Teledyne Z-Trak L2PC: payloadSize is miscalculated, due to Genicam standard violation

[bishoy-g]

Describe the bug
When trying to retrieve the PayloadSize (arv_camera_get_payload) using a certain camera (Teledyne Z-Trak L2PC), I always get 0. We have multiple camera models from Teledyne and other makers and all of them report a correct value except this specific model. We have 4 cameras of this model and the behavior is the same. We contacted the manufacturer but they could not help because the payload size is reported correctly in their acquisition software when viewing the features tree and nodes.

To Reproduce
I am attaching the camera's geni features schema xml and hope it can be useful to reproduce. I get the 0 payload size from the arv-camera-test as well and not only from our application.

Expected behavior
A size that is larger than 0 to represent the payload size according the expression formula

Camera description:

• Manufacturer: Teledyne
• Model: Z-Trak L2PC
• Interface: Ethernet 1Gb

Platform description:

• Aravis version 0.8.0
• OS: Ubuntu 20.04
• Hardware: x64

Attachment:
features_ztrack.txt

Thank you for your support and for all the efforts put into this library.

[EmmanuelP]

Hi,

Thanks for the report. Could you attach the output of arv-camera-test-0.8 -d evaluator:4 ?

[bishoy-g]

Hi Emmanuel,

Thanks for the prompt reply, please find the attached output as requested. Seems like there is an error in parsing the expression by the evaluator.

evaluator_output.txt

[EmmanuelP]

It looks like the IntSwissKnife node is incorrect wrt the Genicam standard. Page 40 of https://www.emva.org/wp-content/uploads/GenICam_Standard_v2_1_1.pdf :

The SwissKnife syntax has some extensions: You can use named constants using the
Constant entry and named sub expressions using the Expression entry as shown in the
following example. The sub expressions may not refer to other sub expressions.

The definition of PayloadSize for this camera is:

      <IntSwissKnife Name="PayloadSizeVal">
         <pVariable Name="PACKET_SIZE">pGevSCPSPacketSizeReg</pVariable>
         <pVariable Name="PIXEL_SIZE">PixelSizeVal</pVariable>
         <pVariable Name="WIDTH">width_user_space</pVariable>
         <pVariable Name="HEIGHT">Height_Convertor</pVariable>
         <pVariable Name="MAX_CHUNK_SIZE">max_chunk_size</pVariable>
         <pVariable Name="IS_AREASCAN">isAreascan</pVariable>
         <pVariable Name="POINTS_PER_PROFILE_WITH_METADATA">width_linescan3d_metadata</pVariable>
         <pVariable Name="PROFILES_PER_SCAN">profilesPerScan_Val</pVariable>
         <Expression Name="DATA_PACKET_SIZE">PACKET_SIZE - 48</Expression>
         <Expression Name="NUM_PIXELS_AREASCAN">WIDTH * HEIGHT</Expression>
         <Expression Name="NUM_PIXELS_LINESCAN">POINTS_PER_PROFILE_WITH_METADATA * PROFILES_PER_SCAN</Expression>
         <Expression Name="DATA_SIZE">((IS_AREASCAN ? NUM_PIXELS_AREASCAN : NUM_PIXELS_LINESCAN) * PIXEL_SIZE / 8)</Expression>
         <!-- #elif //def AVAILABLE -->
         <!--<Expression Name="DATA_SIZE">((IS_AREASCAN ? NUM_PIXELS_AREASCAN : NUM_PIXELS_LINESCAN) * PIXEL_SIZE / 8) + ((CHUNK_MODE) ? MAX_CHUNK_SIZE : 0)</Expression>-->
         <Formula>((DATA_SIZE / DATA_PACKET_SIZE) + ((DATA_SIZE % DATA_PACKET_SIZE) ? 1 : 0)) * DATA_PACKET_SIZE</Formula>
         <Representation>Linear</Representation>
      </IntSwissKnife>

DATA_SIZE makes use of NUM_PIXELS_AREASCAN and NUM_PIXELS_LINESCAN.

Aravis is checking for use of sub-expression from a sub-expression and throws an error if it happens:

aravis/src/arvevaluator.c

Lines 1046 to 1062 in c07e8be

	if (sub_expression != NULL) {
	char *string;
	if (state->in_sub_expression) {
	status = ARV_EVALUATOR_STATUS_FORBIDDEN_RECUSRION;
	goto CLEANUP;
	}
	string = g_strdup_printf ("(%s)", sub_expression);
	state->in_sub_expression = TRUE;
	status = parse_to_stacks (evaluator, string, state);
	state->in_sub_expression = FALSE;
	g_free (string);
	if (status != ARV_EVALUATOR_STATUS_SUCCESS) {
	goto CLEANUP;
	}