Bit rate on Rear Camera different to that of the front

[Demo]

I have the A229 Pro 2 channel.Today I noticed that the bitrate for the front camera video is 59.87Mbit/s but that of the rear is 23.82 Mbit/s. Is this normal? In the menu I have selected Maximum bit rate and there is no option for different bit rates front and rear. This is happening at 2560 x 1440 and also at 2560 x1080 for the rear. I have the latest firmware.

I have put the question to Viofo but thought I would ask here also.

 

[Paulbri]

I have the A229 Pro 2 channel.Today I noticed that the bitrate for the front camera video is 59.87Mbit/s but that of the rear is 23.82 Mbit/s. Is this normal? In the menu I have selected Maximum bit rate and there is no option for different bit rates front and rear. This is happening at 2560 x 1440 and also at 2560 x1080 for the rear. I have the latest firmware.

I have put the question to Viofo but thought I would ask here also.

I'm not an expert but logic dictates that the front camera's bitrate is higher than the rear one because the front camera is 4K and the rear one is 2K. If you change both camera's resolutions to be the same let's say 2K I would assume the bitrate would then be the same. You can test it out yourself.

 

[Nigel]

I have the A229 Pro 2 channel.Today I noticed that the bitrate for the front camera video is 59.87Mbit/s but that of the rear is 23.82 Mbit/s. Is this normal? In the menu I have selected Maximum bit rate and there is no option for different bit rates front and rear. This is happening at 2560 x 1440 and also at 2560 x1080 for the rear. I have the latest firmware.

I have put the question to Viofo but thought I would ask here also.

The front sensor has 2x the pixels of the rear, thus twice the detail, so if recording at 4K front and 2K rear, you would expect the front to have about 2x the bitrate. The front image also tends to be more important, so it does normally get some extra priority on bitrate.

59.87Mbit/s is very high for a front dashcam, it is over 2x the maximum on most 4K dashcams.
23.82 Mbit/s is also very high for a rear dashcam, again about 2x the typical bitrate for a rear dashcam.

This is happening at 2560 x 1440 and also at 2560 x1080 for the rear.

I would expect lower bitrates for the lower resolutions. Saving memory space (via lower bitrate) is the main reason for using a lower resolution, but I think you are just saying that the front bitrate is higher than the rear for each resolution, which is normal, most people want more detail stored for the front than the rear, that is why we only have 2K resolution at the rear while we have 4K at the front.

You could argue that when set to 2K resolution, you should get the same bitrate and resolution from front and rear, at around 30Mb/s @ 2K resolution for both, but the main reason for using the 2K resolution setting is to save memory space, so it would normally be more sensible to halve both front and rear bitrate, and store the front at 2K and the rear at FHD resolution.

 

[Paulbri]

59.87Mbit/s is very high for a front dashcam, it is over 2x the maximum on most 4K dashcams.
23.82 Mbit/s is also very high for a rear dashcam, again about 2x the typical bitrate for a rear dashcam.

OP mentioned he has it set to the Maximum bitrate hence the size.

My A229 Pro 2 CH on Max bitrate is front 49.21Mbit/s rear 22.18Mbit/s (correction as pointed out by Karagandinez my setting was on High not Maximum for these values).

 

[Karagandinez]

My A229 Pro 2 CH on Max bitrate is front 49.21Mbit/s rear 22.18Mbit/s

Read here:

Post in thread 'VIOFO A229 Pro - Testing / Review - RCG'

Sep 26, 2023

Power Consumption Test Data

3-Channel Front + Rear + Interior



2-Channel Front + Rear



2-Channel Front + Interior



1-Channel Front



Summary Of Video Bitrate Data

• rcg530

• 

 

[Paulbri]

@Karagandinez thanks for sharing these charts very helpful (bookmarked) and also answer OP's question that for 2-channel A229 Pro when the bitrate is set to max the front 59.87Mbit/s and rear 23.82 Mbit/s is normal and not double as @Nigel suggested. It only drops to 36.00 Mbit/s for the main 4K camera in a 3-channel mode because it needs to record an additional FHD camera. And my findings are similar although a bit lower for my main camera at 49.21Mbit/s and 22.18Mbit/s for the rear camera.

 

[Demo]

Thanks everyone. The relationship between resolution, bitrate, file size and video quality is something I have yet to wrap my head around. I was curious about this because the video coming from the rear cam is worse than I get from my A119 V3 which is also 2K and at 2560 x 1440 at 30.4 Mb/s

 

[Karagandinez]

And my findings are similar although a bit lower for my main camera at 49.21Mbit/s and 22.18Mbit/s for the rear camera.

So your bitrate is not maximum...
Check the settings in the menu.

 

[Paulbri]

So your bitrate is not maximum...
Check the settings in the menu.

Ah, you are correct. I just checked and indeed I set it to High, not Maximum. Will test it with Maximum on my way home later tonight but I'm pretty sure it will be closer to 59.80 Mbit/s. @Karagandinez I was just testing your knowledge

 

[Nigel]

Thanks everyone. The relationship between resolution, bitrate, file size and video quality is something I have yet to wrap my head around.

Resolution is the number of pixels (dots of colour/brightness) that make up the image, effectively this is the image size.
Bitrate is the amount of data (detail) stored per second, more bitrate = more detail.
File size = bitrate * number of seconds. (normally divided by 8 due to the conversion from bits to bytes.)
Image quality = resolution/bitrate. The number of bits per pixel, so if you have higher resolution (more pixels), then to keep the same image quality you need higher bitrate. 4K has 4x more pixels than FHD, so needs 4x more bitrate for the same image quality, remember resolution is image size, not image quality.

You might think that resolution defines the amount of detail, but due to image compression, it does not. Resolution does set a maximum detail, but the actual detail is controlled by the bitrate.

There is also frame rate (fps / frames per second), this doesn't have much effect on the above, except that increasing the frame rate requires extra bitrate to store the increased temporal resolution, so increased frame rate generally means less image quality, unless there is a sufficient increase in bitrate to match the increase in frame rate, which normally there isn't.

I was curious about this because the video coming from the rear cam is worse than I get from my A119 V3 which is also 2K and at 2560 x 1440 at 30.4 Mb/s

Yes, the V3 has more bitrate, so more image quality, although the V3 sensor does not have as much dynamic range, does not have DOL-HDR, and has less sensitivity, resulting in more motion blur, over exposed highlights (number plates at night), and less ability to read fast moving number plates at night. The A229 rear camera is a smaller camera, with smaller lens, without CPL, which does affect image quality. The A229 rear is really the better dashcam, even if it does have less image quality.

 

[Karagandinez]

Yes, the V3 has more bitrate, so more image quality, although the V3 sensor does not have as much dynamic range, does not have DOL-HDR, and has less sensitivity, resulting in more motion blur, over exposed highlights (number plates at night), and less ability to read fast moving number plates at night.

V3 reads oncoming car numbers normally at night.

Post in thread 'Best v3 settings'

Mar 26, 2022

V2.6T_(20211203)_HDR_Auto
2560x1080
High bitrate
HDR_Auto (Day=Off, Night=On)
EV=-1,3
30fps

Spoiler: Day

Spoiler: Night

• Karagandinez

• 

 

[rcg530]

@Karagandinez thanks for sharing these charts very helpful (bookmarked) and also answer OP's question that for 2-channel A229 Pro when the bitrate is set to max the front 59.87Mbit/s and rear 23.82 Mbit/s is normal and not double as @Nigel suggested. It only drops to 36.00 Mbit/s for the main 4K camera in a 3-channel mode because it needs to record an additional FHD camera. And my findings are similar although a bit lower for my main camera at 49.21Mbit/s and 22.18Mbit/s for the rear camera.

Those charts are from my review of the A229 Pro dash camera.

Thread 'VIOFO A229 Pro - Testing / Review - RCG'

Sep 26, 2023

On Tuesday 26-Sep-2023, I was given permission from VIOFO to start posting info about the A229 Pro / A229 Plus dash cameras. I have not started my testing of the A229 Plus dash camera yet since it is scheduled to arrive later today.

A229 Pro Unboxing

The VIOFO A229 Pro will be sold in two configurations. A three channel configuration with front, rear and interior cameras and a two channel configuration with a front and rear camera. I was provided a 3-channel A229 Pro dash camera by VIOFO free of charge for my testing / review. I should also receive an A229 Plus dash camera from...

• rcg530
• Replies: 174
• Forum: A229 Pro

• 

With the early versions of the A229 Pro firmware installed, the front camera bitrate was only 36.0 Mbps when in a 2-channel (front+rear) configuration. VIOFO upped the front camera video bitrate to 59.8 Mbps starting with the v1.0_230915 firmware in the same two channel configuration.

 

[Paulbri]

Those charts are from my review of the A229 Pro dash camera.

Thanks @rcg530 for making those charts very helpful.

With the early versions of the A229 Pro firmware installed, the front camera bitrate was only 36.0 Mbps when in a 2-channel (front+rear) configuration. VIOFO upped the front camera video bitrate to 59.8 Mbps starting with the v1.0_230915 firmware in the same two channel configuration.

I see, maybe that's why @Nigel said it's 2x the bitrate but he mentioned 2x the maximum on most 4K dashcams.

I wouldn't say the quality of the video doubled for me going from 36.0 Mbps to 59.8 at maximum bitrate. Do you think is worth the extra space it takes up on the max bit rate?
I can see from your dashcam list you have used a few. How is A229 Pro's video quality compares to others especially at double the bitrate of A229?

Thanks

 

[Nigel]

I wouldn't say the quality of the video doubled for me going from 36.0 Mbps to 59.8 at maximum bitrate. Do you think is worth the extra space it takes up on the max bit rate?

If you are driving slowly then it doesn't need that much bitrate, when parked, low bitrate parking mode is perfectly good quality with only 6 Mb/s, but when going fast under trees, it does use it all and you will get nearly double the quality. For slower speeds, it is worth using the higher bitrates if you are going to be editing the video into movies, the extra quality does allow some adjustments in brightness etc. without imperfections becoming visible, but if used as only an accident camera, you don't need all the quality, and for city driving only, you can turn the bitrate down.