Example Demo Substream Generator

Table of Contents

• Description
• Prebuilt Binaries
• Source Code
  • Filter

Description

Shows how to create substreams.

Prebuilt Binaries

• Demo Substream Generator

Source Code

./examples/demo_adtfplugins/demo_substream_generator/

Filter

substream_generator_filter.cpp

 
#include "substream_generator_filter.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;
 
// this creates the plugin entry methods and class factories
ADTF_PLUGIN("Demo Substream Generator Plugin", cDemoSubStreamGenerator);
 
cDemoSubStreamGenerator::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/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.");
}
 
cDemoSubStreamGenerator::~cDemoSubStreamGenerator() = default;
 
tResult cDemoSubStreamGenerator::Process(tNanoSeconds tmTrigger, IRunner* /*pRunner*/)
{
    ++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;
}