diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 2e7204d933..fbca611abf 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3484,9 +3484,8 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
                         h->droppable         = last_pic_droppable;
                         return AVERROR_INVALIDDATA;
                     } else if (last_pic_droppable != h->droppable) {
-                        av_log(h->avctx, AV_LOG_ERROR,
-                               "Cannot combine reference and non-reference fields in the same frame\n");
-                        av_log_ask_for_sample(h->avctx, NULL);
+                        av_log_ask_for_sample(h->avctx,
+                                              "Found reference and non-reference fields in the same frame.\n");
                         h->picture_structure = last_pic_structure;
                         h->droppable         = last_pic_droppable;
                         return AVERROR_PATCHWELCOME;
diff --git a/libavformat/anm.c b/libavformat/anm.c
index f93c57e08a..79d31c1671 100644
--- a/libavformat/anm.c
+++ b/libavformat/anm.c
@@ -134,9 +134,9 @@ static int read_header(AVFormatContext *s)
     /* color cycling and palette data */
     st->codec->extradata_size = 16*8 + 4*256;
     st->codec->extradata      = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
-    if (!st->codec->extradata)
+    if (!st->codec->extradata) {
         return AVERROR(ENOMEM);
-
+    }
     ret = avio_read(pb, st->codec->extradata, st->codec->extradata_size);
     if (ret < 0)
         return ret;
@@ -155,14 +155,15 @@ static int read_header(AVFormatContext *s)
 
     /* find page of first frame */
     anm->page = find_record(anm, 0);
-    if (anm->page < 0)
+    if (anm->page < 0) {
         return anm->page;
+    }
 
     anm->record = -1;
     return 0;
 
 invalid:
-    av_log_ask_for_sample(s, NULL);
+    av_log_ask_for_sample(s, "Invalid header element encountered.\n");
     return AVERROR_PATCHWELCOME;
 }
 
diff --git a/libavformat/spdifenc.c b/libavformat/spdifenc.c
index aaf0568763..41ed724759 100644
--- a/libavformat/spdifenc.c
+++ b/libavformat/spdifenc.c
@@ -412,8 +412,7 @@ static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
     if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
         /* if such frames exist, we'd need some more complex logic to
          * distribute the TrueHD frames in the MAT frame */
-        av_log(s, AV_LOG_ERROR, "TrueHD frame too big, %d bytes\n", pkt->size);
-        av_log_ask_for_sample(s, NULL);
+        av_log_ask_for_sample(s, "TrueHD frame too big, %d bytes\n", pkt->size);
         return AVERROR_PATCHWELCOME;
     }
 
diff --git a/libavformat/xwma.c b/libavformat/xwma.c
index db7d9716ca..1a1e6e3844 100644
--- a/libavformat/xwma.c
+++ b/libavformat/xwma.c
@@ -85,9 +85,8 @@ static int xwma_read_header(AVFormatContext *s)
      * anyway.
      */
     if (st->codec->codec_id != AV_CODEC_ID_WMAV2) {
-        av_log(s, AV_LOG_WARNING, "unexpected codec (tag 0x04%x; id %d)\n",
+        av_log_ask_for_sample(s, "unexpected codec (tag 0x04%x; id %d)\n",
                               st->codec->codec_tag, st->codec->codec_id);
-        av_log_ask_for_sample(s, NULL);
     } else {
         /* In all xWMA files I have seen, there is no extradata. But the WMA
          * codecs require extradata, so we provide our own fake extradata.
@@ -101,9 +100,8 @@ static int xwma_read_header(AVFormatContext *s)
              * if it will work, but just go on and try it, after asking
              * the user for a sample.
              */
-            av_log(s, AV_LOG_WARNING, "unexpected extradata (%d bytes)\n",
+            av_log_ask_for_sample(s, "unexpected extradata (%d bytes)\n",
                                   st->codec->extradata_size);
-            av_log_ask_for_sample(s, NULL);
         } else {
             st->codec->extradata_size = 6;
             st->codec->extradata      = av_mallocz(6 + FF_INPUT_BUFFER_PADDING_SIZE);