[gst-devel] Where'd the timestamps go?

Stefan Kost ensonic at hora-obscura.de
Wed Apr 14 15:17:49 CEST 2010


hi,
Wes Miller wrote:
> What i want is to copy a single jpeg image t some to be given timestamp from
> a saved MJPEG-in-a-matroska-file a into a jpg file.  Actually, to pick out a
> list of individual frames from the saved stream and put them individually
> into separate jpg files and then later to reassemble them.  A crude foorm of
> stream editing to be fancied up later.
>   
So you have a mkv file of lets say 100 frames and you like to have
frames 5, 36 and 82 saved to individual jpegs?
Some ideas:
- you can write an application that does:
 - filesrc location="file.mkv" ! mkvdemux ! appsink
 - save the wanted buffers to separate files from the appsink callback
- or
  - filesrc location="file.mkv" ! mkvdemux ! multifilesink
  - have a buffer probe on the video src-pad of mkv and drop all not
wanted frames
- or
 ...

Stefan
> My problem is that i just seem to be missing the ah-ha moment on writing
> gstreams in programs.  The book gets me mouth wateringly close but I can't
> quite yet form the questions into word that it isn't answering.  As I
> learn/figure out more....  Unless someone wants to volunteer a pretty
> complete example of connecting up sometimes and request pads in C.  :-)
>
> In the mean time, I'd like to analyze the stream-in-a-file outside gstreamer
> to pick out the frame I want.  So knowing where it stuck the timestamp would
> help.  Only problem is, where ever it is stuck it is not ASCII.  A hex dump
> of the file is massively unhelpful until you learn the flags and find where
> the content "elements" are in the file.  e.g. FFD8 starts a new jpeg.
>
>
>   





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