Feedback object delay

Tony Question

Jul 6, 2010 00:00

Two quick questions:

1) Is the feedback object simply adding 1 sample delay or more?

2) How is the block to block delay management handled by the compiler? Is there a fixed delay added to the audio path for each block? (e.g. arbitrary value) We're doing some filtering which requires us very precise understanding of that concept as we're delaying down to the sample and mixing signals. In Sharc, we'd know exactly what's going on, but here, we're quire lost as to how the delay/time alignment is managed within the structure. E.g See the attached file showing 2 paths from a same source and being mixed together. Obviously that's not what we're doing, but the concept is similar. One path has one extra block (Parametric), does this mean that samples from that path will be delayed when mixed or the compiler is smart enough to add delay to the path?

If the compiler doesn't take care of it, then I guess that our only way would be having symetrical path before mixing signals from a same source..

Got my gist?

Thanks for your support.

Report

ADIApproved Reply

Jul 6, 2010 00:00

The feedback cell will add a 1-sample delay into the signal path and is also used by the compiler to properly recognize feedback paths. Without this block, SigmaStudio cannot compile a design with a feedback path.

Some blocks will introduce a delay into the signal path, but only as expected. What I mean is that blocks such as delays (obviously) and IIR filters, which use a feedback path in the algorithm, will delay the signal from input to output. Functions like mixing two signals together should not introduce any additional latency from input to output. The compiler will not add delays to a path to match the latency of another signal path. In your example, if you want the two paths to have identical latency, then you should add a delay block in the unfiltered path.