[FFmpeg-user] Can't write packet with unknown timestamp

[Michael Koch]

Mark,

>>> Okay. What can be concatenated? That purpose does the 'concat:' filter
>>> serve?
>>>
>>
>> What an big ignorance? You are using concat protocol.
>> Finally learn something....
>
> Like I wrote: What can be concatenated? What purpose does the 
> 'concat:' protocol serve?

There are three different things: concat demuxer, concat protocol and 
concat filter.
It's described here:
https://trac.ffmpeg.org/wiki/Concatenate

Michael