@irbisadm/iso-codec-string

Parse and generate ISO/RFC codec strings — the dot-separated identifiers used in the MIME codecs= parameter (e.g. vp09.00.51.08, av01.0.13M.08.0.112.01.01.01.0) — in pure TypeScript, with no runtime dependencies.

Useful for reading codec parameters out of a codecs= string, checking support with MediaSource.isTypeSupported(), or building a correct codec string from a set of parameters.

Supported codecs

Codec	Parse	Generate
VP8	✅	✅
VP9	✅	✅
AV1	✅	✅
H.264 (AVC)	✅	✅
H.265 (HEVC)	✅	✅
H.266 (VVC)	✅	✅
LCEVC	✅	✅
APV	✅	✅
EVC	✅	✅
L-HEVC	✅	✅
MP4 (mp4a/mp4v — AAC, MP3, MPEG-4/2)	✅	✅
AVS3 video/audio (avs3/lav3/av3a)	✅	✅
AVS2 audio (cavs)	✅	✅
MPEG-H 3D Audio (mha1/mhm1)	✅	✅
Parameterless (DTS, VC-1, Opus, FLAC, Vorbis, ALAC, PCM, AMR, 3GPP text, CEA-608/708, DRA)	✅	✅
Uncompressed (uncv/unci)	✅	✅
Subtitles (WebVTT wvtt, TTML stpp)	✅	✅

Install

npm install @irbisadm/iso-codec-string

Ships as an ES module with bundled TypeScript declarations. Requires Node.js >= 18.

Usage

Parse a codec string

codecInfoFactory picks the right codec from the string prefix and returns a populated info object.

import { codecInfoFactory } from '@irbisadm/iso-codec-string';

const info = codecInfoFactory('vp09.00.51.08');
console.log(info.level); // VpxLevel.LEVEL_5_1

Build a codec string

Construct an info object, set its fields, and serialize with toString().

import { vpx } from '@irbisadm/iso-codec-string';

const info = new vpx.Vp9Info();
info.level = vpx.VpxLevel.LEVEL_5_1;
info.bitDepth = vpx.VpxBitDepth.BIT_DEPTH_8;
console.log(info.toString()); // 'vp09.00.51.08'

Setters validate cross-field constraints — for example, VP9 profile 2 requires a 10- or 12-bit depth, and an incompatible combination throws.

Human-readable output

Every info object can expand its numeric fields into display strings.

import { av1 } from '@irbisadm/iso-codec-string';

const info = av1.Av1Info.fromString('av01.0.13M.08.0.112.01.01.01.0');
console.log(info.toHumanReadable());
// { profile: 'main', level: '5.1', tier: 'main', bitDepth: '8', ... }

H.264 / AVC

The AVC codec string encodes profile_idc, the constraint-set flags, and level_idc as three hex bytes. Fields are exposed as raw bytes and decoded in toHumanReadable().

import { h264 } from '@irbisadm/iso-codec-string';

const info = h264.H264Info.fromString('avc1.640028');
console.log(info.toHumanReadable().profile); // 'High'
console.log(info.toHumanReadable().level);   // '4.0'
console.log(info.toString());                // 'avc1.640028'

API

• codecInfoFactory(codecString) — dispatches by prefix (vp08/vp8, vp09/vp9, av01, avc1/avc2/avc3/avc4, hev1/hvc1, vvc1/vvi1, lvc1, apv1, evc1, lhv1/lhe1, mp4a/mp4v, avs3/lav3, av3a, cavs, mha1/mha2/mhm1/mhm2, uncv/unci, stpp) and returns the matching info object (Vp8Info, Vp9Info, Av1Info, H264Info, H265Info, H266Info, LcevcInfo, ApvInfo, EvcInfo, LhevcInfo, Mp4Info, Avs3VideoInfo, Avs3AudioInfo, MpeghInfo, UncvInfo). Recognised parameterless 4CCs (DTS, VC-1, Opus, FLAC, Vorbis, ALAC, PCM) return a SimpleCodecInfo. Throws Unknown codec for anything else.
• vpx — namespace exporting Vp8Info, Vp9Info, vpxInfoFactory, and the Vpx* enums.
• av1 — namespace exporting Av1Info and the Av1* enums.
• h264 — namespace exporting H264Info, AvcProfileIdc, and the hProfile/hLevel helpers.
• h265 — namespace exporting H265Info, HevcProfileIdc, and the hProfile/hLevel/hTier helpers.
• h266 — namespace exporting H266Info, VvcProfileIdc, and the hProfile/hLevel/hTier helpers. The mandatory profile/tier/level is decoded; the optional VVC constraint (C), sub-profile (S) and output-layer-set (O) fields are preserved verbatim for round-tripping.
• lcevc — namespace exporting LcevcInfo and LcevcProfile (MPEG-5 Part 2 enhancement codec, lvc1.vprf<profile>.vlev<level>).
• apv — namespace exporting ApvInfo (Advanced Professional Video, apv1.apvf<profile>.apvl<level>.apvb<band>).
• evc — namespace exporting EvcInfo, EvcProfile (MPEG-5 Part 1, evc1.vprf<profile>.vlev<level>). Mandatory profile/level are decoded; the optional toolset, bit-depth and colour parameters are preserved verbatim.
• lhevc — namespace exporting LhevcInfo (Layered HEVC — SHVC / MV-HEVC, lhv1/lhe1). The HEVC profile-tier-level is exposed via .ptl (an H265Info); the optional scalability field is preserved verbatim in .scalability.
• mp4 — namespace exporting Mp4Info and the OTI helpers (hObjectTypeIndication, hAudioObjectType). Covers the RFC 6381 mp4a/mp4v ObjectTypeIndication scheme — AAC, MP3, MPEG-4 Visual, MPEG-2 video/audio and more (mp4a.40.2, mp4a.69, mp4v.20.9, …).
• avs3 — namespace exporting Avs3VideoInfo (avs3.<profile>.<level>) and Avs3AudioInfo (av3a.<codec_id>) for the AVS3 video/audio standard. lav3 (library track) shares the video format.
• avs2 — namespace exporting Avs2AudioInfo for AVS2 audio (cavs.<audio_codec_id>).
• stpp — namespace exporting StppInfo for TTML / timed-text subtitles (stpp[.<mode>[.<profile>]], e.g. stpp.ttml.im1t), with the TTML profile decoded to a description. WebVTT (wvtt) is parameterless and handled by SimpleCodecInfo.
• mpegh — namespace exporting MpeghInfo (MPEG-H 3D Audio, mha1/mha2/mhm1/mhm2 + a profileLevelId, e.g. mhm1.0c).
• simple — namespace exporting SimpleCodecInfo and the SIMPLE_CODECS registry for parameterless 4CCs (DTS dtsc/dtse/…, vc-1, opus, flac, vorbis, alac, wvtt (WebVTT), tx3g, c608/c708, samr/sawb, dra1, and PCM variants such as ipcm/fpcm/twos/sowt).
• uncv — namespace exporting UncvInfo for uncompressed video/images (uncv/unci), with an optional profile 4CC (uncv.rgba, uncv.i420, …) decoded to a pixel-format description.
• Shared ISO/IEC 23001-8:2016 colour enums (ColourPrimaries, TransferCharacteristics, MatrixCoefficients, VideoFullRangeFlag) are re-exported from both namespaces.

Each info class exposes fromString() (parse), toString() (serialize), toHumanReadable(), and per-field getters/setters.

Contributing

Contributions are welcome. Commits follow Conventional Commits and releases are automated with semantic-release. See CONTRIBUTING.md for details.

License

MIT © 2024 Igor Sheko. See LICENSE.