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node-av / lib / Dictionary

Class: Dictionary ​

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

Key-value dictionary for FFmpeg options and metadata.

Stores string key-value pairs used throughout FFmpeg for options, metadata, and configuration. Provides methods for setting, getting, and manipulating dictionary entries. Used extensively for codec options, format options, and metadata handling.

Direct mapping to FFmpeg's AVDictionary.

Example ​

typescript
import { Dictionary, FFmpegError } from 'node-av';
import { AV_DICT_IGNORE_SUFFIX } from 'node-av/constants';

// Create from object
const dict = Dictionary.fromObject({
  'title': 'My Video',
  'artist': 'Me',
  'year': '2024'
});

// Set individual values
const dict2 = new Dictionary();
dict2.alloc();
let ret = dict2.set('preset', 'fast');
FFmpegError.throwIfError(ret, 'set');

// Parse from string
ret = dict2.parseString('key1=value1:key2=value2', '=', ':');
FFmpegError.throwIfError(ret, 'parseString');

// Get all entries
const entries = dict2.getAll();
console.log(entries); // { key1: 'value1', key2: 'value2' }

See ​

Implements ​

Constructors ​

Constructor ​

new Dictionary(): Dictionary

Defined in: src/lib/dictionary.ts:51

Returns ​

Dictionary

Methods ​

[dispose]() ​

[dispose](): void

Defined in: src/lib/dictionary.ts:382

Dispose of the dictionary.

Implements the Disposable interface for automatic cleanup. Equivalent to calling free().

Returns ​

void

Example ​

typescript
{
  using dict = new Dictionary();
  dict.alloc();
  dict.set('key', 'value');
  // Use dict...
} // Automatically freed when leaving scope

Implementation of ​

Disposable.[dispose]

alloc() ​

alloc(): void

Defined in: src/lib/dictionary.ts:125

Allocate a dictionary.

Allocates memory for the dictionary structure. Must be called before using the dictionary.

Direct mapping to av_dict_alloc().

Returns ​

void

Throws ​

If allocation fails (ENOMEM)

Example ​

typescript
const dict = new Dictionary();
dict.alloc();
// Dictionary is now ready for use

See ​

free To deallocate

copy() ​

copy(dst, flags): number

Defined in: src/lib/dictionary.ts:174

Copy entries to another dictionary.

Copies all entries from this dictionary to the destination.

Direct mapping to av_dict_copy().

Parameters ​

dst ​

Dictionary

Destination dictionary

flags ​

AVDictFlag = AVFLAG_NONE

Copy flags

Returns ​

number

0 on success, negative AVERROR on error:

  • AVERROR_ENOMEM: Memory allocation failure

Example ​

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

const dst = new Dictionary();
dst.alloc();
const ret = src.copy(dst);
FFmpegError.throwIfError(ret, 'copy');

count() ​

count(): number

Defined in: src/lib/dictionary.ts:261

Count dictionary entries.

Returns the number of key-value pairs in the dictionary.

Direct mapping to av_dict_count().

Returns ​

number

Number of entries

Example ​

typescript
const count = dict.count();
console.log(`Dictionary has ${count} entries`);

free() ​

free(): void

Defined in: src/lib/dictionary.ts:146

Free the dictionary.

Releases all memory associated with the dictionary. The dictionary becomes invalid after calling this.

Direct mapping to av_dict_free().

Returns ​

void

Example ​

typescript
dict.free();
// Dictionary is now invalid

See ​

get() ​

get(key, flags): null | string

Defined in: src/lib/dictionary.ts:242

Get a dictionary entry.

Retrieves the value for a given key.

Direct mapping to av_dict_get().

Parameters ​

key ​

string

Entry key to look up

flags ​

AVDictFlag = AVFLAG_NONE

Search flags (e.g., AV_DICT_IGNORE_SUFFIX)

Returns ​

null | string

Entry value, or null if not found

Example ​

typescript
const value = dict.get('bitrate');
if (value) {
  console.log(`Bitrate: ${value}`);
}

// Case-insensitive search
import { AV_DICT_MATCH_CASE } from 'node-av/constants';
const title = dict.get('Title', AV_DICT_MATCH_CASE);

See ​

getAll() ​

getAll(): Record<string, string>

Defined in: src/lib/dictionary.ts:282

Get all dictionary entries.

Returns all key-value pairs as a JavaScript object.

Returns ​

Record<string, string>

Object with all entries

Example ​

typescript
const entries = dict.getAll();
for (const [key, value] of Object.entries(entries)) {
  console.log(`${key}: ${value}`);
}

See ​

get To get individual entries

getNative() ​

getNative(): NativeDictionary

Defined in: src/lib/dictionary.ts:362

Internal

Get the underlying native Dictionary object.

Returns ​

NativeDictionary

The native Dictionary binding object

Implementation of ​

NativeWrapper.getNative

getString() ​

getString(keyValSep, pairsSep): null | string

Defined in: src/lib/dictionary.ts:351

Convert dictionary to string.

Serializes all entries to a formatted string.

Direct mapping to av_dict_get_string().

Parameters ​

keyValSep ​

string

Separator between key and value

pairsSep ​

string

Separator between pairs

Returns ​

null | string

Formatted string, or null on error

Example ​

typescript
// Serialize to colon-separated format
const str = dict.getString('=', ':');
console.log(str); // "key1=val1:key2=val2"

// Serialize to comma-separated format
const csv = dict.getString('=', ',');
console.log(csv); // "key1=val1,key2=val2"

See ​

parseString To parse from string

parseString() ​

parseString(str, keyValSep, pairsSep, flags): number

Defined in: src/lib/dictionary.ts:321

Parse entries from a string.

Parses key-value pairs from a formatted string and adds them to the dictionary.

Direct mapping to av_dict_parse_string().

Parameters ​

str ​

string

String to parse

keyValSep ​

string

Separator between key and value

pairsSep ​

string

Separator between pairs

flags ​

AVDictFlag = AVFLAG_NONE

Parse flags

Returns ​

number

0 on success, negative AVERROR on error:

  • AVERROR_EINVAL: Invalid format
  • AVERROR_ENOMEM: Memory allocation failure

Example ​

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

// Parse colon-separated pairs
let ret = dict.parseString('key1=val1:key2=val2', '=', ':');
FFmpegError.throwIfError(ret, 'parseString');

// Parse comma-separated pairs
ret = dict.parseString('width=1920,height=1080', '=', ',');
FFmpegError.throwIfError(ret, 'parseString');

See ​

getString To serialize to string

set() ​

set(key, value, flags): number

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

Set a dictionary entry.

Sets or updates a key-value pair in the dictionary.

Direct mapping to av_dict_set().

Parameters ​

key ​

string

Entry key

value ​

string

Entry value

flags ​

AVDictFlag = AVFLAG_NONE

Set flags (e.g., AV_DICT_DONT_OVERWRITE)

Returns ​

number

0 on success, negative AVERROR on error:

  • AVERROR_ENOMEM: Memory allocation failure

Example ​

typescript
import { FFmpegError } from 'node-av';
import { AV_DICT_DONT_OVERWRITE } from 'node-av/constants';

// Set or update entry
let ret = dict.set('bitrate', '128k');
FFmpegError.throwIfError(ret, 'set');

// Set only if not exists
ret = dict.set('preset', 'fast', AV_DICT_DONT_OVERWRITE);
FFmpegError.throwIfError(ret, 'set');

See ​

get To retrieve values

fromNative() ​

static fromNative(native): Dictionary

Defined in: src/lib/dictionary.ts:100

Internal

Create dictionary from native instance.

Parameters ​

native ​

NativeDictionary

Native dictionary instance

Returns ​

Dictionary

Dictionary wrapper

fromObject() ​

static fromObject(obj, flags): Dictionary

Defined in: src/lib/dictionary.ts:83

Create dictionary from JavaScript object.

Convenience method to create a dictionary from a plain object.

Parameters ​

obj ​

Record<string, string | number>

Object with string key-value pairs

flags ​

AVDictFlag = AVFLAG_NONE

Flags for setting entries

Returns ​

Dictionary

New dictionary with entries from object

Example ​

typescript
const metadata = Dictionary.fromObject({
  'title': 'My Song',
  'album': 'My Album',
  'date': '2024',
  'track': '1/10'
});

// Use for codec options
const options = Dictionary.fromObject({
  'preset': 'medium',
  'crf': 23,
  'profile': 'high'
});