[mythtv-users] mythtranscode in V31

[John Finlay]

On 4/5/2020 12:08 PM, David King wrote:
> On 4/5/20 1:07 PM, John Finlay wrote:
>> On 4/4/2020 9:25 PM, David King wrote:
>>> On 4/4/20 2:41 PM, James Abernathy wrote:
>>>> I guess a detected commercial list is different from a cut list????
>>> True, they are indeed two separate things.  The "mythutil --gencutlist
>>> ..." command-line utility can be used to automatically generate a
>>> cutlist from the commercial marks.  But this would require a custom
>>> transcoding script, and since you're still going to manually edit the
>>> file to adjust the location of the cuts anyway, mythutil probably isn't
>>> an answer for you.
>>>
>>> I have a custom script that I use to do sort of the same thing that you
>>> are doing, except that my ultimate target is to put the cleaned up
>>> recording into a TV Series/Season folder in the Videos part of MythTV,
>>> not to have it replace the original recording file.  One of the things I
>>> learned when doing this is that the cuts made by running "mythtranscode
>>> --honorcutlist" outputing into a file aren't precise.  These cuts are
>>> made at keyframe boundaries.  So, when you're editing your recording, if
>>> you're putting your cut points on individual frames that are in between
>>> the keyframes, this level of precision is going to be lost when these
>>> recordings are transcoded.  The way to make precise frame-level cuts is
>>> to use the "mythtranscode --cleancut" option.  The problem with that
>>> option is that it requires that the output be directed into FIFO pipes,
>>> one for the audio and one for video.  Something else has to be running
>>> at the other end of those pipes, ffmpeg for example, reading the data
>>> from the pipes and encoding it into a video file.  Once again, this
>>> means writing your own script.
>>>
>>> If you decide to go that route:
>>>
>>> Here's a template for a custom transcoding script:
>>> https://www.mythtv.org/wiki/Transcode_wrap
>>>
>>> Here's the script that I use to transcode a recording into a video
>>> file.  It has lots of extraneous stuff in it that you might not care
>>> about, but it does show how I did the mythtranscode
>>> --cleancut->pipes->ffmpeg->file thing that I described above:
>>> https://github.com/dlk3/recording2video
>>>
>>> David King
>>> dave at daveking dot com
>>>
>>>
>> The last time I used mythtranscode specifying the lossless cut of
>> mpeg2 files with the -m (--mepg2) option the cutlist cuts not on
>> keyframes were honored by transcoding the section between the cutpoint
>> and the next keyframe while copying the parts between keyframes. Has
>> mythtranscode has been changed since then (0.29)?
>>
>> John
> I never tried the "--mpeg2" option.  It probably works just as you say
> it does, I'd have no idea.  I'm biased against MPG or TS files as being
> less compact than MKV (H264) files with similar quality.
>
> David King
> dave at daveking dot com
>
>

My process is to:

- set the cut points in the mpeg2 file
- lossless transcode to remove cuts
- transcode to h264 with handbrake or ffmpeg for archiving