AlexxIT/go2rtc · error

multitrans: talkback error

Error message

multitrans: talkback error: %s

What it means

openTalkChannel checks the Multitrans talkback HTTP response body for the literal "error_code":0 (mirroring the reference Python client). If the body lacks it, the whole response body is included in the error. The endpoint responded 200 OK but reported an application-level talkback failure.

Solutions

1. Log/inspect string(res.Body) in the error to read the actual error_code and message.
2. Confirm the device supports talkback and no other session is using the audio channel.
3. Check the credentials/token used when constructing the talkback request URL.
4. Retry after closing other talkback sessions; some devices allow a single talkback client.
5. If the server uses spaced JSON, parse the body as JSON instead of the substring check (library-side fix).

Example fix

// before (client side retry loop slams an occupied channel)
for {
    _ = client.StartTalkback(media)
}
// after
if err := client.StartTalkback(media); err != nil {
    log.Printf("talkback busy/failed: %v", err)
    time.Sleep(5 * time.Second)
}

// check the device exposes a talkback endpoint before opening the channel
if !device.Capabilities.Talkback { return errors.New("talkback unsupported") }

if err := openTalkback(media); err != nil {
    if strings.Contains(err.Error(), "talkback error") {
        log.Printf("talkback body: %v", err) // includes raw response body
        time.Sleep(backoff)
        retry()
    }
}

When it happens

Trigger: Opening a talkback (two-way audio) channel where the server returns a body with a non-zero error_code, a JSON shape like "error_code": 0 (with space, which the naive bytes.Contains misses), or an HTML error page instead of JSON.

Common situations: Camera rejects talkback because another client holds the audio channel; wrong credentials embedded in the talkback URL; device firmware returns pretty-printed JSON the string check misreads; talkback unsupported on the device model.

Related errors

• streams: source empty
• tuya:
• ivideon: can't get live_stream
• api.StreamNotFound
• not homekit source

AI-assisted analysis of AlexxIT/go2rtc@c245815e75 (2026-09-07). Data as JSON: /api/errors/3469d18e5ac8165a. Report an issue: GitHub.

Appendix: source

Thrown at pkg/multitrans/client.go:185

	data := fmt.Sprintf("MULTITRANS %s RTSP/1.0\r\nCSeq: 2\r\nSession: %s\r\nContent-Type: application/json\r\nContent-Length: %d\r\n\r\n%s",
		uri, session, len(payload), payload)

	if _, err := c.conn.Write([]byte(data)); err != nil {
		return err
	}

	res, err := tcp.ReadResponse(c.rd)
	if err != nil {
		return err
	}

	if res.StatusCode != http.StatusOK {
		return errors.New("multitrans: talkback failed: " + res.Status)
	}

	// Python checks for "error_code":0 in body.
	if !bytes.Contains(res.Body, []byte(`"error_code":0`)) {
		return fmt.Errorf("multitrans: talkback error: %s", string(res.Body))
	}

	return nil
}

func (c *Client) GetTrack(media *core.Media, codec *core.Codec) (*core.Receiver, error) {
	return nil, core.ErrCantGetTrack
}

func (c *Client) Start() error {
	_ = c.closed.Wait()
	return nil
}

func (c *Client) Stop() error {
	c.closed.Done(nil)
	return c.Connection.Stop()
}

View on GitHub (pinned to c245815e75)