[Mp4-tech] JM8.6 H.264 rate control for TMN H.263 codec

[Sandip Ray]

Hi,

I want to add a generic rate control algorithm in H.263 TMN encoder because the available rate control algorithm is not good enough to track bitrate efficiently. I earlier worked on JM8.6 rate control algorithm. I feel it is a generic least mean square based rate control algorithm. Please correct me if I am wrong.

I understand that quantization parameter(QP) has range 0 to 51 in H.264 whereas it is 1 to 31 in H.263. The relation between QP and generated bits per frame are not same in both codecs.  H.263 quantizer uses following algorithm which is different from H.264 quantizer.

if (Mode == MODE_INTRA || Mode == MODE_INTRA_Q) { /* Intra */

qcoeff[0] = mmax(1,mmin(254,coeff[0]/8));

for (i = 1; i < 64; i++) {

level = (abs(coeff[i])) / (2*QP);

qcoeff[i] = mmin(127,mmax(-127,sign(coeff[i]) * level));

}

}

else { /* non Intra */

for (i = 0; i < 64; i++) {

level = (abs(coeff[i])-QP/2) / (2*QP);

qcoeff[i] = mmin(127,mmax(-127,sign(coeff[i]) * level));

}

}

In this scenario, Can I use H.264 rate control algorithm in TMN H.263 encoder ?

I will be grateful for any kind of help or pointers in this regard.

Thanks and Regards,

Sandip


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