Topfield make a variety of personal video recorders that allow for the
transfer of recorded programmes via an onboard USB port. The ".rec"
files they produce are MPEG2 transport streams with a 3760 byte header
containing archive information for the PVR. This patch checks for the
presence of "TFrc" in the first four bytes of a file and identifies it
as an mpeg transport stream if present. It subsequently skips this
header when the services are probed. With the patch in place these
files are then fully supported by ffmpeg.

topfield.rec is a short example of a topfield recording.

Index: libavformat/mpegts.c
===================================================================
--- libavformat/mpegts.c	(revision 15938)
+++ libavformat/mpegts.c	(working copy)
@@ -1179,6 +1179,13 @@
     int score, fec_score, dvhs_score;
 #define CHECK_COUNT 10
 
+    /* check for Topfield PVR "REC" file header */
+    if(size>=4) {
+        if (p->buf[0]=='T' && p->buf[1]=='F' && p->buf[2]=='r' && p->buf[3]=='c') {
+           return AVPROBE_SCORE_MAX;
+       }
+    }
+
     if (size < (TS_FEC_PACKET_SIZE * CHECK_COUNT))
         return -1;
 
@@ -1194,7 +1201,7 @@
     else                                    return -1;
 #else
     /* only use the extension for safer guess */
-    if (match_ext(p->filename, "ts"))
+    if (match_ext(p->filename, "ts") || match_ext(p->filename, "rec"))
         return AVPROBE_SCORE_MAX;
     else
         return 0;
@@ -1252,6 +1259,16 @@
     len = get_buffer(pb, buf, sizeof(buf));
     if (len != sizeof(buf))
         goto fail;
+
+    /* check for Topfield PVR "REC" file header and skip it */
+    if (buf[0]=='T' && buf[1]=='F' && buf[2]=='r' && buf[3]=='c') {
+        pos += 0xeb0;
+        url_fseek(pb, pos, SEEK_SET);
+        len = get_buffer(pb, buf, sizeof(buf));
+        if (len != sizeof(buf))
+            goto fail;
+    }
+
     ts->raw_packet_size = get_packet_size(buf, sizeof(buf));
     if (ts->raw_packet_size <= 0)
         goto fail;