How to set the correct bitrate of 'vpuenc' on MX6Q?

[RobbieJiang]

Hi,

I'm using gst-fsl-plugins to encode and stream live video on MX6Q/Linux-3.0.35 platform.

The input video of 'vpuenc' is 640x480@25fps and the encoding standard is H.264.

In my application scenario,  I'd like to use fixed bitrate (CBR) of vpuenc.

So I need set the 'bitrate' property of 'vpuenc' element to some value, instead of 0.

My question is, how to estimate / set the correct 'bitrate' property of vpuenc?

IMHO, perhaps the input video size, encoding frame rate, and gopsize may affect the required bitrate.

What's the relationship of these properties?

If the bitrate property is set too small, like 5kbps for a 640x480@25fps, what will happen?

Does the 'vpuenc' output the encoded video stream with the bitrate exactly as specified by the 'bitrate' property?

Thanks,

Robbie

[igorpadykov]

Hi Robbie

some details are described in attached i.MX_6_VPU_Application_Programming_

Interface_Linux_Reference_Manual.pdf sect.4.2.3.2 Initiating Picture Encoding.

Yes bitrate may affect video quality and file size, this is described in resources

devoted to video encoding, like below

https://trac.ffmpeg.org/wiki/Encode/H.264

Best regards

igor

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