diff --git a/libavformat/av1.c b/libavformat/av1.c
index 876fd92733..709484b361 100644
--- a/libavformat/av1.c
+++ b/libavformat/av1.c
@@ -82,7 +82,6 @@ int ff_av1_filter_obus_buf(const uint8_t *in, uint8_t **out, int *size)
 
     memset(buf + len, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 
-    av_freep(out);
     *out  = buf;
     *size = len;
 
diff --git a/libavformat/av1.h b/libavformat/av1.h
index acba12612c..52d0814e86 100644
--- a/libavformat/av1.h
+++ b/libavformat/av1.h
@@ -68,6 +68,7 @@ int ff_av1_filter_obus(AVIOContext *pb, const uint8_t *buf, int size);
  *
  * @return 0 in case of success, a negative AVERROR code in case of failure.
  *         On failure, out and size are unchanged
+ * @note *out will be treated as unintialized on input and will not be freed.
  */
 int ff_av1_filter_obus_buf(const uint8_t *in, uint8_t **out, int *size);
 
diff --git a/libavformat/avc.c b/libavformat/avc.c
index e4e82e1864..cd15ac3cdb 100644
--- a/libavformat/avc.c
+++ b/libavformat/avc.c
@@ -101,7 +101,6 @@ int ff_avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
 
     ff_avc_parse_nal_units(pb, buf_in, *size);
 
-    av_freep(buf);
     *size = avio_close_dyn_buf(pb, buf);
     return 0;
 }
@@ -109,7 +108,7 @@ int ff_avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
 int ff_isom_write_avcc(AVIOContext *pb, const uint8_t *data, int len)
 {
     AVIOContext *sps_pb = NULL, *pps_pb = NULL, *sps_ext_pb = NULL;
-    uint8_t *buf = NULL, *end, *start = NULL;
+    uint8_t *buf, *end, *start;
     uint8_t *sps, *pps, *sps_ext;
     uint32_t sps_size = 0, pps_size = 0, sps_ext_size = 0;
     int ret, nb_sps = 0, nb_pps = 0, nb_sps_ext = 0;
diff --git a/libavformat/hevc.h b/libavformat/hevc.h
index bb144397c0..0f56325c1c 100644
--- a/libavformat/hevc.h
+++ b/libavformat/hevc.h
@@ -73,6 +73,7 @@ int ff_hevc_annexb2mp4(AVIOContext *pb, const uint8_t *buf_in,
  *        parameter set NAL units shall be written, may be NULL
  * @return 0 in case of success, a negative value corresponding to an AVERROR
  *         code in case of failure
+ * @note *buf_out will be treated as uninitialized on input and won't be freed.
  */
 int ff_hevc_annexb2mp4_buf(const uint8_t *buf_in, uint8_t **buf_out,
                            int *size, int filter_ps, int *ps_count);