How to tell if faststart for video is set using ffmpeg or ffprobe

Question

I am having trouble figuring out how to determine if faststart is set on an MP4 video.

I understand that "moov atom" is the data that needs to be located at the beginning of the file for faststart to be enabled, instead of at the end of the file.

I specifically want to use ffmpeg or ffprobe to determine if it has been moved to the beginning or not already.

On a side note, I understand I can run the following command to move it from the end to the beginning (but I want to find out if it is already there):

ffmpeg -i infile.mp4 -map 0 -c:v copy -c:a copy -c:s copy -c:d copy -c:t copy -movflags +faststart outfile.mp4

Answer 1

Run

ffmpeg -v trace -i file.mp4 2>&1 | grep -e type:'mdat' -e type:'moov'

This will produce an output like,

[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000036ca40] type:'mdat' parent:'root' sz: 62740 48 65044 [mov,mp4,m4a,3gp,3g2,mj2 @ 000000000036ca40] type:'moov' parent:'root' sz: 2264 62788 65044

Since moov appears second, it is at the end in this example.

On bash-like shells, escape the single quotes:

ffmpeg -v trace -i file.mp4 2>&1 | grep -e type:\'mdat\' -e type:\'moov\'

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For Windows, findstr can be used,

ffmpeg -v trace -i file.mp4 2>&1 | findstr /l "type:'moov' type:'mdat'"