diff --git a/audio/audio.c b/audio/audio.c
index dfd32912da..f28e91853f 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -548,6 +548,24 @@ static size_t audio_pcm_hw_get_live_in(HWVoiceIn *hw)
     return live;
 }
 
+static size_t audio_pcm_hw_conv_in(HWVoiceIn *hw, void *pcm_buf, size_t samples)
+{
+    size_t conv = 0;
+    STSampleBuffer *conv_buf = hw->conv_buf;
+
+    while (samples) {
+        uint8_t *src = advance(pcm_buf, conv * hw->info.bytes_per_frame);
+        size_t proc = MIN(samples, conv_buf->size - conv_buf->pos);
+
+        hw->conv(conv_buf->samples + conv_buf->pos, src, proc);
+        conv_buf->pos = (conv_buf->pos + proc) % conv_buf->size;
+        samples -= proc;
+        conv += proc;
+    }
+
+    return conv;
+}
+
 /*
  * Soft voice (capture)
  */
@@ -1219,7 +1237,6 @@ static void audio_run_out (AudioState *s)
 static size_t audio_pcm_hw_run_in(HWVoiceIn *hw, size_t samples)
 {
     size_t conv = 0;
-    STSampleBuffer *conv_buf = hw->conv_buf;
 
     if (hw->pcm_ops->run_buffer_in) {
         hw->pcm_ops->run_buffer_in(hw);
@@ -1235,11 +1252,7 @@ static size_t audio_pcm_hw_run_in(HWVoiceIn *hw, size_t samples)
             break;
         }
 
-        proc = MIN(size / hw->info.bytes_per_frame,
-                   conv_buf->size - conv_buf->pos);
-
-        hw->conv(conv_buf->samples + conv_buf->pos, buf, proc);
-        conv_buf->pos = (conv_buf->pos + proc) % conv_buf->size;
+        proc = audio_pcm_hw_conv_in(hw, buf, size / hw->info.bytes_per_frame);
 
         samples -= proc;
         conv += proc;