Sub-Stream Settings for AI Analytics: CP Plus, Prama/Hikvision, Matrix and Sparsh
Which sub-stream settings should AI analytics use? As of 14 Oct 2026, CP Plus, Matrix and Sparsh documents cap the sub-stream at D1 (704 or 720 × 576). Prama PT-NC140D3-N(D2) and Hikvision DS-2CD1043G2-I(UF) specs allow 1280 × 720. For analytics: H.264/H.265, CBR, a PAL frame rate (25 fps or a divisor), I-frame interval = 2 × fps, smart codec off.
Last checked: 14 Oct 2026.
Verified against
- CP Plus, User Manual, Network Camera, Version 1.0.1 (listed for CP-UNC-TS41PL3), §4.2.2 Encode bar and Table 4-17 video parameters, PDF pp. 19, 64–66, multicast PDF p. 99 (PDF).
- CP Plus, CP-UNC-TA61L3C-LQ datasheet, p. 4 (PDF).
- Hikvision, Network Camera User Manual UD19347B-C, baseline V5.6.5, 28 Dec 2023, Video Settings, printed pp. 96–99; System Service, printed p. 57 (PDF).
- Prama, product specification pages for PT-NC140D3-N(D2), PT-NC320P1-N(D2) and PT-NC120D3-N(D2) on pramaindia.in (PT-NC140D3-N(D2), PT-NC320P1-N(D2), PT-NC120D3-N(D2)).
- Hikvision, DS-2CD1043G2-I(UF) datasheet V5.7.1, 25 Apr 2023 (PDF).
- Matrix, SATATYA PZCR50ML42CWP System Manual, §8.1.1 Video (printed pp. 48–50) and Table 24 RTSP URLs (PDF); RIDR50FL40CWP technical specifications (PDF).
- Sparsh, SC-INA40D-3L25 and SC-ISE20B-3M25C datasheets (posted July 2026) and Sparsh X Camera Manual (posted 24 Jul 2026), from Sparsh support downloads.
- Checked 14 Oct 2026.
- Prama's I-frame figures are carried over from the Hikvision manual.
Sub-stream defaults and what to set for AI
| Brand / document | Sub-stream per vendor (resolution @ fps, 50 Hz) | Bitrate range (kbps) | I-frame interval (frames) | Smart codec and the sub-stream | Source |
|---|---|---|---|---|---|
| CP Plus CP-UNC-TA61L3C-LQ (6 MP) | Sub 1 and sub 2: D1 704 × 576, VGA, CIF @ 1–25 fps; max fps "depends on main stream frame rates" | 3–8192 (H.265 and H.264) | Range follows fps; manual recommends 2 × fps | Smart Codec / AI Codec stop third stream, ROI and smart event detection; AI Codec forces CBR | Datasheet p. 4; manual PDF pp. 65–66 |
| Prama PT-NC140D3-N(D2) (4 MP) | 1280 × 720, 640 × 480, 640 × 360 @ 25 fps; codecs H.265/H.264/MJPEG | 32–8192 ("32 Kbps to 8 Mbps"), CBR/VBR | Not published | Smart codec not listed for this model; PT-NC120D3-N(D2) lists iH.265/iH.264 on the main stream only | Prama product page |
| Hikvision DS-2CD1043G2-I(UF) (4 MP) | 1280 × 720, 640 × 480, 640 × 360 @ 25 fps; codecs H.265/H.264/MJPEG | 32–8192 (datasheet); manual: 32–16384, platform-dependent | 1–400 | H.264+/H.265+ appear only on the main stream | Datasheet; manual pp. 97–99 |
| Matrix SATATYA PZCR50ML42CWP (PTZ) | Secondary stream: 704 × 576, 640 × 480, 640 × 360, 352 × 288, 320 × 240 | 16–16384 | 1–120, default 50; "must be a multiple of the number of frames" | Smart Stream, a 10-level codec, on/off | System manual §8.1.1 |
| Matrix SATATYA RIDR50FL40CWP (5 MP) | 4 stream profiles; Profile 2 = D1 @ 30 fps | Not published (the row repeats "2592 x 1944") | Not published | Not stated | Spec sheet |
| Sparsh SC-INA40D-3L25 (4 MP) | D1 720 × 576, VGA, CIF @ 15 fps | 211–8192, CBR/VBR | Not published | Not published | Sparsh support |
| Sparsh SC-ISE20B-3M25C (2 MP) | D1 720 × 576, VGA, CIF @ 25 fps | 211–8192, CBR/VBR | Not published | Not published | Sparsh support |
Starting point for AI on any of these (editorial guideline, not a vendor figure): the largest sub-stream size the model offers (D1, or 1280 × 720 on the Prama and Hikvision 4 MP models above), 10–12.5 fps for machine running/idle, I-frame interval = 2 × fps, CBR, H.264 or H.265. Raise fps only for fast events such as a press stroke.
The sub-stream's RTSP path differs by brand: Hikvision /Streaming/channels/102, CP Plus …&subtype=1, Matrix rtsp://IP:RTSP Port/sub. Full strings are on the RTSP/ONVIF cheat sheet and in the ONVIF/RTSP compatibility matrix.
Why analytics reads the sub-stream
Hikvision's manual (printed p. 97) says the main stream "is usually for recording and live view with good bandwidth", and the sub-stream "can be used for live view when the bandwidth is limited".
CP Plus's manual (§4.2.2) describes the sub stream as the option that "requires less bandwidth" and replaces the main stream "when bandwidth is not enough".
An analytics box decoding 16 cameras is exactly that bandwidth-limited viewer. The NVR keeps recording the main stream at full resolution.
Use the main stream instead when the analytics must read detail: a counter, a gauge, a small part. Check pixels per metre with the lens and DORI calculator before you decide.
Settings to set, in order
- Enable the sub-stream. CP Plus Table 4-17 says it is "enabled by default". On Hikvision, the third stream is "not enabled by default" on some models and is switched on under System Service (printed p. 57).
- Codec: H.264 or H.265. CP Plus allows MJPEG only on sub-streams (TA61L3C-LQ datasheet) and forces CBR with it (Table 4-17).
- Resolution: the largest sub-stream option. On Matrix the secondary stream tops out at 704 × 576; the tertiary stream reaches 1920 × 1080 (§8.1.1), which can serve analytics if the secondary is taken.
- Frame rate: a PAL value. On CP Plus the sub-stream ceiling follows the main stream's fps, so lowering the main stream can lower the sub-stream's limit (TA61L3C-LQ datasheet).
- CBR. CP Plus CBR "keeps close to the defined bit rate value"; VBR "changes as monitoring scene changes" (Table 4-17).
- I-frame interval = 2 × fps. CP Plus recommends it in Table 4-17. On Matrix it also satisfies the rule that the interval be a multiple of the frame rate.
- Smart codec off on cameras that feed analytics, then save and re-test the stream in VLC.
Settings vanish after a reset. The CP Plus reset and static-IP guide and the Prama/Hikvision reset and SADP guide cover getting back in first.
Where brands differ
- Smart codec scope. Hikvision offers H.264+/H.265+ only on the main stream (printed p. 98), so its sub-stream stays plain. For CP Plus's Smart Codec and AI Codec, the manual says that once enabled the camera "would stop supporting the third stream, ROI, and smart event detection".
- Hikvision locks fields. With H.264+/H.265+ on, "profile, I frame interval, video quality, and SVC are greyed out", and toggling needs a reboot (printed p. 98).
- I-frame range. Hikvision 1–400; Matrix PTZ 1–120, default 50; CP Plus ties the range to fps; Sparsh publishes none (checked 14 Oct 2026).
- Sparsh contradicts itself. Page 1 of the SC-INA40D-3L25 sheet lists both "Dual Streaming" and a "Triple Streaming" feature block; its spec row says "2 Streams". The X Camera Manual sends settings questions to the NVR manual. Ask Sparsh which is right for your firmware.
- Prama vs Hikvision. Prama's PT-NC140D3-N(D2) page lists the same sub-stream sizes, fps and bitrate as Hikvision's DS-2CD1043G2-I(UF). The 2 MP PT-NC320P1-N(D2) stops at 640 × 480 and adds a 1 fps third stream (640 × 360), so check the model before choosing the sub-stream for analytics. Use the Prama/Hikvision RTSP guide for the stream path and check the web UI.
What breaks in a factory
- 50 Hz mains. Use PAL frame rates under LED and tube lights, and fix banding before tuning analytics. The Sparsh SC-INA40D-3L25 sheet lists anti-flicker with a 50 Hz option.
- Busy scenes and VBR. Moving belts, steam and dust make VBR bitrate climb mid-shift. CBR on sub-streams keeps each camera's load flat on a shared PoE switch.
- Power cuts. Hikvision says H.264+/H.265+ needs "at least 24 hours to adapt to a fixed monitoring scene" (printed p. 99). Expect uneven main-stream bitrate after an outage.
- Multicast floods. CP Plus defaults multicast to 224.1.2.4, sub stream 1 on port 40016 (PDF p. 99). Without IGMP snooping, multicast reaches every switch port.
- Bandwidth arithmetic (assumption, not a vendor figure): 32 cameras × 1 Mbps CBR sub-streams = 32 Mbps into the analytics box, against 128 Mbps at 4 Mbps main streams.
When to call the installer / what to ask the vendor
Call the installer before changing streams the NVR already uses; some NVRs show the sub-stream in multi-view. Ask the vendor for the sub-stream maximum resolution and fps of your exact model, the I-frame range in its firmware, and whether its smart codec disables the events you paid for. The CP Plus RTSP/ONVIF page lists the account details to collect at the same time.
Mama reads existing cameras over RTSP/ONVIF, usually a sub-stream set as above, and tells the owner how long each machine stood idle. Leave an email or phone in the form below.
FAQ
Should AI detection use the main stream or the sub-stream? Use the sub-stream for presence, motion or machine on/off. Use the main stream when the model must read detail. Hikvision and CP Plus manuals position the sub-stream for limited bandwidth, not fine detail.
What should the I-frame interval be for a CCTV camera? CP Plus recommends twice the frame rate, for example 50 at 25 fps. Hikvision allows 1–400; Matrix's PTZ manual allows 1–120 with a default of 50.
Does turning on Smart Codec or H.265+ affect analytics? On CP Plus, yes: the manual says Smart Codec and AI Codec stop smart event detection, ROI and the third stream. Hikvision's H.264+/H.265+ applies to the main stream only and greys out the I-frame setting.