Meter out only a little bit of data at a time.

src/pipeline/ParallelStep.cpp

@@ -240,7 +240,7 @@ std::shared_ptr<short> ParallelStep::execute(std::shared_ptr<short> inputSamples
     
     ThreadInfo* outputTask = threads_[stepToOutput];
 
-    *numOutputSamples = codec2_fifo_used(outputTask->outputFifo);
+    *numOutputSamples = std::min(codec2_fifo_used(outputTask->outputFifo), numInputSamples * outputSampleRate_ / inputSampleRate_);
     codec2_fifo_read(outputTask->outputFifo, outputTask->tempOutput.get(), *numOutputSamples);    
     return outputTask->tempOutput;
 }