Cabin Camera
On the A129 IR, the second camera is a seperate unit on a short or long cable (both provided), this allows far more flexibility in the positioning of both the cabin lens and the main lens for a good view from each.
With the B2W, both lenses are attached to the main unit so the main unit needs to be positioned where it can see both forward and backwards. However installation is simpler, just one unit to stick to the glass, no need to run an extra cable or to find a mounting place for the rear camera. Since the lenses are mounted on the bottom of the main unit, the main unit can be hidden behind the rear view mirror if desired, with the lenses hanging just below the mirror so able to see underneath it, the small lenses are then not very visible. Alternatively it can be mounted to the passenger side of the rear view mirror in full view of the passengers as a warning that they are being recorded, it has a reasonably bright LCD screen to make that clear (can be turned off). You might also want to choose the position so that a lens can easily be rotated towards the driver's door to record conversations.
For those that are deciding between a cabin camera and a rear window camera, the advantages of the cabin camera over a rear camera are:
- Can record the driver, giving proof that the driver was driving sensibly and not distracted by texting on a mobile phone etc.
- Records the passengers, giving evidence of their behaviour.
- Records through the windows what is happening behind and to the sides of the car (when not blocked by heads).
- Easier installation - either integrated lenses, or just a short cable so that the camera can be stuck to the rear view mirror or other appropriate location.
The advantage of a rear camera is a much improved view out the back of the vehicle, allowing a greater chance of the number plates of the vehicle behind to be recorded, and possibly the face of the driver.
For many people thinking of installing a rear camera, a cabin camera is a good alternative with much easier installation.
Horizontal Lens Adjustment
The lenses on the B2W rotate horizontally, rotating a lens to point at the driver's window to record an interaction with police/customer/etc is very easy.
The A129 IR does not have any horizontal adjustment, unless you mount it on something adjustable. The rear view mirror is a good place to mount it that can easily be adjusted. The standard mount is for sticking to a flat surface and has no adjustment other than vertical, but it can of course be stuck to an adjustable mount.
Cabin Illumination
Both cameras have 4 infrared LEDs surrounding the lens which provide adequate illumination of the cabin even in complete darkness. Neither produces enough light for a really sharp image, unless the car's cabin lighting is also on, but there is plenty of light to see what is happening.
The B2W uses 940nm IR LEDs which are truly invisible, the A129 IR uses 850nm IR LEDs which have a faint red glow in the dark, which I quite like, maybe a useful reminder to passengers that they should behave, once they have been pointed out and they know what they are. Neither can be seen from outside the car, you need to look directly at the LEDs to see the faint red glow on the A129 IR lamps. When parked, they are bright enough to illuminate the number plate of the car parked behind sufficiently to be read, if it is in view.
For a camera to be able to see the infrared light, the normal IR-cut filter must be removed from the lens. The A129 IR has no IR-cut filter so it always sees IR light. When not using an IR-cut filter, the video is normally recorded in monochrome (Black and White), however the A129 IR does give the option to record the colour view. The colours could potentially be useful evidence, however including the IR light turns a lot of things a pink colour, they no longer look correct to human eyes. The B2W has a mechanical IR-cut filter that can be removed manually or automatically at night, it can record in monochrome at night and in normal colour during daylight.
Video Quality
There is not much difference in image quality. They are both the same resolution and have similar dynamic range. The A129 has slightly more sensitive image sensors and tends to have a slightly brighter image giving a little more detail in the shadows, there is not much difference.
Both cameras can become a little pixelated when at speed under trees, especially on the road surface, the A129 being a little better, but again it is not a big difference.
Both cameras do a decent job at night since they both have Sony Starvis sensors on both exterior and interior lenses. In low light conditions the A129 IR normally has a cleaner and brighter image, although not always.
Only the A129 IR has a CPL filter option to remove windscreen reflections, worth considering if you drive a vehicle with bad windscreen reflections.
Audio Quality
There is decent audio from both cameras, and both do much better than was available on previous generations of dashcam. Both are perfectly adequate for recording conversations within the car, or close to an open window. Volume is little higher on the A129, it seems to pick up external sounds from greater distances and with greater clarity which may be an advantage if there is an argument about what somebody said. The B2W sounds slightly muffled by comparison. It is not a huge difference, but is noticeable.
Resolution
Both cameras have the same resolution - Full HD 1080P 30fps for all lenses, and since the field of view is also similar, number plate readability is approximately the same.
Both cameras can also do 60fps if used as a single channel camera (no rear camera). I'm not sure what this feature is intended for though, if I wanted a single channel camera, I wouldn't buy a dual channel camera!
Bitrate
The bitrate is the amount of image information that is stored on the memory card each second, a higher bitrate means that more information is being stored, file sizes will be larger, and less minutes of video can be stored on the memory card. All video recordings are compressed to save space, the lower the bitrate the more compression is necessary and the more information is thrown away in order to fit the recording into the available bitrate.
At the maximum bitrate setting, the A129 IR has 16Mb/s on both channels. Not enough for perfection, but a perfectly acceptable bitrate for a 1080 resolution dashcam.
The B2W gives a choice of recording at 12Mb/s Front + 12Mb/s Rear or 16Mb/s Front + 8Mb/s Rear. Since most of the view inside the cabin doesn't change much over time, the cabin view doesn't require as much bitrate as the front view so the 16+8 combination gives better detail overall and not far from the detail of the A129 IR.
Even at the 16+12 setting, the B2W does seem to suffer more than the A129 IR from compression artefacts like pixelation when moving quickly under trees, however as a dashcam rather than a movie camera, a bit of pixelation isn't a problem, using the saved bitrate to ensure readable number plates is sensible. When driving in the city, the compression artefacts are always hard to see on both cameras.
Codecs
Both cameras record H264 video stored in a seperate .mp4 file for each view and split into short files of eg. 3 minutes (configurable setting) by the loop recording. Front and cabin files are synchronised so that sections of video are more easily found.
Single channel audio from the internal microphone is recorded in both front and cabin .mp4 files using an AAC codec.
This should make the video files viewable on almost any device, for example - phone | tablet | computer | TV, and at 1080 resolution and 16Mb/s maximum bitrate, it should not need a particularly fast device to play smoothly.
Field of View
The bigger the field of view, the more that can be seen, but also the less detail that can be see in individual objects. A number plate can be read further away with a narrow field of view, but only if it hasn't fallen off the side of the image because of the narrower field of view.
The specifications say: B2W front and cabin = 132°, A129 IR front = 140° and cabin = 160°.
However, that is the field of view of the lenses, not the image, and since they have different sensors the figures are not directly comparable. In reality there is not much difference between them, the rear camera on the A129 IR has a slightly wider field of view than the B2W rear camera, but a small change in positioning of the camera will have a bigger effect on what it can see, and the A129 IR rear camera is more flexible in its positioning since it is seperate to the main camera. The Front cameras have very similar field of view.
Bluetooth
The A129 has an optional Bluetooth remote control which can be mounted in a convenient location on your dashboard or steering wheel, and which locks the current video file and takes a snapshot when pressed.
Both cameras have buttons on the camera for locking the current file, however reaching up behind the rear view mirror to press buttons while driving is not very safe, with the remote control button you can keep your eyes on the road. There is no remote for the B2W, the lock button on the main camera is quite large and easy to find through feel though.
