[gstreamer-bugs] [Bug 606662] h264: add stream-format to output caps

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=606662
  GStreamer | gst-plugins-ugly | git

--- Comment #20 from Felipe Contreras <felipe.contreras at gmail.com> 2010-01-18 00:30:02 UTC ---
(In reply to comment #19)
> (In reply to comment #18)
> > That's because ffdec_h264 is wrongly adding a parser (only on byte-stream
> > mode), see gst_ffmpegdec_open().
> 
> "wrongly"?  Not in the current way of doing things.

Yes, wrongly, because it should not be needed.

> > It is possible to generate a muxed clip that
> > contains trimmed access-units, it would play fine on totem, but not ffplay
> > (mplayer, vlc, and pretty much everything out there).
> 
> I don't know what this means.  If this means "totem plays broken files better
> than ffplay", I'm ok with that.

It means gst-ffmpeg is doing something nobody is doing. Therefore we shouldn't
rely on that behavior.

> > This is precisely the reason why rtph264dec+ffdec_h264 only works on bytestream
> > mode:
> 
> Actually, I think it only works in bytestream mode because H.264 over RTP is
> only specified in bytestream mode.  Unless there's an RFC after 3984 that I
> don't know about.  It seems unlikely, though, since AVC format is fundamentally
> incapable of resynchronization after dropping packets.

RFC 3984 on section 1.1 clearly states that neither byte-stream nor avc are
relevant:

---
Annex B of H.264 defines an encapsulation process to transmit such NAL units
over byte-stream oriented networks.  In the scope of this memo, Annex B is not
relevant.
---

This means it's up to the decoder/depayloader to agree on an interface: could
be byte-stream, could be avc, could be something custom. It doesn't matter
because the RTP stream is different anyway.

> > /* FIXME, non-bytestream handling is freaking out ffmpeg. Apparently we need to
> >  * group all NAL units belonging to one frame together */
> 
> Of course.  That is how AVC format is defined.

Right, and the decoders out there assume the same for byte-stream format.

-- 
Configure bugmail: https://bugzilla.gnome.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.