Bitrate, resolution and color depth - who knows?

[HeePee]

I've a Mio Mivue 618 dash cam. However, this question applies to any type of dash cam.

On the Mivue 618 dash cam, both the 1080p and 1296p resolution use the same bitrate of 15 mbps.

Looking at the recorded video files, the 1080p has a much more clear picture with more details, although the resolution is lower than the 1296p.

Question: Is this because the 1296p has less color depth?
After all, they both use a bitrate of 15 mbps. But as 1296p has more pixels than 1080p, the bits per pixel have to be less for 1296p. They use the same bitrate (and therefore same file size), so, something has to go, right? As the bits per pixel stand for the color depth, it would explain why 1080p is more clear and ''sharper''. Sharper as in, 'you can distinguish details much better'. Because with more colors per pixel, there's more to show. And I suspect that (because of the same bitrate), the 1026p video has a much lower color depth than the 1080p video.

Is this a right conclusion??

Cheers.

 

[Zardoz66]

I found this:


https://dashcamtalk.com/forum/bookmarks/?type=post&id=244461

 

[jokiin]

you can't have 30% bigger picture at the same bitrate and get the same result

 

[HeePee]

Thanks, seen that. But it doesn't say anything about color depth as an explanation of 1080p having a better picture. I was wondering if that is the case.

 

[HeePee]

you can't have 30% bigger picture at the same bitrate and get the same result

I know. So, what makes (in this case with the same bitrate) the 1080p picture better than the 1296p picture? Is that indeed due to the color depth (higher for 1080p)?

 

[jokiin]

I know. So, what makes (in this case with the same bitrate) the 1080p picture better than the 1296p picture? Is that indeed due to the color depth (higher for 1080p)?

technically it's the same as having a higher bitrate when used at 1080p, not to do with colour depth, just bitrate

 

[thancam]

I've a Mio Mivue 618 dash cam. However, this question applies to any type of dash cam.

On the Mivue 618 dash cam, both the 1080p and 1296p resolution use the same bitrate of 15 mbps.

Looking at the recorded video files, the 1080p has a much more clear picture with more details, although the resolution is lower than the 1296p.

Question: Is this because the 1296p has less color depth?
After all, they both use a bitrate of 15 mbps. But as 1296p has more pixels than 1080p, the bits per pixel have to be less for 1296p. They use the same bitrate (and therefore same file size), so, something has to go, right? As the bits per pixel stand for the color depth, it would explain why 1080p is more clear and ''sharper''. Sharper as in, 'you can distinguish details much better'. Because with more colors per pixel, there's more to show. And I suspect that (because of the same bitrate), the 1026p video has a much lower color depth than the 1080p video.

Is this a right conclusion??

Cheers.

At 1296p, they split a pixel into 2 or 3 pixels and they are the same with the orginal one. So, if birate in 2 cases are the same: mean something missing in 1296p.
1296p is the way they made for advertisement, not something's useful.

 

[HeePee]

@thancam. Thanks! So, knowing that the bitrate (15 mbps) for 1080p and 1296p is the same on this Mio Mivue 618, would you recommend to set the dash cam to record in 1080p?

 

[jokiin]

At 1296p, they split a pixel into 2 or 3 pixels and they are the same with the orginal one. So, if birate in 2 cases are the same: mean something missing in 1296p.
1296p is the way they made for advertisement, not something's useful.

depends what sensor and chipset they are using and if it's interpolated or the different resolutions are cropped, sensor supports this resolution, not sure if the chipset does though

 

[HeePee]

depends what sensor and chipset they are using and if it's interpolated or the different resolutions are cropped, sensor supports this resolution, not sure if the chipset does though

It's a AR0330 CMOS and an AIT8428 processor. 1296 is a supported resolution.

 

[jokiin]

It's a AR0330 CMOS and an AIT8428 processor. 1296 is a supported resolution.

yes sensor supports it, no idea if the chipset supports this res natively or if it's interpolated, even if it's native if there is no corresponding increase in bitrate then the 1080p results will most often look better

 

[Zardoz66]

yeah but at the but the same bitrate is going to look worse at the higher res 1296p then the 1080p. higher resolution is not always better if you don't have the bitrate to support it.

 

[thancam]

@thancam. Thanks! So, knowing that the bitrate (15 mbps) for 1080p and 1296p is the same on this Mio Mivue 618, would you recommend to set the dash cam to record in 1080p?

you should set the resolution you think/feel it's best. Trust in eyes and details of image. Dont trust in information which manufacturer give. The image says itself.

 

[Nigel]

I've a Mio Mivue 618 dash cam. However, this question applies to any type of dash cam.

On the Mivue 618 dash cam, both the 1080p and 1296p resolution use the same bitrate of 15 mbps.

Looking at the recorded video files, the 1080p has a much more clear picture with more details, although the resolution is lower than the 1296p.

Question: Is this because the 1296p has less color depth?
After all, they both use a bitrate of 15 mbps. But as 1296p has more pixels than 1080p, the bits per pixel have to be less for 1296p. They use the same bitrate (and therefore same file size), so, something has to go, right? As the bits per pixel stand for the color depth, it would explain why 1080p is more clear and ''sharper''. Sharper as in, 'you can distinguish details much better'. Because with more colors per pixel, there's more to show. And I suspect that (because of the same bitrate), the 1026p video has a much lower color depth than the 1080p video.

Is this a right conclusion??

Cheers.

I don't think it will be anything to do with colour depth, probably both modes are 10bit from the sensor and 8bit in the H264 compressed file.

With the same bitrate there should be the same amount of detail in the image overall, however the processor will not be powerful enough or have enough time to do a good job of the compression so to fit the whole 1296 image into the same space as 1080 it has to choose something to throw away rather than compress to make space for the extra pixels, colour information is one of the easiest things to throw away and human eyes are less sensitive to colour than contrast so colour is also the best thing to throw away first.

I have never seen a good quality 1296p image from the AR0330, not sure if the sensor is at fault or if it is because it is always paired with cheap processors, it is OK at 1080 but is getting a bit old now, there are much better sensors available these days.

15mbps is a little low for 1080 even with current processors, for 1296 30fps you want more like 24mbps for a high quality video with H264.

 

[HeePee]

Thanks guys, for all the answers. Really appreciated. There's so much new stuff to learn.

BTW, I saw an original 1440p/30fps footage (downloaded, not youtube) of the Viofo A119. Unbelievable, the video quality is amazing. What a huge difference with the dash cam I have today. I already know what my next dash cam is going to be

 

[thancam]

Thanks guys, for all the answers. Really appreciated. There's so much new stuff to learn.

BTW, I saw an original 1440p/30fps footage (downloaded, not youtube) of the Viofo A119. Unbelievable, the video quality is amazing. What a huge difference with the dash cam I have today. I already know what my next dash cam is going to be

wait until SG663DC going to release next month then decide later Many ppl in here waiting for that

 

[Zardoz66]

Thanks guys, for all the answers. Really appreciated. There's so much new stuff to learn.

BTW, I saw an original 1440p/30fps footage (downloaded, not youtube) of the Viofo A119. Unbelievable, the video quality is amazing. What a huge difference with the dash cam I have today. I already know what my next dash cam is going to be

I just got my A119 about a week ago. its amazing for the price. dont know much about the SG663DC yet, but ig you are in the market A119 still not a bad option at all IMO...

 

[HeePee]

For those interested; As a follow up, I downloaded MediaInfo from https://mediaarea.net/en/MediaInfo.
It's software that gives in-depth detail about the (encoding) specs of a video. The software is available for both Windows and Mac.

Except for the resolution (of course), the video info for the 1296p and 1080p recorded video file are exactly the same (yes, including bit rate and bit depth).

The only difference of all the specs (and there were a lot) is:

1080p - Bits/(Pixel*Frame) : 0.234
1296p - Bits/(Pixel*Frame) : 0.164

Now, I don't know exactly what this is.

a) Can someone explain?
b) What's better 0.234 or 0.164?

Thanks!


PS:
Here the full detail (there are some small differences in the audio):


1080P

--------


Format : MPEG-4

Format profile : QuickTime

Codec ID : qt 0000.02 (qt )

File size : 528 MiB

Duration : 5mn 0s

Overall bit rate : 14.8 Mbps


Video

ID : 1

Format : AVC

Format/Info : Advanced Video Codec

Format profile : Baseline@L4

Format settings, CABAC : No

Format settings, ReFrames : 1 frame

Format settings, GOP : M=1, N=15

Codec ID : avc1

Codec ID/Info : Advanced Video Coding

Duration : 5mn 0s

Bit rate : 14.5 Mbps

Width : 1 920 pixels

Height : 1 080 pixels

Display aspect ratio : 16:9

Frame rate mode : Constant

Frame rate : 29.918 fps

Color space : YUV

Chroma subsampling : 4:2:0

Bit depth : 8 bits

Scan type : Progressive

Bits/(Pixel*Frame) : 0.234

Stream size : 519 MiB (98%)

Language : English


Audio

ID : 2

Format : ADPCM

Codec ID : 11

Codec ID/Hint : Intel

Duration : 5mn 0s

Bit rate mode : Constant

Bit rate : 272 Kbps

Channel(s) : 2 channels

Channel positions : Front: L R

Sampling rate : 32.0 KHz

Stream size : 9.73 MiB (2%)

Language : English


1296P

--------


Format : MPEG-4

Format profile : QuickTime

Codec ID : qt 0000.02 (qt )

File size : 528 MiB

Duration : 5mn 0s

Overall bit rate : 14.8 Mbps


Video

ID : 1

Format : AVC

Format/Info : Advanced Video Codec

Format profile : Baseline@L4

Format settings, CABAC : No

Format settings, ReFrames : 1 frame

Format settings, GOP : M=1, N=15

Codec ID : avc1

Codec ID/Info : Advanced Video Coding

Duration : 5mn 0s

Bit rate : 14.5 Mbps

Width : 2 304 pixels

Height : 1 296 pixels

Display aspect ratio : 16:9

Frame rate mode : Constant

Frame rate : 29.918 fps

Color space : YUV

Chroma subsampling : 4:2:0

Bit depth : 8 bits

Scan type : Progressive

Bits/(Pixel*Frame) : 0.162

Stream size : 519 MiB (98%)

Language : English


Audio

ID : 2

Format : ADPCM

Codec ID : 11

Codec ID/Hint : Intel

Duration : 5mn 0s

Source duration : 5mn 0s

Bit rate mode : Constant

Bit rate : 256 Kbps

Nominal bit rate : 272 Kbps

Channel(s) : 2 channels

Channel positions : Front: L R

Sampling rate : 32.0 KHz

Stream size : 9.16 MiB (2%)

Source stream size : 9.73 MiB (2%)

Language : English

 

[flip9]

The only difference of all the specs (and there were a lot) is:

1080p - Bits/(Pixel*Frame) : 0.234
1296p - Bits/(Pixel*Frame) : 0.164

Now, I don't know exactly what this is.

a) Can someone explain?
b) What's better 0.234 or 0.164?

Its just the density. If you packed 15mbps of data into 1080p it will be denser compared to 1296p.

 

[Nigel]

Its just the density. If you packed 15mbps of data into 1080p it will be denser compared to 1296p.

It is still the same density per degree of field of view, assuming both resolutions use the same field of view which is quite often not the case.

15mb/s of information is 15mb/s of information, the difference is only in how it is used, a trade off between resolution and pixel quality.