topic Re: v4l2jpegdec C example in i.MX Processors

v4l2jpegdec C example

jonners_guttman — Mon, 05 Aug 2019 14:44:27 GMT

Hi,

Can anyone provide a C example of how to use the v4l2jpegdec element in gstreamer.

The jpeg image should be an "appsrc" - I have the jpeg image in memory and need to pass this into the v4l2jpegdec decoder.

The decoded image should be sent to an "appsink" element so I get the decoded image in memory.

Many thanks for any help,

Jonners.

Re: v4l2jpegdec C example

joanxie — Wed, 07 Aug 2019 04:58:53 GMT

v4l2jpegdec should be used in the imx8QM which is under preproduction, so I couldn't checked for you, if you have already have this, I suggest that you use "gst-inspect-1.0 v4l2jpegdec " to check the source code path, then you can find the source code, I think it should be included in the gst plugins

Re: v4l2jpegdec C example

jonners_guttman — Wed, 07 Aug 2019 08:11:46 GMT

Hi Joan,

Many thanks for your response.

v4l2jpegdec is on my system ☺

What I am trying to achieve is to have a jpeg image in a buffer in my application (appsrc) and use the hardware decoder on the iMX8X to decode the jpeg into RGB raw data returned in a buffer to my application (appsink.)

I have this working using the “jpegdec” element – however, this is a software decoder and very slow (5 frames per second for a 1080p JPEG). If I replace the “jpegdec” element with “v4l2jpegdec” then I get the following error:

Elements created.

firmware version is 1.3.1

Error received from element mySrc: Internal data stream error.[VPU Decoder] error: don't find buffer when wait_rst_done is true, ctx->firmware_stopped=0fin=0

Debugging information: ../../../../git/libs/gst/base/gstbasesrc[VPU Decoder] error: don't find buffer when wait_rst_done is true, ctx->firmware_stopped=0fin=0

.c(3055): gst_base_src_loop (): /GstPipeline:myPipeline/GstAppSrc[VPU Decoder] error: don't find buffer when wait_rst_done is true, ctx->firmware_stopped=0fin=0

:mySrc:

streaming stopped, reason not-negotiated (-4)

I think this is positive as the VPU decoder has been initialise. I think my problem is that the jpeg image is not in the correct memory for the hardware decoder.

Is this something you might be able to help with?

Attached is a copy of my test application.

Kind regards,

Jonners.

Re: v4l2jpegdec C example

joanxie — Thu, 08 Aug 2019 04:56:35 GMT

did you use imx8x or imx8qm board? if imx8x, pls tell me your test steps and gstreamer commands, let me test on my imx8x board

Re: v4l2jpegdec C example

jonners_guttman — Thu, 08 Aug 2019 06:38:12 GMT

Hi Joan,

I did this in an iMX8X board. I have attached my test application source code.

Kind regards,

Jonners.

Re: v4l2jpegdec C example

joanxie — Fri, 09 Aug 2019 03:22:38 GMT

refer to the release note of 4.14.98:

i.MX 8QuadMax and 8QuadXPlus Decoder: HEVC, H.264, MPEG4, MPEG2

it seems that imx8qxp doesn't support jpeg decoder on VPU(hardware)