Archive for September, 2021

How to perform fast motion search

Saturday, September 25th, 2021

To answer the obvious question with the obvious answer, brute force searching for a decent motion vector takes insanely large time. For example, VP6 motion search area be up to 63×63 pixels and checking all possible positions there requires a lot of tries. And if you remember that VP6 has quarterpel motion compensation precision, you should multiply that number by 16 possible sub-pixel positions. Obviously in order to reduce the number of tries various tricks are employed.

While by itself fast motion search methods I describe here are not that complex, it was rather hard to locate books where such details of developing video encoders are presented. At last I’ve found two or three books with the chapters dedicated to motion compensation plus the papers referenced there. The results of this mini-research are given below.

VP6 — interframe encoder done, what’s next?

Thursday, September 23rd, 2021

I’ve finally finished implementing the rest of the features required for interframes: motion estimation, previous or golden frame selection (along with golden frame itself), four motion vectors per macroblock are finally supported. How I implemented fast motion search deserves a separate post that I hope to write at the weekend, the rest of things should be in this post.

VP6 — simple interframe encoder done

Saturday, September 18th, 2021

As I said in the previous post detailing the roadmap, there’s a lot to do for an interframe encoder. Now I have the basics implemented but there’s a lot more to do.

VP6 — interframe encoder roadmap

Saturday, September 11th, 2021

Before I start working on I’d like to summarise things that should be done for interframe encoding.

VP6 — simple intraframe encoder, part 2

Friday, September 10th, 2021

At last I have a working intraframe VP6 encoder. And the encoded data is decoded fine by the reference decoder as well as by open-source ones. So here I’ll describe what I had to do in order to achieve that result.

VP6 — simple intraframe encoder, part 1

Sunday, September 5th, 2021

I admit that I haven’t spent much time on writing encoder but I still have some progress to report.