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authorChristophe Fergeau <cfergeau@mandriva.com>2010-08-02 12:40:35 +0200
committerChristophe Fergeau <cfergeau@mandriva.com>2010-08-02 12:40:35 +0200
commita5fad660c5746c711fa97a2dbbe01f175dcd0d40 (patch)
treeb5b9abee80a5ad4035985e4ae955c72edf18c275 /airtunes2.rst
parentMore detailed packet payload/UDP port descriptions (diff)
downloadAirtunes2-a5fad660c5746c711fa97a2dbbe01f175dcd0d40.tar.xz
Airtunes2-a5fad660c5746c711fa97a2dbbe01f175dcd0d40.zip
Clarify initial seq_num and rtp timestamp values
The initial Sequence Number and RTP Timestamp values to use in the RTP Audio packets can be specified in the RECORD RTSP request, this wasn't explicit through the spec, clarify that.
Diffstat (limited to 'airtunes2.rst')
-rw-r--r--airtunes2.rst11
1 files changed, 6 insertions, 5 deletions
diff --git a/airtunes2.rst b/airtunes2.rst
index 4af1764..6ec0e1b 100644
--- a/airtunes2.rst
+++ b/airtunes2.rst
@@ -25,8 +25,10 @@ Streaming audio to an AirTunes 2 compatible server
If encryption is necessary, a random key and IV (initialization vector) for AES
encryption, 16 bytes each, should be generated.
-Every stream has a timestamp (uint64; initially set to ``INITIAL_TIMESTAMP``,
-see Constants_) and sequence number (int16; initially set to 0) attached to it.
+Every stream has an associated RTP timestamp (uint32; initially set to a
+random number transmitted to the server in the RECORD RTSP request)
+and a sequence number (int16; initially set to random value transmitted to
+the server in the RECORD RTSP request).
Both are updated when sending audio packets. Audio data is encapsulated in
RTP packets which are sent sent as UDP packets to the audio port.
@@ -216,7 +218,6 @@ TIMESTAMPS_PER_SECOND 44100 Timestamps per second
TIMESYNC_INTERVAL 44100 Once per second
TIME_PER_PACKET FRAMES_PER_PACKET / 44100 Milliseconds
PACKET_BACKLOG 1000 Packet resend buffer size
-INITIAL_TIMESTAMP 0x10000000
===================== ========================= ==========================
@@ -292,9 +293,9 @@ Headers | ``Range: ntp={Note 1}``
Note 1: Normal play time (apparently always 0), float, >=0. (TODO)
-Note 2: Apparently a random number between 0 and 8192. (TODO)
+Note 2: Initial value for the RTP Sequence Number, random 16 bit value
-Note 3: Apparently always zero. (TODO)
+Note 3: Initial value for the RTP Timestamps, random 32 bit value
SET_PARAMETER
~~~~~~~~~~~~~