diff --git a/audio/decode/ad_mpg123.c b/audio/decode/ad_mpg123.c
index 777c20c2c9..8ea06dd5ab 100644
--- a/audio/decode/ad_mpg123.c
+++ b/audio/decode/ad_mpg123.c
@@ -310,6 +310,11 @@ static int decode_audio(sh_audio_t *sh, struct mp_audio *buffer, int maxlen)
             return -1;
     }
 
+    if (sh->samplerate != buffer->rate ||
+        !mp_chmap_equals(&sh->channels, &buffer->channels) ||
+        sh->sample_format != buffer->format)
+        return 0;
+
     size_t got_now = 0;
     ret = mpg123_replace_buffer(con->handle, buf, maxlen * con->sample_size);
     if (ret != MPG123_OK)
diff --git a/audio/decode/dec_audio.c b/audio/decode/dec_audio.c
index 0aee681def..c79e4ffc42 100644
--- a/audio/decode/dec_audio.c
+++ b/audio/decode/dec_audio.c
@@ -267,7 +267,6 @@ static int filter_n_bytes(sh_audio_t *sh, struct mp_audio_buffer *outbuf,
             // first, and don't signal a format change to the caller yet.
             if (mp_audio_buffer_samples(sh->decode_buffer) > 0)
                 break;
-            reinit_audio_buffer(sh);
             error = -2;
             break;
         }
@@ -288,6 +287,11 @@ static int filter_n_bytes(sh_audio_t *sh, struct mp_audio_buffer *outbuf,
     // remove processed data from decoder buffer:
     mp_audio_buffer_skip(sh->decode_buffer, len);
 
+    // Assume the filter chain is drained from old data at this point.
+    // (If not, the remaining old data is discarded.)
+    if (error == -2)
+        reinit_audio_buffer(sh);
+
     return error;
 }
 
diff --git a/audio/filter/af.c b/audio/filter/af.c
index 63013e81d9..c315ea8f7c 100644
--- a/audio/filter/af.c
+++ b/audio/filter/af.c
@@ -695,9 +695,11 @@ struct af_instance *af_add(struct af_stream *s, char *name, char **args)
 struct mp_audio *af_play(struct af_stream *s, struct mp_audio *data)
 {
     struct af_instance *af = s->first;
+    assert(mp_audio_config_equals(af->data, data));
     // Iterate through all filters
     do {
         data = af->play(af, data);
+        assert(mp_audio_config_equals(af->data, data));
         af = af->next;
     } while (af && data);
     return data;