[FFmpeg-user] Is there a reason the default vsync for the mp4 muxer is not 2?

[André Hänsel]

>2018-05-23 16:24 GMT+02:00, André Hänsel <andre at webkr.de>:
>>>> I added -vsync 2 to the command line options and I got a file
>>>> that has roughly the same number of frames as the input.
>>
>>> But it is - unfortunately! - an invalid file.
>>
>> Is there a ticket/additional info about what is/can be invalid in this file?
>
>I don't remember atm, sorry, git blame may help you.

Hm, I found https://github.com/FFmpeg/FFmpeg/commit/91360ce61d00bb20429fb41857abebf50a5c6b1d. It says timespamps must start at 0 and that "causes sync problems" - is that about audio? I don't have any audio in my files, maybe that is why I'm not experiencing problems?

>> With -enc_time_base -1 -vsync 2 my output files seem just fine.
>
>Do you have access to an isom stream analyzer?
>If not, this discussion won't be very fruitful, sorry;-(

I usually use http://mp4parser.com/, which shows hex, which I cross reference with https://developer.apple.com/library/content/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html.