[FFmpeg-devel] [PATCH 1/2] avformat/apetag: fix flag value to signal footer presence

[James Almer]

According to the spec[1], a value of 0 means the footer is present and a value
of 1 means it's absent, the exact opposite of header presence flag where 1
means present and 0 absent.
The reason for this is compatibility with APEv1 tags, where there's no header,
footer presence was mandatory for all files, and the flags field was a zeroed
reserved field.

[1] http://wiki.hydrogenaud.io/index.php?title=Ape_Tags_Flags

Signed-off-by: James Almer <jamrial at gmail.com>
---
Files already created are obviously wrong, but fortunately having the flag
mistakenly reporting there's no footer is harmless in APEv2 tags stored at
the end of the file (The only kind we can read and write), since footer is
mandatory in those and no and such software really bothers looking at the
flag.

I renamed the constant just to have it as reference, or until someone feels
like adding support for APEv2 tags at the beginning of a file, where footer
becomes optional.

 libavformat/apetag.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavformat/apetag.c b/libavformat/apetag.c
index 08e80f4aa3..a05b32d9e5 100644
--- a/libavformat/apetag.c
+++ b/libavformat/apetag.c
@@ -30,7 +30,7 @@
 #include "internal.h"
 
 #define APE_TAG_FLAG_CONTAINS_HEADER  (1 << 31)
-#define APE_TAG_FLAG_CONTAINS_FOOTER  (1 << 30)
+#define APE_TAG_FLAG_LACKS_FOOTER     (1 << 30)
 #define APE_TAG_FLAG_IS_HEADER        (1 << 29)
 #define APE_TAG_FLAG_IS_BINARY        (1 << 1)
 
@@ -189,8 +189,7 @@ int ff_ape_write_tag(AVFormatContext *s)
         goto end;
 
     // flags
-    avio_wl32(dyn_bc, APE_TAG_FLAG_CONTAINS_HEADER | APE_TAG_FLAG_CONTAINS_FOOTER |
-                     APE_TAG_FLAG_IS_HEADER);
+    avio_wl32(dyn_bc, APE_TAG_FLAG_CONTAINS_HEADER | APE_TAG_FLAG_IS_HEADER);
     ffio_fill(dyn_bc, 0, 8);             // reserved
 
     ff_standardize_creation_time(s);
@@ -232,7 +231,7 @@ int ff_ape_write_tag(AVFormatContext *s)
     avio_wl32(s->pb, count);            // tag count
 
     // flags
-    avio_wl32(s->pb, APE_TAG_FLAG_CONTAINS_HEADER | APE_TAG_FLAG_CONTAINS_FOOTER);
+    avio_wl32(s->pb, APE_TAG_FLAG_CONTAINS_HEADER);
     ffio_fill(s->pb, 0, 8);             // reserved
 
 end:
-- 
2.11.0