[libcamera-devel] JPEG support for libcamera

[Nicolas Dufresne]

Le lundi 04 juillet 2022 à 20:07 +0200, Pavel Machek via libcamera-devel a
écrit :
> JPEG is very similar to MJPEG format (AFAICT, it may contain extra
> EXIF headers). Add support for it. Tested with PinePhone and command
> line cam utility.
> 
> Signed-off-by: Pavel Machek <pavel at ucw.cz>
> 
> diff --git a/include/linux/drm_fourcc.h b/include/linux/drm_fourcc.h
> index ea11dcb4..b30a705d 100644
> --- a/include/linux/drm_fourcc.h
> +++ b/include/linux/drm_fourcc.h
> @@ -352,6 +352,7 @@ extern "C" {
>  
>  /* Compressed formats */
>  #define DRM_FORMAT_MJPEG	fourcc_code('M', 'J', 'P', 'G') /* Motion-JPEG */
> +#define DRM_FORMAT_JPEG	fourcc_code('J', 'P', 'E', 'G') /* JFIF JPEG */

I personally don't see the point of adding a second JPEG format in the public
API. JPEG being duplicated is an absurdity because there is no decoders that do
differentiate any of these. I'd rather hide deeply this strange duplication that
originates from V4L2. Remember that there is a third JPEG format in V4L2 which
is also not going to be differentiated by the decoders.

regards,
Nicolas

>  
>  /*
>   * Bayer formats
> diff --git a/src/cam/sdl_sink.cpp b/src/cam/sdl_sink.cpp
> index f8e3e95d..673bd642 100644
> --- a/src/cam/sdl_sink.cpp
> +++ b/src/cam/sdl_sink.cpp
> @@ -63,6 +63,7 @@ int SDLSink::configure(const libcamera::CameraConfiguration &config)
>  
>  	switch (cfg.pixelFormat) {
>  #ifdef HAVE_SDL_IMAGE
> +	case libcamera::formats::JPEG:
>  	case libcamera::formats::MJPEG:
>  		texture_ = std::make_unique<SDLTextureMJPG>(rect_);
>  		break;
> diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-utils.cpp
> index 3f242286..fd5689d9 100644
> --- a/src/gstreamer/gstlibcamera-utils.cpp
> +++ b/src/gstreamer/gstlibcamera-utils.cpp
> @@ -80,6 +80,7 @@ bare_structure_from_format(const PixelFormat &format)
>  					 gst_video_format_to_string(gst_format), nullptr);
>  
>  	switch (format) {
> +	case formats::JPEG:
>  	case formats::MJPEG:
>  		return gst_structure_new_empty("image/jpeg");
>  	default:
> diff --git a/src/libcamera/formats.cpp b/src/libcamera/formats.cpp
> index 283ecb3d..c5e97198 100644
> --- a/src/libcamera/formats.cpp
> +++ b/src/libcamera/formats.cpp
> @@ -944,6 +944,19 @@ const std::map<PixelFormat, PixelFormatInfo> pixelFormatInfo{
>  	} },
>  
>  	/* Compressed formats. */
> +	{ formats::JPEG, {
> +		.name = "JPEG",
> +		.format = formats::JPEG,
> +		.v4l2Formats = {
> +			.single = V4L2PixelFormat(V4L2_PIX_FMT_JPEG),
> +			.multi = V4L2PixelFormat(),
> +		},
> +		.bitsPerPixel = 0,
> +		.colourEncoding = PixelFormatInfo::ColourEncodingYUV,
> +		.packed = false,
> +		.pixelsPerGroup = 1,
> +		.planes = {{ { 1, 1 }, { 0, 0 }, { 0, 0 } }},
> +	} },
>  	{ formats::MJPEG, {
>  		.name = "MJPEG",
>  		.format = formats::MJPEG,
> diff --git a/src/libcamera/formats.yaml b/src/libcamera/formats.yaml
> index 7dda0132..6b931c34 100644
> --- a/src/libcamera/formats.yaml
> +++ b/src/libcamera/formats.yaml
> @@ -76,6 +76,8 @@ formats:
>    - YVU444:
>        fourcc: DRM_FORMAT_YVU444
>  
> +  - JPEG:
> +      fourcc: DRM_FORMAT_JPEG
>    - MJPEG:
>        fourcc: DRM_FORMAT_MJPEG
>  
> diff --git a/src/libcamera/v4l2_pixelformat.cpp b/src/libcamera/v4l2_pixelformat.cpp
> index 58fc4e9d..82dfbd1e 100644
> --- a/src/libcamera/v4l2_pixelformat.cpp
> +++ b/src/libcamera/v4l2_pixelformat.cpp
> @@ -183,6 +183,8 @@ const std::map<V4L2PixelFormat, V4L2PixelFormat::Info> vpf2pf{
>  	/* Compressed formats. */
>  	{ V4L2PixelFormat(V4L2_PIX_FMT_MJPEG),
>  		{ formats::MJPEG, "Motion-JPEG" } },
> +	{ V4L2PixelFormat(V4L2_PIX_FMT_JPEG),
> +		{ formats::JPEG, "JPEG" } },
>  };
>  
>  } /* namespace */
>