diff --git a/libavformat/rtmpproto.c b/libavformat/rtmpproto.c
index 38e2a0061a..5532b50489 100644
--- a/libavformat/rtmpproto.c
+++ b/libavformat/rtmpproto.c
@@ -3021,6 +3021,9 @@ static int rtmp_write(URLContext *s, const uint8_t *buf, int size)
                                                      &rt->nb_prev_pkt[1],
                                                      channel)) < 0)
                     return ret;
+                // Force sending a full 12 bytes header by cleaing the
+                // channel id, to make it not match a potential earlier
+                // packet in the same channel.
                 rt->prev_pkt[1][channel].channel_id = 0;
             }