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node-av / lib / OutputFormat

Class: OutputFormat ​

Defined in: src/lib/output-format.ts:46

Output format descriptor for muxing media files.

Represents a muxer that can write specific media container formats. Each format handles specific file types (e.g., MP4, MKV, AVI) and knows how to combine streams and write them to output. Contains default codec suggestions for audio, video, and subtitles.

Direct mapping to FFmpeg's AVOutputFormat.

Example ​

typescript
import { OutputFormat, FormatContext, FFmpegError } from 'node-av';
import { AV_CODEC_ID_H264, AV_CODEC_ID_AAC } from 'node-av/constants';

// Guess format from filename
const format = OutputFormat.guessFormat(null, 'output.mp4', null);
if (!format) {
  throw new Error('Could not determine output format');
}

console.log(`Format: ${format.name}`);
console.log(`Description: ${format.longName}`);
console.log(`Default video codec: ${format.videoCodec}`);
console.log(`Default audio codec: ${format.audioCodec}`);

// Use specific format
const mkvFormat = OutputFormat.guessFormat('matroska', null, null);

// Use with format context
const formatContext = new FormatContext();
formatContext.outputFormat = format;
const ret = await formatContext.allocOutputContext('output.mp4');
FFmpegError.throwIfError(ret, 'allocOutputContext');

See ​

Implements ​

Constructors ​

Constructor ​

new OutputFormat(native): OutputFormat

Defined in: src/lib/output-format.ts:54

Internal

Parameters ​

native ​

NativeOutputFormat

The native output format instance

Returns ​

OutputFormat

Accessors ​

audioCodec ​

Get Signature ​

get audioCodec(): AVCodecID

Defined in: src/lib/output-format.ts:152

Default audio codec.

Suggested audio codec for this format.

Direct mapping to AVOutputFormat->audio_codec.

Returns ​

AVCodecID

extensions ​

Get Signature ​

get extensions(): null | string

Defined in: src/lib/output-format.ts:130

File extensions.

Comma-separated list of file extensions for this format.

Direct mapping to AVOutputFormat->extensions.

Returns ​

null | string

flags ​

Get Signature ​

get flags(): AVFormatFlag

Defined in: src/lib/output-format.ts:185

Format flags.

Combination of AVFMT_* flags indicating format capabilities.

Direct mapping to AVOutputFormat->flags.

Returns ​

AVFormatFlag

longName ​

Get Signature ​

get longName(): null | string

Defined in: src/lib/output-format.ts:119

Format long name.

Human-readable description of the format.

Direct mapping to AVOutputFormat->long_name.

Returns ​

null | string

mimeType ​

Get Signature ​

get mimeType(): null | string

Defined in: src/lib/output-format.ts:141

MIME type.

MIME type(s) associated with this format.

Direct mapping to AVOutputFormat->mime_type.

Returns ​

null | string

name ​

Get Signature ​

get name(): null | string

Defined in: src/lib/output-format.ts:108

Format short name.

Short identifier for the format (e.g., 'mp4', 'mkv').

Direct mapping to AVOutputFormat->name.

Returns ​

null | string

subtitleCodec ​

Get Signature ​

get subtitleCodec(): AVCodecID

Defined in: src/lib/output-format.ts:174

Default subtitle codec.

Suggested subtitle codec for this format.

Direct mapping to AVOutputFormat->subtitle_codec.

Returns ​

AVCodecID

videoCodec ​

Get Signature ​

get videoCodec(): AVCodecID

Defined in: src/lib/output-format.ts:163

Default video codec.

Suggested video codec for this format.

Direct mapping to AVOutputFormat->video_codec.

Returns ​

AVCodecID

Methods ​

getNative() ​

getNative(): NativeOutputFormat

Defined in: src/lib/output-format.ts:196

Internal

Get the underlying native OutputFormat object.

Returns ​

NativeOutputFormat

The native OutputFormat binding object

Implementation of ​

NativeWrapper.getNative

guessFormat() ​

static guessFormat(shortName, filename, mimeType): null | OutputFormat

Defined in: src/lib/output-format.ts:93

Guess output format from name, filename, or MIME type.

Determines the appropriate output format based on provided hints. At least one parameter should be non-null.

Direct mapping to av_guess_format().

Parameters ​

shortName ​

Format short name (e.g., 'mp4', 'mkv', null to ignore)

null | string

filename ​

Output filename for extension detection (null to ignore)

null | string

mimeType ​

MIME type hint (null to ignore)

null | string

Returns ​

null | OutputFormat

Detected format, or null if not determined

Example ​

typescript
// Guess from filename extension
const format1 = OutputFormat.guessFormat(null, 'video.mp4', null);
// Returns MP4 format

// Use specific format
const format2 = OutputFormat.guessFormat('matroska', null, null);
// Returns MKV format

// Guess from MIME type
const format3 = OutputFormat.guessFormat(null, null, 'video/mp4');
// Returns MP4 format

// Priority: shortName > filename > mimeType
const format4 = OutputFormat.guessFormat('mkv', 'video.mp4', null);
// Returns MKV format (shortName takes precedence)