Streaming 1080p24 H264/AVC and MPEG4/AAC, lip synchronization using gstrtpbin, unable to link in video_00? (bug?)

[Martin Lund]

Hi,

I'm on a mission to have a server stream a file containing H264/AVC
and MPEG4/AAC to two other hosts. One of these hosts will play the
video stream and the other will play the audio stream. I need A/V lip
syncrhonization between these two hosts so as far as I understand I
need to use the gstrtpbin plugin in order to utilize the RTP/RTCP
protocol to obtain this kind of synchronization.

I'm playing around with gst-launch to test the RTP/RTCP stuff. My
server pipeline is based on the RTP reference example found here:
http://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/tests/examples/rtp/server-v4l2-H264-alsasrc-PCMA.sh

This is the basic server pipeline I'm trying to configure (assumes it
all running on the same server, ie. no "host=" stuff):

gst-launch
                \
    gstrtpbin name=rtpbin
                \
        filesrc location=battleship.mp4 ! qtdemux name=demux
                \
            demux.video_00 ! queue ! rtph264pay !
rtpbin.send_rtp_sink_0               \
                  rtpbin.send_rtp_src_0 ! udpsink port=5000
                \
                  rtpbin.send_rtcp_src_0 ! udpsink port=5001
sync=false async=false    \
                  udpsrc port=5005 ! rtpbin.recv_rtcp_sink_0
                \
            demux.audio_00 ! queue ! rtpmp4apay !
rtpbin.send_rtp_sink_1               \
                  rtpbin.send_rtp_src_1 ! udpsink port=5002
                \
                  rtpbin.send_rtcp_src_1 ! udpsink port=5003
sync=false async=false    \
                  udpsrc port=5007 ! rtpbin.recv_rtcp_sink_1

This fails to link in the video stream?

With debug enabled it spews out various errors regarding
demux:video_00 and queue0 unable to connect:

GST_ELEMENT_PADS gstutils.c:1101:gst_element_get_compatible_pad:
finding pad in queue0 compatible with demux:video_00
GST_PADS gstutils.c:1032:gst_pad_check_link: trying to link
demux:video_00 and queue0:sink
GST_CAPS gstpad.c:2336:gst_pad_get_caps_reffed:<demux:video_00> get pad caps
GST_CAPS gstpad.c:2246:gst_pad_get_caps_unlocked:<demux:video_00> get pad caps
GST_CAPS gstpad.c:2250:gst_pad_get_caps_unlocked:<demux:video_00>
dispatching to pad getcaps function
GST_CAPS gstpad.c:2263:gst_pad_get_caps_unlocked:<demux:video_00> pad
getcaps returned video/x-h264, stream-format=(string)avc,
alignment=(string)au, level=(string)4, profile=(string)high,
codec_data=(buffer)01640028ffe1001c67640028acd94078067b016a020202800000030080015f90078c18cb01000668ebe08cb22c,
width=(int)1920, height=(int)816, framerate=(fraction)45000/1877,
pixel-aspect-ratio=(fraction)1/1
GST_ELEMENT_PADS
gstutils.c:1195:gst_element_get_compatible_pad:<queue0> Could not find
a compatible unlinked always pad to link to demux:video_00, now
checking request pads
...
GST_ELEMENT_PADS gstutils.c:1829:gst_element_link_pads_full: no link
possible from demux:video_00 to queue0
default gstutils.c:2037:gst_element_link_pads_filtered: Could not link
pads: demux:video_00 - queue0:(null)


Yet, the same troublesome pipeline elements is tested to work
perfectly for direct streaming when not in combination with gstrtpbin:

gst-launch filesrc location=battleship.mp4 ! qtdemux name=demux \
demux.video_00 ! queue ! rtph264pay ! udpsink port=3000 \
demux.audio_00 ! queue ! rtpmp4apay ! udpsink port=5000

So obviously demux:video_00 and queue0:sink can actually connect.

What I don't understand why my server pipeline does not work in
combination with gstrtpbin... Might this be a bug or am I missing
something here?

I'm testing on Ubuntu 12.04, gstreamer: base 0.10.36, good 0.10.31,
bad 0.10.22.3.

Any help/input is appreciated.

Br, Martin

P.s. The clip I'm using is found here
http://download4.dvdloc8.com/trailers/divxdigest/battleship-trailer2.zip