Re: [Discuss-gnuradio] how to implement auto-correction of sample rate in flow graph ?

[Marcus Müller]

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Hi Artem,

your citing that thread of 2010 clearly shows you still didn't get the
problem. Point being: If your source has a different speed than your
sink, you'll need resampling in Software. This has nothing to do with
synchronizing. I won't further elaborate on this.

On 13.12.2013 09:24, Artem Pisarenko wrote:
> I wonder why nobody did it already. Please, comment on.

Because: GNU Radio is still a sample based software radio framework.
You don't want added or removed  samples. As a GR user, you can safely
assume that two samples are always 1/f_sample apart. That is the way
meaningful DSP becomes possible. I don't see any usefulness in your
proposal.

If there are two streams of different sampling clocks to be
synchronized, chances are high you want to have rational resampling
rather than padding/dropping. The latter just wreaks havoc on every
aspect of the signal. Don't do it unless you care for the matching
number of samples in two streams more than for the signal represented.

If your two sampling clocks diverge over time, well that's a hardware
problem that can hardly be solved in software if the error exceeds the
size of default buffers. With usable hardware, this should not happen.

Blocks shouldn't care for their own buffer "fill"; that's the job of
the runtime and GR does this fairly well, to be honest. Your Virtual
machine audio related problem is hardly a proof of shortcomings of
this concept.

Greetings,

Marcus
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