Direct answer
Use passthrough when the source codec and parameters are accepted by the destination. Probe the camera first, then validate browser or downstream support; transcode only the incompatible tracks.
Why this happens
Restreaming can change transport and fan out sessions without decoding video. It saves CPU and preserves quality, but it cannot make an unsupported codec suddenly playable.
Browsers normally need a gateway that converts the camera feed into a web-native delivery path.
A controlled test
Test video and audio separately and compare gateway CPU, startup time and target-client compatibility.
Change one variable at a time. Keep the camera model, firmware, endpoint and account recorded; then test network reachability, protocol response, media transport and decoding as separate layers.
Use a dedicated view-only account and a trusted local diagnostic tool. Redact credentials, private addresses and identifying data before sharing output.
Diagnostic sequence
| Check | Action | Evidence of progress |
|---|---|---|
| Source | Probe codec, profile, resolution and audio. | The compressed tracks are known. |
| Destination | List accepted codecs and containers. | Compatibility is explicit. |
| Passthrough | Remux or relay without video decode. | CPU remains low and quality is unchanged. |
| Fallback | Transcode only the failing track or profile. | The added capacity and latency are bounded. |
Evidence to keep
Document which tracks pass through, which are converted and why. That prevents future operators from assuming the gateway transcodes everything.
Boundary and safety note
A low-CPU relay can still expose credentials or become a single point of failure; secure and monitor it like any other gateway.
For remote viewing, use a managed VPN instead of exposing RTSP or camera administration ports directly to the public internet.
SmartRTSP
SmartRTSP is a camera-focused RTSP and ONVIF viewer for Apple devices, Windows and Android. It fits direct viewing, discovery and multi-camera checks; keep a dedicated NVR or VMS when continuous recording, evidence export or centralized enterprise controls are required.
Frequently asked questions
Is restreaming the same as transcoding?
No. Restreaming can relay or repackage compressed media without decoding and re-encoding it.
Why does passthrough fail in a browser?
The browser may not support the camera codec or packetization even though another RTSP client does.
Can audio be transcoded while video passes through?
Yes, if the gateway supports independent track handling.
Primary references
- FFmpeg — RTSP protocol options and examples
- IETF RFC 7826 — Real-Time Streaming Protocol 2.0
- MDN — Media container and codec formats on the web
Related SmartRTSP guide
Open related guideReuse compressed camera video to reduce compute while checking codec, audio and packetization compatibility end to end.