lavf/apetag: move common stuff between writer and reader to single file

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/apetag.c

@@ -26,8 +26,6 @@
 #include "apetag.h"
 #include "internal.h"
 
-#define APE_TAG_VERSION               2000
-#define APE_TAG_FOOTER_BYTES          32
 #define APE_TAG_FLAG_CONTAINS_HEADER  (1 << 31)
 #define APE_TAG_FLAG_IS_HEADER        (1 << 29)
 #define APE_TAG_FLAG_IS_BINARY        (1 << 1)
@@ -127,7 +125,7 @@ void ff_ape_parse_tag(AVFormatContext *s)
     avio_seek(pb, file_size - APE_TAG_FOOTER_BYTES, SEEK_SET);
 
     avio_read(pb, buf, 8);     /* APETAGEX */
-    if (strncmp(buf, "APETAGEX", 8)) {
+    if (strncmp(buf, APE_TAG_PREAMBLE, 8)) {
         return;
     }
 

libavformat/apetag.h

@@ -25,6 +25,10 @@
 
 #include "avformat.h"
 
+#define APE_TAG_PREAMBLE        "APETAGEX"
+#define APE_TAG_VERSION         2000
+#define APE_TAG_FOOTER_BYTES    32
+
 /**
  * Read and parse an APE tag
  */

libavformat/apetagenc.c

@@ -24,10 +24,6 @@
 #include "avformat.h"
 #include "apetag.h"
 
-#define APE_TAG_PREAMBLE        "APETAGEX"
-#define APE_TAG_VERSION         2000
-#define APE_TAG_FOOTER_BYTES    32
-
 static int string_is_ascii(const uint8_t *str)
 {
     while (*str && *str >= 0x20 && *str <= 0x7e ) str++;