ulc-codec Demonstration 20210821

Many milestones were surpassed between this posting and the last, and quality has improved on all fronts. Higher bitrate (96kbps, 128kbps) demos of this song and others are available on GitHub.

Because of the GBA's 8bit audio DAC, I had to perform a lot of equalization to get the track to sound right. After listening to it a lot more and comparing to the original, I realized I wasn't doing it justice and started the equalization process from scratch; sounds a lot closer to the original now. May have gone overboard on the bass, though...

Hadn't intended to update on here any further, but made a major breakthrough in quality. Additionally, new interface should look more slick.

Quality improvements from new a quantizer selection strategy. Not all /that/ noticeable in this demo (especially from an integer DCT), but more high-frequency bands are kept now, making things sound 'clearer'.

• Fixed a bug that might've caused audio glitching when Timer1 interrupt was interrupted by VBlank interrupt
• Minor improvements to quantizer optimization in encoder
• Micro-optimizations in DCT-II/DCT-IV routines