NodeAV

node-av / lib / CodecParser

Class: CodecParser ​

Defined in: src/lib/codec-parser.ts:53

Parser for extracting codec frames from raw bitstream data.

Analyzes and splits raw bitstream data into individual codec frames. Essential for processing elementary streams, extracting NAL units, and handling frame boundaries in raw codec data. Commonly used for parsing H.264/H.265 streams, AAC ADTS streams, and other raw formats.

Direct mapping to FFmpeg's AVCodecParserContext.

Example ​

typescript
import { CodecParser, CodecContext, Packet, FFmpegError } from 'node-av';
import { AV_CODEC_ID_H264 } from 'node-av/constants';

// Create and initialize parser
const parser = new CodecParser();
parser.init(AV_CODEC_ID_H264);

// Parse raw data into packets
const packet = new Packet();
packet.alloc();

const rawData = Buffer.from([...]); // Raw H.264 stream
const ret = parser.parse2(
  codecContext,
  packet,
  rawData,
  0n,  // pts
  0n,  // dts
  0    // position
);

if (ret > 0) {
  // Got complete packet, ret is consumed bytes
  console.log(`Parsed ${ret} bytes into packet`);
}

// Cleanup
parser.close();

See ​

Implements ​

Constructors ​

Constructor ​

new CodecParser(): CodecParser

Defined in: src/lib/codec-parser.ts:56

Returns ​

CodecParser

Accessors ​

repeatPict ​

Get Signature ​

get repeatPict(): number

Defined in: src/lib/codec-parser.ts:171

Number of pictures to repeat for field-based interlaced content.

Used to calculate frame duration for interlaced video: frame_duration = (1 + repeat_pict) * time_base

Commonly used in H.264 to display telecined material. Value comes from the codec parser after parsing a frame.

Direct mapping to AVCodecParserContext.repeat_pict.

Example ​
typescript
const parser = stream.parser;
if (parser) {
  const fields = 1 + parser.repeatPict;
  console.log(`Frame uses ${fields} fields`);
}
Returns ​

number

Repeat picture count (0 for progressive, >0 for interlaced)

Methods ​

[dispose]() ​

[dispose](): void

Defined in: src/lib/codec-parser.ts:222

Dispose of the codec parser.

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

Returns ​

void

Example ​

typescript
{
  using parser = new CodecParser();
  parser.init(AV_CODEC_ID_H264);
  // Use parser...
} // Automatically closed when leaving scope

Implementation of ​

Disposable.[dispose]

close() ​

close(): void

Defined in: src/lib/codec-parser.ts:192

Close the codec parser.

Releases all resources associated with the parser. The parser becomes invalid after calling this.

Direct mapping to av_parser_close().

Returns ​

void

Example ​

typescript
parser.close();
// Parser is now invalid

See ​

getNative() ​

getNative(): NativeCodecParser

Defined in: src/lib/codec-parser.ts:203

Internal

Get the underlying native CodecParser object.

Returns ​

NativeCodecParser

The native CodecParser binding object

Implementation of ​

NativeWrapper.getNative

init() ​

init(codecId): void

Defined in: src/lib/codec-parser.ts:84

Initialize parser for specific codec.

Sets up the parser to handle a specific codec format. Must be called before parsing data.

Direct mapping to av_parser_init().

Parameters ​

codecId ​

AVCodecID

Codec ID to parse

Returns ​

void

Throws ​

If codec parser not available

Example ​

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

const parser = new CodecParser();
parser.init(AV_CODEC_ID_AAC);
// Parser ready for AAC ADTS streams

See ​

parse2() ​

parse2(codecContext, packet, data, pts, dts, pos): number

Defined in: src/lib/codec-parser.ts:145

Parse bitstream data into packets.

Analyzes raw bitstream data and extracts complete codec frames. May require multiple calls to accumulate enough data for a complete frame. Returns the number of bytes consumed from the input buffer.

Direct mapping to av_parser_parse2().

Parameters ​

codecContext ​

CodecContext

Codec context for parser state

packet ​

Packet

Packet to receive parsed frame

data ​

Buffer

Raw bitstream data to parse

pts ​

bigint

Presentation timestamp for data

dts ​

bigint

Decoding timestamp for data

pos ​

number

Byte position in stream

Returns ​

number

Number of bytes consumed from data, negative on error:

  • AVERROR_EINVAL: Invalid parameters
  • AVERROR_ENOMEM: Memory allocation failure

Example ​

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

let offset = 0;
while (offset < rawData.length) {
  const remaining = rawData.subarray(offset);
  const ret = parser.parse2(
    codecContext,
    packet,
    remaining,
    pts,
    dts,
    offset
  );

  if (ret < 0) {
    FFmpegError.throwIfError(ret, 'parse2');
  }

  offset += ret;

  if (packet.size > 0) {
    // Got complete packet
    await processPacket(packet);
    packet.unref();
  }
}

See ​

init To initialize parser