diff --git a/doc/APIchanges b/doc/APIchanges
index 762c2d6628..963ad477bf 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,10 @@ The last version increases of all libraries were on 2023-02-09
 
 API changes, most recent first:
 
+2023-09-07 - xxxxxxxxxx - lavf 60.xx.100 - avio.h
+  Constify the buffer pointees in the write_packet and write_data_type
+  callbacks of AVIOContext.
+
 2023-09-07 - xxxxxxxxxx - lavc 60.26.100 - defs.h
   Add AV_PROFILE_* and AV_LEVEL_* replacements in defs.h for the
   defines from avcodec.h. The latter are deprecated.
diff --git a/libavformat/avio.c b/libavformat/avio.c
index 5e1acba31b..053cb2e05a 100644
--- a/libavformat/avio.c
+++ b/libavformat/avio.c
@@ -421,7 +421,11 @@ int ffurl_read_complete(URLContext *h, unsigned char *buf, int size)
                                   h->prot->url_read, NULL, 1);
 }
 
+#if FF_API_AVIO_WRITE_NONCONST
 int ffurl_write2(void *urlcontext, uint8_t *buf, int size)
+#else
+int ffurl_write2(void *urlcontext, const uint8_t *buf, int size)
+#endif
 {
     URLContext *h = urlcontext;
 
diff --git a/libavformat/avio.h b/libavformat/avio.h
index 5f13e0622d..887a397c37 100644
--- a/libavformat/avio.h
+++ b/libavformat/avio.h
@@ -238,7 +238,11 @@ typedef struct AVIOContext {
     void *opaque;           /**< A private pointer, passed to the read/write/seek/...
                                  functions. */
     int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
+#if FF_API_AVIO_WRITE_NONCONST
     int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
+#else
+    int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size);
+#endif
     int64_t (*seek)(void *opaque, int64_t offset, int whence);
     int64_t pos;            /**< position in the file of the current buffer */
     int eof_reached;        /**< true if was unable to read due to error or eof */
@@ -286,8 +290,13 @@ typedef struct AVIOContext {
     /**
      * A callback that is used instead of write_packet.
      */
+#if FF_API_AVIO_WRITE_NONCONST
     int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
                            enum AVIODataMarkerType type, int64_t time);
+#else
+    int (*write_data_type)(void *opaque, const uint8_t *buf, int buf_size,
+                           enum AVIODataMarkerType type, int64_t time);
+#endif
     /**
      * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
      * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
@@ -407,7 +416,11 @@ AVIOContext *avio_alloc_context(
                   int write_flag,
                   void *opaque,
                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
+#if FF_API_AVIO_WRITE_NONCONST
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
+#else
+                  int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size),
+#endif
                   int64_t (*seek)(void *opaque, int64_t offset, int whence));
 
 /**
diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index aef6ab660e..bd58499b64 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -89,7 +89,11 @@ void ffio_init_context(FFIOContext *s,
                   int write_flag,
                   void *opaque,
                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
+#if FF_API_AVIO_WRITE_NONCONST
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
+#else
+                  int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size),
+#endif
                   int64_t (*seek)(void *opaque, int64_t offset, int whence));
 
 /**
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index ad5827f216..c55fe8a837 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -84,7 +84,11 @@ void ffio_init_context(FFIOContext *ctx,
                   int write_flag,
                   void *opaque,
                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
+#if FF_API_AVIO_WRITE_NONCONST
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
+#else
+                  int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size),
+#endif
                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
 {
     AVIOContext *const s = &ctx->pub;
@@ -143,7 +147,11 @@ AVIOContext *avio_alloc_context(
                   int write_flag,
                   void *opaque,
                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
+#if FF_API_AVIO_WRITE_NONCONST
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
+#else
+                  int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size),
+#endif
                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
 {
     FFIOContext *s = av_malloc(sizeof(*s));
@@ -165,12 +173,20 @@ static void writeout(AVIOContext *s, const uint8_t *data, int len)
     if (!s->error) {
         int ret = 0;
         if (s->write_data_type)
+#if FF_API_AVIO_WRITE_NONCONST
             ret = s->write_data_type(s->opaque, (uint8_t *)data,
+#else
+            ret = s->write_data_type(s->opaque, data,
+#endif
                                      len,
                                      ctx->current_type,
                                      ctx->last_time);
         else if (s->write_packet)
+#if FF_API_AVIO_WRITE_NONCONST
             ret = s->write_packet(s->opaque, (uint8_t *)data, len);
+#else
+            ret = s->write_packet(s->opaque, data, len);
+#endif
         if (ret < 0) {
             s->error = ret;
         } else {
@@ -1396,7 +1412,11 @@ typedef struct DynBuffer {
     uint8_t io_buffer[1];
 } DynBuffer;
 
+#if FF_API_AVIO_WRITE_NONCONST
 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
+#else
+static int dyn_buf_write(void *opaque, const uint8_t *buf, int buf_size)
+#endif
 {
     DynBuffer *d = opaque;
     unsigned new_size;
@@ -1428,7 +1448,11 @@ static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
     return buf_size;
 }
 
+#if FF_API_AVIO_WRITE_NONCONST
 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
+#else
+static int dyn_packet_buf_write(void *opaque, const uint8_t *buf, int buf_size)
+#endif
 {
     unsigned char buf1[4];
     int ret;
@@ -1565,7 +1589,11 @@ void ffio_free_dyn_buf(AVIOContext **s)
     avio_context_free(s);
 }
 
+#if FF_API_AVIO_WRITE_NONCONST
 static int null_buf_write(void *opaque, uint8_t *buf, int buf_size)
+#else
+static int null_buf_write(void *opaque, const uint8_t *buf, int buf_size)
+#endif
 {
     DynBuffer *d = opaque;
 
diff --git a/libavformat/hdsenc.c b/libavformat/hdsenc.c
index 080a873ee8..7062441b70 100644
--- a/libavformat/hdsenc.c
+++ b/libavformat/hdsenc.c
@@ -112,7 +112,11 @@ static int parse_header(OutputStream *os, const uint8_t *buf, int buf_size)
     return 0;
 }
 
+#if FF_API_AVIO_WRITE_NONCONST
 static int hds_write(void *opaque, uint8_t *buf, int buf_size)
+#else
+static int hds_write(void *opaque, const uint8_t *buf, int buf_size)
+#endif
 {
     OutputStream *os = opaque;
     if (os->out) {
diff --git a/libavformat/smoothstreamingenc.c b/libavformat/smoothstreamingenc.c
index 3c050ca54e..0379e9a079 100644
--- a/libavformat/smoothstreamingenc.c
+++ b/libavformat/smoothstreamingenc.c
@@ -75,7 +75,11 @@ typedef struct SmoothStreamingContext {
     int nb_fragments;
 } SmoothStreamingContext;
 
+#if FF_API_AVIO_WRITE_NONCONST
 static int ism_write(void *opaque, uint8_t *buf, int buf_size)
+#else
+static int ism_write(void *opaque, const uint8_t *buf, int buf_size)
+#endif
 {
     OutputStream *os = opaque;
     if (os->out)
diff --git a/libavformat/url.h b/libavformat/url.h
index bba1a9a1df..f0327218d4 100644
--- a/libavformat/url.h
+++ b/libavformat/url.h
@@ -194,7 +194,11 @@ static inline int ffurl_read(URLContext *h, uint8_t *buf, int size)
  */
 int ffurl_read_complete(URLContext *h, unsigned char *buf, int size);
 
+#if FF_API_AVIO_WRITE_NONCONST
 int ffurl_write2(void *urlcontext, uint8_t *buf, int size);
+#else
+int ffurl_write2(void *urlcontext, const uint8_t *buf, int size);
+#endif
 /**
  * Write size bytes from buf to the resource accessed by h.
  *
@@ -203,7 +207,11 @@ int ffurl_write2(void *urlcontext, uint8_t *buf, int size);
  */
 static inline int ffurl_write(URLContext *h, const uint8_t *buf, int size)
 {
+#if FF_API_AVIO_WRITE_NONCONST
     return ffurl_write2(h, (uint8_t*)buf, size);
+#else
+    return ffurl_write2(h, buf, size);
+#endif
 }
 
 int64_t ffurl_seek2(void *urlcontext, int64_t pos, int whence);
diff --git a/libavformat/version_major.h b/libavformat/version_major.h
index 293fbd3397..1b43fe64cb 100644
--- a/libavformat/version_major.h
+++ b/libavformat/version_major.h
@@ -45,6 +45,7 @@
 #define FF_API_GET_END_PTS              (LIBAVFORMAT_VERSION_MAJOR < 61)
 #define FF_API_AVIODIRCONTEXT           (LIBAVFORMAT_VERSION_MAJOR < 61)
 #define FF_API_AVFORMAT_IO_CLOSE        (LIBAVFORMAT_VERSION_MAJOR < 61)
+#define FF_API_AVIO_WRITE_NONCONST      (LIBAVFORMAT_VERSION_MAJOR < 61)
 
 
 #define FF_API_R_FRAME_RATE            1
