Axis Zipstream 2 Tested
Smart codecs are one of the big trends in the industry now.
Axis was the first manufacturer to launch a smart codec, releasing Zipstream in Spring 2015, but since then they have been followed by others, including Hikvision H.264+, Panasonic Smart Coding, Dahua Smart H.264+, and more.
Now, Axis released their second generation of Zipstream to push bitrate savings even further, adding Dynamic frames per second (FPS) and higher dynamic compression levels.
We tested this new enhanced Zipstream on three Axis cameras (M, P and Q series) to see how it performed. In this report, we share our results and Axis' competitive outlook versus other Smart Codecs.
In our tests, Axis' enhancements to Zipstream both resulted in noticeable savings compared to original Zipstream.
- Dynamic FPS produced the greatest savings, with bitrate reductions of 98-99% possible in still scenes, with bitrates as low as 1-2 Kb/s for 1080p streams. However, these savings are practically eliminated in busy scenes where even small amounts of motion are constant, such as intersections/roadways or public areas, as the framerate rarely or never decreases.
- Extreme dynamic compression produced modest savings over Zipstream's "High" setting, reducing bitrate by a few percent in most scenes. Additionally, this Extreme setting is effective in scenes with higher motion, where Dynamic FPS provides little to no benefit. However, notable visible compression artifacts/pixelation were present in some of our tests.
Zipstream with Dynamic FPS worked properly in Genetec Security Center, Milestone XProtect, Axxon Next, and Network Optix, with no live, playback, or recording issues. However, playback was spotty in Exacq when using Dynamic FPS, with scrubbing/clicking to move the timeline indicator unusable. Additionally, gaps in recorded video were present, not seen in other VMSes.
While other smart codecs, such as Hikvision's H.264+ have come close to or matched the bitrate reductions seen in the original Zipstream, the addition of Dynamic FPS gives the advantage again to Axis, giving supported models the lowest bandwidth consumption we have seen in our tests.
Whether others can or will add this capability to their smart CODEC and close this gap again remains to be seen.
Enhanced Zipstream is available as a firmware update on select Axis cameras, mostly mid to high end P/Q series, though also including some lower cost models such as the new M11 series. More models may be added via firmware in upcoming releases.
Added Configuration Options
Axis has added two settings, both found on the main Zipstream configuration tab, seen below. We detail both of these options independently in this report.
The largest bitrate savings in Axis' improved Zipstream come from their new Dynamic FPS feature, which reduces framerate to 1 when there is no activity in the scene, and increases to the camera's configured FPS on motion.
Savings with Dynamic FPS on were dramatic in still scenes, with bitrates dropping to near 1 Kb/s. However, in high motion scenes, such as intersections, roadways, busy hallways or common areas, Dynamic FPS's benefits are limited, as the FOV never becomes low enough motion to reduce frame rate. This is in the chart below:
No Minimum FPS for Dynamic FPS
Note that there is no minimum FPS setting, though Axis states a future update will add this feature.
"Extreme" Dynamic Compression
The second change made in Axis Zipstream is the addition of an "Extreme" dynamic compression mode, in addition to Low, Medium, and High in previous versions.
This setting provided an additional 5-10% savings compared to the previous "High" setting in our tests. These savings were present in all scenes, regardless of frequency of motion.
Extreme dynamic compression has noticeable additional impact on image quality compared to High. Significant smearing and compression artifacts may be seen on background objects, such as the drop ceiling in this example:
However, these effects are not seen on more detailed objects, such as the TVL chart or cameras/shelves below, despite the scene remaining static.
During testing, Zipstream caused two errors in ExacqVision not seen in other VMSes:
Jumpy Playback Control
When attempting to play back one section of video, the timeline indicator frequently jumped to another section of video. Clicking at a specific point to begin playback was practically unusable, seen below. Exacq tells us this is due to their "SpeedSearch" scrubbing feature, which uses I-frames to load video as users scrub through video. In cases of very long GOPs, the client jumps back to the last I-frame, resulting in the jump backwards below.
Exacq also displayed regular gaps in the timeline, shown below. These gaps occurred every 20-40 minutes on all cameras tested. Exacq says that these are not actual gaps in recording, and all video is stored (confirmed in our testing), but this is due to the received framerate dropping below 1 FPS, which the VMS interprets as video loss.
Exacq plans to address both these issues in upcoming releases.
Aside from the errors seen in Exacq, above, all tested VMSes worked properly with Zipstream using Dynamic FPS, including Genetec Security Center, Milestone XProtect, Network Optix, and Axxon Next. No gaps in recorded video or jumpy playback were seen.
We were unable to test Zipstream with Avigilon, as no Axis cameras using new firmware would connect to the VMS, with Zipstream on or off. We will update these results if this issue is remedied.
The following cameras and firmware versions were used in this test:
- Axis Q1615: 18.104.22.168
- Axis Q1635: 22.214.171.124
- Axis M1125: 6.35.2
- Axis P3225-LVE: 6.30.1
The following VMS software versions were used for testing:
- Avigilon Control Center Enterprise: 126.96.36.199
- Axxon Next: 4.1
- ExacqVision Professional: 188.8.131.52464
- Genetec Security Center: 5.3 SR3
- Milestone XProtect Corporate: 2016 R2 (10.1a)
- Network Optix Nx Witness: 184.108.40.20600