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node-av / lib / Filter

Class: Filter ​

Defined in: src/lib/filter.ts:40

Filter descriptor for video/audio processing.

Represents a filter that can be used in filter graphs for processing audio and video frames. Filters can be sources (no inputs), sinks (no outputs), or processors (with both inputs and outputs). Each filter has specific capabilities and pad configurations.

Direct mapping to FFmpeg's AVFilter.

Example ​

typescript
import { Filter } from 'node-av';

// Get a specific filter
const scaleFilter = Filter.getByName('scale');
if (scaleFilter) {
  console.log(`Filter: ${scaleFilter.name}`);
  console.log(`Description: ${scaleFilter.description}`);
  console.log(`Inputs: ${scaleFilter.inputs.length}`);
  console.log(`Outputs: ${scaleFilter.outputs.length}`);
}

// List all video filters
const filters = Filter.getList();
const videoFilters = filters.filter(f => f.isVideo());
console.log(`Found ${videoFilters.length} video filters`);

See ​

Implements ​

Constructors ​

Constructor ​

new Filter(native): Filter

Defined in: src/lib/filter.ts:48

Internal

Parameters ​

native ​

NativeFilter

The native filter instance

Returns ​

Filter

Accessors ​

description ​

Get Signature ​

get description(): null | string

Defined in: src/lib/filter.ts:131

Filter description.

Human-readable description of what the filter does.

Direct mapping to AVFilter->description.

Returns ​

null | string

flags ​

Get Signature ​

get flags(): number

Defined in: src/lib/filter.ts:166

Filter flags.

Combination of AVFILTER_FLAG_* values indicating filter capabilities.

Direct mapping to AVFilter->flags.

Returns ​

number

inputs ​

Get Signature ​

get inputs(): FilterPad[]

Defined in: src/lib/filter.ts:143

Input pads.

Array of input pad descriptors. Empty array for source filters.

Direct mapping to AVFilter->inputs.

Returns ​

FilterPad[]

name ​

Get Signature ​

get name(): null | string

Defined in: src/lib/filter.ts:120

Filter name.

Unique identifier for the filter (e.g., 'scale', 'overlay').

Direct mapping to AVFilter->name.

Returns ​

null | string

outputs ​

Get Signature ​

get outputs(): FilterPad[]

Defined in: src/lib/filter.ts:155

Output pads.

Array of output pad descriptors. Empty array for sink filters.

Direct mapping to AVFilter->outputs.

Returns ​

FilterPad[]

Methods ​

getNative() ​

getNative(): NativeFilter

Defined in: src/lib/filter.ts:257

Internal

Get the underlying native Filter object.

Returns ​

NativeFilter

The native Filter binding object

Implementation of ​

NativeWrapper.getNative

isAudio() ​

isAudio(): boolean

Defined in: src/lib/filter.ts:246

Check if filter processes audio.

Returns ​

boolean

True if filter has audio inputs or outputs

Example ​

typescript
const filters = Filter.getList();
const audioFilters = filters.filter(f => f.isAudio());
console.log(`Audio filters: ${audioFilters.length}`);

See ​

isVideo To check for video filters

isSink() ​

isSink(): boolean

Defined in: src/lib/filter.ts:210

Check if filter is a sink.

Sink filters consume frames without output (e.g., 'nullsink', 'buffersink').

Returns ​

boolean

True if filter has no outputs

Example ​

typescript
const filter = Filter.getByName('nullsink');
if (filter?.isSink()) {
  console.log('This is a sink filter');
}

See ​

isSource To check for source filters

isSource() ​

isSource(): boolean

Defined in: src/lib/filter.ts:188

Check if filter is a source.

Source filters generate frames without input (e.g., 'testsrc', 'color', 'anullsrc').

Returns ​

boolean

True if filter has no inputs

Example ​

typescript
const filter = Filter.getByName('testsrc');
if (filter?.isSource()) {
  console.log('This is a source filter');
}

See ​

isSink To check for sink filters

isVideo() ​

isVideo(): boolean

Defined in: src/lib/filter.ts:228

Check if filter processes video.

Returns ​

boolean

True if filter has video inputs or outputs

Example ​

typescript
const filters = Filter.getList();
const videoFilters = filters.filter(f => f.isVideo());
console.log(`Video filters: ${videoFilters.length}`);

See ​

isAudio To check for audio filters

getByName() ​

static getByName(name): null | Filter

Defined in: src/lib/filter.ts:78

Get a filter by name.

Retrieves a specific filter descriptor by its name. Common filter names include 'scale', 'crop', 'overlay', 'aformat', etc.

Direct mapping to avfilter_get_by_name().

Parameters ​

name ​

string

Name of the filter

Returns ​

null | Filter

Filter instance if found, null otherwise

Example ​

typescript
// Get video scaling filter
const scale = Filter.getByName('scale');
if (!scale) {
  throw new Error('Scale filter not available');
}

// Get audio format filter
const aformat = Filter.getByName('aformat');

See ​

getList To list all available filters

getList() ​

static getList(): Filter[]

Defined in: src/lib/filter.ts:108

Get list of all available filters.

Returns an array of all registered filters in FFmpeg. Useful for discovering available filters or building filter lists.

Returns ​

Filter[]

Array of all available filters

Example ​

typescript
// List all filters
const filters = Filter.getList();
console.log(`Total filters: ${filters.length}`);

// Find all source filters (generators)
const sources = filters.filter(f => f.isSource());
console.log(`Source filters: ${sources.length}`);

// Find all sink filters (outputs)
const sinks = filters.filter(f => f.isSink());
console.log(`Sink filters: ${sinks.length}`);

See ​

getByName To get a specific filter