[gstreamer-bugs] [Bug 623678] New: qtmux: Write AAC/H.264 bitrate if available

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=623678
  GStreamer | gst-plugins-bad | unspecified

           Summary: qtmux: Write AAC/H.264 bitrate if available
    Classification: Desktop
           Product: GStreamer
           Version: unspecified
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-bad
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: arun at accosted.net
         QAContact: gstreamer-bugs at lists.sourceforge.net
      GNOME target: ---
     GNOME version: ---


This collects avg/max bitrate tags for streams if available, and writes them
out if possible (to the ESDS for AAC streams and "btrt" atom for H.264
streams). The AAC patch is fairly straight-forward, but the H.264 patch needs
some explanation.

As far as I can tell, the "btrt" atom (called MPEG4BitrateBox in the spec) got
dropped from ISO/IEC 14496-15 sometime after 2004. The newer spec drops this
box in favour of using using the UUID PROF box which goes just after "ftyp" and
is somewhat more comprehensive. Unfortunately, we don't always have enough
information to populate it fully (for example, does the stream have a variable
bitrate/frame-rate, is it protected, etc.). Given this, I think it makes more
sense to just use the "btrt" atom till we have a convincing reason to not use
the uuid instead.

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