Roon 1.3 (Build 216)、PCM 768kHz・DSD512へのアップコンバートに対応

Roon 1.3 (Build 216) Is Live! - Roon Labs

New DSP Functionality
The DSP functionality we are releasing today closes up a lot of loose ends that didn’t quite make it into 1.3, and also addresses some feedback that we’ve received since.
・Support for DSD512 and 768kHz output for devices that support it.
・Support for processing DSD content natively without performing a PCM conversion. This will be turned on by default, but can be disabled if needed.
・A setting that allows for signal paths performing DSD output to use multiple cores for processing. This comes with a small efficiency tradeoff, but it makes high rate DSD output practical on some systems where it otherwise wouldn’t be.
・Significant performance optimizations to the sample rate converters and sigma-delta modulators (needed to make DSD512 practical).
・New SDM filter options, developed using the CLANS (closed loop analysis of noise shapers) method.
・New SRC filter choices: Smooth vs Precise filters. The Precise filters are steeper than the old ones, but designed around similar goals. The Smooth filters are ultra-slow-roll-off filters optimized for a very clean transient response. “Precise, Minimum Phase” is the new default.
・The default DSD output gain adjustment is now 0dB--we do not believe that this will cause stability issues. If you ever touched this setting, your chosen value will be preserved, but for people who never interacted with it, the new default will be used. The default of -3dB caused an offset between PCM and DSD when using volume leveling in conjunction with the (enabled by default) DSD processing capabilities, which is not acceptable behavior.

　1.3当初のPCM 384kHz・DSD256に続き、PCM 768kHz・DSD512出力にも対応。
　

　こんなにも早くSonica DACのフルスペックを使い切ることになるとは……

　

　DSDとPCMのレートに加えて、諸々の設定の種類も増えている。

　

　で、DSD512で再生を始めたら……

　10秒程度で再生が不安定になり、止まり、この通り。

　上のシグナルパスをよくよく見ると、「Processing speed」が1.0を下回っているので、やはり処理が追いついていなかったようだ。
　そこで「Parallelize Sigma-Delta Modulator」を「Yes」にすると、「Processing speed」が1.6x前後になり、再生が安定した。