* Mark Burton on Friday, April 14, 2017 at 22:44:52 +0100
>> On 14 Apr 2017, at 22:22, Christian Ebert <[email protected]> wrote:
>>>> Also, when you run with -v verbose, you'll see a delay (depends
>>>> on audio codec), for you case it's probably 1024. Maybe try:
>>>> 
>>>> -filter:a aresample=first_pts=0,asetpts=PTS-STARTPTS+1024
>>> 
>>> 1024 looks correct. This method successfully changes the start, and the 
>>> encoded audio plays, almost, 100% in sync. Its slightly cut off at the 
>>> head, but only very slightly. However the downside of this method is that 
>>> the audio now overruns the end of the picture further and is not trimmed 
>>> from remaining samples I’m guessing. This results in a blank video frame 
>>> being added to the tail of clip. ffprobe for ffmpeg_v3 attached.
>>> 
>>> I tried using -shortest, but that didn’t help address the above issue.
>> 
>> Inserting
>> 
>> -t `ffprobe -v quiet -of default=nw=1:nk=1 -select_streams V -show_entries 
>> stream=duration SyncTest24p.mov`
>> 
>> into your commandline should do the trick.
> 
> Adding '-t 2.000000’ to the command does help a little, but ultimately the 
> final audio packet is still too large - 6ms in this case - and the black 
> frame still occurs.

Works for me with all my sample results I checked.

Somewhat counterintuitive, but you never know:

-filter:a aresample=async=1:first_pts=0,asetpts=PTS-STARTPTS+1024

combined with the -t incantation.

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