[libcamera-devel,v3,5/6] libcamera: pipeline: extend pipelines to support stream configuration

Message ID 20190127002208.18913-6-niklas.soderlund@ragnatech.se
State Superseded
Headers show
Series
  • libcamera: add basic support for streams and format configuration
Related show

Commit Message

Niklas Söderlund Jan. 27, 2019, 12:22 a.m. UTC
All streams which are to be used for capture needs to be configured at
the same time. This allows the pipeline handler to take any dependences
between the different streams and there configuration into account when
setting up the hardware.

Extend the pipeline API and all pipeline implementations with two new
functions, one to read the configuration and one to update it. Both
functions operate on a group of streams which the pipeline handler
should consider when performing the operations.

In the current implemented pipelines this is rather easy as they only
have one stream each per camera. Furthermore as there is yet no way for
the pipeline handlers to interact with the hardware all they do is log
that the format have been read or updated. Future work based on more
components are needed to make the pipelines actually interact with the
hardware.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
---
 src/libcamera/include/pipeline_handler.h |  8 ++++++
 src/libcamera/pipeline/ipu3/ipu3.cpp     | 32 ++++++++++++++++++++++
 src/libcamera/pipeline/uvcvideo.cpp      | 35 ++++++++++++++++++++++++
 src/libcamera/pipeline/vimc.cpp          | 35 ++++++++++++++++++++++++
 src/libcamera/pipeline_handler.cpp       | 34 +++++++++++++++++++++++
 5 files changed, 144 insertions(+)

Comments

Laurent Pinchart Jan. 28, 2019, 12:09 a.m. UTC | #1
Hi Niklas,

Thank you for the patch.

On Sun, Jan 27, 2019 at 01:22:07AM +0100, Niklas Söderlund wrote:
> All streams which are to be used for capture needs to be configured at

s/needs/need/

> the same time. This allows the pipeline handler to take any dependences

s/dependences/dependencies/

> between the different streams and there configuration into account when

s/there configuration/their configurations/

> setting up the hardware.
> 
> Extend the pipeline API and all pipeline implementations with two new
> functions, one to read the configuration and one to update it. Both
> functions operate on a group of streams which the pipeline handler
> should consider when performing the operations.

I don't think we should have a function to read the current
configuration, and if we did, it shouldn't be virtual, but implemented
in PipelineHandler using a cache.

What we need is a function for a pipeline handler to return a default
configuration for a set of streams, in order for applications not to
have to create a configuration from scratch but start from a known to
work (and recommended) config.

> In the current implemented pipelines this is rather easy as they only
> have one stream each per camera. Furthermore as there is yet no way for
> the pipeline handlers to interact with the hardware all they do is log
> that the format have been read or updated. Future work based on more
> components are needed to make the pipelines actually interact with the
> hardware.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> ---
>  src/libcamera/include/pipeline_handler.h |  8 ++++++
>  src/libcamera/pipeline/ipu3/ipu3.cpp     | 32 ++++++++++++++++++++++
>  src/libcamera/pipeline/uvcvideo.cpp      | 35 ++++++++++++++++++++++++
>  src/libcamera/pipeline/vimc.cpp          | 35 ++++++++++++++++++++++++
>  src/libcamera/pipeline_handler.cpp       | 34 +++++++++++++++++++++++
>  5 files changed, 144 insertions(+)
> 
> diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> index ca77a40b96e69b66..c19eb9b73ede8720 100644
> --- a/src/libcamera/include/pipeline_handler.h
> +++ b/src/libcamera/include/pipeline_handler.h
> @@ -17,6 +17,8 @@ namespace libcamera {
>  class CameraManager;
>  class DeviceEnumerator;
>  class MediaDevice;
> +class Stream;
> +class StreamConfiguration;
>  
>  class Camera;
>  class CameraData
> @@ -38,6 +40,12 @@ public:
>  	PipelineHandler(CameraManager *manager);
>  	virtual ~PipelineHandler();
>  
> +	virtual std::map<unsigned int, StreamConfiguration>
> +	streamConfiguration(const Camera *camera,
> +			    const std::vector<Stream> &streams) const = 0;
> +	virtual int configureStreams(const Camera *camera,

Even if you don't need to modify the state of the Camera object now, you
may need that later. Beside, this method is called by the Camera class
from a non-cost instance, so that won't be a problem.

> +				     std::map<unsigned int, StreamConfiguration> &config) = 0;
> +
>  	virtual bool match(DeviceEnumerator *enumerator) = 0;
>  
>  protected:
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index dbb2a89163c36cbc..ff4d73f947a683ca 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -28,6 +28,12 @@ public:
>  	PipelineHandlerIPU3(CameraManager *manager);
>  	~PipelineHandlerIPU3();
>  
> +	std::map<unsigned int, StreamConfiguration>
> +	streamConfiguration(const Camera *camera,
> +			    const std::vector<Stream> &streams) const;
> +	int configureStreams(const Camera *camera,
> +			     std::map<unsigned int, StreamConfiguration> &config);
> +
>  	bool match(DeviceEnumerator *enumerator);
>  
>  private:
> @@ -61,6 +67,32 @@ PipelineHandlerIPU3::~PipelineHandlerIPU3()
>  		imgu_->release();
>  }
>  
> +std::map<unsigned int, StreamConfiguration>
> +PipelineHandlerIPU3::streamConfiguration(const Camera *camera,
> +					 const std::vector<Stream> &streams) const
> +{
> +	std::map<unsigned int, StreamConfiguration> configs;
> +
> +	StreamConfiguration config;
> +
> +	LOG(IPU3, Info) << "TODO: Fetch stream configuration";
> +
> +	configs[0] = config;
> +
> +	return configs;
> +}
> +
> +int PipelineHandlerIPU3::configureStreams(const Camera *camera,
> +					  std::map<unsigned int, StreamConfiguration> &config)
> +{
> +	StreamConfiguration *cfg = &config[0];
> +
> +	LOG(IPU3, Info) << "TODO: Configure the camera for resolution " <<
> +		cfg->width << "x" << cfg->height;
> +
> +	return 0;
> +}
> +
>  bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
>  {
>  	DeviceMatch cio2_dm("ipu3-cio2");
> diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> index bc4a8d7236be589d..bba4655a0a26b622 100644
> --- a/src/libcamera/pipeline/uvcvideo.cpp
> +++ b/src/libcamera/pipeline/uvcvideo.cpp
> @@ -9,18 +9,27 @@
>  #include <libcamera/stream.h>
>  
>  #include "device_enumerator.h"
> +#include "log.h"
>  #include "media_device.h"
>  #include "pipeline_handler.h"
>  #include "v4l2_device.h"
>  
>  namespace libcamera {
>  
> +LOG_DEFINE_CATEGORY(UVC)
> +
>  class PipelineHandlerUVC : public PipelineHandler
>  {
>  public:
>  	PipelineHandlerUVC(CameraManager *manager);
>  	~PipelineHandlerUVC();
>  
> +	std::map<unsigned int, StreamConfiguration>
> +	streamConfiguration(const Camera *camera,
> +			    const std::vector<Stream> &streams) const;
> +	int configureStreams(const Camera *camera,
> +			     std::map<unsigned int, StreamConfiguration> &config);
> +
>  	bool match(DeviceEnumerator *enumerator);
>  
>  private:
> @@ -42,6 +51,32 @@ PipelineHandlerUVC::~PipelineHandlerUVC()
>  		media_->release();
>  }
>  
> +std::map<unsigned int, StreamConfiguration>
> +PipelineHandlerUVC::streamConfiguration(const Camera *camera,
> +					const std::vector<Stream> &streams) const
> +{
> +	std::map<unsigned int, StreamConfiguration> configs;
> +
> +	StreamConfiguration config;
> +
> +	LOG(UVC, Info) << "TODO: Fetch stream configuration";
> +
> +	configs[0] = config;
> +
> +	return configs;
> +}
> +
> +int PipelineHandlerUVC::configureStreams(const Camera *camera,
> +					 std::map<unsigned int, StreamConfiguration> &config)
> +{
> +	StreamConfiguration *cfg = &config[0];
> +
> +	LOG(UVC, Info) << "TODO: Configure the camera for resolution " <<
> +		cfg->width << "x" << cfg->height;
> +
> +	return 0;
> +}
> +
>  bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
>  {
>  	DeviceMatch dm("uvcvideo");
> diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> index c426a953aea1b3dd..c9810a8e192ac68b 100644
> --- a/src/libcamera/pipeline/vimc.cpp
> +++ b/src/libcamera/pipeline/vimc.cpp
> @@ -9,17 +9,26 @@
>  #include <libcamera/stream.h>
>  
>  #include "device_enumerator.h"
> +#include "log.h"
>  #include "media_device.h"
>  #include "pipeline_handler.h"
>  
>  namespace libcamera {
>  
> +LOG_DEFINE_CATEGORY(VIMC)
> +
>  class PipeHandlerVimc : public PipelineHandler
>  {
>  public:
>  	PipeHandlerVimc(CameraManager *manager);
>  	~PipeHandlerVimc();
>  
> +	std::map<unsigned int, StreamConfiguration>
> +	streamConfiguration(const Camera *camera,
> +			    const std::vector<Stream> &streams) const;
> +	int configureStreams(const Camera *camera,
> +			     std::map<unsigned int, StreamConfiguration> &config);
> +
>  	bool match(DeviceEnumerator *enumerator);
>  
>  private:
> @@ -37,6 +46,32 @@ PipeHandlerVimc::~PipeHandlerVimc()
>  		media_->release();
>  }
>  
> +std::map<unsigned int, StreamConfiguration>
> +PipeHandlerVimc::streamConfiguration(const Camera *camera,
> +				     const std::vector<Stream> &streams) const
> +{
> +	std::map<unsigned int, StreamConfiguration> configs;
> +
> +	StreamConfiguration config;
> +
> +	LOG(VIMC, Info) << "TODO: Fetch stream configuration";
> +
> +	configs[0] = config;
> +
> +	return configs;
> +}
> +
> +int PipeHandlerVimc::configureStreams(const Camera *camera,
> +				      std::map<unsigned int, StreamConfiguration> &config)
> +{
> +	StreamConfiguration *cfg = &config[0];
> +
> +	LOG(VIMC, Info) << "TODO: Configure the camera for resolution " <<
> +		cfg->width << "x" << cfg->height;
> +
> +	return 0;
> +}
> +
>  bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
>  {
>  	DeviceMatch dm("vimc");
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 1c8640799f714686..ee6d80908f67d564 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -75,6 +75,40 @@ PipelineHandler::~PipelineHandler()
>  {
>  };
>  
> +
> +/**
> + * \fn PipelineHandler::streamConfiguration(const Camera *camera, * const std::vector<Stream> &streams)

You don't need to specify the function parameters when the function
isn't overloaded.

> + * \brief Retrieve a group of stream configurations for a specified camera
> + * \param[in] camera The camera to fetch the configuration from
> + * \param[in] streams An array of streams to fetch information about
> + *
> + * Retrieve the species camera's configuration for a specified group of streams.
> + * The caller shall populate the \a streams array with the streams it wish to
> + * fetch the configuration from. The map of stream IDs and configuration
> + * returned can then be examined by the caller to learn about the parameters for
> + * the specified streams.
> + *
> + * The intended companion to this is \a configureStreams() which can be used to
> + * change the group of streams parameters.
> + *
> + * \return A map of successfully retrieved stream IDs and configurations or an
> + * empty map on error.
> + */
> +
> +/**
> + * \fn PipelineHandler::configureStreams(const Camera *camera, std::map<unsigned int, StreamConfiguration> &config)
> + * \brief Configure a group of streams for capture
> + * \param[in] camera The camera to apply the configuration to

You could simply say "The camera to configure".

> + * \param[in] config A map of stream configurations to apply
> + *
> + * Configure the specified group of streams for \a camera according to the
> + * configuration specified in \a configs. The intended caller of this interface
> + * is the Camera class which will receive configuration to apply from the
> + * application.
> + *
> + * \return 0 on success or a negative error code on error.
> + */
> +
>  /**
>   * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
>   * \brief Match media devices and create camera instances
Jacopo Mondi Jan. 28, 2019, 11:30 a.m. UTC | #2
Hi Niklas, Laurent

On Mon, Jan 28, 2019 at 02:09:10AM +0200, Laurent Pinchart wrote:
> Hi Niklas,
>
> Thank you for the patch.
>
> On Sun, Jan 27, 2019 at 01:22:07AM +0100, Niklas Söderlund wrote:
> > All streams which are to be used for capture needs to be configured at
>
> s/needs/need/
>
> > the same time. This allows the pipeline handler to take any dependences
>
> s/dependences/dependencies/
>
> > between the different streams and there configuration into account when
>
> s/there configuration/their configurations/
>
> > setting up the hardware.
> >
> > Extend the pipeline API and all pipeline implementations with two new
> > functions, one to read the configuration and one to update it. Both
> > functions operate on a group of streams which the pipeline handler
> > should consider when performing the operations.
>
> I don't think we should have a function to read the current
> configuration, and if we did, it shouldn't be virtual, but implemented
> in PipelineHandler using a cache.
>
> What we need is a function for a pipeline handler to return a default
> configuration for a set of streams, in order for applications not to
> have to create a configuration from scratch but start from a known to
> work (and recommended) config.
>

I'm sure this has been considered, and I even re-call we discussed
that possibly, but I fail to remember why StreamConfigurations should
be associated with IDs and not be part of the Stream itself.

I would go futher, and ask why Streams are not created with a default
configuration embedded, instead of asking for a default configuration
with streamConfiguration().

I recall the problem was that not all streams could be part of a
configureStreams() request, and that's why we pass configurations+id.
Isn't enough to include in the requests a reference to the Streams the
application actually wants to setup?

Thanks
  j


> > In the current implemented pipelines this is rather easy as they only
> > have one stream each per camera. Furthermore as there is yet no way for
> > the pipeline handlers to interact with the hardware all they do is log
> > that the format have been read or updated. Future work based on more
> > components are needed to make the pipelines actually interact with the
> > hardware.
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> > ---
> >  src/libcamera/include/pipeline_handler.h |  8 ++++++
> >  src/libcamera/pipeline/ipu3/ipu3.cpp     | 32 ++++++++++++++++++++++
> >  src/libcamera/pipeline/uvcvideo.cpp      | 35 ++++++++++++++++++++++++
> >  src/libcamera/pipeline/vimc.cpp          | 35 ++++++++++++++++++++++++
> >  src/libcamera/pipeline_handler.cpp       | 34 +++++++++++++++++++++++
> >  5 files changed, 144 insertions(+)
> >
> > diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> > index ca77a40b96e69b66..c19eb9b73ede8720 100644
> > --- a/src/libcamera/include/pipeline_handler.h
> > +++ b/src/libcamera/include/pipeline_handler.h
> > @@ -17,6 +17,8 @@ namespace libcamera {
> >  class CameraManager;
> >  class DeviceEnumerator;
> >  class MediaDevice;
> > +class Stream;
> > +class StreamConfiguration;
> >
> >  class Camera;
> >  class CameraData
> > @@ -38,6 +40,12 @@ public:
> >  	PipelineHandler(CameraManager *manager);
> >  	virtual ~PipelineHandler();
> >
> > +	virtual std::map<unsigned int, StreamConfiguration>
> > +	streamConfiguration(const Camera *camera,
> > +			    const std::vector<Stream> &streams) const = 0;
> > +	virtual int configureStreams(const Camera *camera,
>
> Even if you don't need to modify the state of the Camera object now, you
> may need that later. Beside, this method is called by the Camera class
> from a non-cost instance, so that won't be a problem.
>
> > +				     std::map<unsigned int, StreamConfiguration> &config) = 0;
> > +
> >  	virtual bool match(DeviceEnumerator *enumerator) = 0;
> >
> >  protected:
> > diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > index dbb2a89163c36cbc..ff4d73f947a683ca 100644
> > --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > @@ -28,6 +28,12 @@ public:
> >  	PipelineHandlerIPU3(CameraManager *manager);
> >  	~PipelineHandlerIPU3();
> >
> > +	std::map<unsigned int, StreamConfiguration>
> > +	streamConfiguration(const Camera *camera,
> > +			    const std::vector<Stream> &streams) const;
> > +	int configureStreams(const Camera *camera,
> > +			     std::map<unsigned int, StreamConfiguration> &config);
> > +
> >  	bool match(DeviceEnumerator *enumerator);
> >
> >  private:
> > @@ -61,6 +67,32 @@ PipelineHandlerIPU3::~PipelineHandlerIPU3()
> >  		imgu_->release();
> >  }
> >
> > +std::map<unsigned int, StreamConfiguration>
> > +PipelineHandlerIPU3::streamConfiguration(const Camera *camera,
> > +					 const std::vector<Stream> &streams) const
> > +{
> > +	std::map<unsigned int, StreamConfiguration> configs;
> > +
> > +	StreamConfiguration config;
> > +
> > +	LOG(IPU3, Info) << "TODO: Fetch stream configuration";
> > +
> > +	configs[0] = config;
> > +
> > +	return configs;
> > +}
> > +
> > +int PipelineHandlerIPU3::configureStreams(const Camera *camera,
> > +					  std::map<unsigned int, StreamConfiguration> &config)
> > +{
> > +	StreamConfiguration *cfg = &config[0];
> > +
> > +	LOG(IPU3, Info) << "TODO: Configure the camera for resolution " <<
> > +		cfg->width << "x" << cfg->height;
> > +
> > +	return 0;
> > +}
> > +
> >  bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
> >  {
> >  	DeviceMatch cio2_dm("ipu3-cio2");
> > diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> > index bc4a8d7236be589d..bba4655a0a26b622 100644
> > --- a/src/libcamera/pipeline/uvcvideo.cpp
> > +++ b/src/libcamera/pipeline/uvcvideo.cpp
> > @@ -9,18 +9,27 @@
> >  #include <libcamera/stream.h>
> >
> >  #include "device_enumerator.h"
> > +#include "log.h"
> >  #include "media_device.h"
> >  #include "pipeline_handler.h"
> >  #include "v4l2_device.h"
> >
> >  namespace libcamera {
> >
> > +LOG_DEFINE_CATEGORY(UVC)
> > +
> >  class PipelineHandlerUVC : public PipelineHandler
> >  {
> >  public:
> >  	PipelineHandlerUVC(CameraManager *manager);
> >  	~PipelineHandlerUVC();
> >
> > +	std::map<unsigned int, StreamConfiguration>
> > +	streamConfiguration(const Camera *camera,
> > +			    const std::vector<Stream> &streams) const;
> > +	int configureStreams(const Camera *camera,
> > +			     std::map<unsigned int, StreamConfiguration> &config);
> > +
> >  	bool match(DeviceEnumerator *enumerator);
> >
> >  private:
> > @@ -42,6 +51,32 @@ PipelineHandlerUVC::~PipelineHandlerUVC()
> >  		media_->release();
> >  }
> >
> > +std::map<unsigned int, StreamConfiguration>
> > +PipelineHandlerUVC::streamConfiguration(const Camera *camera,
> > +					const std::vector<Stream> &streams) const
> > +{
> > +	std::map<unsigned int, StreamConfiguration> configs;
> > +
> > +	StreamConfiguration config;
> > +
> > +	LOG(UVC, Info) << "TODO: Fetch stream configuration";
> > +
> > +	configs[0] = config;
> > +
> > +	return configs;
> > +}
> > +
> > +int PipelineHandlerUVC::configureStreams(const Camera *camera,
> > +					 std::map<unsigned int, StreamConfiguration> &config)
> > +{
> > +	StreamConfiguration *cfg = &config[0];
> > +
> > +	LOG(UVC, Info) << "TODO: Configure the camera for resolution " <<
> > +		cfg->width << "x" << cfg->height;
> > +
> > +	return 0;
> > +}
> > +
> >  bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
> >  {
> >  	DeviceMatch dm("uvcvideo");
> > diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> > index c426a953aea1b3dd..c9810a8e192ac68b 100644
> > --- a/src/libcamera/pipeline/vimc.cpp
> > +++ b/src/libcamera/pipeline/vimc.cpp
> > @@ -9,17 +9,26 @@
> >  #include <libcamera/stream.h>
> >
> >  #include "device_enumerator.h"
> > +#include "log.h"
> >  #include "media_device.h"
> >  #include "pipeline_handler.h"
> >
> >  namespace libcamera {
> >
> > +LOG_DEFINE_CATEGORY(VIMC)
> > +
> >  class PipeHandlerVimc : public PipelineHandler
> >  {
> >  public:
> >  	PipeHandlerVimc(CameraManager *manager);
> >  	~PipeHandlerVimc();
> >
> > +	std::map<unsigned int, StreamConfiguration>
> > +	streamConfiguration(const Camera *camera,
> > +			    const std::vector<Stream> &streams) const;
> > +	int configureStreams(const Camera *camera,
> > +			     std::map<unsigned int, StreamConfiguration> &config);
> > +
> >  	bool match(DeviceEnumerator *enumerator);
> >
> >  private:
> > @@ -37,6 +46,32 @@ PipeHandlerVimc::~PipeHandlerVimc()
> >  		media_->release();
> >  }
> >
> > +std::map<unsigned int, StreamConfiguration>
> > +PipeHandlerVimc::streamConfiguration(const Camera *camera,
> > +				     const std::vector<Stream> &streams) const
> > +{
> > +	std::map<unsigned int, StreamConfiguration> configs;
> > +
> > +	StreamConfiguration config;
> > +
> > +	LOG(VIMC, Info) << "TODO: Fetch stream configuration";
> > +
> > +	configs[0] = config;
> > +
> > +	return configs;
> > +}
> > +
> > +int PipeHandlerVimc::configureStreams(const Camera *camera,
> > +				      std::map<unsigned int, StreamConfiguration> &config)
> > +{
> > +	StreamConfiguration *cfg = &config[0];
> > +
> > +	LOG(VIMC, Info) << "TODO: Configure the camera for resolution " <<
> > +		cfg->width << "x" << cfg->height;
> > +
> > +	return 0;
> > +}
> > +
> >  bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
> >  {
> >  	DeviceMatch dm("vimc");
> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > index 1c8640799f714686..ee6d80908f67d564 100644
> > --- a/src/libcamera/pipeline_handler.cpp
> > +++ b/src/libcamera/pipeline_handler.cpp
> > @@ -75,6 +75,40 @@ PipelineHandler::~PipelineHandler()
> >  {
> >  };
> >
> > +
> > +/**
> > + * \fn PipelineHandler::streamConfiguration(const Camera *camera, * const std::vector<Stream> &streams)
>
> You don't need to specify the function parameters when the function
> isn't overloaded.
>
> > + * \brief Retrieve a group of stream configurations for a specified camera
> > + * \param[in] camera The camera to fetch the configuration from
> > + * \param[in] streams An array of streams to fetch information about
> > + *
> > + * Retrieve the species camera's configuration for a specified group of streams.
> > + * The caller shall populate the \a streams array with the streams it wish to
> > + * fetch the configuration from. The map of stream IDs and configuration
> > + * returned can then be examined by the caller to learn about the parameters for
> > + * the specified streams.
> > + *
> > + * The intended companion to this is \a configureStreams() which can be used to
> > + * change the group of streams parameters.
> > + *
> > + * \return A map of successfully retrieved stream IDs and configurations or an
> > + * empty map on error.
> > + */
> > +
> > +/**
> > + * \fn PipelineHandler::configureStreams(const Camera *camera, std::map<unsigned int, StreamConfiguration> &config)
> > + * \brief Configure a group of streams for capture
> > + * \param[in] camera The camera to apply the configuration to
>
> You could simply say "The camera to configure".
>
> > + * \param[in] config A map of stream configurations to apply
> > + *
> > + * Configure the specified group of streams for \a camera according to the
> > + * configuration specified in \a configs. The intended caller of this interface
> > + * is the Camera class which will receive configuration to apply from the
> > + * application.
> > + *
> > + * \return 0 on success or a negative error code on error.
> > + */
> > +
> >  /**
> >   * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
> >   * \brief Match media devices and create camera instances
>
> --
> Regards,
>
> Laurent Pinchart
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel@lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
Laurent Pinchart Jan. 28, 2019, 9:57 p.m. UTC | #3
Hi Jacopo,

On Mon, Jan 28, 2019 at 12:30:19PM +0100, Jacopo Mondi wrote:
> On Mon, Jan 28, 2019 at 02:09:10AM +0200, Laurent Pinchart wrote:
> > On Sun, Jan 27, 2019 at 01:22:07AM +0100, Niklas Söderlund wrote:
> > > All streams which are to be used for capture needs to be configured at
> >
> > s/needs/need/
> >
> > > the same time. This allows the pipeline handler to take any dependences
> >
> > s/dependences/dependencies/
> >
> > > between the different streams and there configuration into account when
> >
> > s/there configuration/their configurations/
> >
> > > setting up the hardware.
> > >
> > > Extend the pipeline API and all pipeline implementations with two new
> > > functions, one to read the configuration and one to update it. Both
> > > functions operate on a group of streams which the pipeline handler
> > > should consider when performing the operations.
> >
> > I don't think we should have a function to read the current
> > configuration, and if we did, it shouldn't be virtual, but implemented
> > in PipelineHandler using a cache.
> >
> > What we need is a function for a pipeline handler to return a default
> > configuration for a set of streams, in order for applications not to
> > have to create a configuration from scratch but start from a known to
> > work (and recommended) config.
> 
> I'm sure this has been considered, and I even re-call we discussed
> that possibly, but I fail to remember why StreamConfigurations should
> be associated with IDs and not be part of the Stream itself.
> 
> I would go futher, and ask why Streams are not created with a default
> configuration embedded, instead of asking for a default configuration
> with streamConfiguration().
> 
> I recall the problem was that not all streams could be part of a
> configureStreams() request, and that's why we pass configurations+id.
> Isn't enough to include in the requests a reference to the Streams the
> application actually wants to setup?

One issue we need to solve is to provide a default configuration for a
subset of streams. This isn't equivalent to adding default
configurations for each stream in the subset. For instance, when you
have shared resources, you need to assign them to streams in the best
possible way for the subset of streams that the application wants to
use. A global default for each stream wouldn't work in this case.

> > > In the current implemented pipelines this is rather easy as they only
> > > have one stream each per camera. Furthermore as there is yet no way for
> > > the pipeline handlers to interact with the hardware all they do is log
> > > that the format have been read or updated. Future work based on more
> > > components are needed to make the pipelines actually interact with the
> > > hardware.
> > >
> > > Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> > > ---
> > >  src/libcamera/include/pipeline_handler.h |  8 ++++++
> > >  src/libcamera/pipeline/ipu3/ipu3.cpp     | 32 ++++++++++++++++++++++
> > >  src/libcamera/pipeline/uvcvideo.cpp      | 35 ++++++++++++++++++++++++
> > >  src/libcamera/pipeline/vimc.cpp          | 35 ++++++++++++++++++++++++
> > >  src/libcamera/pipeline_handler.cpp       | 34 +++++++++++++++++++++++
> > >  5 files changed, 144 insertions(+)
> > >
> > > diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> > > index ca77a40b96e69b66..c19eb9b73ede8720 100644
> > > --- a/src/libcamera/include/pipeline_handler.h
> > > +++ b/src/libcamera/include/pipeline_handler.h
> > > @@ -17,6 +17,8 @@ namespace libcamera {
> > >  class CameraManager;
> > >  class DeviceEnumerator;
> > >  class MediaDevice;
> > > +class Stream;
> > > +class StreamConfiguration;
> > >
> > >  class Camera;
> > >  class CameraData
> > > @@ -38,6 +40,12 @@ public:
> > >  	PipelineHandler(CameraManager *manager);
> > >  	virtual ~PipelineHandler();
> > >
> > > +	virtual std::map<unsigned int, StreamConfiguration>
> > > +	streamConfiguration(const Camera *camera,
> > > +			    const std::vector<Stream> &streams) const = 0;
> > > +	virtual int configureStreams(const Camera *camera,
> >
> > Even if you don't need to modify the state of the Camera object now, you
> > may need that later. Beside, this method is called by the Camera class
> > from a non-cost instance, so that won't be a problem.
> >
> > > +				     std::map<unsigned int, StreamConfiguration> &config) = 0;
> > > +
> > >  	virtual bool match(DeviceEnumerator *enumerator) = 0;
> > >
> > >  protected:
> > > diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > index dbb2a89163c36cbc..ff4d73f947a683ca 100644
> > > --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > @@ -28,6 +28,12 @@ public:
> > >  	PipelineHandlerIPU3(CameraManager *manager);
> > >  	~PipelineHandlerIPU3();
> > >
> > > +	std::map<unsigned int, StreamConfiguration>
> > > +	streamConfiguration(const Camera *camera,
> > > +			    const std::vector<Stream> &streams) const;
> > > +	int configureStreams(const Camera *camera,
> > > +			     std::map<unsigned int, StreamConfiguration> &config);
> > > +
> > >  	bool match(DeviceEnumerator *enumerator);
> > >
> > >  private:
> > > @@ -61,6 +67,32 @@ PipelineHandlerIPU3::~PipelineHandlerIPU3()
> > >  		imgu_->release();
> > >  }
> > >
> > > +std::map<unsigned int, StreamConfiguration>
> > > +PipelineHandlerIPU3::streamConfiguration(const Camera *camera,
> > > +					 const std::vector<Stream> &streams) const
> > > +{
> > > +	std::map<unsigned int, StreamConfiguration> configs;
> > > +
> > > +	StreamConfiguration config;
> > > +
> > > +	LOG(IPU3, Info) << "TODO: Fetch stream configuration";
> > > +
> > > +	configs[0] = config;
> > > +
> > > +	return configs;
> > > +}
> > > +
> > > +int PipelineHandlerIPU3::configureStreams(const Camera *camera,
> > > +					  std::map<unsigned int, StreamConfiguration> &config)
> > > +{
> > > +	StreamConfiguration *cfg = &config[0];
> > > +
> > > +	LOG(IPU3, Info) << "TODO: Configure the camera for resolution " <<
> > > +		cfg->width << "x" << cfg->height;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
> > >  {
> > >  	DeviceMatch cio2_dm("ipu3-cio2");
> > > diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> > > index bc4a8d7236be589d..bba4655a0a26b622 100644
> > > --- a/src/libcamera/pipeline/uvcvideo.cpp
> > > +++ b/src/libcamera/pipeline/uvcvideo.cpp
> > > @@ -9,18 +9,27 @@
> > >  #include <libcamera/stream.h>
> > >
> > >  #include "device_enumerator.h"
> > > +#include "log.h"
> > >  #include "media_device.h"
> > >  #include "pipeline_handler.h"
> > >  #include "v4l2_device.h"
> > >
> > >  namespace libcamera {
> > >
> > > +LOG_DEFINE_CATEGORY(UVC)
> > > +
> > >  class PipelineHandlerUVC : public PipelineHandler
> > >  {
> > >  public:
> > >  	PipelineHandlerUVC(CameraManager *manager);
> > >  	~PipelineHandlerUVC();
> > >
> > > +	std::map<unsigned int, StreamConfiguration>
> > > +	streamConfiguration(const Camera *camera,
> > > +			    const std::vector<Stream> &streams) const;
> > > +	int configureStreams(const Camera *camera,
> > > +			     std::map<unsigned int, StreamConfiguration> &config);
> > > +
> > >  	bool match(DeviceEnumerator *enumerator);
> > >
> > >  private:
> > > @@ -42,6 +51,32 @@ PipelineHandlerUVC::~PipelineHandlerUVC()
> > >  		media_->release();
> > >  }
> > >
> > > +std::map<unsigned int, StreamConfiguration>
> > > +PipelineHandlerUVC::streamConfiguration(const Camera *camera,
> > > +					const std::vector<Stream> &streams) const
> > > +{
> > > +	std::map<unsigned int, StreamConfiguration> configs;
> > > +
> > > +	StreamConfiguration config;
> > > +
> > > +	LOG(UVC, Info) << "TODO: Fetch stream configuration";
> > > +
> > > +	configs[0] = config;
> > > +
> > > +	return configs;
> > > +}
> > > +
> > > +int PipelineHandlerUVC::configureStreams(const Camera *camera,
> > > +					 std::map<unsigned int, StreamConfiguration> &config)
> > > +{
> > > +	StreamConfiguration *cfg = &config[0];
> > > +
> > > +	LOG(UVC, Info) << "TODO: Configure the camera for resolution " <<
> > > +		cfg->width << "x" << cfg->height;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
> > >  {
> > >  	DeviceMatch dm("uvcvideo");
> > > diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> > > index c426a953aea1b3dd..c9810a8e192ac68b 100644
> > > --- a/src/libcamera/pipeline/vimc.cpp
> > > +++ b/src/libcamera/pipeline/vimc.cpp
> > > @@ -9,17 +9,26 @@
> > >  #include <libcamera/stream.h>
> > >
> > >  #include "device_enumerator.h"
> > > +#include "log.h"
> > >  #include "media_device.h"
> > >  #include "pipeline_handler.h"
> > >
> > >  namespace libcamera {
> > >
> > > +LOG_DEFINE_CATEGORY(VIMC)
> > > +
> > >  class PipeHandlerVimc : public PipelineHandler
> > >  {
> > >  public:
> > >  	PipeHandlerVimc(CameraManager *manager);
> > >  	~PipeHandlerVimc();
> > >
> > > +	std::map<unsigned int, StreamConfiguration>
> > > +	streamConfiguration(const Camera *camera,
> > > +			    const std::vector<Stream> &streams) const;
> > > +	int configureStreams(const Camera *camera,
> > > +			     std::map<unsigned int, StreamConfiguration> &config);
> > > +
> > >  	bool match(DeviceEnumerator *enumerator);
> > >
> > >  private:
> > > @@ -37,6 +46,32 @@ PipeHandlerVimc::~PipeHandlerVimc()
> > >  		media_->release();
> > >  }
> > >
> > > +std::map<unsigned int, StreamConfiguration>
> > > +PipeHandlerVimc::streamConfiguration(const Camera *camera,
> > > +				     const std::vector<Stream> &streams) const
> > > +{
> > > +	std::map<unsigned int, StreamConfiguration> configs;
> > > +
> > > +	StreamConfiguration config;
> > > +
> > > +	LOG(VIMC, Info) << "TODO: Fetch stream configuration";
> > > +
> > > +	configs[0] = config;
> > > +
> > > +	return configs;
> > > +}
> > > +
> > > +int PipeHandlerVimc::configureStreams(const Camera *camera,
> > > +				      std::map<unsigned int, StreamConfiguration> &config)
> > > +{
> > > +	StreamConfiguration *cfg = &config[0];
> > > +
> > > +	LOG(VIMC, Info) << "TODO: Configure the camera for resolution " <<
> > > +		cfg->width << "x" << cfg->height;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
> > >  {
> > >  	DeviceMatch dm("vimc");
> > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > > index 1c8640799f714686..ee6d80908f67d564 100644
> > > --- a/src/libcamera/pipeline_handler.cpp
> > > +++ b/src/libcamera/pipeline_handler.cpp
> > > @@ -75,6 +75,40 @@ PipelineHandler::~PipelineHandler()
> > >  {
> > >  };
> > >
> > > +
> > > +/**
> > > + * \fn PipelineHandler::streamConfiguration(const Camera *camera, * const std::vector<Stream> &streams)
> >
> > You don't need to specify the function parameters when the function
> > isn't overloaded.
> >
> > > + * \brief Retrieve a group of stream configurations for a specified camera
> > > + * \param[in] camera The camera to fetch the configuration from
> > > + * \param[in] streams An array of streams to fetch information about
> > > + *
> > > + * Retrieve the species camera's configuration for a specified group of streams.
> > > + * The caller shall populate the \a streams array with the streams it wish to
> > > + * fetch the configuration from. The map of stream IDs and configuration
> > > + * returned can then be examined by the caller to learn about the parameters for
> > > + * the specified streams.
> > > + *
> > > + * The intended companion to this is \a configureStreams() which can be used to
> > > + * change the group of streams parameters.
> > > + *
> > > + * \return A map of successfully retrieved stream IDs and configurations or an
> > > + * empty map on error.
> > > + */
> > > +
> > > +/**
> > > + * \fn PipelineHandler::configureStreams(const Camera *camera, std::map<unsigned int, StreamConfiguration> &config)
> > > + * \brief Configure a group of streams for capture
> > > + * \param[in] camera The camera to apply the configuration to
> >
> > You could simply say "The camera to configure".
> >
> > > + * \param[in] config A map of stream configurations to apply
> > > + *
> > > + * Configure the specified group of streams for \a camera according to the
> > > + * configuration specified in \a configs. The intended caller of this interface
> > > + * is the Camera class which will receive configuration to apply from the
> > > + * application.
> > > + *
> > > + * \return 0 on success or a negative error code on error.
> > > + */
> > > +
> > >  /**
> > >   * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
> > >   * \brief Match media devices and create camera instances

Patch

diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index ca77a40b96e69b66..c19eb9b73ede8720 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -17,6 +17,8 @@  namespace libcamera {
 class CameraManager;
 class DeviceEnumerator;
 class MediaDevice;
+class Stream;
+class StreamConfiguration;
 
 class Camera;
 class CameraData
@@ -38,6 +40,12 @@  public:
 	PipelineHandler(CameraManager *manager);
 	virtual ~PipelineHandler();
 
+	virtual std::map<unsigned int, StreamConfiguration>
+	streamConfiguration(const Camera *camera,
+			    const std::vector<Stream> &streams) const = 0;
+	virtual int configureStreams(const Camera *camera,
+				     std::map<unsigned int, StreamConfiguration> &config) = 0;
+
 	virtual bool match(DeviceEnumerator *enumerator) = 0;
 
 protected:
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index dbb2a89163c36cbc..ff4d73f947a683ca 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -28,6 +28,12 @@  public:
 	PipelineHandlerIPU3(CameraManager *manager);
 	~PipelineHandlerIPU3();
 
+	std::map<unsigned int, StreamConfiguration>
+	streamConfiguration(const Camera *camera,
+			    const std::vector<Stream> &streams) const;
+	int configureStreams(const Camera *camera,
+			     std::map<unsigned int, StreamConfiguration> &config);
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -61,6 +67,32 @@  PipelineHandlerIPU3::~PipelineHandlerIPU3()
 		imgu_->release();
 }
 
+std::map<unsigned int, StreamConfiguration>
+PipelineHandlerIPU3::streamConfiguration(const Camera *camera,
+					 const std::vector<Stream> &streams) const
+{
+	std::map<unsigned int, StreamConfiguration> configs;
+
+	StreamConfiguration config;
+
+	LOG(IPU3, Info) << "TODO: Fetch stream configuration";
+
+	configs[0] = config;
+
+	return configs;
+}
+
+int PipelineHandlerIPU3::configureStreams(const Camera *camera,
+					  std::map<unsigned int, StreamConfiguration> &config)
+{
+	StreamConfiguration *cfg = &config[0];
+
+	LOG(IPU3, Info) << "TODO: Configure the camera for resolution " <<
+		cfg->width << "x" << cfg->height;
+
+	return 0;
+}
+
 bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch cio2_dm("ipu3-cio2");
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index bc4a8d7236be589d..bba4655a0a26b622 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -9,18 +9,27 @@ 
 #include <libcamera/stream.h>
 
 #include "device_enumerator.h"
+#include "log.h"
 #include "media_device.h"
 #include "pipeline_handler.h"
 #include "v4l2_device.h"
 
 namespace libcamera {
 
+LOG_DEFINE_CATEGORY(UVC)
+
 class PipelineHandlerUVC : public PipelineHandler
 {
 public:
 	PipelineHandlerUVC(CameraManager *manager);
 	~PipelineHandlerUVC();
 
+	std::map<unsigned int, StreamConfiguration>
+	streamConfiguration(const Camera *camera,
+			    const std::vector<Stream> &streams) const;
+	int configureStreams(const Camera *camera,
+			     std::map<unsigned int, StreamConfiguration> &config);
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -42,6 +51,32 @@  PipelineHandlerUVC::~PipelineHandlerUVC()
 		media_->release();
 }
 
+std::map<unsigned int, StreamConfiguration>
+PipelineHandlerUVC::streamConfiguration(const Camera *camera,
+					const std::vector<Stream> &streams) const
+{
+	std::map<unsigned int, StreamConfiguration> configs;
+
+	StreamConfiguration config;
+
+	LOG(UVC, Info) << "TODO: Fetch stream configuration";
+
+	configs[0] = config;
+
+	return configs;
+}
+
+int PipelineHandlerUVC::configureStreams(const Camera *camera,
+					 std::map<unsigned int, StreamConfiguration> &config)
+{
+	StreamConfiguration *cfg = &config[0];
+
+	LOG(UVC, Info) << "TODO: Configure the camera for resolution " <<
+		cfg->width << "x" << cfg->height;
+
+	return 0;
+}
+
 bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("uvcvideo");
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index c426a953aea1b3dd..c9810a8e192ac68b 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -9,17 +9,26 @@ 
 #include <libcamera/stream.h>
 
 #include "device_enumerator.h"
+#include "log.h"
 #include "media_device.h"
 #include "pipeline_handler.h"
 
 namespace libcamera {
 
+LOG_DEFINE_CATEGORY(VIMC)
+
 class PipeHandlerVimc : public PipelineHandler
 {
 public:
 	PipeHandlerVimc(CameraManager *manager);
 	~PipeHandlerVimc();
 
+	std::map<unsigned int, StreamConfiguration>
+	streamConfiguration(const Camera *camera,
+			    const std::vector<Stream> &streams) const;
+	int configureStreams(const Camera *camera,
+			     std::map<unsigned int, StreamConfiguration> &config);
+
 	bool match(DeviceEnumerator *enumerator);
 
 private:
@@ -37,6 +46,32 @@  PipeHandlerVimc::~PipeHandlerVimc()
 		media_->release();
 }
 
+std::map<unsigned int, StreamConfiguration>
+PipeHandlerVimc::streamConfiguration(const Camera *camera,
+				     const std::vector<Stream> &streams) const
+{
+	std::map<unsigned int, StreamConfiguration> configs;
+
+	StreamConfiguration config;
+
+	LOG(VIMC, Info) << "TODO: Fetch stream configuration";
+
+	configs[0] = config;
+
+	return configs;
+}
+
+int PipeHandlerVimc::configureStreams(const Camera *camera,
+				      std::map<unsigned int, StreamConfiguration> &config)
+{
+	StreamConfiguration *cfg = &config[0];
+
+	LOG(VIMC, Info) << "TODO: Configure the camera for resolution " <<
+		cfg->width << "x" << cfg->height;
+
+	return 0;
+}
+
 bool PipeHandlerVimc::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("vimc");
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 1c8640799f714686..ee6d80908f67d564 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -75,6 +75,40 @@  PipelineHandler::~PipelineHandler()
 {
 };
 
+
+/**
+ * \fn PipelineHandler::streamConfiguration(const Camera *camera, * const std::vector<Stream> &streams)
+ * \brief Retrieve a group of stream configurations for a specified camera
+ * \param[in] camera The camera to fetch the configuration from
+ * \param[in] streams An array of streams to fetch information about
+ *
+ * Retrieve the species camera's configuration for a specified group of streams.
+ * The caller shall populate the \a streams array with the streams it wish to
+ * fetch the configuration from. The map of stream IDs and configuration
+ * returned can then be examined by the caller to learn about the parameters for
+ * the specified streams.
+ *
+ * The intended companion to this is \a configureStreams() which can be used to
+ * change the group of streams parameters.
+ *
+ * \return A map of successfully retrieved stream IDs and configurations or an
+ * empty map on error.
+ */
+
+/**
+ * \fn PipelineHandler::configureStreams(const Camera *camera, std::map<unsigned int, StreamConfiguration> &config)
+ * \brief Configure a group of streams for capture
+ * \param[in] camera The camera to apply the configuration to
+ * \param[in] config A map of stream configurations to apply
+ *
+ * Configure the specified group of streams for \a camera according to the
+ * configuration specified in \a configs. The intended caller of this interface
+ * is the Camera class which will receive configuration to apply from the
+ * application.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
 /**
  * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
  * \brief Match media devices and create camera instances