topic Re: opencv with gstreamer in VideoCapture doesn't work in i.MX Processors

opencv with gstreamer in VideoCapture doesn't work

yibhan — Thu, 07 May 2020 01:02:40 GMT

Hello guys,

I have built imx-image-multimeia in yocto(kernel 5.4.3.1) and added opencv some packages such as

CORE_IMAGE_EXTRA_INSTALL += " opencv-apps opencv-samples python3-opencv".

and then bitbake ima-image-multimedia -c populate_sdk.

and CROSS_COMPILE=/opt/fsl-imx-x11/5.4-zeus/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-

and SDKTARGETSYSROOT=/opt/fsl-imx-x11/5.4-zeus/sysroots/cortexa9t2hf-neon-poky-linux-gnueabi.

but, when i run web cam app, some error occurred and stopped. I thought the pipeline would be right below

v4l2src device=/dev/video2 ! 'video/x-raw,width=640,height=480' ! imxv4l2sink. it works, but

VideoCapture cap("imxv4l2src device=/dev/video2 ! 'video/x-raw,width=640,height=480' ! appsink") doesn't work and below error is:

/usr/src/debug/opencv/4.1.2.imx-r0/git/modules/videoio/src/cap_gstreamer.cpp (933) open OpenCV | GStreamer warning: Cannot query video position: status=0, value=-1, duration=-1

I think it is caused by opencv with gstreamer but, I have no idea.

Could you tell me how to debug?

Re: opencv with gstreamer in VideoCapture doesn't work

yibhan — Thu, 07 May 2020 01:27:42 GMT

Below build configuration to be used:

Build Configuration:
BB_VERSION           = "1.44.0"
BUILD_SYS            = "x86_64-linux"
NATIVELSBSTRING      = "ubuntu-16.04"
TARGET_SYS           = "arm-poky-linux-gnueabi"
MACHINE              = "imx6qpsabresd"
DISTRO               = "fsl-imx-x11"
DISTRO_VERSION       = "5.4-zeus"
TUNE_FEATURES        = "arm vfp cortexa9 neon thumb callconvention-hard"
TARGET_FPU           = "hard"
meta
meta-poky            = "HEAD:0275e68b0576cdefc19718e4b1977044f9f43f48"
meta-oe
meta-multimedia
meta-python          = "HEAD:aad5b3d070cd8c58828b0975cf861d8ebc90f460"
meta-freescale       = "HEAD:0be39721cea6e04c589a419f4bb07fabd0da6704"
meta-freescale-3rdparty = "HEAD:aea3771baa77e74762358ceb673d407e36637e5f"
meta-freescale-distro = "HEAD:ca27d12e4964d1336e662bcc60184bbff526c857"
meta-bsp
meta-sdk
meta-ml              = "HEAD:435f5e984856a943986491fddd061734a0b9eba5"
meta-browser         = "HEAD:5f365ef0f842ba4651efe88787cf9c63bc8b6cb3"
meta-rust            = "HEAD:5cda04c7c2158fc982502ca1e7893f71e4ca1729"
meta-gnome
meta-networking
meta-filesystems     = "HEAD:aad5b3d070cd8c58828b0975cf861d8ebc90f460"
meta-qt5             = "HEAD:432ad2aa6c3a13253fefc909faba368851d21fb1"

Re: opencv with gstreamer in VideoCapture doesn't work

igorpadykov — Thu, 07 May 2020 04:35:07 GMT

Hi Yibeom

for supported i.MX GStreamer plugins one can refer to Table 15. i.MX GStreamer 1.0 plugins

attached Release Notes, seems there is no opencv.

Best regards
igor
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Re: opencv with gstreamer in VideoCapture doesn't work

yibhan — Thu, 07 May 2020 05:16:36 GMT

Hello igorpadykov,

I don't think so, there is something wrong in my side, but I can't find any reason.

Am i missing some of packages?

Re: opencv with gstreamer in VideoCapture doesn't work

Shinra — Wed, 06 Jan 2021 15:28:02 GMT

Got the exact same problem. For reference my pipeline is:

cap_send = cv2.VideoCapture('v4l2src device=/dev/video0 ! video/x-raw,framerate=30/1,width=1920,height=1080 ! videoconvert ! appsink',cv2.CAP_GSTREAMER)

Did you manage to solve it ?