ADAPTIVE INTERPOLATION FILTER FOR H.264/AVC Bhavana Prabhakar Student Id: Department of Electrical Engineering

H.264/ Advanced Video Coding [18]

H.264/ADVANCED VIDEO CODING: Encoder block diagram H.264 [18]

H.264/ADVANCED VIDEO CODING: Decoder block diagram H.264 [18]

What is Adaptive Interpolation Filter [AIF] ? Interpolation process of (a) the filter in H.264/AVC, (b) the non-separable AIF, and (c) the separable AIF [16] = m times the sampling rate due to interpolation.

Integer samples (shaded blocks with upper-case letters) and fractional sample positions (non-shaded blocks with lower-case letters). Example for filter size 6 x6. [16]

1. Adaptive interpolation filter, which is independently estimated for every image. The filter coefficients, which are used for the calculation of the half-pel positions, are estimated iteratively using a numerical approach. The quarter-pel positions are calculated using a bilinear filter. [3] 2. 3-D filter- Combining two techniques[4]  2-D spatial filter  Motion compensated interpolation filter (MCIF) The main disadvantage of MCIF is the sensitivity concerning displacement vector estimation errors. Thus, the maximal bit-rate savings could not be achieved in case of quarter-pel motion accuracy.

 The method is nondeterministic in terms of time and requires a significantly higher encoder complexity, i.e., the highest gains cannot be guaranteed given a particular increase of encoder complexity due to its numerical approach.  Besides aliasing, there are further distorting factors, which impair the efficiency of motion compensated prediction.  Motion blur typically occurs in video sequences when the relative motion between the camera and the objects in the scene being captured is faster than the camera exposure time allows.  Further distorting factors, caused by limited amplitude resolution of displacement vectors or by large quantization errors in the reference images, were analyzed in [3].

 In order to guarantee a limited increase of encoder complexity compared to the standard H.264/AVC on the one hand and to reach the theoretical bound for the coding gain obtained by means of a 2-D filter on the other hand, a non-separable filter scheme is proposed. An individual filter shall be used for the interpolation of each fractional-pel position.  For all fractional-pel positions, the filter coefficients are estimated minimizing the prediction error energy, i.e., the squared difference between the original and the predicted image signals.

An individual filter is to be used for the interpolation of each fractional-pel position The estimation of the coefficients and the motion compensation are performed in the steps given in [16] Filter coefficients are to be coded Filter coefficients are subject to quantization, followed by prediction and entropy coding The aliasing effects are minimized by suppressing the high- frequency components Steps to reduce blurring effects. STEPS TAKEN FOR IMPLEMENTATION OF AN AIF

AIF: Adaptive interpolation filter AVC: Advanced video coding BD – ROM: Blue ray disc – read only memory CIF: Common intermediate format HD – DVD: High definition - digital video disc ITU: International telecommunication union KTA: Key technical area MCIF: Motion compensated interpolation filter MPEG: Moving picture experts group VCEG: Video coding experts group

[1] JVT of ISO/IEC & ITU-T, Draft ITU-T Recommendation H.264 and Draft ISO/IEC AVC, Doc JVT-Go50. Pattaya, Thailand, [2] O. Werner, “Drift analysis and drift reduction for multi resolution hybrid video coding”, Signal processing: image commun., vol. 8, no. 5, pp. 387–409, Jul [3] T. Wedi and H. G. Musmann, “Motion and aliasing compensated prediction for hybrid video coding”, IEEE Trans. circuits syst. video technol., vol. 13, no. 7, pp. 577–586, Jul [4] T. Wedi, “Adaptive interpolation filter for motion and aliasing compensated prediction”, in Proc VCIP, San Jose, CA, USA, pp. 415–422, Jan [5] M. Budagavi, “Video compression using blur compensation”, in Proc.IEEE ICIP, Genova, Italy, pp. 882–885, Sep [6] R. E. Crochiere and L. R. Rabiner, “Multi-rate signal processing”, Englewood Cliffs, NJ: Prentice Hall, pp. 88–91, [7] R. W. Schaefer and A. V. Oppenheim, “Discrete-time signal processing”, Englewood Cliffs, NJ: Prentice-Hall, [8] T. Wiegand et al, “Overview of the H.264/AVC video coding standard”, IEEE Trans. circuits syst. video technol., vol. 13, no. 7, pp , Jul [9] Y. Vatis and J. Ostermann, “Locally adaptive non separable interpolation filter for H.264/AVC”, in Proc. IEEE ICIP, Atlanta, GA, pp. 33–36, Oct [10] T.Wedi, “Adaptive interpolation filter for motion compensated prediction”, Proc. IEEE ICIP, Rochester, NY, pp. 509–512, Sep

[11] H.264/AVC reference software version JM Jan [Online]. [12] KTA software, version JM11.0 KTA Mar [Online]. [13] Y. Vatis and J. Ostermann, “Prediction of P- and B-frames using a 2-D non-separable adaptive Wiener interpolation filter”,in ITU-T SG16/Q [15] (VCEG) Doc VCEG-AD08, Hangzhou, China, Oct [14] Y. Vatis and J. Ostermann, ITU-T SG16/Q [15] (VCEG) VCEG-AE16, Marrakech, Morocco, Jan [[15]] S. Wittman and T. Wedi, “Separable adaptive interpolation filter”,in ITU-T SG16/Q6, Doc. C-0219, Geneva, Switzerland, Jul [16] Y. Vatis and J. Ostermann “Adaptive interpolation filter for H.264/AVC”, IEEE Trans. circuits syst. video technol., vol. 19, pp , Feb [17] D. Rusanovskyy, K. Ugur, and J. Lainema, “Adaptive interpolation with directional filters”, in ITU-T SG16/Q.6 Doc. VCEG-AG21, Shenzhen,China, Oct [18] D. Marpe, T. Wiegand and G. J. Sullivan, “The H.264/MPEG-4 AVC standard and its applications”, IEEE Communications Magazine, vol. 44, pp , Aug [19] T. Wiegand and G. J. Sullivan, “The picturephone is here:Really”, IEEE Spectrum, vol.48, pp , Sep [20] I. E. Richardson, “The H.264 Advanced Video Compression Standard”, 2nd Edition, Wiley 2010.