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -317,6 +317,11 @@ public:
* frames.
*/
bool disableStartupFrameDrops;
+ /*
+ * Always process a pending request with the last captured sensor
+ * frame.
+ */
+ bool returnNewestFrames;
};
Config config_;
@@ -1457,6 +1462,7 @@ int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
.minTotalUnicamBuffers = 4,
.numOutput0Buffers = 1,
.disableStartupFrameDrops = false,
+ .returnNewestFrames = false,
};
char const *configFromEnv = utils::secure_getenv("LIBCAMERA_RPI_CONFIG_FILE");
@@ -1493,6 +1499,8 @@ int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
phConfig["num_output0_buffers"].get<unsigned int>(config.numOutput0Buffers);
config.disableStartupFrameDrops =
phConfig["disable_startup_frame_drops"].get<bool>(config.disableStartupFrameDrops);
+ config.returnNewestFrames =
+ phConfig["return_newest_frames"].get<bool>(config.returnNewestFrames);
if (config.minTotalUnicamBuffers < config.minUnicamBuffers) {
LOG(RPI, Error) << "Invalid configuration: min_total_unicam_buffers must be >= min_unicam_buffers!";
@@ -2349,6 +2357,21 @@ bool RPiCameraData::findMatchingBuffers(BayerFrame &bayerFrame, FrameBuffer *&em
if (bayerQueue_.empty())
return false;
+ /*
+ * If the pipeline is configured to only ever return the most recently
+ * captured frame, empty the buffer queue until a single element is
+ * left, corresponding to the most recent buffer. Note that this will
+ * likely result in possibly avoidable dropped frames.
+ */
+ if (config_.returnNewestFrames && !unicam_[Unicam::Image].isExternal()) {
+ while (bayerQueue_.size() > 1) {
+ FrameBuffer *bayer = bayerQueue_.front().buffer;
+
+ unicam_[Unicam::Image].returnBuffer(bayer);
+ bayerQueue_.pop();
+ }
+ }
+
/*
* Find the embedded data buffer with a matching timestamp to pass to
* the IPA. Any embedded buffers with a timestamp lower than the
--
2.25.1