Change "Width, Height and PixelFormat" in GStreamer filter aravissrc

[robertofem]

Describe the bug I am using Gstreamer to build a pipeline that reads data from a camera and prints them to screen (later to save them to mp4). I need to change more parameters than those available through aravissrc filter properties, like Height, Width and PixelFormat (I want RGB image and always get Mono). I have a working pipeline with aravissrc, queue, videoconvert and xvimagesink GstElements. I try to get the aravis camera object (ArvCamera) and device object (ArvDevice) to later use the Aravis functions (arv_device_set_integer_feature_value, arv_camera_set_region, etc.) to modify the settings of the camera (these configuration functions work when I use only aravis without gstreamer). However when I do that and check for returned value with ARV_IS_CAMERA it is never a correct camera). It does the same regardless where I put this piece of code after creating elements, after linking them in the pipeline and even after starting the pipeline.

I have to include #include <arv.h> in the file in order to find ArvCamera object. I wonder if this is needed or there is a possibility to use Aravis objects just using the gst.h file.

To Reproduce I just add the following aravis code in a working pipeline after creating Gst elements and after linking them. Neither works.

#include <gst/gst.h>
#include <arv.h> 

...

/* Initialize GStreamer */
gst_init (&argc, &argv);

/* Create the elements */
arvsrc = gst_element_factory_make ("aravissrc", "video_source");
vidqueue = gst_element_factory_make ("queue", "video_queue");
vidconvert = gst_element_factory_make ("videoconvert", "video_convert");
vidsink = gst_element_factory_make ("xvimagesink", "video_sink");

/* Create the empty pipeline */
pipeline = gst_pipeline_new ("arv2screen-pipeline");

if (!pipeline || !arvsrc || !vidqueue || !vidconvert || !vidsink) {
  g_printerr ("Not all elements could be created.\n");
  return -1;
}

/* This is the problematic code  */
ArvCamera* cam;
g_object_get (arvsrc, "camera", &cam, NULL); 
if (ARV_IS_CAMERA (cam)) g_printerr ("It is a camera.\n");
else g_printerr ("It is not a camera.\n");

/* Link elements  */
gst_bin_add_many (GST_BIN (pipeline), arvsrc, vidqueue, vidconvert, vidsink, NULL);
if (gst_element_link_many (arvsrc, vidqueue, NULL) != TRUE ||
gst_element_link_many (vidqueue, vidconvert, NULL) != TRUE ||
gst_element_link_many (vidconvert, vidsink, NULL) != TRUE ) {
  g_printerr ("Elements could not be linked.\n");
  gst_object_unref (pipeline);
  return -1;
}

Compilation command

cc arv2screen.c -o arv2screen `pkg-config --cflags --libs gstreamer-1.0` `pkg-config --cflags --libs aravis-0.6`

Expected behavior To get a correct ArvCamera pointer of the internal camera handler used by the Gstreamer aravissrc plugin.

Camera description:

• Manufacturer: iDS
• Model: GV-5860CP-C-HQ-R2
• Interface: Gige

Platform description:

• Aravis version: 0.8.0 and 0.6.0 on along with Gstreamer 1.0
• OS: Ubuntu 20.04
• Hardware: x86_64

Additional context Add any other context about the problem here.

[EmmanuelP]

The ArvCamera object returned by g_object_get (arvsrc, "camera", &cam, NULL); is only valid after the pipeline has started.

But aravissrc has also a features property that lets you set additional features as a space separated list of feature assignations. The string is sent as is to arv_device_set_features_fro_string(), just before the stream creation.

Does that solve your issue ?

[EmmanuelP]

Please note that after the acquisition is started, there is some features that can no be changed, like Width, Height or PixelFormat.

[robertofem]

Hello, thanks for the quick and accurate response (and for the aravis library).

I am using gstreamer-1.0 downloaded with apt-get, which uses aravis 0.6, which does not have featrures property in it. But I can see the master version has it. I will compile aravis master, make gstreamer use the newest aravissrc and let you know if it works (I dont know if it is better to just install a newer gstreamer).

[robertofem]

Hello,

I uninstalled aravis 0.6 and installed 0.8 compiling from source to have the "features" property. Now I get this error when running gst-launch-1.0 aravissrc ! videoconvert ! xvimagesink :

Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
ERROR: from element /GstPipeline:pipeline0/GstAravis:aravis0: Could not set caps on camera "": Value not found in <Enumeration> 'TriggerSelector'
Additional debug info:
../gst/gstaravis.c(369): gst_aravis_set_caps (): /GstPipeline:pipeline0/GstAravis:aravis0
Execution ended after 0:00:00.198166929
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

Aravis seems to work fine since "arv-camera-test-0.8" runs fine. The new aravis 0.8.11 plugin gets recognized by "gst-inspect-1.0 aravis".

Is there any incompatibility between aravis 0.8.11 and the version of gstreamer-1.0 (i am currently running gstreamer core 1.16.2, the one installed with apt-get in ubuntu 20.04) ? Should I update gstreamer?