0803 higher bitrate

[sergjjj]

I changed DVR from F500LH to 0803 and unfortunately saw compression artifacts on 0803, licence plates is unredable.
on F500LHD i have modiflied firmware with higher bitrate (18Mbps instead of 12Mbps), image was clear without artifacts.
It is possible to modifly 0803 Firmware? (i use Procam CX4 Firmware)

 

[reverend]

@Tobi@s wrote this which can change the bitrate of A7 based firmwares:

http://dashcamtalk.com/forum/threads/app-a7tool-0-7-4-ambarella-a2-a7-firmware-tool.6029/unread

 

[sergjjj]

*toostupidtouseA7tool* (

can someone explain?

 

[Tobi@s]

How to Change Bitrate step by step:

Step 1:
File > Load A7 Firmware - select your Firmware.bin

Step 2:
Sections > Export all

Step 3:
Tools > Bitrate Editor

Step 4:
File > Load PRI -- Select the PRI.a7s you gathered by Section Export

Step 5:
Adjust the Bitrate (column 1)

Edit all rows (158 values) (but not the cells with 0.X values)

Tip: Use CTRL + F6 to copy down the value from the cell above

Step 7: Press Apply 🙂

Step 8: Build > Firmware bin

You'll get an a7firmware.bin
Rename it to firmware.bin and copy it onto your sdcard - then Flash it.

 

[sergjjj]

great! thanks

what does Range [min] Range [max] value does? i must set it to 2.0?
what maximum bitrate you try?
ambarella a7 can encode 48 Mrgabits?

 

[Tobi@s]

I'm not 100% sure but I think 48 worked for me. I use 32.0 mbit

Range is for variable bitrates. if you set both values to 2 it's not very variable anymore 😀

 

[Nigel]

Edit all rows (158 values) (but not the cells with 0.X values)

Do you know why there are 158 rows? There can't be that many combinations of resolution/quality settings...

Am I correct in thinking the Range values are fractions of the rate, so the sensible values for fixed rate are 1.0 and 1.0, not 2.0 and 2.0 as in the example which would give a range starting at twice the specified bitrate?

Can you clearly tell the difference in videos using 32.0 mbit instead of the standard rates?

 

[CheckYourLights]

How to Change Bitrate step by step

Thanks been wanting to play with my A7 box but was a little lost as well. This should be a sticky or something.

 

[Tobi@s]

MrSir is going to create a Video tutorial for A7Tool 🙂

 

[mr_milo]

Are there any videos comparing the standard and custom bitrates? Thx

 

[borland]

How does bit rate affect frame rate? Can the frame rate be lowered to give a time lapse affect?

 

[reverend]

The bitrate doesn't change frame rate - you're just making the quality of each frame higher or lower.

There's a point where there's not a massive difference which is around the 12 and 18Mbps most manufacturers use, but it's fantastic with this tool you can tweak it to suit 🙂

 

[sergjjj]

i modifly bitrate from 20 to 40 Mbps, difference is minimal
i disappointed at 0803 model, much more noise than my old F500LHD
Left 0803, Right F500LHD

 

[rtrski]

Are those images zoomed differently, or do the 2 cameras have different fields of regard?

If the cameras have different fields of regard, as appears above, the 0803 on the left appears to be a wider angle...which means fewer pixels per license plate, regardless of framerate, for the same pixel density.

Some decrease in apparent readability would be expected in this situation.

Also looks like you have more 'sky' to the left vs. the right, so exposure differences might also mean you're getting a tad more noise on the plates for the 0803...but I wouldn't expect that to be as severe an effect.

 

[Nigel]

Are those images zoomed differently, or do the 2 cameras have different fields of regard?

The amount of zoom should be the other way around since the 0803 has a higher resolution, maybe it was only in 720 mode?

 

[mr_milo]

Well I gave the bitrate change a try and bricked my 0803. 🙁
I thought I was being smart about it by making a backup of my firmware (original E-Prance w/GPS and No internal) and then modifying that back-up. It seems that something happened during my backup that wasn't good but I didn't realized that until I modded it and wrote it back. 😡
Thanks for the great threads in this forum, I now have it fixed but have lost the original firmware in the process.

 

[Tobi@s]

Can you tell me what you did with a7tool exactly? (step by step)

 

[mr_milo]

It wasn't anything in a7tool that caused the problem it must have been a bad back up.
I went to your webpage and copied the information for the fwbackup under the autoexec hacks section of the 0803 files, then I made my "autoexec.ash" using Notepad++.
I then opened my backed up firmware file in A7tool and edited the bitrate information per your other post, applied it and built the new firmware.
So far so good with no errors anywhere. Then I copied the firmware to the SD and performed the update. Again everything went well and it gave me the firmware updated (or similar) message. I clicked OK and it rebooted but nothing happened. Just a black screen and a blue LED.

After repairing the 0803 I updated the firmware with my un-edited backup and the same thing happened! So it was definitely the backup and not the modifications. I have since installed the E-Prance two card firmware. When I saw it was working OK, I modified it too and updated again. All works good now. Thx