How to set constant bitrate??

[Lorenzo88]

Hello guys,

I got honeslty lost reading all the threads and didn't find the answer i was looking for, so im just gonna ask here

I was wondering if its possible to get a constant bitrate at 40 and 50mbps. I'm currently testing both bitrates and i see that the bitrate is never constant on the video, e.g when i set 50mbps via script results are usally 42/45/46mbps

My script only has mbps increase and noise reduction:

#fullHD 60 fps 35 Mbps
#writew 0xC05C1EE2 0x420C

#fullHD 60 fps 40 Mbps
#writew 0xC05C1EE2 0x4220

#fullHD 60 fps 50 Mbps
#writew 0xC05C1EE2 0x4248

#de-noise values between 0-16383 (0x0000-0x3FFF)
t ia2 -adj tidx -1 500 -1

How can i make each bitrate to be constant??

Thanks in advance.

 

[palarran]

Why do you want constant bitrate? Usually CBR is not an optimal choice... Because you have a worst quality when you have a complex section while you waste data on simple sections....

 

[gente]

How can i make each bitrate to be constant??

...you can change the bitrate table in firmware setting all required bitrates to "1" for CBR.

 

[Lorenzo88]

Why do you want constant bitrate? Usually CBR is not an optimal choice... Because you have a worst quality when you have a complex section while you waste data on simple sections....

So if i understand right, if the camera is set to 40mbps i'll get an higher bitrate recording for instance a scenario full of details then a room with black walls and just me in the middle??

 

[gente]

So if i understand right, if the camera is set to 40mbps i'll get an higher bitrate recording for instance a scenario full of details then a room with black walls and just me in the middle??

"What is the difference between CBR and VBR encoding?
Constant bit rate (CBR) encoding persists the set data rate to your setting over the whole video clip. Use CBR only if your clip contains a similar motion level across the entire duration. CBR is most commonly used for streaming video content using the Flash Media Server (rtmp)

Variable bit rate (VBR) encoding adjusts the data rate down and to the upper limit you set, based on the data required by the compressor. VBR takes longer to encode but produces the most favorable results. VBR is most commonly used for http delivery if video content (http progressive)

We recommend you do not use CBR unless you have a specific need for playback on a device that only supports CBR. Our default VRB mode will produce higher quality at competitive bitrates."

look here: https://en.wikipedia.org/wiki/Variable_bitrate

 

[Lorenzo88]

"What is the difference between CBR and VBR encoding?
Constant bit rate (CBR) encoding persists the set data rate to your setting over the whole video clip. Use CBR only if your clip contains a similar motion level across the entire duration. CBR is most commonly used for streaming video content using the Flash Media Server (rtmp)

Variable bit rate (VBR) encoding adjusts the data rate down and to the upper limit you set, based on the data required by the compressor. VBR takes longer to encode but produces the most favorable results. VBR is most commonly used for http delivery if video content (http progressive)

We recommend you do not use CBR unless you have a specific need for playback on a device that only supports CBR. Our default VRB mode will produce higher quality at competitive bitrates."

look here: https://en.wikipedia.org/wiki/Variable_bitrate

Thats some good info right there, thanks mate!!

So in case i want to use CBR can i do that through scripts or i necessarily have to use a custom firmware??

I'm absolutely unfamiliar with custom fw...dho