[libcamera-devel] [PATCH] cam: Print timestamp of captured buffers

[Kieran Bingham]

Hi Laurent,

On 22/08/2020 14:35, Laurent Pinchart wrote:
> Print the timestamp of the captured buffer in addition to the frame
> rate, as this is more precise information that can help debugging issue.
> While at it, compute the frame rate on the buffer timestamps instead of
> sampling the clock in the request completion handler.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/cam/capture.cpp | 18 +++++++++++-------
>  src/cam/capture.h   |  4 ++--
>  2 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/src/cam/capture.cpp b/src/cam/capture.cpp
> index af9029b743de..5510c009ca57 100644
> --- a/src/cam/capture.cpp
> +++ b/src/cam/capture.cpp
> @@ -5,7 +5,6 @@
>   * capture.cpp - Cam capture
>   */
>  
> -#include <chrono>
>  #include <iomanip>
>  #include <iostream>
>  #include <limits.h>
> @@ -159,14 +158,19 @@ void Capture::requestComplete(Request *request)
>  
>  	const Request::BufferMap &buffers = request->buffers();
>  
> -	std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
> -	double fps = std::chrono::duration_cast<std::chrono::milliseconds>(now - last_).count();
> -	fps = last_ != std::chrono::steady_clock::time_point() && fps
> -	    ? 1000.0 / fps : 0.0;
> -	last_ = now;
> +	/*
> +	 * Compute the frame rate. The timestamp is arbitrarily retrieved from
> +	 * the first buffer, as all buffers should have matching timestamps.
> +	 */
> +	uint64_t ts = buffers.begin()->second->metadata().timestamp;

how many seconds does this add? (Sorry I /reallly/ hate std::pair
nomenclature... and using it like this in the context of a timestamp too
... :-S)

Other than that,

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> +	double fps = ts - last_;
> +	fps = last_ != 0 && fps ? 1000000000.0 / fps : 0.0;
> +	last_ = ts;
>  
>  	std::stringstream info;
> -	info << "fps: " << std::fixed << std::setprecision(2) << fps;
> +	info << ts / 1000000000 << "."
> +	     << std::setw(6) << std::setfill('0') << ts / 1000 % 1000000
> +	     << " (" << std::fixed << std::setprecision(2) << fps << " fps)";
>  
>  	for (auto it = buffers.begin(); it != buffers.end(); ++it) {
>  		const Stream *stream = it->first;
> diff --git a/src/cam/capture.h b/src/cam/capture.h
> index b4e39d51fdfa..0aebdac944cf 100644
> --- a/src/cam/capture.h
> +++ b/src/cam/capture.h
> @@ -7,8 +7,8 @@
>  #ifndef __CAM_CAPTURE_H__
>  #define __CAM_CAPTURE_H__
>  
> -#include <chrono>
>  #include <memory>
> +#include <stdint.h>
>  
>  #include <libcamera/buffer.h>
>  #include <libcamera/camera.h>
> @@ -38,7 +38,7 @@ private:
>  
>  	std::map<const libcamera::Stream *, std::string> streamName_;
>  	BufferWriter *writer_;
> -	std::chrono::steady_clock::time_point last_;
> +	uint64_t last_;
>  
>  	EventLoop *loop_;
>  	unsigned int captureCount_;
> 

-- 
Regards
--
Kieran