[FFmpeg-cvslog] mxf: Override faulty PreviousPartition entries

[Luca Barbato]

ffmpeg | branch: master | Luca Barbato <lu_zero at gentoo.org> | Thu Mar 13 16:12:05 2014 +0100| [842ea36c747eb6537c4236114346cb7a3e9a8df1] | committer: Luca Barbato

mxf: Override faulty PreviousPartition entries

Some files set the PreviousPartition field to point to its own offset.

If we are parsing forward the Previous partition is immediately known
and its value could be used, otherwise we can safely point to the
header.

Reported-By: Jean Baptiste Kempf <jb at videolan.org>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=842ea36c747eb6537c4236114346cb7a3e9a8df1
---

 libavformat/mxfdec.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 734c50a..39ab462 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -478,6 +478,26 @@ static int mxf_read_partition_pack(void *arg, AVIOContext *pb, int tag, int size
     avio_read(pb, op, sizeof(UID));
     nb_essence_containers = avio_rb32(pb);
 
+    if (partition->this_partition &&
+        partition->previous_partition == partition->this_partition) {
+        av_log(mxf->fc, AV_LOG_ERROR,
+               "PreviousPartition equal to ThisPartition %"PRIx64"\n",
+               partition->previous_partition);
+        /* override with the actual previous partition offset */
+        if (!mxf->parsing_backward && mxf->last_forward_partition > 1) {
+            MXFPartition *prev =
+                mxf->partitions + mxf->last_forward_partition - 2;
+            partition->previous_partition = prev->this_partition;
+        }
+        /* if no previous body partition are found point to the header
+         * partition */
+        if (partition->previous_partition == partition->this_partition);
+            partition->previous_partition = 0;
+        av_log(mxf->fc, AV_LOG_ERROR,
+               "Overriding PreviousPartition with %"PRIx64"\n",
+               partition->previous_partition);
+    }
+
     /* some files don'thave FooterPartition set in every partition */
     if (footer_partition) {
         if (mxf->footer_partition && mxf->footer_partition != footer_partition) {