How do I access the start offset displayed by ffprobe?

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allister
Posts: 1
Joined: Tue Oct 28, 2014 2:45 pm

How do I access the start offset displayed by ffprobe?

Post by allister » Tue Oct 28, 2014 3:29 pm

Hello!
I am new to ffmpeg but it has already proved to be a very useful tool.

I have a number of mp4 files recorded from different CCTV camera angles.
I am using the command "ffmpeg -itsoffset 1.2345 -i ch04_01:02:03.mp4 -c copy ch04_01:02:03_.mp4"
to set an start offset to a known frame e.g. when the time overlay changes to the next second.

I know that I can preserve this offset when cutting the files with -copyts.
This means that a new cropped file has an offset to the frame with the time I have selected.
This seems to work as I had hoped.

Now, I want to play my files in sync with each other.
I am playing multiple files in a C# application using axwindowsmediaplayer.
My problem is that this offset is not taken into account when playing.

So, my question is, how is this offset (start offset, start time or time stamp?) stored and how can I access it?
I know it is in the file, I can see it using ffprobe, even ffplay uses this value even if not to skip to the offset time.
Is the offset found in a particular atom in the mp4 file?

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