Gstreamer with h264 annex b

[Michał Wróbel]

On 05.03.2015 13:06, sivan wrote:
> When I open it with wireshark, I see the format is different then annex b:
>
> I don't see the 00 00 00 01 sequence that suppose to be in the beginning of
> each frame
That's perfectly OK.

Actually, RFC6184 specifies that 00 00 00 01 sequence inside an RTP
packet would be an error:

"This payload specification can only be used to carry the "naked" H.264
NAL unit stream over RTP and not the bitstream format discussed in Annex
B of H.264."

Please, don't violate this rule. Even if many H.264 stream receivers
seem to parse such packets without any error or warning.

On 05.03.2015 14:43, sivan wrote:
> How can I use the current gstreamer to get the h264 frames and I also need the sps and pps from the stream
According to RFC6184, it is acceptable to have SPS and PPS inside an RTP
packet stream. It is called "in-band signalling of parameter sets".
However, it is not recommended when an unreliable medium is used:

"If in-band signaling of parameter sets is used, the sender SHOULD take
the error characteristics into account and use mechanisms to provide a
high probability for delivering the parameter sets correctly. 
Mechanisms that increase the probability for a correct reception include
packet repetition, FEC, and retransmission.  The use of an unreliable,
out-of-band control protocol has similar disadvantages as the in-band
signaling (possible loss) and, in addition, may also lead to
difficulties in the synchronization (see below).  Therefore, it is NOT
RECOMMENDED."

It may be done to work reliably, but requires some special attention.
Many receivers/decoders will wait for SPS/PPS before attempting to
decode the video. Some do not - they try their best to decode, most of
the time without success, which results in a glitch when starting to
receive the stream.

An typical out-of-the-band signaling of parameter sets is to provide
description of the session via SDP (in a file or on-line via RTSP -
check out gst-rtsp-server).


Having that said... if you still want to just stream RTP with in-band
signalling, here's a gst-launch oneliner for x264enc:

gst-launch-1.0 videotestsrc ! 'video/x-raw, framerate=30/1, width=640,
height=480' ! queue ! x264enc tune=4 ! rtph264pay ! udpsink
host=224.0.0.1 port=5000

However, here it is x264enc which inserts SPS/PPS into the stream at
each keyframe.


If you have a stream without SPS/PPS (from some other encoder), use
config-interval property of rtph264pay.

Best regards,
Michał Wróbel

-- 
Michał Wróbel
Software developer

michal.wrobel at flytronic.pl
mobile phone: +48 501 386 897

Flytronic sp. z o.o.
UAV R&D Center
www.flytronic.pl
tel. +48 32 461 23 50
fax  +48 32 461 23 54
ul. Bojkowska 43, 44-100 Gliwice
NIP:969 151 39 93, REGON:  240851769, KRS  0000298330, Sąd Rejonowy w Gliwicach, X Wydział Gospodarczy Krajowego Rejestru Sądowego

-- 
Niniejsza wiadomość jest przeznaczona tylko dla jej adresata i nie może być ujawniona osobom trzecim. Jeśli nie jest Pan/i zamierzonym adresatem niniejszej wiadomości bądź osobą przez niego upoważnioną do jej odbioru lub przekazania adresatowi, informujemy, że jej rozpowszechnianie, dystrybucja, kopiowanie lub inne działanie o podobnym charakterze jest zabronione. Jeżeli wiadomość dotarła do Pan/i omyłkowo, prosimy o poinformowanie nadawcy oraz usunięcie wiadomości z poczty bez otwierania załączników. Dziękujemy.

This e-mail is intended solely for the addressee(s) and must not be disclosed to third parties. If you are not the addressee of this e-mail or has not been authorized by the addressee to receive or forward this message, we inform that its disclosure, distribution, copying or any other similar action is unlawful. If you have received this e-mail in error, please notify the sender immediately by return e-mail. Please then delete the e-mail from your mail box without opening attachments. Thank you.
--