Method outputChunk

src/audio_encoder.ts:251–321

(currentConfigId: number)

	}

	private outputChunk(currentConfigId: number) {
		if (this.currentConfigId !== currentConfigId) {
			return;
		}

		assert(this.codecContext);
		assert(this.config);

		if (!this.packet.data) {
			return;
		}
		let data: Uint8Array = this.packet.data;

		let metadata: EncodedAudioChunkMetadata | undefined;
		if (this.chunkOutputted) {
			metadata = {};
		} else {
			this.chunkTimestampOffset = Math.max(0, -Number(this.packet.pts)); // So that the chunks aren't negative

			const codecString = this.config.codec;
			let description = this.codecContext.extraData
				? toUint8Array(this.codecContext.extraData)
				: undefined;

			if (
				description
				// eslint-disable-next-line @stylistic/max-len
				// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-member-access
				&& this.codecContext.codecId === AV_CODEC_ID_AAC && (this.config as any).aac?.format === 'adts'
			) {
				this.aacAudioSpecificConfig = parseAacAudioSpecificConfig(description);
				description = undefined; // Not used with 'adts' format
			}

			if (description && this.codecContext.codecId === AV_CODEC_ID_FLAC) {
				// FFmpeg uses the STREAMINFO block as the extradata, but WebCodecs wants a different format:
				// 1. The bytes 0x66 0x4C 0x61 0x43 ("fLaC" in ASCII)
				// 2. A metadata block (called the STREAMINFO block) as described in section 7 of [FLAC]
				// 3. Other optional metadata blocks (not included here, because, well, they're optional)
				description = new Uint8Array([
					0x66, 0x4c, 0x61, 0x43, // 'fLaC'
					128, 0, 0, description.byteLength,
					...description,
				]);
			}

			metadata = {
				decoderConfig: {
					codec: codecString,
					sampleRate: this.codecContext.sampleRate,
					numberOfChannels: this.codecContext.channels,
					description,
				},
			};
		}

		// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-member-access
		if (this.aacAudioSpecificConfig && (this.config as any).aac?.format === 'adts') {