[mythtv-users] Commercial Detection

[Anthony Giggins]

On 9 March 2012 19:30, Lawrence Rust <lvr at softsystem.co.uk> wrote:

> On Fri, 2012-03-09 at 13:44 +1000, Anthony Giggins wrote:
> >
> >
> > On 8 March 2012 20:47, Lawrence Rust <lvr at softsystem.co.uk> wrote:
> >         On Wed, 2012-03-07 at 23:13 +0000, Thomas Boehm wrote:
> >         > Martin Moores wrote:
> >         > > On 7 March 2012 21:58, Doug Lytle <support at drdos.info
> >         > > <mailto:support at drdos.info>> wrote:
> >         > >
> >         > >
> >         > >     And I believe there was an external script based on
> >         volume changes on a
> >         > >     channel that people have reported good results with.
> >         > >
> >         > >
> >         > > Indeed, I never got around to trying that, but many said
> >         they had a lot
> >         > > of success with it:
> >         >
> >         > It works very well for me. I changed the script so that it
> >         runs on all
> >         > channels, not only the white listed ones. If there is really
> >         a show
> >         > which doesn't get marked properly, I still press the forward
> >         button a
> >         > few times as I did before, but most of the times it works.
> >         >
> >         > The mythcommflag which comes with MythTV takes much longer
> >         and basically
> >         > doesn't work at all in the UK.
> >
> >
> >         I use a script based on the wiki article
> >         www.mythtv.org/wiki/Mythcommflag-wrapper with good success on
> >         most UK
> >         Freesat channels.
> >
> >         I found that changing the silence threshold to -76 dB from -70
> >         significantly improved accuracy.  Also, decreasing the
> >         coalescence time
> >         from 400 to 360 seconds reduced the prevalence of false
> >         positives.  The
> >         last useful tweak is to the awk program to add 'cut to
> >         beginning' or
> >         'cut to end' without leaving 'dangling' frames.
> >
> >         This generally leaves a few frames of ads/titles before and
> >         after each
> >         cut.  The only annoyance is that the post ad cut doesn't
> >         position to a
> >         keyframe so the cut isn't entirely invisible.  I'm working on
> >         that and
> >         back tracking from the start of cut to detect a scene change.
> >
> >         The script can be found here:
> >
> http://www.softsystem.co.uk/download/mythtv/mythcommflag-silence.sh
> >
> >         To run it as a user job, start mythtv-setup and find
> >         General/JobQueue
> >         (Global) and set the Ad-detection command:
> >         mythcommflag-silence.sh -j %JOBID% -C
> >
> >         The -C option copies the list to the cutlist.
> >
> >         --
> >
> > I get an error in this script when running from a command prompt
> >
> > ./mythcommflag-silence.sh -c 4010 -s "2011-09-29 21:10:00"
> > -i /storage3/recordings/4010_20110929211000.mpg
> > mythcommflag-silence.sh: line 11: syntax error near unexpected token
> > `cat'
>
> This looks like a difference in sh implementations.  From the sh man
> page 'man sh|grep -A 3 Function':
>
>   Functions
>     The syntax of a function definition is
>
>           name () command
>
> See also the POSIX doc on shell functions:
>
> http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_05
>
> As I understand it, a valid function can be:
>
> f1() echo "f1"
>
> Note the absence of { } around the command - these are for grouping and
> are theoretically optional although I am aware that bash requires them.
> The Help() function in mythcommflag-silence.sh doesn't include the
> braces and so is tickling this particular bug.  For reference I'm
> running Ubuntu and sh is provided by dash, what distribution and sh are
> you running?
>
> Pragmatically I updated the script to include the braces which should
> fix this problem.  Would you confirm that this change fixes the problem
> for you?  Thanks for your feedback.
>
> --
> Lawrence
>
> I'm running mythdora 12.23 aka fedora 12

Was this right ?

Help() { cat >&2 <<END
Detect commercial breaks in a TV recording using silence detection.
Usage: ${myname##*/} [options]
Options:
  -b <n>    Coalesce ad breaks upto [$MAXCOMMBREAKSECS] Seconds
  -c <n>    Channel ID
  -d <f>    Min silence duration [$SILENCE_DURATION] Seconds
  -i <path> Recording filename
  -j <n>    Job ID
  -s <s>    Start-time
  -t <n>    Silence threshold [$SILENCE_THRESHOLD] dB (-96..0)
  -C        Copy to cutlist [$COPYTOCUTLIST]
  -M <path> MythTV settings folder [$MYTHCONFDIR]
  -h        Display this help and exit
  -V        Display version and exit

A job ID, channel ID and start-time or a recording filename must be
specified.
END
}


I tried running with with dash but it doesn't seem to do anything

$ dash ./mythcommflag-silence.sh -i
/storage3/recordings/4010_20110929211000.mpg
$

Cheers,

Anthony
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