What's difference result when I setup -frag and -dash with MP4Box?

Question

I have read MP4Box Doc about Mpeg-Dash, but I don't clearly understand about "MP4Box -dash 10000 -frag 2000 largeFile.mp4" and MP4Box -dash 10000 -frag 1000 largeFile.mp4. When I open the *.mpd File I found the duration of SegmentList is 10023(about 10 sec). If the -frag 2000 or 1000 is no used?

I'm designing a HTML5 Video Player(like this sample), and I using MP4Box tool to create DASH Video. But I don't clearly understand what's the difference when I convert my video with -frag 2000 and 1000. For example: I don't the mean about my video with 10 second segments and 1 second fragments. maybe My Video Player do not need to set this option?

Are you sure this question is *programming* related in a way [compatible with the site's rules](http://stackoverflow.com/help/on-topic)? — fvu, May 17 '17 at 11:11

score 1 · Accepted Answer · answered May 17 '17 at 19:31

1

GPAC contributor here. It is difficult to help you without a full example. I stronlgy recommend to describe bugs on our bug tracker (https://github.com/gpac/gpac/issues).

When I open the *.mpd File I found the duration of SegmentList is 10023(about 10 sec). If the -frag 2000 or 1000 is no used?

Three points:

1) You probably get 10023 ms (instead of 10000 ms) because you may use an old version of MP4Box. Please consider using the latest version.

2) Fragments are an MP4 feature and is not seen at the MPEG-DASH level. Segments is also an MP4 feature (basically a segment contains fragments) that is seen by MPEG-DASH. Therefore you can't see it in the MP4 but it may have consequences on your playback.

3) The blog article you mention (http://gpac.io/2011/02/02/mp4box-fragmentation-segmentation-splitting-and-interleaving/ contains all the information you need. If you think we can improve it, please leave a message there. Thanks!

answered May 17 '17 at 19:31

R. Bouqueau

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Thanks, I don't know the concept before that a segment contains fragments. The comment feature of MP4Box Blog is closed. – scott1028 May 18 '17 at 00:21
So If I just want to divide my video by 10 seconds, I only need to set `-dash 10` (segment duration) and make my player to read this *.mpd right? – scott1028 May 18 '17 at 00:32
I will ask for the blog post comments. – R. Bouqueau May 18 '17 at 11:10
Yes, ```-dash 10000``` (it is in ms) will do the trick for you. – R. Bouqueau May 18 '17 at 11:10

What's difference result when I setup -frag and -dash with MP4Box?

1 Answers1