[mythtv-users] mac build (really about h264 editing)

[Leo Butler]

John Pilkington <johnpilk222 at gmail.com> writes:

> On 01/03/2021 11:39, James wrote:
>> 
>>> On 1 Mar 2021, at 7:06 pm, Dennis Alders <dennis.alders at gmail.com> wrote:
>>>
>>> James,
>>> I am interested in the h2643cut.sh script. Could you share it with me?
>> Dennis it is here
>> http://tigger.ws/downloads/h264cut.sh
>> I have a directory structure
>> /store
>> searching eg 0301 lets you choose the recording
>> you need a work dir. Mine is /store/TScut_work
>> Finally my destination hierachy is. /store/Movies/Myth-A .. Myth-Z
>> <enter> chooses the destination based on name, but you can override eg I don't want 'The Jackal' stored under Myth-T rather Myth-J
>> but heck it's a bash script, hack it as you will.
>> I've not had a failure in 100s of cuts.
>> James
>> 
>>>> On 30 Jan 2021, at 14:31, James Linder <jam at tigger.ws> wrote:
>>>>
>>>>
>>>>
>>>>> On 30 Jan 2021, at 9:18 pm, John Hoyt <john.hoyt at gmail.com> wrote:
>>>>>
>>>>> I think it is fixed
>>>>>
>>>>> Great!
>>>>>
>>>>> John P - a big thank you for pointing me to the solution!
>>>>
>>>> Also
>>>> cut the video
>>>>
>>>> I've got an h263cut.sh based on what someone posted a year or 2 ago
>>>>   generate a cutlist-times
>>>>   use mythffmpeg to cut each segment based on those times
>>>>   use mythffmpeg to concat each segment
>>>>
>>>> When all is done, a minute, the resultant file has no errors
>>>>
>>>> Mail me if anyone wants a copy
>>>> James
>
> Hi James:  You kindly sent me that script at the time.  I had to hack
> it because I didn't have your directory structure, but when I got it 
> working the results had serious A/V sync problems.
>
> I noticed that it used the 'demux' mode of concat in ffmpeg, rather
> than the 'protocol' version, and I have tweaked one of my scripts the
> do the same.  I'm still experimenting and am now reasonably happy -
> but I'm still not sure why I got the A/V sync problem and you
> presumably don't.

I would guess that the audio and video in your recordings are more out
of alignment. I found that when I was using the concat demuxer.

I would recommend using the concat filter

https://ffmpeg.org/ffmpeg-all.html#concat-3

This allows one to cut and transcode in one pass, whereas with the
concat demuxer, one needs two passes.

I have implemented this (in guile scheme)

https://git.sdf.org/nb0yjxtr/ffmpeg-mythtv.git

See:

https://git.sdf.org/nb0yjxtr/ffmpeg-mythtv/src/branch/master/ffmpeg-myth.scm

Leo