sceAudioPropagationSourceRender takes the system, an array of RenderInfo
descriptors and their count: PPSA21564 and PPSA21567 pass one RenderInfo
{0x010107d6, 0x30} per call, with the source handle at +0x10, its output
buffer at +0x18, the buffer size in bytes at +0x20 and the word 2 at
+0x28, once per audio grain for each propagated source.
Without acoustic propagation a source contributes nothing, so each
output buffer is zeroed for its size. Every RenderInfo is checked first
(descriptor, a live source of this system, a non-empty output), and a
count of 0 or a format word other than 2 throws, as neither has been
observed.