[FFmpeg-cvslog] avformat/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 01:24:27 2017 -0300| [84d874a680ff647bc84de44967b638f246a8b832] | committer: James Almer

avformat/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.

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: James Almer <jamrial at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=84d874a680ff647bc84de44967b638f246a8b832
---

 libavformat/apetag.c | 6 +++++-
 libavformat/apetag.h | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavformat/apetag.c b/libavformat/apetag.c
index a05b32d..b23f8cd 100644
--- a/libavformat/apetag.c
+++ b/libavformat/apetag.c
@@ -150,7 +150,6 @@ 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) {
@@ -166,6 +165,11 @@ 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;
 
diff --git a/libavformat/apetag.h b/libavformat/apetag.h
index cf2a5f8..49cd10e 100644
--- a/libavformat/apetag.h
+++ b/libavformat/apetag.h
@@ -28,6 +28,7 @@
 #define APE_TAG_PREAMBLE        "APETAGEX"
 #define APE_TAG_VERSION         2000
 #define APE_TAG_FOOTER_BYTES    32
+#define APE_TAG_HEADER_BYTES    32
 
 /**
  * Read and parse an APE tag