<div dir="ltr"><div dir="ltr">Hi David,<div><br></div><div>Thank you for your feedback.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 15 Apr 2021 at 15:26, David Plowman <<a href="mailto:david.plowman@raspberrypi.com">david.plowman@raspberrypi.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Naush<br>
<br>
Thanks for this patch, I think it's a good idea!<br>
<br>
On Thu, 15 Apr 2021 at 11:18, Naushir Patuck <<a href="mailto:naush@raspberrypi.com" target="_blank">naush@raspberrypi.com</a>> wrote:<br>
><br>
> The controller algorithms currently run on every frame provided to the<br>
> IPA by the pipeline handler. This may be undesirable for very fast fps<br>
> operating modes where it could significantly increase the computation<br>
> cycles (per unit time) without providing any significant changes to the<br>
> IQ parameters. The added latencies could also cause dropped frames.<br>
><br>
> Pass the FrameBuffer timestamp to the IPA through the controls. This<br>
> timestamp will be used to rate-limit the controller algorithms to run<br>
> with a minimum inter-frame time given by a compile time constant,<br>
> currently set to 16.66ms.<br>
><br>
> Signed-off-by: Naushir Patuck <<a href="mailto:naush@raspberrypi.com" target="_blank">naush@raspberrypi.com</a>><br>
> ---<br>
> src/ipa/raspberrypi/raspberrypi.cpp | 39 ++++++++++++++++++-<br>
> .../pipeline/raspberrypi/raspberrypi.cpp | 5 +++<br>
> 2 files changed, 42 insertions(+), 2 deletions(-)<br>
><br>
> diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp<br>
> index dad6395f0823..aa071473d6e7 100644<br>
> --- a/src/ipa/raspberrypi/raspberrypi.cpp<br>
> +++ b/src/ipa/raspberrypi/raspberrypi.cpp<br>
> @@ -61,6 +61,14 @@ constexpr unsigned int DefaultExposureTime = 20000;<br>
> constexpr double defaultMinFrameDuration = 1e6 / 30.0;<br>
> constexpr double defaultMaxFrameDuration = 1e6 / 0.01;<br>
><br>
> +/*<br>
> + * Determine the minimum allowable inter-frame duration (in us) to run the<br>
> + * controller algorithms. If the pipeline handler provider frames at a rate<br>
> + * higher than this, we rate-limit the controller prepare() and process() calls<br>
<br>
It wasn't clear to me whether prepare() was being rate-limited too?<br>
More on that below...<br>
<br>
> + * to lower than or equal to this rate.<br>
> + */<br>
> +constexpr double controllerMinFrameDuration = 1e6 / 60.0;<br>
> +<br>
> LOG_DEFINE_CATEGORY(IPARPI)<br>
><br>
> class IPARPi : public ipa::RPi::IPARPiInterface<br>
> @@ -68,7 +76,7 @@ class IPARPi : public ipa::RPi::IPARPiInterface<br>
> public:<br>
> IPARPi()<br>
> : controller_(), frameCount_(0), checkCount_(0), mistrustCount_(0),<br>
> - lsTable_(nullptr), firstStart_(true)<br>
> + lastRunTimestamp_(0), lsTable_(nullptr), firstStart_(true)<br>
> {<br>
> }<br>
><br>
> @@ -145,6 +153,12 @@ private:<br>
> /* How many frames we should avoid running control algos on. */<br>
> unsigned int mistrustCount_;<br>
><br>
> + /* Frame timestamp for the last run of the controller. */<br>
> + uint64_t lastRunTimestamp_;<br>
> +<br>
> + /* Do we run a Controller::process() for this frame? */<br>
> + bool processPending_;<br>
> +<br>
> /* LS table allocation passed in from the pipeline handler. */<br>
> FileDescriptor lsTableHandle_;<br>
> void *lsTable_;<br>
> @@ -406,7 +420,7 @@ void IPARPi::signalStatReady(uint32_t bufferId)<br>
> {<br>
> if (++checkCount_ != frameCount_) /* assert here? */<br>
> LOG(IPARPI, Error) << "WARNING: Prepare/Process mismatch!!!";<br>
> - if (frameCount_ > mistrustCount_)<br>
> + if (processPending_ && frameCount_ > mistrustCount_)<br>
> processStats(bufferId);<br>
<br>
Although not related directly to this bit of code, I wonder whether we<br>
have an interaction between skipping the algorithms and the frame<br>
dropping that we do at startup (while waiting for those algorithms to<br>
converge)? i.e. are we elapsing those "drop frames" at a faster rate<br>
than the IPA can run in order to achieve convergence during those<br>
frames?<br></blockquote><div><br></div><div>Yes, this is possible. Perhaps I should change the logic a bit so that we</div><div>run controller prepare()/process() on every frame when frameCount_ <= mistrustCount_.</div><div>This is not going to cause any problems, as mistrustCount_ is only a few frames.</div><div>What do you think?</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
><br>
> reportMetadata();<br>
> @@ -894,6 +908,7 @@ void IPARPi::returnEmbeddedBuffer(unsigned int bufferId)<br>
><br>
> void IPARPi::prepareISP(const ipa::RPi::ISPConfig &data)<br>
> {<br>
> + int64_t frameTimestamp = data.controls.get(controls::draft::SensorTimestamp);<br>
> struct DeviceStatus deviceStatus = {};<br>
> bool success = false;<br>
><br>
> @@ -919,6 +934,26 @@ void IPARPi::prepareISP(const ipa::RPi::ISPConfig &data)<br>
> fillDeviceStatus(exposureLines, gainCode, deviceStatus);<br>
> }<br>
><br>
> + if (lastRunTimestamp_ &&<br>
> + frameTimestamp - lastRunTimestamp_ < controllerMinFrameDuration * 1e3) {<br>
> + /*<br>
> + * Ensure we update the controller metadata with the new frame's<br>
> + * exposure/gain values so that the correct values are returned<br>
> + * out in libcamera metadata later on. All other metadata values<br>
> + * must remain the same as the last frame.<br>
> + */<br>
> + rpiMetadata_.Set("device.status", deviceStatus);<br>
> + processPending_ = false;<br>
> + LOG(IPARPI, Debug) << "Rate-limiting the controller! inter-frame duration: "<br>
> + << frameTimestamp - lastRunTimestamp_<br>
> + << ", min duration "<br>
> + << controllerMinFrameDuration * 1e3;<br>
> + return;<br>
> + }<br>
> +<br>
> + lastRunTimestamp_ = frameTimestamp;<br>
> + processPending_ = true;<br>
> +<br>
> ControlList ctrls(ispCtrls_);<br>
><br>
> rpiMetadata_.Clear();<br>
<br>
So here I'm inferring that we don't skip prepare(). Mostly I think<br>
this is fine as prepare() does much less work. Probably ALSC is the<br>
worst as it interpolates lens shading tables.<br></blockquote><div><br></div><div>I stopped running prepare() as I wanted to avoid the whole cycle of pulling</div><div>out controller metadata, setting ControlLists and writing controls to the v4l2 device.</div><div>All of this probably adds quite a bit of latency that we probably do not need.</div><div>Besides, running prepare() without running process() durning a normal</div><div>(or steady state) run seems a bit pointless to me, unless I missed something?</div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
One little corner we might want to watch out for is something like the<br>
AE/AGC lock count. This counts in Agc::Prepare() how long things<br>
appear to be "steady", and if Process() runs less often than<br>
Prepare(), it seems possible that Prepare() may see things as steadier<br>
than they really are. Maybe we're ok, but it's just something to<br>
check.<br>
<br>
Also, I have a feeling we may get conflicts here with the<br>
CamHelper::Prepare/Process patch. Now it's a race to see who gets in<br>
first! :)<br></blockquote><div><br></div><div>Yes, we do have a race on our hands here.</div><div><br></div><div>Regards,</div><div>Naush</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
Thanks!<br>
<br>
David<br>
<br>
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> index 2a917455500f..9cf9c8c6cebd 100644<br>
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> @@ -1414,6 +1414,11 @@ void RPiCameraData::unicamBufferDequeue(FrameBuffer *buffer)<br>
> * DelayedControl and queue them along with the frame buffer.<br>
> */<br>
> ControlList ctrl = delayedCtrls_->get(buffer->metadata().sequence);<br>
> + /*<br>
> + * Add the frame timestamp to the ControlList for the IPA to use<br>
> + * as it does not receive the FrameBuffer object.<br>
> + */<br>
> + ctrl.set(controls::draft::SensorTimestamp, buffer->metadata().timestamp);<br>
> bayerQueue_.push({ buffer, std::move(ctrl) });<br>
> } else {<br>
> embeddedQueue_.push(buffer);<br>
> --<br>
> 2.25.1<br>
><br>
</blockquote></div></div>