osmux only lags ~0.15 ms at maximum to transmit one scheduled RTP message
according to my tests with PCAP traces.
Yes, only ~0.15 milliseconds, this is not wrong :-).
This is good news, our timer infrastructure seems to be quite precise.
This fixes the algorithms to include the messages in order in the
batch based on the TRP SSRC (from lower to higher).
This is very important to reduce the amount of bytes that we
spend on the osmux header.
This patch cleans up the transmission path for osmux, this involves
the functions that extract the messages from the batch and the one
that reconstruct the timing.
They now take a list that contains the reconstructed RTP messages:
osmux_xfrm_output(osmuxh, &h_output, &list);
osmux_tx_sched(&list, &tv, tx_cb, NULL);
This patch adds the counter field to the osmux header, so we can
reduce the size of the batch even further, eg.
osmuxhdr (ctr=3)
speech
speech
speech
osmuxhdr (ctr=2)
speech
speech
...
The new header is the following:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FT | CTR |F|Q| SeqNR | Circuit ID |AMR-FT |AMR-CMR|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The counter field is 3 bits long, thus, we can batch up to 8
RTP speech frames into one single batch per circuit ID.
I have also removed the RTP marker, since it can be reconstructed
from the AMR information.
Moreover, the entire workflow has been also reworked. Whenever a
packet arrives, we introduce it into the batch list. This batch
list contains a list of RTP messages ordered by RTP SSRC. Then,
once the batch timer expires or the it gets full, we build the
batch from the list of RTP messages.
Note that this allows us to put several speech frame into one
single osmux header without actually worrying about the amount
of messages that we'll receive.
The functions that reconstruct the RTP messages has been also
adjusted. Now, it returns a list of RTP messages per RTP SSRC
that has been extracted from the batch.
This function schedules the transmission of a RTP message that was
obtained from one osmux batch. It takes the time (in microseconds)
after which the message should be transmitted.
I was using AMR CMR 2 (15 bytes) as the initial tests were done
with the codec variant.
This patch fixes this by using the new generic osmo_amr_bytes
extracted from 3GPP TS 26.101.
This patch splits osmo_rtp_parse in two functions:
osmo_rtp_get_hdr
osmo_rtp_get_payload
So we can validate corrent RTP header to access its fields. Then,
obtain the payload.
This patch adds the osmo-pcap-test infrastructure that allows you
to take packets stored in one pcap file, convert them to msgb and
pass it to some function.
The infrastructure also provides timing reconstruction based on
the pcap file information.
This is useful for easy protocol development, automated testing and
fuzzying of the existing code to validate the code.
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
This patch adds the initial RTP support for libosmo-netif, it's based
on Harald's RTP support available in openBSC.
I have also added a couple of example to show how our new channel
infrastructure interacts with the RTP layer.
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
Pablo Neira Ayuso