CustomFilter class

User-defined filters. More...

Collaboration diagram for CustomFilter class:

Data Structures
interface	CustomFilter
interface	_FilterPid
interface	_BufferOccupancy
interface	_FilterPacket
interface	_FilterEvent

Detailed Description

A custom filter allows your application to interact closely with the media pipeline, but cannot be used in graph resolution. Custom filters can be sources, sinks, or intermediate filters. The following limitations however exist:

• custom filters will not be cloned
• custom filters cannot be used as sources of filters loading a source filter graph dynamically, such as the dashin filter.
• custom filters cannot be used as destination of filters loading a destination filter graph dynamically, such as the dasher filters.

A custom filter must implement the CustomFilter class, and optionally provide the following methods

• configure_pid: callback for PID configuration, mandatory if your filter is not a source
• process: callback for processing
• process_event: callback for processing and event
• reconfigure_output: callback for output reconfiguration (PID capability negotiation)

A custom filter must also declare its capabilities, input and output, using push_cap method

let fs = new gpac.FilterSession();
let cust = fs.new_filter("NodeJS_Test");
 
//we accept any number of input pids
cust.set_max_pids(-1);
cust.pids = [];
 
cust.push_cap('StreamType', 'Visual', gpac.GF_CAPS_INPUT);
cust.push_cap('StreamType', 'Audio', gpac.GF_CAPS_INPUT);
 
cust.configure_pid = function(pid, is_remove)
{
        if (this.pids.indexOf(pid) < 0) {
                this.pids.push(pid);
                console.log('New PID !');
        } else if (is_remove) {
                console.log('PID remove !');
        } else {
                console.log('PID reconfigure !');
        }
        return gpac.GF_OK;
}
 
cust.process = function() {
        let nb_eos=0;
 
        this.pids.forEach(pid =>{
                if (pid.eos) {
                        nb_eos++;
                        return;
                }
                let pck = pid.get_packet();
                if (!pck) return;
                //do something
 
                //done
                pid.drop_packet();
                return;
        }
        if (nb_eos == this.pids.length)
                return gpac.GF_EOS;
 
        return gpac.GF_OK;
}
cust.process_event = function(evt)
{
        //do something, return true to cancel event
 
        return false;
}

See GF_Filter

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Data Structure Documentation

_BufferOccupancy

interface _BufferOccupancy

buffer occupancy descriptor

Data Fields
unsigned long	max_units	maximum number of packets (partial or full AU) allowed in buffer
unsigned long	nb_pck	number of block allowed in buffer
unsigned long	max_dur	maximum buffer duration in microseconds
unsigned long	dur	buffer duration in microseconds
boolean	is_final_flush	if true, the session has been aborted and this is the final flush for this buffer

_FilterEvent

interface _FilterEvent

event object for filters and GPAC event proc.

The variables defined have the same names as the fields in the various unions of __gf_filter_event.

The variables are defined depending on the event type.

Additional variables are defined:

• name: string decribing the event type
• ui_type: integer giving the UI event type (see GF_Event)
• ui_name: string decribing the UI event type

Events properties are read-only for input events and read/write for events created by the JS code.