[LAD] Drift compensation document

[Fred Gleason]

On Sep 2, 2017, at 06:26, benravin <ben.alex at outlook.com> wrote:

> If audio sample rate of a radio receiver has to be matched with respect to
> transmitter  radio station audio sample rate, then some timing information
> has to be derived.  But, in case of broadcast digital radio receivers, there
> is no information about the time stamps in the received data as metadata
> information. How to timestamp and do the drift compensation in this
> scenario? 

One approach that I’ve used with good success here is to run the decoded PCM through a FIFO buffer between the SRC and the play-out stages and then use the size of that FIFO (which will change dynamically in response to things like network congestion) to feed a PLL that drives the converter ratio for the SRC stage.  The trade-off for this approach of course is increased latency.  If true low-latency operation is required, then some sort of clocking (ala AES67) will be required.

Cheers!


|----------------------------------------------------------------------|
| Frederick F. Gleason, Jr. |              Chief Developer             |
|                           |              Paravel Systems             |
|----------------------------------------------------------------------|
|          A room without books is like a body without a soul.         |
|                                         -- Cicero                    |
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