Hello, This patch adds a V4L2 output device on vimc, that comply with V4L2 API for video output. If there is an output device and a capture device at the same pipeline, one can get a video loopback pipeline feeding frames at the output and then seeing them at the capture. It's possible to insert vimc submodules at the pipeline to modify the image (e.g. a scaler). If one starts a streaming at the capture, with the output off, the capture will display a noisy frame. If one starts a streaming at the output with the capture off, the output will just consume the buffers, without sending them to the pipeline. If both output and capture are streaming, the loopback will happen. The patches 1 and 2 provide some ground to create the output device. The patch 3 creates the device and modify how the vimc-streamer was dealing with the s_stream callback on other vimc modules, to make simpler implementing this callback at vimc-output. Patch 4 change the behavior of the pipeline in order to be closer to a real life hardware. Patches 5-7 updates the default pipeline and the documentation to include the new output device. This is the result of v4l2-compliance after this patch series: $ v4l2-compliance -m0 -s50 Grand Total for vimc device /dev/media0: 476, Succeeded: 476, Failed: 0, Warnings: 0 A git tree up to date with media-master and with this changes can be found at: https://gitlab.collabora.com/tonyk/linux/tree/vimc/output In order to test it, one can follow these instructions: 1 - Configure the pipeline (requires v4l-utils): $ media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]' $ media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]' $ media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]' $ media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]' $ v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440 $ v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81 $ v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81 $ v4l2-ctl -z platform:vimc -e "RGB/YUV Input" -v width=640,height=480 2 - Use a userspace application: 2.a gst-launch (requires gstreamer and gst-plugins-good): Feed frames into the output and grab from the capture (rescaled for convenience): $ gst-launch-1.0 videotestsrc pattern=ball ! \ video/x-raw,width=640,height=480,format=RGB \ ! v4l2sink device=/dev/video2 v4l2src device=/dev/video3 ! \ video/x-raw,width=1920,height=1440,format=RGB ! videoscale ! \ video/x-raw,width=640,height=480 ! videoconvert ! ximagesink 2.b qv4l2 (requires v4l-utils): Open the output device: $ qv4l2 -d2 Open the capture device: $ qv4l2 -d3 Start the streaming at both, at any order. You can change the frame content at "Test Pattern Generator" -> "Test Pattern" on the output. Thanks, André André Almeida (7): media: vimc: Create video module media: vimc: video: Add write file operation media: vimc: Create a V4L2 output device media: vimc: Send null buffer through the pipeline media: vimc: core: Add output device on the pipeline media: vimc.dot: Update default topology diagram media: vimc.rst: Add output device Documentation/media/v4l-drivers/vimc.dot | 4 +- Documentation/media/v4l-drivers/vimc.rst | 12 +- drivers/media/platform/vimc/Makefile | 4 +- drivers/media/platform/vimc/vimc-capture.c | 356 +++---------------- drivers/media/platform/vimc/vimc-common.h | 5 +- drivers/media/platform/vimc/vimc-core.c | 7 +- drivers/media/platform/vimc/vimc-debayer.c | 14 +- drivers/media/platform/vimc/vimc-output.c | 362 ++++++++++++++++++++ drivers/media/platform/vimc/vimc-scaler.c | 13 +- drivers/media/platform/vimc/vimc-sensor.c | 10 +- drivers/media/platform/vimc/vimc-streamer.c | 24 +- drivers/media/platform/vimc/vimc-video.c | 273 +++++++++++++++ drivers/media/platform/vimc/vimc-video.h | 130 +++++++ 13 files changed, 849 insertions(+), 365 deletions(-) create mode 100644 drivers/media/platform/vimc/vimc-output.c create mode 100644 drivers/media/platform/vimc/vimc-video.c create mode 100644 drivers/media/platform/vimc/vimc-video.h -- 2.22.0
