diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 5c07541b36..5ca6f5aa0f 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1523,6 +1523,13 @@ typedef struct AVFormatContext {
      */
     int probe_score;
 
+    /**
+     * number of bytes to read maximally to identify format.
+     * - encoding: unused
+     * - decoding: set by user through AVOPtions (NO direct access)
+     */
+    int format_probesize;
+
     /*****************************************************************
      * All fields below this line are not part of the public API. They
      * may not be used outside of libavformat and can be changed and
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index 359b38483a..12fb0a642b 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -25,6 +25,7 @@
 
 #include "libavutil/opt.h"
 #include "avformat.h"
+#include "internal.h"
 
 #define OFFSET(x) offsetof(AVFormatContext,x)
 #define DEFAULT 0 //should be NAN but it does not work as it is not a constant in glibc as required by ANSI/ISO C
@@ -36,6 +37,7 @@ static const AVOption avformat_options[] = {
 {"avioflags", NULL, OFFSET(avio_flags), AV_OPT_TYPE_FLAGS, {.i64 = DEFAULT }, INT_MIN, INT_MAX, D|E, "avioflags"},
 {"direct", "reduce buffering", 0, AV_OPT_TYPE_CONST, {.i64 = AVIO_FLAG_DIRECT }, INT_MIN, INT_MAX, D|E, "avioflags"},
 {"probesize", "set probing size", OFFSET(probesize), AV_OPT_TYPE_INT, {.i64 = 5000000 }, 32, INT_MAX, D},
+{"formatprobesize", "number of bytes to probe file format", OFFSET(format_probesize), AV_OPT_TYPE_INT, {.i64 = PROBE_BUF_MAX}, 0, INT_MAX-1, D},
 {"packetsize", "set packet size", OFFSET(packet_size), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, 0, INT_MAX, E},
 {"fflags", NULL, OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = AVFMT_FLAG_FLUSH_PACKETS }, INT_MIN, INT_MAX, D|E, "fflags"},
 {"flush_packets", "reduce the latency by flushing out packets immediately", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_FLUSH_PACKETS }, INT_MIN, INT_MAX, D, "fflags"},
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 7e3ec9b859..c9a3d4db1e 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -379,8 +379,6 @@ int av_probe_input_buffer2(AVIOContext *pb, AVInputFormat **fmt,
 
     if (!max_probe_size)
         max_probe_size = PROBE_BUF_MAX;
-    else if (max_probe_size > PROBE_BUF_MAX)
-        max_probe_size = PROBE_BUF_MAX;
     else if (max_probe_size < PROBE_BUF_MIN) {
         av_log(logctx, AV_LOG_ERROR,
                "Specified probe size value %u cannot be < %u\n", max_probe_size, PROBE_BUF_MIN);
@@ -474,7 +472,7 @@ static int init_input(AVFormatContext *s, const char *filename,
         s->flags |= AVFMT_FLAG_CUSTOM_IO;
         if (!s->iformat)
             return av_probe_input_buffer2(s->pb, &s->iformat, filename,
-                                         s, 0, s->probesize);
+                                         s, 0, s->format_probesize);
         else if (s->iformat->flags & AVFMT_NOFILE)
             av_log(s, AV_LOG_WARNING, "Custom AVIOContext makes no sense and "
                                       "will be ignored with AVFMT_NOFILE format.\n");
@@ -491,7 +489,7 @@ static int init_input(AVFormatContext *s, const char *filename,
     if (s->iformat)
         return 0;
     return av_probe_input_buffer2(s->pb, &s->iformat, filename,
-                                 s, 0, s->probesize);
+                                 s, 0, s->format_probesize);
 }
 
 static AVPacket *add_to_pktbuf(AVPacketList **packet_buffer, AVPacket *pkt,