[FFmpeg-cvslog] apetag: account for header size if present when returning the start position

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Fri Feb 10 20:24:27 2017 -0300| [4cc0227040adb9efc63be6a5765e3214f5c6f662] | committer: Anton Khirnov

apetag: account for header size if present when returning the start position

The size field in the header/footer accounts for the entire APE tag
structure except the 32 bytes from header, for compatibility with
APEv1.

Signed-off-by: James Almer <jamrial at gmail.com>

CC: libav-stable at libav.org

Signed-off-by: Anton Khirnov <anton at khirnov.net>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4cc0227040adb9efc63be6a5765e3214f5c6f662
---

 libavformat/apetag.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavformat/apetag.c b/libavformat/apetag.c
index 93a4fb3430..a7cf8530f1 100644
--- a/libavformat/apetag.c
+++ b/libavformat/apetag.c
@@ -31,6 +31,7 @@
 
 #define APE_TAG_VERSION               2000
 #define APE_TAG_FOOTER_BYTES          32
+#define APE_TAG_HEADER_BYTES          32
 #define APE_TAG_FLAG_CONTAINS_HEADER  (1 << 31)
 #define APE_TAG_FLAG_LACKS_FOOTER     (1 << 30)
 #define APE_TAG_FLAG_IS_HEADER        (1 << 29)
@@ -154,7 +155,6 @@ int64_t ff_ape_parse_tag(AVFormatContext *s)
         av_log(s, AV_LOG_ERROR, "Invalid tag size %"PRIu32".\n", tag_bytes);
         return 0;
     }
-    tag_start = file_size - tag_bytes - APE_TAG_FOOTER_BYTES;
 
     fields = avio_rl32(pb);    /* number of fields */
     if (fields > 65536) {
@@ -170,6 +170,11 @@ int64_t ff_ape_parse_tag(AVFormatContext *s)
 
     avio_seek(pb, file_size - tag_bytes, SEEK_SET);
 
+    if (val & APE_TAG_FLAG_CONTAINS_HEADER)
+        tag_bytes += APE_TAG_HEADER_BYTES;
+
+    tag_start = file_size - tag_bytes;
+
     for (i=0; i<fields; i++)
         if (ape_tag_read_field(s) < 0) break;