node-av / lib / IOContext

Class: IOContext

Defined in: src/lib/io-context.ts:74

I/O context for custom input/output operations.

Provides an abstraction layer for all I/O operations in FFmpeg. Enables reading from and writing to various sources including files, network streams, memory buffers, and custom callbacks. Essential for implementing custom protocols or handling non-standard I/O scenarios.

Direct mapping to FFmpeg's AVIOContext.

Example

import { IOContext, FFmpegError } from 'node-av';
import { AVIO_FLAG_READ, AVIO_FLAG_WRITE, AVSEEK_SET } from 'node-av/constants';

// Open file for reading
const io = new IOContext();
const ret = await io.open2('input.mp4', AVIO_FLAG_READ);
FFmpegError.throwIfError(ret, 'open2');

// Read data
const data = await io.read(4096);
if (data instanceof Buffer) {
  console.log(`Read ${data.length} bytes`);
}

// Seek to position
const pos = await io.seek(1024n, AVSEEK_SET);
console.log(`Seeked to position ${pos}`);

// Get file size
const fileSize = await io.size();
console.log(`File size: ${fileSize}`);

// Close when done
await io.closep();

// Custom I/O with callbacks
const customIO = new IOContext();
let position = 0n;
const buffer = Buffer.from('Hello World');

customIO.allocContextWithCallbacks(
  4096,  // Buffer size
  0,     // Read mode
  (size) => {
    // Read callback
    const end = Number(position) + size;
    const chunk = buffer.subarray(Number(position), end);
    position = BigInt(end);
    return chunk;
  },
  null,  // No write callback for read mode
  (offset, whence) => {
    // Seek callback
    if (whence === AVSEEK_SET) position = offset;
    else if (whence === AVSEEK_CUR) position += offset;
    else if (whence === AVSEEK_END) position = BigInt(buffer.length) + offset;
    return position;
  }
);

See

• AVIOContext - FFmpeg Doxygen
• FormatContext For using with demuxing/muxing

Extends

• OptionMember<NativeIOContext>

Implements

• AsyncDisposable
• NativeWrapper<NativeIOContext>

Constructors

Constructor

new IOContext(): IOContext

Defined in: src/lib/io-context.ts:75

Returns

IOContext

Overrides

OptionMember<NativeIOContext>.constructor

Properties

native

protected native: NativeIOContext

Defined in: src/lib/option.ts:999

Inherited from

OptionMember.native

Accessors

bufferSize

Get Signature

get bufferSize(): number

Defined in: src/lib/io-context.ts:180

Internal buffer size.

Size of the internal buffer used for I/O operations.

Direct mapping to AVIOContext->buffer_size.

Returns

number

---

direct

Get Signature

get direct(): number

Defined in: src/lib/io-context.ts:154

Direct mode flag.

If set, the I/O context will attempt to avoid buffering.

Direct mapping to AVIOContext->direct.

Returns

number

Set Signature

set direct(value): void

Defined in: src/lib/io-context.ts:158

Parameters

value

number

Returns

void

---

eof

Get Signature

get eof(): boolean

Defined in: src/lib/io-context.ts:104

End of file indicator.

True if end of file has been reached during reading.

Direct mapping to AVIOContext->eof_reached.

Returns

boolean

---

error

Get Signature

get error(): number

Defined in: src/lib/io-context.ts:115

Error code.

Contains the last error that occurred, or 0 if no error.

Direct mapping to AVIOContext->error.

Returns

number

---

maxPacketSize

Get Signature

get maxPacketSize(): number

Defined in: src/lib/io-context.ts:139

Maximum packet size.

Used to limit packet sizes in network protocols. 0 means no limit.

Direct mapping to AVIOContext->max_packet_size.

Returns

number

Set Signature

set maxPacketSize(value): void

Defined in: src/lib/io-context.ts:143

Parameters

value

number

Returns

void

---

pos

Get Signature

get pos(): bigint

Defined in: src/lib/io-context.ts:169

Current position.

Current byte position in the stream.

Direct mapping to AVIOContext->pos.

Returns

bigint

---

seekable

Get Signature

get seekable(): number

Defined in: src/lib/io-context.ts:127

Seekability indicator.

Non-zero if the underlying resource supports seeking. Some protocols like pipes or network streams may not be seekable.

Direct mapping to AVIOContext->seekable.

Returns

number

---

writeFlag

Get Signature

get writeFlag(): boolean

Defined in: src/lib/io-context.ts:191

Write flag.

True if opened for writing, false for reading.

Direct mapping to AVIOContext->write_flag.

Returns

boolean

Methods

[asyncDispose]()

[asyncDispose](): Promise<void>

Defined in: src/lib/io-context.ts:791

Dispose of the I/O context asynchronously.

Implements the AsyncDisposable interface for automatic cleanup. Closes the context and releases resources.

Returns

Promise<void>

Example

{
  await using io = new IOContext();
  await io.open2('input.mp4');
  // Use io...
} // Automatically closed when leaving scope

Implementation of

AsyncDisposable.[asyncDispose]

---

allocContext()

allocContext(bufferSize, writeFlag): void

Defined in: src/lib/io-context.ts:215

Allocate I/O context with buffer.

Allocates a basic I/O context with an internal buffer. For custom I/O, use allocContextWithCallbacks instead.

Direct mapping to avio_alloc_context() without callbacks.

Parameters

bufferSize

number

Size of internal buffer

writeFlag

number

1 for write, 0 for read

Returns

void

Example

const io = new IOContext();
io.allocContext(4096, 0); // 4KB buffer for reading

See

allocContextWithCallbacks For custom I/O

---

allocContextWithCallbacks()

allocContextWithCallbacks(bufferSize, writeFlag, readCallback?, writeCallback?, seekCallback?): void

Defined in: src/lib/io-context.ts:274

Allocate I/O context with custom callbacks.

Creates an I/O context with custom read, write, and seek callbacks. Enables implementing custom protocols or data sources.

NOTE: When using JavaScript callbacks, synchronous operations (e.g., readSync, seekSync) cannot be used on this context. This is because JavaScript callbacks require the event loop to be available, which is blocked during synchronous operations. Always use async methods (read, seek) when working with custom callbacks.

Direct mapping to avio_alloc_context() with callbacks.

Parameters

bufferSize

number

Size of internal buffer

writeFlag

1 for write mode, 0 for read mode

0 | 1

readCallback?

Function to read data (null for write-only)

null | (size) => null | number | Buffer<ArrayBufferLike>

writeCallback?

Function to write data (null for read-only)

null | (buffer) => number | void

seekCallback?

Function to seek in stream (optional)

null | (offset, whence) => number | bigint

Returns

void

Example

import { AVSEEK_SET, AVSEEK_CUR, AVSEEK_END, AVSEEK_SIZE } from 'node-av/constants';

const data = Buffer.from('Custom data source');
let position = 0;

io.allocContextWithCallbacks(
  4096,
  0, // Read mode
  (size) => {
    // Read callback
    if (position >= data.length) return -541; // EOF
    const chunk = data.subarray(position, position + size);
    position += chunk.length;
    return chunk;
  },
  null,
  (offset, whence) => {
    // Seek callback
    if (whence === AVSEEK_SIZE) return BigInt(data.length);
    if (whence === AVSEEK_SET) position = Number(offset);
    else if (whence === AVSEEK_CUR) position += Number(offset);
    else if (whence === AVSEEK_END) position = data.length + Number(offset);
    return BigInt(position);
  }
);

See

allocContext For simple allocation

---

closep()

closep(): Promise<number>

Defined in: src/lib/io-context.ts:397

Close I/O context.

Closes the I/O context and releases associated resources. Flushes any buffered data before closing.

Direct mapping to avio_closep().

Returns

Promise<number>

0 on success, negative AVERROR on error

Example

const ret = await io.closep();
if (ret < 0) {
  console.error('Error closing I/O context');
}

See

open2 To open resources

---

closepSync()

closepSync(): number

Defined in: src/lib/io-context.ts:422

Close I/O context synchronously. Synchronous version of closep.

Closes the I/O context and frees resources. Sets internal pointer to NULL.

Direct mapping to avio_closep().

Returns

number

0 on success, negative AVERROR on error

Example

const ret = io.closepSync();
if (ret < 0) {
  console.error(`Failed to close: ${ret}`);
}

See

closep For async version

---

flush()

flush(): Promise<void>

Defined in: src/lib/io-context.ts:669

Flush buffered data.

Forces any buffered data to be written to the underlying resource.

Direct mapping to avio_flush().

Returns

Promise<void>

Example

await io.write(data);
await io.flush(); // Ensure data is written

See

write For writing data

---

flushSync()

flushSync(): void

Defined in: src/lib/io-context.ts:689

Flush buffered data synchronously. Synchronous version of flush.

Forces any buffered data to be written to the underlying resource.

Direct mapping to avio_flush().

Returns

void

Example

io.writeSync(data);
io.flushSync(); // Ensure data is written

See

flush For async version

---

freeContext()

freeContext(): void

Defined in: src/lib/io-context.ts:298

Free I/O context.

Releases the I/O context and its resources. The context becomes invalid after calling this.

Direct mapping to avio_context_free().

Returns

void

Example

io.freeContext();
// Context is now invalid

---

getNative()

getNative(): NativeIOContext

Defined in: src/lib/io-context.ts:772

Internal

Get the underlying native IOContext object.

Returns

NativeIOContext

The native IOContext binding object

Implementation of

NativeWrapper.getNative

---

getOption()

Get an option value from this object.

Uses the AVOption API to retrieve options.

Direct mapping to av_opt_get* functions.

Param

Option name

Param

Option type (defaults to AV_OPT_TYPE_STRING)

Param

Search flags (default: AV_OPT_SEARCH_CHILDREN)

Example

import { AV_OPT_TYPE_STRING, AV_OPT_TYPE_RATIONAL, AV_OPT_TYPE_PIXEL_FMT, AV_OPT_TYPE_INT64 } from 'node-av/constants';

// String options (default)
const preset = obj.getOption('preset');
const codec = obj.getOption('codec', AV_OPT_TYPE_STRING);

// Typed options
const framerate = obj.getOption('framerate', AV_OPT_TYPE_RATIONAL); // Returns {num, den}
const pixFmt = obj.getOption('pix_fmt', AV_OPT_TYPE_PIXEL_FMT); // Returns AVPixelFormat
const bitrate = obj.getOption('bitrate', AV_OPT_TYPE_INT64); // Returns bigint

Call Signature

getOption(name, type?, searchFlags?): null | string

Defined in: src/lib/option.ts:1217

Parameters

name

string

type?

AVOptionTypeString

searchFlags?

AVOptionSearchFlags

Returns

null | string

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | string

Defined in: src/lib/option.ts:1218

Parameters

name

string

type

AVOptionTypeColor

searchFlags?

AVOptionSearchFlags

Returns

null | string

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1221

Parameters

name

string

type

AVOptionTypeInt

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | bigint

Defined in: src/lib/option.ts:1222

Parameters

name

string

type

AVOptionTypeInt64

searchFlags?

AVOptionSearchFlags

Returns

null | bigint

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1223

Parameters

name

string

type

AVOptionTypeUint

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | bigint

Defined in: src/lib/option.ts:1224

Parameters

name

string

type

AVOptionTypeUint64

searchFlags?

AVOptionSearchFlags

Returns

null | bigint

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1225

Parameters

name

string

type

AVOptionTypeFlags

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | boolean

Defined in: src/lib/option.ts:1226

Parameters

name

string

type

AVOptionTypeBool

searchFlags?

AVOptionSearchFlags

Returns

null | boolean

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1227

Parameters

name

string

type

AVOptionTypeDuration

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1228

Parameters

name

string

type

AVOptionTypeConst

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1231

Parameters

name

string

type

AVOptionTypeDouble

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | number

Defined in: src/lib/option.ts:1232

Parameters

name

string

type

AVOptionTypeFloat

searchFlags?

AVOptionSearchFlags

Returns

null | number

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | IRational

Defined in: src/lib/option.ts:1235

Parameters

name

string

type

AVOptionTypeRational

searchFlags?

AVOptionSearchFlags

Returns

null | IRational

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | IRational

Defined in: src/lib/option.ts:1236

Parameters

name

string

type

AVOptionTypeVideoRate

searchFlags?

AVOptionSearchFlags

Returns

null | IRational

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | AVPixelFormat

Defined in: src/lib/option.ts:1237

Parameters

name

string

type

AVOptionTypePixelFmt

searchFlags?

AVOptionSearchFlags

Returns

null | AVPixelFormat

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | AVSampleFormat

Defined in: src/lib/option.ts:1238

Parameters

name

string

type

AVOptionTypeSampleFmt

searchFlags?

AVOptionSearchFlags

Returns

null | AVSampleFormat

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | { height: number; width: number; }

Defined in: src/lib/option.ts:1239

Parameters

name

string

type

AVOptionTypeImageSize

searchFlags?

AVOptionSearchFlags

Returns

null | { height: number; width: number; }

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | ChannelLayout

Defined in: src/lib/option.ts:1240

Parameters

name

string

type

AVOptionTypeChLayout

searchFlags?

AVOptionSearchFlags

Returns

null | ChannelLayout

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | Dictionary

Defined in: src/lib/option.ts:1241

Parameters

name

string

type

AVOptionTypeDict

searchFlags?

AVOptionSearchFlags

Returns

null | Dictionary

Inherited from

OptionMember.getOption

Call Signature

getOption(name, type, searchFlags?): null | string

Defined in: src/lib/option.ts:1242

Parameters

name

string

type

AVOptionTypeBinary

searchFlags?

AVOptionSearchFlags

Returns

null | string

Inherited from

OptionMember.getOption

---

listOptions()

listOptions(): OptionInfo[]

Defined in: src/lib/option.ts:1358

List all available options for this object.

Uses the AVOption API to enumerate all options. Useful for discovering available settings and their types.

Direct mapping to av_opt_next() iteration.

Returns

OptionInfo[]

Array of option information objects

Example

const options = obj.listOptions();
for (const opt of options) {
  console.log(`${opt.name}: ${opt.help}`);
  console.log(`  Type: ${opt.type}, Default: ${opt.defaultValue}`);
  console.log(`  Range: ${opt.min} - ${opt.max}`);
}

See

OptionInfo For option metadata structure

Inherited from

OptionMember.listOptions

---

open2()

open2(url, flags): Promise<number>

Defined in: src/lib/io-context.ts:335

Open resource for I/O.

Opens a URL or file for reading or writing. Automatically selects the appropriate protocol handler.

Direct mapping to avio_open2().

Parameters

url

string

URL or file path to open

flags

AVIOFlag = AVIO_FLAG_READ

Open flags (AVIO_FLAG_READ, AVIO_FLAG_WRITE, etc.)

Returns

Promise<number>

0 on success, negative AVERROR on error:

• AVERROR_ENOENT: File not found
• AVERROR_EACCES: Permission denied
• AVERROR_ENOMEM: Memory allocation failure

Example

import { FFmpegError } from 'node-av';
import { AVIO_FLAG_READ, AVIO_FLAG_WRITE } from 'node-av/constants';

// Open for reading
const ret = await io.open2('input.mp4', AVIO_FLAG_READ);
FFmpegError.throwIfError(ret, 'open2');

// Open for writing
const ret2 = await io.open2('output.mp4', AVIO_FLAG_WRITE);
FFmpegError.throwIfError(ret2, 'open2');

See

closep To close after use

---

open2Sync()

open2Sync(url, flags): number

Defined in: src/lib/io-context.ts:373

Open resource for I/O synchronously. Synchronous version of open2.

Opens a URL or file for reading or writing. Automatically selects the appropriate protocol handler.

Direct mapping to avio_open2().

Parameters

url

string

URL or file path to open

flags

AVIOFlag = AVIO_FLAG_READ

Open flags (AVIO_FLAG_READ, AVIO_FLAG_WRITE, etc.)

Returns

number

0 on success, negative AVERROR on error:

• AVERROR_ENOENT: File not found
• AVERROR_EACCES: Permission denied
• AVERROR_ENOMEM: Memory allocation failure

Example

import { FFmpegError } from 'node-av';
import { AVIO_FLAG_READ, AVIO_FLAG_WRITE } from 'node-av/constants';

// Open for reading
const ret = io.open2Sync('input.mp4', AVIO_FLAG_READ);
FFmpegError.throwIfError(ret, 'open2');

// Open for writing
const ret2 = io.open2Sync('output.mp4', AVIO_FLAG_WRITE);
FFmpegError.throwIfError(ret2, 'open2');

See

open2 For async version

---

read()

read(size): Promise<number | Buffer<ArrayBufferLike>>

Defined in: src/lib/io-context.ts:451

Read data from I/O context.

Reads up to the specified number of bytes from the stream.

Direct mapping to avio_read().

Parameters

size

number

Maximum number of bytes to read

Returns

Promise<number | Buffer<ArrayBufferLike>>

Buffer with data, or error code if negative:

• AVERROR_EOF: End of file reached
• AVERROR_EIO: I/O error

Example

const data = await io.read(4096);
if (data instanceof Buffer) {
  console.log(`Read ${data.length} bytes`);
} else {
  console.error(`Read error: ${data}`);
}

See

write For writing data

---

readSync()

readSync(size): number | Buffer<ArrayBufferLike>

Defined in: src/lib/io-context.ts:479

Read data from I/O context synchronously. Synchronous version of read.

Reads up to the specified number of bytes from the stream.

Direct mapping to avio_read().

Parameters

size

number

Number of bytes to read

Returns

number | Buffer<ArrayBufferLike>

Buffer with data, or negative AVERROR on error

Example

const result = io.readSync(4096);
if (Buffer.isBuffer(result)) {
  console.log(`Read ${result.length} bytes`);
} else {
  console.log(`Read error: ${result}`);
}

See

read For async version

---

seek()

seek(offset, whence): Promise<bigint>

Defined in: src/lib/io-context.ts:560

Seek to position in stream.

Changes the current position in the stream. Not all streams support seeking.

Direct mapping to avio_seek().

Parameters

offset

bigint

Byte offset to seek to

whence

AVSeekWhence

Seek origin (AVSEEK_SET, AVSEEK_CUR, AVSEEK_END)

Returns

Promise<bigint>

New position, or negative AVERROR on error:

• AVERROR_EINVAL: Invalid arguments
• AVERROR_ENOSYS: Seeking not supported

Example

import { AVSEEK_SET, AVSEEK_CUR, AVSEEK_END } from 'node-av/constants';

// Seek to absolute position
const pos1 = await io.seek(1024n, AVSEEK_SET);

// Seek relative to current position
const pos2 = await io.seek(512n, AVSEEK_CUR);

// Seek relative to end
const pos3 = await io.seek(-1024n, AVSEEK_END);

See

• tell To get current position
• skip For relative seeking

---

seekSync()

seekSync(offset, whence): bigint

Defined in: src/lib/io-context.ts:597

Seek to position in stream synchronously. Synchronous version of seek.

Changes the current position in the stream. Not all streams support seeking.

Direct mapping to avio_seek().

Parameters

offset

bigint

Byte offset to seek to

whence

AVSeekWhence

Seek origin (AVSEEK_SET, AVSEEK_CUR, AVSEEK_END)

Returns

bigint

New position, or negative AVERROR on error:

• AVERROR_EINVAL: Invalid arguments
• AVERROR_ENOSYS: Seeking not supported

Example

import { AVSEEK_SET, AVSEEK_CUR, AVSEEK_END } from 'node-av/constants';

// Seek to absolute position
const pos1 = io.seekSync(1024n, AVSEEK_SET);

// Seek relative to current position
const pos2 = io.seekSync(512n, AVSEEK_CUR);

// Seek relative to end
const pos3 = io.seekSync(-1024n, AVSEEK_END);

See

seek For async version

---

setOption()

Set an option on this object.

Uses the AVOption API to set options. Available options depend on the specific object type.

Direct mapping to av_opt_set* functions.

Param

Option name

Param

Option value

Param

Option type (defaults to AV_OPT_TYPE_STRING)

Param

Search flags (default: AV_OPT_SEARCH_CHILDREN)

Example

import { FFmpegError } from 'node-av';
import { AV_OPT_TYPE_STRING, AV_OPT_TYPE_INT64, AV_OPT_TYPE_RATIONAL, AV_OPT_TYPE_PIXEL_FMT } from 'node-av/constants';

// String options (default)
let ret = obj.setOption('preset', 'fast');
FFmpegError.throwIfError(ret, 'set preset');

ret = obj.setOption('codec', 'h264', AV_OPT_TYPE_STRING);
FFmpegError.throwIfError(ret, 'set codec');

// Integer options
ret = obj.setOption('bitrate', 2000000, AV_OPT_TYPE_INT64);
FFmpegError.throwIfError(ret, 'set bitrate');

ret = obj.setOption('threads', 4, AV_OPT_TYPE_INT);
FFmpegError.throwIfError(ret, 'set threads');

// Complex types with proper types
ret = obj.setOption('framerate', {num: 30, den: 1}, AV_OPT_TYPE_RATIONAL);
FFmpegError.throwIfError(ret, 'set framerate');

ret = obj.setOption('pix_fmt', AV_PIX_FMT_YUV420P, AV_OPT_TYPE_PIXEL_FMT);
FFmpegError.throwIfError(ret, 'set pixel format');

Call Signature

setOption(name, value, type?, searchFlags?): number

Defined in: src/lib/option.ts:1006

Parameters

name

string

value

string

type?

AVOptionTypeString

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1007

Parameters

name

string

value

string

type

AVOptionTypeColor

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1010

Parameters

name

string

value

number

type

AVOptionTypeInt

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1011

Parameters

name

string

value

bigint

type

AVOptionTypeInt64

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1012

Parameters

name

string

value

number

type

AVOptionTypeUint

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1013

Parameters

name

string

value

bigint

type

AVOptionTypeUint64

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1014

Parameters

name

string

value

number

type

AVOptionTypeFlags

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1015

Parameters

name

string

value

boolean

type

AVOptionTypeBool

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1016

Parameters

name

string

value

number

type

AVOptionTypeDuration

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1017

Parameters

name

string

value

number

type

AVOptionTypeConst

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1020

Parameters

name

string

value

number

type

AVOptionTypeDouble

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1021

Parameters

name

string

value

number

type

AVOptionTypeFloat

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1024

Parameters

name

string

value

IRational

type

AVOptionTypeRational

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1025

Parameters

name

string

value

IRational

type

AVOptionTypeVideoRate

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1026

Parameters

name

string

value

AVPixelFormat

type

AVOptionTypePixelFmt

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1027

Parameters

name

string

value

AVSampleFormat

type

AVOptionTypeSampleFmt

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1028

Parameters

name

string

value

height

number

width

number

type

AVOptionTypeImageSize

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1029

Parameters

name

string

value

number | bigint

type

AVOptionTypeChLayout

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1030

Parameters

name

string

value

Buffer

type

AVOptionTypeBinary

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1031

Parameters

name

string

value

number[]

type

AVOptionTypeBinaryIntArray

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

Call Signature

setOption(name, value, type, searchFlags?): number

Defined in: src/lib/option.ts:1032

Parameters

name

string

value

Dictionary

type

AVOptionTypeDict

searchFlags?

AVOptionSearchFlags

Returns

number

Inherited from

OptionMember.setOption

---

size()

size(): Promise<bigint>

Defined in: src/lib/io-context.ts:622

Get stream size.

Returns the total size of the stream in bytes. Not all streams have a known size.

Direct mapping to avio_size().

Returns

Promise<bigint>

Size in bytes, or negative AVERROR if unknown:

• AVERROR_ENOSYS: Size not available

Example

const size = await io.size();
if (size >= 0n) {
  console.log(`Stream size: ${size} bytes`);
} else {
  console.log('Stream size unknown');
}

---

sizeSync()

sizeSync(): bigint

Defined in: src/lib/io-context.ts:650

Get stream size synchronously. Synchronous version of size.

Returns the total size of the stream in bytes. Not all streams have a known size.

Direct mapping to avio_size().

Returns

bigint

Size in bytes, or negative AVERROR if unknown:

• AVERROR_ENOSYS: Size not available

Example

const size = io.sizeSync();
if (size >= 0n) {
  console.log(`Stream size: ${size} bytes`);
} else {
  console.log('Stream size unknown');
}

See

size For async version

---

skip()

skip(offset): Promise<bigint>

Defined in: src/lib/io-context.ts:714

Skip bytes in stream.

Advances the position by the specified offset. More efficient than reading and discarding data.

Direct mapping to avio_skip().

Parameters

offset

bigint

Number of bytes to skip

Returns

Promise<bigint>

New position after skipping

Example

// Skip 1024 bytes forward
const newPos = await io.skip(1024n);
console.log(`New position: ${newPos}`);

See

seek For absolute positioning

---

skipSync()

skipSync(offset): bigint

Defined in: src/lib/io-context.ts:740

Skip bytes in stream synchronously. Synchronous version of skip.

Advances the position by the specified offset. More efficient than reading and discarding data.

Direct mapping to avio_skip().

Parameters

offset

bigint

Number of bytes to skip

Returns

bigint

New position after skipping

Example

// Skip 1024 bytes forward
const newPos = io.skipSync(1024n);
console.log(`New position: ${newPos}`);

See

skip For async version

---

tell()

tell(): bigint

Defined in: src/lib/io-context.ts:761

Get current position.

Returns the current byte position in the stream.

Direct mapping to avio_tell().

Returns

bigint

Current position in bytes

Example

const position = io.tell();
console.log(`Current position: ${position}`);

See

seek To change position

---

write()

write(buffer): Promise<void>

Defined in: src/lib/io-context.ts:501

Write data to I/O context.

Writes buffer data to the stream.

Direct mapping to avio_write().

Parameters

buffer

Buffer

Data to write

Returns

Promise<void>

Example

const data = Buffer.from('Hello World');
await io.write(data);

See

• read For reading data
• flush To flush buffers

---

writeSync()

writeSync(buffer): void

Defined in: src/lib/io-context.ts:523

Write data to I/O context synchronously. Synchronous version of write.

Writes buffer data to the stream.

Direct mapping to avio_write().

Parameters

buffer

Buffer

Data to write

Returns

void

Example

const data = Buffer.from('Hello, World!');
io.writeSync(data);

See

write For async version

---

fromNative()

static fromNative(native): IOContext

Defined in: src/lib/io-context.ts:91

Internal

Find input format by short name.

Creates an IOContext instance from a native binding object. Used internally for wrapping native I/O contexts.

Parameters

native

NativeIOContext

Native IOContext binding object

Returns

IOContext

Wrapped IOContext instance