AlexxIT/go2rtc · error

hds: write buffer too big

Error message

hds: write buffer too big

What it means

HDS Write guard: the payload exceeds the protocol maximum of 0xFFFFFF bytes (the 3-byte length field in the frame header cannot represent it). The write is refused before any bytes hit the wire; the caller must split the data.

Solutions

1. Chunk writes into blocks smaller than ~16MB
2. Stream data incrementally instead of building one huge buffer
3. Bound snapshot/media payloads upstream to fit HDS frame limits

When it happens

Trigger: Thrown at pkg/hap/hds/hds.go:126 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of AlexxIT/go2rtc@c245815e75 (2026-09-07). Data as JSON: /api/errors/b2f1ca71f3ca5a94. Report an issue: GitHub.

Appendix: source

Thrown at pkg/hap/hds/hds.go:126

	for {
		b, err := c.read()
		if err != nil {
			return total, err
		}

		n, err := w.Write(b)
		total += int64(n)
		if err != nil {
			return total, err
		}
	}
}

func (c *Conn) Write(b []byte) (n int, err error) {
	n = len(b)

	if n > 0xFFFFFF {
		return 0, errors.New("hds: write buffer too big")
	}

	verify := make([]byte, 4)
	binary.BigEndian.PutUint32(verify, 0x01000000|uint32(n))
	if _, err = c.wr.Write(verify); err != nil {
		return
	}

	nonce := make([]byte, hap.NonceSize)
	binary.LittleEndian.PutUint64(nonce, c.encryptCnt)
	c.encryptCnt++

	buf := make([]byte, n+hap.Overhead)
	if _, err = chacha20poly1305.EncryptAndSeal(c.encryptKey, buf[:0], nonce, b, verify); err != nil {
		return
	}

	if _, err = c.wr.Write(buf); err != nil {

View on GitHub (pinned to c245815e75)