i.MX ProcessorsのトピックRe: H.264 VBR Encoding in i.MX6

H.264 VBR Encoding in i.MX6

ko-hey — Fri, 21 Oct 2016 07:07:34 GMT

Hi all

I have a question about i.MX6 VPU API in L4.1.15.
Specifically, I want to test H.264 VBR encoding which has bitrate limitation in i.MX6.

I set following parameters but it shows no change.

・userQpMin
・userQpMax
・bitRate
・userQpMinEnable

Also following thread said i.MX6 doesn't support useQPMin paratemer, too.
https://community.nxp.com/thread/391632

Is the above thread correct ?

furthermore, if someone know the other method to achieve H.264 VBR encoding with bitrate limitation, please tell me how to do.

Ko-hey

Re: H.264 VBR Encoding in i.MX6

ko-hey — Wed, 26 Oct 2016 02:04:34 GMT

Could someone follow this thread and reply the question ?

Ko-hey

Re: H.264 VBR Encoding in i.MX6

joanxie — Thu, 27 Oct 2016 09:09:46 GMT

As I known, if you want to test VBR, bitrate should set to 0, and you should set quant number, refer to the vpu api document, quantParam is used for all quantization parameters with VBR (no rate control). The range of value is 1-31 for MPEG-4 and 0-51 for H.264. When rate control is enabled, this field is ignored.

Re: H.264 VBR Encoding in i.MX6

ko-hey — Fri, 28 Oct 2016 02:12:00 GMT

Thank you for reply.

I tried set to a quantParam and understood that it can use for test VBR in static.

However, automatically (dynamically) changing a QP is my purpose of using userQpMin and userQpMax.

So it doesn't suit for me.

Do you have any idea that doing dynamically bitrate limitation in i.MX6 ?

Ko-hey

Re: H.264 VBR Encoding in i.MX6

joanxie — Fri, 28 Oct 2016 08:15:41 GMT

what do you mean that doing dynamically bitrate limitation? you want to set bitrate on the fly or no bitrate control?

Re: H.264 VBR Encoding in i.MX6

ko-hey — Mon, 31 Oct 2016 01:30:40 GMT

Sorry for Insufficient description.

When user set quantParam, the bitrate becomes a specific value.

This means that anytime same bitrate.

However, when user use userQpMin and userQpMax parameter, the bitrate becomes various value.

I said that is dynamically.

Could you understand my meaning ?

Ko-hey