I've completed my contribution. It modifies several GNU Radio in-tree packages.
Expectations: As described here: http://gnuradio.4.n7.nabble.com/how-to-implement-auto-correction-of-sample-rate-in-flow-graph-tp45268p45337.html with difference about correction method (see result). - sources and sinks interface enchancement, they provide output of their current buffer measurements (consists of relative buffer filling and maybe some other metadata) via asynchronous message port "sync_out". - addition of special resampler block, it accepts messages at its "sync_in" port and performs auto-correction of resampler ratio. Block configuration is well-defined, operation is indpendent of graph structure, hardware, data stream dynamic and jitter, etc. Result: Due to lack of my knowledge in some areas and disappointing gnu radio limitations, I wasn't able to make it properly and resulted in limited implementation. Also I've used fractional resampler block as base for design, so correction performed properly (instead of "blind" adding/deleting samples, as supposed to be initially). Implementation has bad performance characteristics and obscure configuration (some parameters are determined experimentally), but it works. I modified audio sink block from gr-audio (only alsa implementation) as example of hardware block implementing required interface. See attached GRC graph as an example of usage. It implements audio loopback and therefore doesn't introduce real sample rate skew, it just shows how it works. No critics about design accepted. (I asked for help beforehand, nobody advised.) Patch for GNU Radio tree <http://gnuradio.4.n7.nabble.com/file/n45723/gnuradio_feature__auto_correction_of_sample_rate.patch> Example graph <http://gnuradio.4.n7.nabble.com/file/n45723/test_auto_sample_rate.grc> -- View this message in context: http://gnuradio.4.n7.nabble.com/how-to-implement-auto-correction-of-sample-rate-in-flow-graph-tp45268p45723.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
