Method and System for an Audio Pipeline Architecture
Described are the architecture of such a system, algorithms for time synchronization during a multiway conferencing session, methods to fight with network imperfections such as jitter to improve synchronization, methods of introducing buffering delays to create handicaps for players with faster connections, methods which help players with synchronization (such as a synchronized metronome during a music conferencing session), methods for synchronized recording and live delivery of synchronized data to the audience watching the distributed interaction live over the Internet.
1 . A method for smooth splicing wave fragment comprising:
selecting a time shift interval;
performing linear cross-mixing Wk W′k=Wk−x during 1-2 ms for backward time shift;
performing a forward time shift Wk W′k=Wk+x and performing linear cross-mixing during a time span of 20 ms if sound data in a playout buffer exceeds a threshold value.
2 . The method of claim 1 , wherein selecting a time shift interval comprises minimizing a value calculated by a function
F
(
x
)
=
∑
i
=
0
L
W
c
+
i
-
W
c
+
i
-
x
·
[
1
+
P
(
L
-
i
)
2
(
1
+
sign
(
i
-
(
L
-
X
0
)
)
)
]
,
where
x
∈
[
L
,
2
L
]
,
c is a number of a plurality of samples on which a procedure of information recovery is invoked, W k is a value of a discreet approximation of a wave function on a sample k, L is a length of a “sound window” used to find a pre-granular sound fragment, x is a discreet wave shift, P is a weight function, X o is a plurality of last received samples.
3 . The method of claim 2 , wherein the threshold value is 30 ms.
4 . A computer system including a playout buffer module, the playout buffer module comprising:
means for selecting a time shift interval;
means for performing linear cross-mixing W k W′ k =W k−x during a first time window for backward time shift; and
means for performing a forward time shift W k W′ k =W k+x and performing linear cross-mixing during a second time window if sound data in a playout buffer exceeds a threshold value.
5 . The computer system as recited in claim 4 , wherein the first time window is between about 1 ms-about 2 ms.
6 . The computer system as recited in claim 4 , wherein the second time window is about 20 ms.
7 . The computer system as recited in claim 4 , wherein the means for selecting a time shift interval comprises means for minimizing a value calculated by a function
F
(
x
)
=
∑
i
=
0
L
W
c
+
i
-
W
c
+
i
-
x
·
[
1
+
P
(
L
-
i
)
2
(
1
+
sign
(
i
-
(
L
-
X
0
)
)
)
]
,
where
x
∈
[
L
,
2
L
]
,
c is a number of a plurality of samples on which a procedure of information recovery is invoked, W k is a value of a discreet approximation of a wave function on a sample k, L is a length of a “sound window” used to find a pre-granular sound fragment, x is a discreet wave shift, P is a weight function, X o is a plurality of last received samples.
8 . The computer system as recited in claim 7 , wherein the threshold value is 30 ms.