[mythtv-users] video scan chaos

[jam at tigger.ws]

> On 15 Jan 2019, at 8:00 pm, mythtv-users-request at mythtv.org wrote:
> 
>>> 
>>> I had moved the END cutpoint slightly in an attempt to make a new has,
>>> but after mythtranscode the hash was unchanged.
>>> I moved the START cutpoint slightly, the hash changed and it scanned
>>> correctly.
>> 
>> ISTR reading somewhere that the hash only covers the first 30 seconds of the recording.  I have not attempted to verify this in the code, so I could be wrong. 
> 
> According to the code in the link that was posted
> 
> http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes<http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes>
> 
> The file size AND the sum of the first 64K bytes AND the sum of the last 64K bytes make the hash.
> 
> Whatever happens to the file with myth transcode and in the unlikely event it DID change the hash which matched another file and would 
> not scan, this is what happened.
> 
> Since the commercial channels undoubtably use software to insert ads the chance of exact length matches looks more and more likely!

My saga with “The Man with the Golden Gun.mpg” not appearing or appearing on subsequent scans led me to write hashDups, a tool to show duplicates based on hash.

There were no duplicates of  “The Man with the Golden Gun.mpg” but 20 or 30 other duplicates.
Removing all the other duplicates made "The Man …” consistantly appear on scan!!

I offer the source to any one who wants to mail me. It is a QT console app and needs the QT build enviroment to build and run. I have not tried the linuxdeploytool.

James