| SLAP (Staggered
Layered Audio Protection) is Multicast Technologies transport
mechanism to reduce the effect of time correlated packet loss
on an audio stream. Multiple encodings of a stream are delivered
to the client in a time delayed manner. |
| Consider the
following example (XX denotes packet loss). |
+----+----+----+----+----+----+----+----+----+----+
160kbps MP3 stream | 14 | 13 | 12 | 11 | 10 | XX | XX | XX | 6 | 5 |
+----+----+----+----+----+----+----+----+----+----+
|
| Normally,
when an MP3 player hits this gap in the stream, there will
be an audio defect. However, with SLAP this gap is repaired
transparently. |
| |
+----+----+----+----+----+----+----+----+----+----+
160kbps MP3 stream | 14 | 13 | 12 | 11 | 10 | XX | XX | XX | 6 | 5 |
+----+----+----+----+----+----+----+----+----+----+
|
+----+----+----+----+----+----+----+----+----+----+
32kbps MP3 stream | 10 | 9 | 8 | 7 | 6 | XX | XX | XX | 2 | 1 |
+----+----+----+----+----+----+----+----+----+----+
|
|
| As you can
see, the packet loss occurrs at the same time in both substreams.
But, since the second stream was intentionally delayed to
compensate for such loss, packets 7, 8, and 9 can all be recovered
from the 32kbps substream! |
| For more information
on SLAP please contact our Tech
department. |
