adtf::javascript::scripting::cScriptReader Class Reference

#include <reader.h>

Inherits QObject.

Public Member Functions
Q_INVOKABLE QVariant	getNextSample ()
Q_INVOKABLE QVariant	getLastSample ()
Q_INVOKABLE void	requestSamples (const QVariant &oSubStreamFilter)
Q_INVOKABLE void	cancelRequest (const QVariant &oSubStreamFilter)

Properties
QVariantList	requests

Detailed Description

A Reader that is returned by cScriptFilter::createInputPin.

Samples returned by getNextSample(), getLastSample() and passed via the sample() signal contain the following elements:

• sample.timestamp: contains the timestamp of the sample in nanoseconds.
• sample.substream: contains the name of the substream that the sample belongs to (can be empty)
• sample.data: contains the payload of the sample in one of the following forms:
  • For streams that have a media description:
    • A javascript object that represents the data structure of the media description, i.e sample.data.parent.child.value etc.
  • For streams with stream type "adtf/image"
    • A QImage with the image data.
  • For all others
    • A javascript ArrayBuffer object containing the raw data bytes of the sample

Please keep in mind that when you do not connect a callback to at least one of trigger() or sample(), all incoming samples will be discarded.

Member Function Documentation

cancelRequest()

Q_INVOKABLE void adtf::javascript::scripting::cScriptReader::cancelRequest

(

const QVariant &

oSubStreamFilter

)

Cancels a request for samples from a given Substream. If a Substream has been requested multiple times, all requests must be canceled individually.

Parameters

[in]

oSubStreamFilter

The substream. Request can be of type QString or QRegularExpression. Must be a request that has been made before.

getLastSample()

Q_INVOKABLE QVariant adtf::javascript::scripting::cScriptReader::getLastSample

(

)

Returns the last available sample.

Example Usage

var input = filter.createInputPin("input")
input.trigger.connect(function(timestamp)
{
    console.info("last sample: " + JSON.stringify(input.getLastSample()))
})

Warning

Mind that this does not work for Substreams.

Returns

The last sample available or false.

getNextSample()

Q_INVOKABLE QVariant adtf::javascript::scripting::cScriptReader::getNextSample

(

)

Returns the next available sample.

Example Usage

var input = filter.createInputPin("input")
input.trigger.connect(function(timestamp)
{
    var sampleCount = 0
    while ((sample = input.getNextSample()))
    {
        ++sampleCount
    }
 
    console.info("recieved " + sampleCount + " samples")
})

Returns

The next sample available or false.

requestSamples()

Q_INVOKABLE void adtf::javascript::scripting::cScriptReader::requestSamples

(

const QVariant &

oSubStreamFilter

)

Request samples from Substreams matching the filter by name.

Example Usage

var input = filter.createInputPin("input")
 
// Whenever possible, set up requests for future substreams immediately after the pin was created.
// Trying to wait until a type change would result in potentially never reaching the type change.
 
// Request all streams starting with ^foo using an RegExp object.
input.requestSamples(/^foo/)
// Cancel previous request - type and content of the request must match exactly.
input.cancelRequest(/^foo/)
 
// Clearing all currently active requests.
for (const request of input.requests) {
    input.cancelRequest(request)
}
 
// Request streamy by exact name.
input.requestSamples("stream1")
input.requestSamples("stream2")
 
input.streamTypeChanged.connect(function (type) {
    console.info("stream type : " + JSON.stringify(type))
    // Possible output:
    /*
    {
        "stream_meta_type": "adtf/substreams"
        "properties": {
            // The property "substreams" denotes the use of nested substreams instead of a flat stream type.
            "substreams": "true",
            // Properties of form "substreams/[^/]+" denote presence of a named substream.
            "substreams/stream1": "1",
            // Properties of the nested type are prefixed with "substreams/[^/]+/".
            "substreams/stream1/type": "adtf/plaintype",
            "substreams/stream1/type/md_definitions": "...",
            "substreams/stream1/type/md_struct": "UINT32"
        }
    }
    */
})
 
input.sample.connect(function (sample) {
    // The property substream can only contain stream names that have matched a request.
    if (sample.substream === "stream1") {
        console.info("recieved sample from substream stream1")
    }
    else if (sample.substream === "stream2") {
        console.info("recieved sample from substream stream2")
    }
})

Parameters

[in]

oSubStreamFilter

The Substream. Request can be of type QString or QRegularExpression.

Property Documentation

requests

QVariantList adtf::javascript::scripting::cScriptReader::requests

read

List of currently active requests for Substreams. All list entries are of type QString or QRegularExpression.# Use requestSamples and cancelRequest to manipulate this list.

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The documentation for this class was generated from the following file:

• src/libraries/javascriptfiltersdk/src/reader.h