Video mode frame rate: progress update (1.0.7 in development)

Larry-UMa

Many of you have told us that video mode records at a low frame rate. Over the past weeks we have focused on the video recording path and reworked how it processes frames. Below are the results we currently measure with real cameras on the development build, so you can see where things stand.

These figures are current results on our own test setup and do not represent the final release. Actual frame rates vary with the camera, USB port and cable, resolution, bit depth and exposure time.

Test conditions

Each camera connected to the controller on its own; exposure 0.0001 s (short exposures as for the Sun, Moon and planets); 200 frames per recording; RAW8 unless noted.
Bandwidth and speed settings at the driver defaults.
Frame rates are the steady-state recording rate: for SER from the timestamps of the first and last frame in the file, for AVI from the actual rate stored in the file header. The start-up time between pressing record and the first frame is not included.

USB 3.0

RAW8, SER format, fps:

Player One Ceres 462M: 1920×1080 133.8 · 1280×720 205.4 · 640×480 304.0
ZWO ASI462MC: 1920×1080 25.9 · 1280×720 38.6 · 640×480 57.2
SynCam533C: 1920×1080 74.1 · 1280×720 109.2 · 640×480 159.4

Notes:

AVI: the same as SER for the ZWO ASI462MC and SynCam533C. The Ceres 462M runs fastest, and its AVI is limited by JPEG encoding speed: 96.5 / 184.1 / 297.5 fps.
Higher bit depth at 1920×1080: Ceres 462M RAW16 63.3 fps (AVI 59.8 fps), SynCam533C RAW14 35.6 fps. The ZWO ASI462MC cannot currently record RAW16 reliably on USB 3.0.
ZWO ASI462MC default bandwidth setting in the driver: 40 on USB 3.0 (the lowest value the SDK allows) and 80 on USB 2.0, which is why 640×480 is slower on USB 3.0 than on USB 2.0.

USB 2.0

RAW8, fps, SER and AVI are the same:

Player One Ceres 462M: 1920×1080 15.5 · 1280×720 34.5 · 640×480 102.0
ZWO ASI462MC: 1920×1080 16.7 · 1280×720 37.7 · 640×480 113.0
SynCam533C: 1920×1080 8.9 · 1280×720 13.0 · 640×480 18.8

Notes:

Higher bit depth at 1920×1080: Ceres 462M RAW16 7.7 fps, ZWO ASI462MC RAW16 8.4 fps, SynCam533C RAW14 4.5 fps.
Over USB 2.0 all three cameras are limited by the interface bandwidth (about 30–40 MB/s), so higher bit depths run at about half the RAW8 rate. For higher frame rates, use a USB 3.0 cable and port.

Video mode tips

Camera: a planetary camera with built-in DDR memory is recommended.
Format: prefer RAW8 and the SER format.
Connection: if recording misbehaves on USB 3.0, switch to a USB 2.0 port or cable.

This is where the development build stands today.

moonchild617

Thank you for sharing these detailed video mode benchmark results. It's great to see the recording pipeline being optimized for planetary, solar, and lunar imaging.

As someone focused on planetary capture using USB 3.0 cameras (like the ASI 585MC) on a high focal length optical tube (127mm Maksutov), I would like to offer a few technical suggestions to further enhance the video capture workflow:

Manual USB Bandwidth Adjustment: Since you identified that the ZWO driver defaults the USB bandwidth to a lower value (such as 40 on USB 3.0), it would be extremely beneficial if the SynLink app provided a manual USB Bandwidth slider (from 40% to 100%) in the camera settings. This will allow users to unlock maximum frame rates on high-speed USB 3.0 cameras without guesswork.

Custom Small ROIs & Planetary Auto-Centering: In planetary imaging, using small ROI boxes (like 400x400 or 320x320) is essential to push frame rates past 150-200 FPS. Having support for custom free-form ROIs along with an auto-centering / planetary tracking feature within the ROI box would be a game-changer when working with long focal length telescopes.

Real-time Histogram Peak Percentage: To avoid overexposing bright planetary disks or saturating color channels on one-shot color cameras, having a real-time numerical reading of the peak histogram percentage (%) during live preview and recording would be an invaluable acquisition tool.

Great job refining the SER recording path!

Luxo

Hi Larry, that’s great news !

Yin-UMa

moonchild617
SynLink already supports custom ROIs. You can adjust the ROI aspect ratio on the right side of the screen.
Regarding of suto-centering tracking, we will look into this. Thank you very much for your suggestions.

moonchild617

Yin-UMa thanks