[mythtv-users] Helpful feedback

[John Pilkington]

On 16/04/18 04:26, James Linder wrote:
> 
> 
>> On 15 Apr 2018, at 8:00 pm, mythtv-users-request at mythtv.org wrote:
>>
>>> G?day all
>>>
>>> I?ve been struggling with the local (Australian ABC) HD H264 recordinggs. mythtranscode chokes and all my (undoubtably naive and silly) fiddling with ffmpeg trying to cut commercials fails (ie bitrate is so slow the picture is blocky) (ABC is a non-commercial channel but they sure pack in a lot of Next, Forthcomming, and what's on iView their streaming service)
>>>
>>> I?ve found Shotcut works well (well flawlessly) just a bit slow. The deinterlacer and interpolator are really good.
>>>
>>> James
>>
>> I've just updated mythTScut.sh at the foot of this page:
>>
>> https://www.mythtv.org/wiki/MythDVBcut
>>
>> You might like to try it.  Cuts aren't yet perfect but the transients
>> are usually short-lived.  Video and one audio stream only, two pass,
>> fast.  Desktop interface.
> 
> John for a bear of little brain (AA Milne) I’m totally confused by your script:
> 
> #  Suggested work sequence is:
> #     Preliminary test:  ~/mythTScut.sh /path/to/infile T 1
> #         which will read the database and process a cutlist but should not touch the recording.
> 
> What are we trying to achieve

To establish that the fundamentals are in place:  reading the cutlist 
and database without changing anything, before going ahead.  Terminal 
output is intended to be helpful (?) and the T option should be a 
one-off at setup time.
> 
> 
> #     ionice -c3 ~/mythTScut.sh /path/to/infile R 1 NC
> 
> Umm again what are we trying to achieve

This run seems to be needed to get rid of streams that ffmpeg doesn't 
understand in UK HD broadcasts.  And when I have gone on to the next 
stage without it the files have got much bigger.  I think it 
concatenated more than it was intended to....
> 
> #       It's best to establish the cutlist here, or at least to confirm its accuracy.
> 
> What does best do and what is not best, what does establish the cutlist here mean.

Use the MythTV recordings editor to set cutpoints at keyframes.
Check that you see what you want when the frontend plays over cuts. 
Sometimes if a cutlist has been established for the raw recording it 
might be slightly off after the NC run.

The next stage will do the cutting.  I suggested the V option so that 
the result will be a video and the original recording will still be 
available.  If you're happy with it you could mv or cp the file but it's 
probably easier to do it again with R 1
> 
> #     ionice -c3 ~/mythTScut.sh /path/to/infile V 1
> #     scan for new videos from the mythfrontend 'Watch Videos' screen
> #     ionice -c3 mythutil --rebuild --video /path/to/the/video/outfile
> 
> Again confused about what is happening

So, I'm afraid, am I.  But it's getting clearer.

This process obviously demands some effort and you might not want to do 
it often.  As it is at present any user will get to see a lot of 
diagnostics (and suggestions to fix your code to do it properly.)

I find the editor pretty quick, particularly since I'm only working at 
the keyframe level (and for my SD recordings with mythDVBcut I have 
found that entirely acceptable.)  The actual processing is much faster 
than real time.

At present playback by the frontend handles some cuts in 
recordings-with-cutlists more smoothly than those in the files produced 
by the script - but UPnP playback works for me and the commercials have 
gone.
> 
> I’m not trying in any way to dis your work, I just dont see how to use it
> Thanks so

I hope it will do what you want.  It will be obvious that I'm not a bash 
pro, and I'm still trying to get to grips with small differences between 
what myth does and what ffmpeg expects,,,

John

> James
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