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Reading an image using OMX.broadcom.image_read

Posted: Tue Sep 02, 2014 12:21 pm
by jannewmarch
Has anyone succeeded in reading an image using the OMX.broadcom.image_read component? It has one (output) port that I have disabled, but when I ask to transition to Idle state I get an OMX_ErrorInsufficientResources event and it stays in Loaded state. The URL I am using is a relative local file "image.jpg" using "OMX_IndexParamContentURI: The filename containing the image file can be specified using this parameter". I have malloc'ed an OMX_PORT_PARAM_TYPE with extra space for the URL which I have copied into param_image->contentURI. I haven't done any settings on the output port, waiting for OMX_EventPortSettingsChanged event to occur first - but I never get that far.

Re: Reading an image using OMX.broadcom.image_read

Posted: Tue Sep 19, 2017 6:24 pm
by kwasmich
I recently started to mess around with OpenMAX and got stuck with the same problem. There are code samples out there that encode or decode images in memory using OpenMAX but so far no-one uses image_read. Did you have any success, yet?

Re: Reading an image using OMX.broadcom.image_read

Posted: Tue Sep 19, 2017 8:05 pm
by 6by9
image_read isn't going to work, and I'm surprised if it is actually in the build. (I'll look at removing it tomorrow if it is).

When the chip was used as a co-processor there was a mode where it could also act as the main processor too, and that is the mode that image_read (and image_write) were intended for.

With the Pi the GPU has no direct access to the SD card or other storage, so it can't directly read the image data. You need to be looking at image_decode and passing in the source data via buffers.

Re: Reading an image using OMX.broadcom.image_read

Posted: Wed Sep 20, 2017 6:28 pm
by kwasmich
Thanks for the clarification.

Re: Reading an image using OMX.broadcom.image_read

Posted: Mon Oct 09, 2017 9:49 am
by 6by9
Just FYI, it wasn't quite the tomorrow, but read_media, write_media, write_still, image_read, and image_write have now been removed from the latest firmware (rpi-update, not apt-get) and the IL documentation. (Only niggle is that the documentation HTML files didn't get deleted from https://github.com/raspberrypi/firmware ... components, but they aren't referenced anymore).