Blogging Theora

[xiphmont]

It's time for the latest Thusnelda encoder project update summary!

Although I haven't gotten much time to dive back into Thusnelda coding myself, Tim Terriberry, Greg Maxwell and others have continued the work along at a merry pace. In the past few weeks, they've finally replaced the leaky fDCT from the original VP3 and begun work on adjusting the main quantization matrices and, hopefully soon, adaptive quantization. These improvements all improve fine detail rendering and, somewhat unexpectedly, improve gradient rendering as well:

The screen caps above were produced by Theora 1.0 on the left and an experimental version of Thusnelda with early quant matrix optimization work in addition to the new fDCT on the right. Both clips were encoded in constant-quantizer mode and equal bitrates.

Other improvements, more details and the full update report here.

Comments

Re: Problem with older ffmpeg, not ffmpeg2theora

[(Anonymous)]

Sorry for the spam, I got this wrong. The iDCT the decoder uses is unchanged, the one the encoder uses (the forward one) is the one that has been changed - in fact, to match more closely the inverse one.