[libcamera-devel] [PATCH v3 4/6] libcamera: camera: extend camera object to support streams

[Kieran Bingham]

Hi Niklas,

On 27/01/2019 00:22, Niklas Söderlund wrote:
> A camera consist of one or more video streams origination from the same

A camera *consists* of one or more video streams *originating* from ...

> video source. The different streams could for example have access to
> different hardware blocks in the video pipeline and therefor be able to

therefore

> process the video source in different ways.
> 
> All static information describing each streams needs to be recorded at


describing each stream


> camera creation. After a camera is created an application can retrieve
> the static information about its stream at any time.
> 
> Update all pipeline handlers to register one stream per camera, this
> might be extended in the future for some of the pipelines.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  include/libcamera/camera.h           | 10 ++++-
>  src/libcamera/camera.cpp             | 55 ++++++++++++++++++++++++++--
>  src/libcamera/pipeline/ipu3/ipu3.cpp |  4 +-
>  src/libcamera/pipeline/uvcvideo.cpp  |  4 +-
>  src/libcamera/pipeline/vimc.cpp      |  4 +-
>  5 files changed, 69 insertions(+), 8 deletions(-)
> 
> diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> index 7e358f8c0aa093cf..786d4d7d66bed5b2 100644
> --- a/include/libcamera/camera.h
> +++ b/include/libcamera/camera.h
> @@ -15,12 +15,14 @@
>  namespace libcamera {
>  
>  class PipelineHandler;
> +class Stream;
>  
>  class Camera final
>  {
>  public:
>  	static std::shared_ptr<Camera> create(PipelineHandler *pipe,
> -					      const std::string &name);
> +					      const std::string &name,
> +					      const std::vector<Stream> &streams);
>  
>  	Camera(const Camera &) = delete;
>  	void operator=(const Camera &) = delete;
> @@ -32,6 +34,8 @@ public:
>  	int acquire();
>  	void release();
>  
> +	std::vector<Stream> streams() const;
> +
>  private:
>  	Camera(PipelineHandler *pipe, const std::string &name);
>  	~Camera();
> @@ -39,10 +43,14 @@ private:
>  	friend class PipelineHandler;
>  	void disconnect();
>  
> +	bool haveStreamID(unsigned int id) const;

have? should this be 'hasStreamID()' ?

Looking at the implementation, Yes - I think so.

> +
>  	std::shared_ptr<PipelineHandler> pipe_;
>  	std::string name_;
> +	std::vector<Stream> streams_;
>  
>  	bool acquired_;
> +	bool disconnected_;

Is this related to streams?

>  };
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index 500976b237bcbd2d..3b2c00d0a4bb45d1 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -6,6 +6,7 @@
>   */
>  
>  #include <libcamera/camera.h>
> +#include <libcamera/stream.h>
>  
>  #include "log.h"
>  #include "pipeline_handler.h"
> @@ -56,13 +57,15 @@ LOG_DECLARE_CATEGORY(Camera)
>   * \brief Create a camera instance
>   * \param[in] name The name of the camera device
>   * \param[in] pipe The pipeline handler responsible for the camera device
> + * \param[in] streams Array of streams the camera shall provide
>   *
>   * The caller is responsible for guaranteeing unicity of the camera name.
>   *
>   * \return A shared pointer to the newly created camera object
>   */
>  std::shared_ptr<Camera> Camera::create(PipelineHandler *pipe,
> -				       const std::string &name)
> +				       const std::string &name,
> +				       const std::vector<Stream> &streams)
>  {
>  	struct Allocator : std::allocator<Camera> {
>  		void construct(void *p, PipelineHandler *pipe,
> @@ -76,7 +79,19 @@ std::shared_ptr<Camera> Camera::create(PipelineHandler *pipe,
>  		}
>  	};
>  
> -	return std::allocate_shared<Camera>(Allocator(), pipe, name);
> +	std::shared_ptr<Camera> camera =
> +		std::allocate_shared<Camera>(Allocator(), pipe, name);
> +
> +	for (const Stream &stream : streams) {
> +		if (camera->haveStreamID(stream.id())) {
> +			LOG(Camera, Error) << "Duplication of stream ID";

What about the pipeline adding a stream to a camera instead, and the ID
being allocated by the camera device?

Or does this make things the wrong way around?

I guess it would also have to be a function which only the Pipeline was
able to call somehow...

(we wouldn't want a public Camera API that could arbitrarily add streams!)..


> +			camera.reset();
> +			break;
> +		}
> +		camera->streams_.push_back(stream);
> +	}
> +
> +	return camera;
>  }
>  
>  /**
> @@ -102,7 +117,8 @@ const std::string &Camera::name() const
>   */
>  
>  Camera::Camera(PipelineHandler *pipe, const std::string &name)
> -	: pipe_(pipe->shared_from_this()), name_(name), acquired_(false)
> +	: pipe_(pipe->shared_from_this()), name_(name), acquired_(false),
> +	  disconnected_(false)
>  {
>  }
>  
> @@ -125,10 +141,24 @@ void Camera::disconnect()
>  {
>  	LOG(Camera, Debug) << "Disconnecting camera " << name_;
>  
> -	/** \todo Block API calls when they will be implemented. */
> +	disconnected_ = true;
>  	disconnected.emit(this);
>  }
>  
> +/**
> + * \brief Check if camera have a stream ID

Check if the camera has a particular stream ID


> + * \param[in] id Stream ID to check for
> + * \return ture if stream ID exists, else false

s/ture/True/


> + */
> +bool Camera::haveStreamID(unsigned int id) const
> +{
> +	for (const Stream &stream : streams_)
> +		if (stream.id() == id)
> +			return true;
> +
> +	return false;
> +}
> +
>  /**
>   * \brief Acquire the camera device for exclusive access
>   *
> @@ -164,4 +194,21 @@ void Camera::release()
>  	acquired_ = false;
>  }
>  
> +/**
> + * \brief Retrieve all the camera's stream information
> + *
> + * Retrieve all of the camera's static stream information. The static
> + * information describes among other things how many streams the camera support
> + * and each streams capabilities.
> + *
> + * \return An array of all the camera's streams or an empty list on error.

Is if(disconnected) an error?

I'd say if a camera is disconnected it has no streams ... I don't think
that's an error?

Perhaps:

\return An array of all the camera's streams valid streams.


> + */
> +std::vector<Stream> Camera::streams() const
> +{
> +	if (disconnected_)
> +		return std::vector<Stream>{};
> +
> +	return streams_;
> +}
> +
>  } /* namespace libcamera */
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index d74655d037728feb..dbb2a89163c36cbc 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -9,6 +9,7 @@
>  #include <vector>
>  
>  #include <libcamera/camera.h>
> +#include <libcamera/stream.h>
>  
>  #include "device_enumerator.h"
>  #include "log.h"
> @@ -197,7 +198,8 @@ void PipelineHandlerIPU3::registerCameras()
>  			continue;
>  
>  		std::string cameraName = sensor->name() + " " + std::to_string(id);
> -		std::shared_ptr<Camera> camera = Camera::create(this, cameraName);
> +		std::vector<Stream> streams{ Stream(0) };
> +		std::shared_ptr<Camera> camera = Camera::create(this, cameraName, streams);
>  
>  		/*
>  		 * If V4L2 device creation fails, the Camera instance won't be
> diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> index c51e8bc1f2c2bf25..bc4a8d7236be589d 100644
> --- a/src/libcamera/pipeline/uvcvideo.cpp
> +++ b/src/libcamera/pipeline/uvcvideo.cpp
> @@ -6,6 +6,7 @@
>   */
>  
>  #include <libcamera/camera.h>
> +#include <libcamera/stream.h>
>  
>  #include "device_enumerator.h"
>  #include "media_device.h"
> @@ -64,7 +65,8 @@ bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
>  		return false;
>  	}
>  
> -	std::shared_ptr<Camera> camera = Camera::create(this, media_->model());
> +	std::vector<Stream> streams{ Stream(0) };
> +	std::shared_ptr<Camera> camera = Camera::create(this, media_->model(), streams);
>  	registerCamera(std::move(camera));
>  	hotplugMediaDevice(media_.get());
>  
> diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> index f58a97d51619515d..c426a953aea1b3dd 100644
> --- a/src/libcamera/pipeline/vimc.cpp
> +++ b/src/libcamera/pipeline/vimc.cpp
> @@ -6,6 +6,7 @@
>   */
>  
>  #include <libcamera/camera.h>
> +#include <libcamera/stream.h>
>  
>  #include "device_enumerator.h"
>  #include "media_device.h"
> @@ -56,7 +57,8 @@ bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
>  
>  	media_->acquire();
>  
> -	std::shared_ptr<Camera> camera = Camera::create(this, "Dummy VIMC Camera");
> +	std::vector<Stream> streams{ Stream(0) };
> +	std::shared_ptr<Camera> camera = Camera::create(this, "Dummy VIMC Camera", streams);

Out of interest, UVC exposes two video device nodes. One for the video
data, and one for 'meta' data.

Would we consider this meta data to be a second stream?


>  	registerCamera(std::move(camera));
>  
>  	return true;
> 

-- 
Regards
--
Kieran