Three VBI fixes for ld-decode

ld-cut

@@ -69,13 +69,19 @@ if args.MTF_offset is not None:
 
 if args.seek != -1:
     startloc = ldd.seek(args.start, args.seek) 
-    if startloc > 1:
+    if startloc is None:
+        print("ERROR: Seeking failed")
+        exit(1)
+    elif startloc > 1:
         startloc -= 1
 else:
     startloc = args.start * 2
 
 if args.end != -1:
     endloc = ldd.seek(startloc, args.end)
+    if endloc is None:
+        print("ERROR: Seeking failed")
+        exit(1)
 elif args.length != -1:
     endloc = startloc + (args.length * 2)
 else:

ld-decode

@@ -89,7 +89,9 @@ if system == 'NTSC' and not args.ntscj:
 #print(ldd.blackIRE)
 
 if args.seek != -1:
-    ldd.seek(firstframe, args.seek)
+    if ldd.seek(firstframe, args.seek) is None:
+        print("ERROR: Seeking failed")
+        exit(1)
 
 if args.MTF is not None:
     ldd.rf.mtf_mult = args.MTF

lddecode/core.py

@@ -2489,6 +2489,7 @@ def __init__(self, fname_in, fname_out, freader, analog_audio = 0, digital_audio
 
         self.fieldinfo = []
 
+        self.leadIn = False
         self.leadOut = False
         self.isCLV = False
         self.frameNumber = None
@@ -2659,44 +2660,53 @@ def decodeFrameNumber(self, f1, f2):
         self.clvSeconds = None
         self.clvFrameNum = None
 
+        def decodeBCD(bcd):
+            """Read a BCD-encoded number.
+            Raise ValueError if any of the digits aren't valid BCD."""
+
+            if bcd == 0:
+                return 0
+            else:
+                digit = bcd & 0xF
+                if digit > 9:
+                    raise ValueError("Non-decimal BCD digit")
+                return (10 * decodeBCD(bcd >> 4)) + digit
+
         leadoutCount = 0
 
         for l in f1.linecode + f2.linecode:
             if l is None:
                 continue
-            
+
             if l == 0x80eeee: # lead-out reached
                 leadoutCount += 1
+            elif l == 0x88ffff: # lead-in
+                self.leadIn = True
             elif (l & 0xf0dd00) == 0xf0dd00: # CLV minutes/hours
-                self.clvMinutes = (l & 0xf) + (((l >> 4) & 0xf) * 10) + (((l >> 16) & 0xf) * 60)
-                self.isCLV = True
-                #logging.info('CLV', mins)
+                try:
+                    self.clvMinutes = decodeBCD(l & 0xff) + (decodeBCD((l >> 16) & 0xf) * 60)
+                    self.isCLV = True
+                    #logging.info('CLV', mins)
+                except ValueError:
+                    pass
             elif (l & 0xf00000) == 0xf00000: # CAV frame
                 # Ignore the top bit of the first digit, used for PSC
-                l &= 0x7ffff
-
-                fnum = 0
-                for y in range(16, -1, -4):
-                    fnum *= 10
-                    toadd = l >> y & 0x0f
-                    if toadd > 9:
-                        fnum = -1
-                        break
-                    fnum += toadd
-
-                    fnum = fnum if fnum < 80000 else fnum - 80000
-
-                if fnum >= 0:
-                    return fnum
-
+                try:
+                    return decodeBCD(l & 0x7ffff)
+                except ValueError:
+                    pass
             elif (l & 0x80f000) == 0x80e000: # CLV picture #
-                self.clvSeconds = (((l >> 16) & 0xf) - 10) * 10
-                self.clvSeconds += ((l >> 8) & 0xf)
-
-                self.clvFrameNum = ((l >> 4) & 0xf) * 10
-                self.clvFrameNum += (l & 0xf)
-
-                self.isCLV = True
+                try:
+                    sec1s = decodeBCD((l >> 8) & 0xf)
+                    sec10s = ((l >> 16) & 0xf) - 0xa
+                    if sec10s < 0:
+                        raise ValueError("Digit 2 not in range A-F")
+
+                    self.clvFrameNum = decodeBCD(l & 0xff)
+                    self.clvSeconds = sec1s + (10 * sec10s)
+                    self.isCLV = True
+                except ValueError:
+                    pass
 
             if self.clvMinutes is not None:
                 if self.clvSeconds is not None: # newer CLV
@@ -2913,6 +2923,8 @@ def buildmetadata(self, f):
                         print("file frame %d CLV timecode %d:%.2d.%.2d frame %d" % (rawloc, self.clvMinutes, self.clvSeconds, self.clvFrameNum, self.frameNumber), file=sys.stderr)
                     elif self.frameNumber:
                         print("file frame %d CAV frame %d" % (rawloc, self.frameNumber), file=sys.stderr)
+                    elif self.leadIn:
+                        print("file frame %d lead in" % (rawloc), file=sys.stderr)
                     elif self.leadOut:
                         print("file frame %d lead out" % (rawloc), file=sys.stderr)
                     else:
@@ -2968,21 +2980,19 @@ def seek(self, start, target):
 
         for retries in range(3):
             fnr = self.seek_getframenr(cur)
-            cur = int((self.fieldloc / self.bytes_per_field))
             if fnr is None:
                 return None
-            else:
-                if fnr == target:
-                    logging.info("Finished seek")
-                    print("Finished seeking, starting at frame", fnr, file=sys.stderr)
-                    self.roughseek(cur)
-                    return cur
-                else:
-                    cur += ((target - fnr) * 2) - 1
 
-        print("Finished seeking, starting at frame", fnr, file=sys.stderr)
+            cur = int((self.fieldloc / self.bytes_per_field))
+            if fnr == target:
+                logging.info("Finished seek")
+                print("Finished seeking, starting at frame", fnr, file=sys.stderr)
+                self.roughseek(cur)
+                return cur
+
+            cur += ((target - fnr) * 2) - 1
 
-        return cur - 0
+        return None
 
     def build_json(self, f):
         ''' build up the JSON structure for file output. '''