diff --git a/spa/include/spa/node/io.h b/spa/include/spa/node/io.h
index a0433a09e..c1c725ebf 100644
--- a/spa/include/spa/node/io.h
+++ b/spa/include/spa/node/io.h
@@ -305,14 +305,50 @@ struct spa_io_position {
 	struct spa_io_segment segments[SPA_IO_POSITION_MAX_SEGMENTS];	/**< segments */
 };
 
-/** rate matching */
+/**
+ * Rate matching.
+ *
+ * It is usually set on the nodes that process resampled data, by
+ * the component (audioadapter) that handles resampling between graph
+ * and node rates. The \a flags and \a rate fields may be modified by the node.
+ *
+ * The node can request a correction to the resampling rate in its process(), by setting
+ * \ref SPA_IO_RATE_MATCH_ACTIVE on \a flags, and setting \a rate to the desired rate
+ * correction.  Usually the rate is obtained from DLL or other adaptive mechanism that
+ * e.g. drives the node buffer fill level toward a specific value.
+ *
+ * When resampling to (graph->node) direction, the number of samples produced
+ * by the resampler varies on each cycle, as the rates are not commensurate.
+ *
+ * When resampling to (node->graph) direction, the number of samples consumed by the
+ * resampler varies. Node output ports in process() should produce \a size number of
+ * samples to match what the resampler needs to produce one graph quantum of output
+ * samples.
+ *
+ * Resampling filters introduce processing delay, given by \a delay and \a delay_frac, in
+ * samples at node rate. The delay varies on each cycle e.g. when resampling between
+ * noncommensurate rates.
+ *
+ * The first sample output (graph->node) or consumed (node->graph) by the resampler is
+ * offset by \a delay + \a delay_frac / 1e9 node samples relative to the nominal graph
+ * cycle start position:
+ *
+ * \code{.unparsed}
+ * first_resampled_sample_nsec =
+ *	first_original_sample_nsec
+ *	- (rate_match->delay * SPA_NSEC_PER_SEC + rate_match->delay_frac) / node_rate
+ * \endcode
+ */
 struct spa_io_rate_match {
-	uint32_t delay;			/**< extra delay in samples for resampler */
+	uint32_t delay;			/**< resampling delay, in samples at
+					 * node rate */
 	uint32_t size;			/**< requested input size for resampler */
-	double rate;			/**< rate for resampler */
+	double rate;			/**< rate for resampler (set by node) */
 #define SPA_IO_RATE_MATCH_FLAG_ACTIVE	(1 << 0)
-	uint32_t flags;			/**< extra flags */
-	uint32_t padding[7];
+	uint32_t flags;			/**< extra flags (set by node) */
+	int32_t delay_frac;		/**< resampling delay fractional part,
+					 * in units of nanosamples (1/10^9 sample) at node rate */
+	uint32_t padding[6];
 };
 
 /** async buffers */
diff --git a/spa/plugins/audioconvert/audioconvert.c b/spa/plugins/audioconvert/audioconvert.c
index e0deefe31..056d5eafd 100644
--- a/spa/plugins/audioconvert/audioconvert.c
+++ b/spa/plugins/audioconvert/audioconvert.c
@@ -2162,23 +2162,30 @@ static int ensure_tmp(struct impl *this, uint32_t maxsize, uint32_t maxports)
 static uint32_t resample_update_rate_match(struct impl *this, bool passthrough, uint32_t size, uint32_t queued)
 {
 	uint32_t delay, match_size;
+	int32_t delay_frac;
 
 	if (passthrough) {
 		delay = 0;
+		delay_frac = 0;
 		match_size = size;
 	} else {
 		double rate = this->rate_scale / this->props.rate;
+		double fdelay;
+
 		if (this->io_rate_match &&
 		    SPA_FLAG_IS_SET(this->io_rate_match->flags, SPA_IO_RATE_MATCH_FLAG_ACTIVE))
 			rate *= this->io_rate_match->rate;
 		resample_update_rate(&this->resample, rate);
-		delay = resample_delay(&this->resample);
+		fdelay = resample_delay(&this->resample) + resample_phase(&this->resample);
 		if (this->direction == SPA_DIRECTION_INPUT) {
 			match_size = resample_in_len(&this->resample, size);
 		} else {
+			fdelay *= rate * this->resample.o_rate / this->resample.i_rate;
 			match_size = resample_out_len(&this->resample, size);
-			delay = resample_out_len(&this->resample, delay);
 		}
+
+		delay = (uint32_t)round(fdelay);
+		delay_frac = (int32_t)((fdelay - delay) * 1e9);
 	}
 	match_size -= SPA_MIN(match_size, queued);
 
@@ -2186,6 +2193,7 @@ static uint32_t resample_update_rate_match(struct impl *this, bool passthrough,
 
 	if (this->io_rate_match) {
 		this->io_rate_match->delay = delay + queued;
+		this->io_rate_match->delay_frac = delay_frac;
 		this->io_rate_match->size = match_size;
 	}
 	return match_size;