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CBR and Rate Control - SKIP frames

gidi barak
Intellectual 320 points

Hello

 

I have two issues to ask .

1) I am using H.264 Encoder , platinum version for RTP application - video conf .

Parameter rc_Algo=0 means CBR mode .

Question : What are the condition which the RC-rate control will decide to skip frames ? in

which condition it will decide only change the QP ?

I am facing skip frames phenomena when little motion at the picture .Later on an IDR frame

is forced inside the stream .Is it the regular behaviuer of the Encoder ?

Is it better to use the CBR1 mode , i.e.rc_Algo= 5 for better compensating the bit rate ?Like

smoothing the bit rate change on the line .

 

2) If the decoder asked for Intra frame since it's "gets lost" , where should I see this ? at the RTCP or at the SIP  ? 

Any advice will be helpfull

Thanks

Gidi

 

 

 

 

Is is better

 

 

  • 0
    TI__Genius 17215 points

    Hi Gidi,

    1. The encoder decided to do frame skip based on internal VBV buffer level. If the current buffer level is at a level where it cannot code a frame, it will skip it. In case the encoder decides to code a frame, and during course of coding sees the buffer level going very high, it will try to adjust QP. Did you change the value of maxDelay in the encoder parameter ? It directly effects the buffer level of the encoder. Also, what is the frame rate, bitrate and resoultion used for encoding ?

    Details of rc_Algo = 5 is at http://processors.wiki.ti.com/index.php/DM36x_Rate_Control_Modes.

    2. I am not sure about this, this is more to do with the protocol stack. At a codec level, this request from decoder and to travel back to encoder application and the encoder application should call process call with forceIntra or forceIDR.

    regards

    Yashwant