avformat/aiffenc: Avoid seek when writing id3v2 tags at the end

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/aiffenc.c

@@ -233,25 +233,12 @@ static int aiff_write_trailer(AVFormatContext *s)
     AVCodecParameters *par = s->streams[aiff->audio_stream_idx]->codecpar;
 
     /* Chunks sizes must be even */
-    int64_t file_size, end_size;
-    end_size = file_size = avio_tell(pb);
-    if (file_size & 1) {
+    int64_t file_size, data_size;
+    data_size = avio_tell(pb);
+    if (data_size & 1)
         avio_w8(pb, 0);
-        end_size++;
-    }
 
     if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
-        /* Number of sample frames */
-        avio_seek(pb, aiff->frames, SEEK_SET);
-        avio_wb32(pb, (file_size - aiff->ssnd - 12) / par->block_align);
-
-        /* Sound Data chunk size */
-        avio_seek(pb, aiff->ssnd, SEEK_SET);
-        avio_wb32(pb, file_size - aiff->ssnd - 4);
-
-        /* return to the end */
-        avio_seek(pb, end_size, SEEK_SET);
-
         /* Write ID3 tags */
         if (aiff->write_id3v2)
             if ((ret = put_id3v2_tags(s, aiff)) < 0)
@@ -261,6 +248,14 @@ static int aiff_write_trailer(AVFormatContext *s)
         file_size = avio_tell(pb);
         avio_seek(pb, aiff->form, SEEK_SET);
         avio_wb32(pb, file_size - aiff->form - 4);
+
+        /* Number of sample frames */
+        avio_seek(pb, aiff->frames, SEEK_SET);
+        avio_wb32(pb, (data_size - aiff->ssnd - 12) / par->block_align);
+
+        /* Sound Data chunk size */
+        avio_seek(pb, aiff->ssnd, SEEK_SET);
+        avio_wb32(pb, data_size - aiff->ssnd - 4);
     }
 
     return ret;