diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
index 34e6d88ab9..54972de5e0 100644
--- a/libavformat/aiffdec.c
+++ b/libavformat/aiffdec.c
@@ -268,9 +268,6 @@ static int aiff_read_header(AVFormatContext *s,
 
 got_sound:
     /* Now positioned, get the sound data start and end */
-    if (st->nb_frames)
-        s->file_size = st->nb_frames * st->codec->block_align;
-
     av_set_pts_info(st, 64, 1, st->codec->sample_rate);
     st->start_time = 0;
     st->duration = st->codec->frame_size ?
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 70d466e0d1..61b231ec1d 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -716,10 +716,12 @@ typedef struct AVFormatContext {
      */
     int64_t duration;
 
+#if FF_API_FILESIZE
     /**
      * decoding: total file size, 0 if unknown
      */
-    int64_t file_size;
+    attribute_deprecated int64_t file_size;
+#endif
 
     /**
      * Decoding: total stream bitrate in bit/s, 0 if not
diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c
index 38cde3be50..02d1e3ccaa 100644
--- a/libavformat/cafdec.c
+++ b/libavformat/cafdec.c
@@ -286,8 +286,6 @@ static int read_header(AVFormatContext *s,
                                 "block size or frame size are variable.\n");
         return AVERROR_INVALIDDATA;
     }
-    s->file_size = avio_size(pb);
-    s->file_size = FFMAX(0, s->file_size);
 
     av_set_pts_info(st, 64, 1, st->codec->sample_rate);
     st->start_time = 0;
diff --git a/libavformat/qcp.c b/libavformat/qcp.c
index aefb076e3b..291eb182ed 100644
--- a/libavformat/qcp.c
+++ b/libavformat/qcp.c
@@ -92,8 +92,7 @@ static int qcp_read_header(AVFormatContext *s, AVFormatParameters *ap)
         return AVERROR(ENOMEM);
 
     avio_rb32(pb);                    // "RIFF"
-    s->file_size = avio_rl32(pb) + 8;
-    avio_skip(pb, 8 + 4 + 1 + 1);    // "QLCMfmt " + chunk-size + major-version + minor-version
+    avio_skip(pb, 4 + 8 + 4 + 1 + 1);    // filesize + "QLCMfmt " + chunk-size + major-version + minor-version
 
     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
     st->codec->channels   = 1;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 3115723668..6393b62615 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1837,7 +1837,7 @@ static int has_duration(AVFormatContext *ic)
 static void update_stream_timings(AVFormatContext *ic)
 {
     int64_t start_time, start_time1, end_time, end_time1;
-    int64_t duration, duration1;
+    int64_t duration, duration1, filesize;
     int i;
     AVStream *st;
 
@@ -1872,9 +1872,9 @@ static void update_stream_timings(AVFormatContext *ic)
     }
     if (duration != INT64_MIN) {
         ic->duration = duration;
-        if (ic->file_size > 0) {
+        if (ic->pb && (filesize = avio_size(ic->pb)) > 0) {
             /* compute the bitrate */
-            ic->bit_rate = (double)ic->file_size * 8.0 * AV_TIME_BASE /
+            ic->bit_rate = (double)filesize * 8.0 * AV_TIME_BASE /
                 (double)ic->duration;
         }
     }
@@ -1916,9 +1916,8 @@ static void estimate_timings_from_bit_rate(AVFormatContext *ic)
 
     /* if duration is already set, we believe it */
     if (ic->duration == AV_NOPTS_VALUE &&
-        ic->bit_rate != 0 &&
-        ic->file_size != 0)  {
-        filesize = ic->file_size;
+        ic->bit_rate != 0) {
+        filesize = ic->pb ? avio_size(ic->pb) : 0;
         if (filesize > 0) {
             for(i = 0; i < ic->nb_streams; i++) {
                 st = ic->streams[i];
@@ -1962,7 +1961,7 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
 
     /* estimate the end time (duration) */
     /* XXX: may need to support wrapping */
-    filesize = ic->file_size;
+    filesize = ic->pb ? avio_size(ic->pb) : 0;
     end_time = AV_NOPTS_VALUE;
     do{
         offset = filesize - (DURATION_MAX_READ_SIZE<<retry);
@@ -2026,7 +2025,6 @@ static void estimate_timings(AVFormatContext *ic, int64_t old_offset)
         if (file_size < 0)
             file_size = 0;
     }
-    ic->file_size = file_size;
 
     if ((!strcmp(ic->iformat->name, "mpeg") ||
          !strcmp(ic->iformat->name, "mpegts")) &&
diff --git a/libavformat/version.h b/libavformat/version.h
index 53c585a06b..1a562d6a87 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -86,5 +86,8 @@
 #ifndef FF_API_TIMESTAMP
 #define FF_API_TIMESTAMP               (LIBAVFORMAT_VERSION_MAJOR < 54)
 #endif
+#ifndef FF_API_FILESIZE
+#define FF_API_FILESIZE                (LIBAVFORMAT_VERSION_MAJOR < 54)
+#endif
 
 #endif /* AVFORMAT_VERSION_H */