> On May 28, 2025, at 6:47 PM, Mark Filipak <markfilipak.i...@gmail.com> wrote:
>
> On 28/05/2025 18.46, Alex Xu wrote:
>> I put it there since it was in Huspnet's original command.
>
> Ahem!
>
>> I don't think it
>> matters,
Sorry, I should have made it clear that I'm a hobbyist (in case my post didn't
adequately do that for me). Also, I probably shouldn't have included "-r 24" in
my example without further explanation. I have had better audio sync by using
either "-r 24", "-r 23.976" to specify output frame rate, but that only helps
when I add a frame rate input specification to the beginning of the filter
chain, such as "fps=30000/1001" ("29.97" may be accepted there instead, but I
think it has not always been so). I've also tried ""-fps_mode vfr" instead of
the "-r" specification so I could try "mpdecimate" after "decimate" to clean up
remaining duplicates. I am becoming convinced the the duplicates that remain
after applying "decimate" result from telecine errors in the source video. If
that is true (that I'm transcoding video that contains flaws), then, for my
most commonly transcoded sources, my best audio sync has been achieved using
"-vf fps=30000/1001,fieldmatch,decimate" in the filter chain, then "-r 23.976"
to specify output frame rate. But that's just my experience. I really need to
be working on a passage of an hour or more's duration to make a reliable
assessment. Also, I worked out a pretty robust way to adjust audio tempo for
cases where the audio sync isn't maintained, so I'm not left with no recourse
when sync issues occur. I've done that by creating a script which asks me for a
value in milliseconds for the duration by which the audio is away from the
video at the end of a clip, and reminds me to precede the value by using "-"
(minus) first if the audio is too short. It's an AppleScript, but the basic
functions are easily decipherable for any of you who may be interested in
adapting for your own scripting systems, so I'll be happy to share on request.
L. Lee
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