Testing Camera Capture

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NXP i.MX95

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Camera Kernel Support

To test camera support on the Verdin i.MX95, we are going to use an OV5640 camera sensor. This is a CSI camera module from ARDUCAM. Some of the features of this camera sensor are:

Image Sensor: OV5640 from OmniVision
Still Resolution: 5Megapixels
Interface: MIPI CSI-2
Output Format: 8-/10-bit RGB RAW, RGB, YUV, JPEG
Max Pixel Array: 2592 x 1944 pixels
Sensor image area: 6.287mm x 4.712 mm (7.9mm diagonal)
Pixel Size 1.4μm x 1.4μm
Optical Size: 1/4"

Hardware setup

The camera should include a MIPI CSI cable. This cableis used to connect it to the Verdin Development board on port X47. The right connection and orientation of the cable is in the image below:

Here is how the sensor side should look:

Device Tree Overlay

The OV5640 is not part of the default NXP BSP, but can be integrated via a device tree overlay. The Reference Multimedia Image contains some device tree overlays. Among these overlays, there is one to support this camera sensor with a certain operation frequency. To enable it, modify the file '/boot/overlays.txt to have the following contents:

fdt_overlays=verdin-imx95_dsi-to-hdmi_overlay.dtbo verdin-imx95_spidev_overlay.dtbo verdin-imx95_ov5640-27mhz_overlay.dtbo

After modifying this file, reboot' the board to apply the verdin-imx95_ov5640-27mhz_overlay.dtbo overlay.

Capture Pipeline (Media Graph)

The i.MX95 uses the Media Controller framework to describe and configure the camera pipeline. This pipeline is composed of several interconnected hardware blocks such as the CSI receiver, formatter, crossbar, and ISI.

To visualize the pipeline, you can generate a graph using:

media-ctl --print-dot > graph.dot

The resulting graph.dot file contains the information to see the media graph. To watch the graph, you can copy this file to your host PC and run:

dot -Tpng graph.dot > graph.png

The resulting png file should show a graph like the following:

As you can see the link from the camera to the CSI module is a noncontinuous line. This means this link is not enabled. We are going to enable it in the following section:

Configure Media Pipeline

Minimal Required Setup

Only 3 commands are required:

media-ctl -l "'ov5640 4-003c':0 -> 'csidev-4ad30000.csi':0 [1]"
media-ctl -V "'ov5640 4-003c':0 [fmt:UYVY8_1X16/1920x1080 field:none]"
v4l2-ctl -d /dev/video3 -v width=1920,height=1080,pixelformat=YUYV

media-ctl -l
- Enables the link between the sensor and CSI receiver

media-ctl -V
- Configures the sensor output format and resolution

v4l2-ctl -v
- Configures the capture device (/dev/videoX)

Note

These settings are not persistent. They must be applied after every reboot or automated using systemd.

Full Pipeline Configuration (Optional)

For non-default resolutions:

media-ctl -l "'ov5640 4-003c':0 -> 'csidev-4ad30000.csi':0 [1]"
media-ctl -V "'csidev-4ad30000.csi':0 [fmt:UYVY8_1X16/1280x720 field:none]"
media-ctl -V "'4ac10000.syscon:formatter@20':0 [fmt:UYVY8_1X16/1280x720 field:none]"
media-ctl -V "'crossbar':2 [fmt:UYVY8_1X16/1280x720 field:none]"
media-ctl -V "'mxc_isi.0':0 [fmt:UYVY8_1X16/1280x720 field:none]"

Capture Device

Available nodes:

/dev/video2 → mxc_isi.0.capture
/dev/video3 → mxc_isi.1.capture

Both /dev/video2 and /dev/video3 work.

Recommended:

/dev/video3

Capture with v4l2-ctl

v4l2-ctl -d /dev/video3 --stream-mmap --stream-count=10 --stream-to=/tmp/out.yuyv
<<<<<<<<<<

Each '<' represents one captured frame.

GStreamer Pipelines

Display Camera

gst-launch-1.0 v4l2src device=/dev/video3 ! video/x-raw,format=YUY2,width=1920,height=1080,framerate=30/1 ! videoconvert ! waylandsink

Save Raw Video

gst-launch-1.0 v4l2src device=/dev/video3 num-buffers=100 ! video/x-raw,format=YUY2,width=1920,height=1080 ! filesink location=out.yuyv

Encode to MP4

gst-launch-1.0 -e v4l2src device=/dev/video3 ! video/x-raw,width=1920,height=1080 ! queue ! v4l2h264enc ! h264parse ! qtmux ! filesink location=output.mp4

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