Quick Answer: Should an IP Security Camera Use Main Stream or Sub Stream?

Use the main stream for NVR recording and detailed playback. Use the sub stream for multi-camera display, mobile monitoring and slower internet connections. The main stream protects evidence quality, while the sub stream reduces bandwidth and decoding load.

The best settings depend on resolution, H.264 or H.265, FPS, scene movement, upload speed and NVR decoding capacity. Buyers can compare the Bokysee IP security camera range and review the IP security camera encoding settings guide before sample testing.

What Is the Main Stream on an IP Security Camera?

The main stream is the camera’s primary, higher-quality video stream. It normally uses the required project resolution, a higher bitrate and a frame rate suitable for the monitored activity.

It is used for continuous or event recording, detailed playback, facial or clothing detail, vehicle identification, cashier evidence, digital zoom and high-quality export.

An 8MP camera may output an 8MP main stream, but bitrate and FPS should match the scene. A quiet warehouse aisle needs less data than a vehicle entrance. Too little bitrate produces blockiness and lost motion detail; too much wastes bandwidth and storage.

The main stream is not ideal for every viewing task. Sending sixteen high-resolution main streams to a phone can cause delay even when local recording is stable.

What Is the Sub Stream on an IP Security Camera?

The sub stream is a second, lower-bandwidth stream from the same camera. It normally uses lower resolution, bitrate and FPS.

It supports mobile live view, browser preview, large NVR split screens and remote monitoring over limited upload bandwidth. It should show the scene clearly but is not normally the preferred evidence stream.

Correct sub-stream configuration often fixes the complaint: “The recording is clear, but phone viewing is slow.” The NVR may be recording correctly while the remote client requests more data than the connection or phone can handle.

IP Security Camera Main Stream vs Sub Stream Comparison Table

The streams are not competing choices. Recording only a low-resolution sub stream may save storage but weaken evidence. Removing the sub stream may overload multi-camera displays.

Best Main Stream Settings for IP Security Camera Recording

There is no universal bitrate. The following H.265 ranges are practical starting points and should be tested in the real scene, especially at night.

Set resolution and FPS for the actual scene, define a maximum bitrate for network calculation and test night playback. Trees, rain, vehicles and image noise can require more data than a static indoor scene.

For most projects:

1. Select the resolution needed for identification, not automatically the maximum.

2. Set FPS according to movement.

3. Use VBR where scene complexity changes and the NVR supports it.

4. Set a maximum bitrate for storage and bandwidth planning.

5. Test moving targets at night.

6. Check recorded playback and exported files.

El Bokysee security camera frame-rate guide explains 15 fps, 25 fps and 30 fps applications.

Best Sub Stream Settings for IP Camera Mobile Viewing

A useful sub stream should load quickly without becoming unreadable.

The client must support the codec. A phone or browser may perform better with H.264 sub streams even when the NVR records H.265 main streams. Test the combination because mixed codecs use additional camera resources.

Do not set the sub stream unnecessarily high. Sixteen sub streams at 1 Mbps require roughly 16 Mbps before overhead, which may exceed site upload speed or NVR outgoing bandwidth.

Why an NVR Uses Sub Streams in 9-, 16- or 32-Channel Live View

Displaying many main streams requires substantial decoding power. A recorder may support high-resolution recording but have a lower simultaneous decoding limit.

Typical behavior is:

· One-camera full screen: main stream

· Four-camera split: main or mixed streams

· Nine-camera split: mostly sub streams

· Sixteen- or thirty-two-camera split: sub streams

· Playback of a selected channel: main stream

This does not mean the NVR records low-quality footage. The recording can remain on the main stream while the screen shows a sub stream.

A “resource insufficient” warning may appear when too many high-resolution streams are forced onto the display. Use sub streams for split view and review the NVR decoding specification.

Why IP Camera Remote Viewing Is Slow or Keeps Buffering

Remote performance depends on upload speed at the camera or NVR site, NVR outgoing bandwidth and client decoding. Delay commonly occurs when:

· The app requests the main stream

· Too many cameras are opened

· Sub-stream bitrate is too high

· Site upload speed is limited

· The phone cannot decode the codec smoothly

· Mobile signal or P2P routing is unstable

· Night noise increases VBR bitrate

· Camera and NVR stream settings do not match

Use this calculation:

Required remote upload ≈ number of viewed streams × bitrate per stream

Four 512 Kbps sub streams need about 2 Mbps before overhead. Four 6 Mbps main streams need about 24 Mbps. This explains why one-camera view works while four-camera main-stream view buffers.

For cellular projects, see the Bokysee 4G camera data usage guide.

Main Stream and Sub Stream Settings by IP Security Camera Application

 For license plates or moving vehicles, do not rely on the sub stream as the only evidence source. For remote sites, retain the main stream locally and use event alerts plus a lower-bitrate sub stream to control data use.

How H.264 and H.265 Affect IP Camera Main and Sub Streams

H.265 is designed for more efficient video compression. The official ITU-T H.265 recommendation is the standards reference. In CCTV, H.265 can reduce bandwidth and storage for a comparable quality target, but results depend on the encoder, scene and settings.

A practical configuration may use H.265 for the main recording stream and H.264 for the sub stream to improve client compatibility. Another project may use H.265 on both. The camera, NVR, mobile app, browser and VMS must all support the selected combination.

ONVIF Profile T supports H.264 and H.265 streaming. Review the official ONVIF Profile T page when preparing interoperability requirements.

How RTSP and ONVIF Select IP Security Camera Streams

RTSP is commonly used to retrieve video streams; the official RFC 7826 RTSP 2.0 specification is the protocol reference. Manufacturers may provide different paths for main and sub streams. ONVIF can expose media profiles, but the client still needs a compatible codec and resolution.

If only one stream appears on a third-party NVR, verify that the sub stream is enabled, both media profiles are exposed, the ONVIF user has permission and the codec is supported. An RTSP picture does not prove that ONVIF events, audio or PTZ functions work.

Main Stream and Sub Stream Compatibility Checklist for Bulk Orders

 A representative 5MP PoE IP security camera can be tested with the target NVR before bulk production.

IP Security Camera Main Stream vs Sub Stream FAQ

Does the sub stream reduce main-stream recording quality?

Normally no. They are separate configurations, although both use camera processing resources.

Can an NVR record the sub stream?

Some NVRs can, but the main stream is normally preferred when identification detail matters.

Why is mobile live view blurry while NVR playback is clear?

The app is probably displaying the lower-resolution sub stream while the NVR records the main stream.

Should both streams use the same codec?

Not necessarily. H.265 may be used for recording and H.264 for client compatibility.

Can lowering sub-stream bitrate fix mobile lag?

It can help, but upload speed, outgoing NVR bandwidth, client decoding and latency should also be checked.

Final Recommendation: Configure Both IP Security Camera Streams for Their Correct Jobs

Record the main stream at the quality required for evidence. Use the sub stream to make multi-camera display and remote viewing efficient. Test both streams with the actual NVR, app and internet conditions.

Bokysee supports stream configuration and compatibility testing. Share resolution, camera quantity, NVR model, recording days and remote network conditions to receive a suitable IP security camera and NVR solution.