I have external device streaming data at fixed sample rate and my GNU Radio source block for this device, which feeds flow graph containing some hardware sink operating at same sample rate (e.g. audio sink). My source-device and that sink-device (e.g. soundcard on PC) aren't synchronized, i.e. they clocked from different sources. So I need to do some kind of auto-resampling to eliminate buffer over/under-runs. (Please correct me, if I use wrong terminology. I'm novice and just trying to specify common DSP task, which I'm sure exists.) The first trouble is that I don't know how to make my block adopt to existing sample rate in graph. GNU Radio scheduler asks my block to produce too large chunks of samples which leads to quick underrun of my block's internal buffer (even 500ms pre-buffering is not enough!). Actually there are no failure, taken data just being moved to somewhere between my block and sink (and everything works well when source and sink are synchronous, I checked). But(!) my block loses prebuffered level which deviations I expected to use as reference for corrections. Hungry scheduler eats all data in buffer. Moreover, his extra attempts leads to extra CPU usage - this is the second trouble. I experimented with inserting thread 'sleep's in work() function and it solves issue but breaks data flow (audio device reports underruns, more or less frequent depending on sleep interval). Please, advice on solution. I would appreciate for just pointing me to right direction.
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