Source Code for Demo Substream Generator Plugin

Location

./src/examples/src/adtf/filters/standard_filters/substream_generator_filter/

Build Environment

To see how to set up the build environment have a look at ADTF CMake Environment

this implementation shows:

• how to create a time triggered Filter.
• how to work with adtf::streaming::hollow::stream_meta_type_substreams and adtf::filter::hollow::cSubStreamTypes.
• how to write data with the help of adtf::streaming::flash::output_sample_data.

Implementation

 
#include <adtffiltersdk/adtf_filtersdk.h>
 
using namespace adtf::base;
using namespace adtf::filter;
using namespace adtf::mediadescription;
using namespace adtf::streaming;
using namespace adtf::ucom;
using namespace adtf::util;
using namespace ddl;
 
class cDemoSubStreamGenerator: public cFilter
{
    public:
        ADTF_CLASS_ID_NAME(cDemoSubStreamGenerator,
                           "demo_substream_generator.filter.adtf.cid",
                           "Demo Substream Generator");
    public:
        // this structure is the template for the definition of substream "stream4"
        struct tExampleStructWithUnit { uint32_t val{}; };
 
        cDemoSubStreamGenerator()
        {
            // sets a short description for the component
            SetDescription("Use this filter to generate data of multiple substreams whenever a timer triggers.");
 
            // set help link to jump to documentation from ADTF Configuration Editor
            SetHelpLink("$(ADTF_DIR)/doc/adtf_html/page_demo_substream_generator.html");
 
            CreateRunner("generate_samples");
            SetDescription("generate_samples", "Runner to periodically trigger the function which generates the substreams.");
 
            // we create the definition of substream "stream 4" by using the DDL type reflection of ADTF
            auto oExampleStructDefinition = structure<tExampleStructWithUnit>("tExampleStructWithUnit").Add("val", &tExampleStructWithUnit::val);
            oExampleStructDefinition.setElementUnit("val", ddl::BaseUnit<ddl::unit::Kelvin>());
 
            // we use the helper class cSubStreamTypes to generate a stream type with the
            // adtf::streaming::stream_meta_type_substreams meta type that contains
            // multiple stream type definitions.
            cSubStreamTypes oSubStreams;
            oSubStreams.SetSubStream("stream1", 0, stream_type_plain<uint32_t>());
            oSubStreams.SetSubStream("stream2", 1, stream_type_plain<uint32_t>());
            oSubStreams.SetSubStream("stream3", 2, stream_type_plain<uint32_t>());
            oSubStreams.SetSubStream("stream4", 3, oExampleStructDefinition);
 
            m_pWriter = CreateOutputPin("output", oSubStreams);
            SetDescription("output", "Provides the generated substreams.");
        }
 
        tResult Process(tNanoSeconds tmTrigger, IRunner* /*pRunner*/) override
        {
            ++m_nTriggerCounter;
 
            for (uint32_t nSubStreamId: {0, 1, 2})
            {
                // when generating samples we set the substream id.
                // in this case we just pass it to the output_sample_data constructor.
                // Otherwise take a look at adtf::streaming::set_sample_substream_id() and
                // adtf::streaming::hollow::ISample::SetSubStreamId().
                output_sample_data<uint32_t> oNewData(tmTrigger, m_nTriggerCounter + (nSubStreamId * 1000), nSubStreamId);
                m_pWriter->Write(oNewData.Release());
            }
 
            // we create a sample containing the time, value and substream id
            // the value is copied into the sample buffer in this process
            output_sample_data<tExampleStructWithUnit> oExampleOutputSampleData(tmTrigger, tExampleStructWithUnit{m_nTriggerCounter + (3 /*substreamId*/ * 1000)}, 3);
            m_pWriter->Write(oExampleOutputSampleData.Release());
 
            RETURN_NOERROR;
        }
 
    private:
        ISampleWriter* m_pWriter = nullptr;
        uint32_t m_nTriggerCounter = 0;
};
 
// this creates the plugin entry methods and class factories
ADTF_PLUGIN("Demo Substream Generator Plugin", cDemoSubStreamGenerator);