seeking in fragmented mp4 files

Sebastian Dröge sebastian at
Wed Apr 9 23:40:08 PDT 2014

On Mi, 2014-04-09 at 12:47 +0200, Lajos Okos wrote:
> Hi,
> I'm testing fragmented MP4 files with the playbin pipeline. The files play
> fine unless I want to seek in them. Seeking doesn't work. The reason seems
> to be the qtdemux that is forwarding the seek events upstream if the mp4
> file is fragmented. I don't need any of the smooth streaming functionality,
> I have the audio and the video tracks in a single mp4 file and I don't want
> to change bitrate. The reason I'm using fragmented mp4 is that the files
> are in record while playback should start.
> Is there a way to catch and handle the forwarded seek events from qtdemux
> in the application? What should the seek handle do?
> Should I construct a different pipeline with opening some type of a
> manifest file rather than the media file itself? How should the manifest
> file look like in this simple case?

If you would use a manifest file then the seeking would work as usually
with fragmented MP4 the upstream elements are responsible for seeking...
and then just provide the fragment that contains the requested position.

To make this work without that you will have to change qtdemux to fall
back to trying to seek itself on fragmented MP4 if upstream failed to

Sebastian Dröge, Centricular Ltd -
Expertise, Straight from the Source
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