RE: Simultanous PID!?

["Thomas 'Dent' Mirlacher" <dent@cosy.sbg.ac.at>]

On Tue, 30 Apr 2002, Maciocco, Christian wrote:

> That's a limitation of hardware based MPEG-2 TS decoder, usually limited to
> 8, 16 or 32 PIDs. Software based decoder such as the one available with
> Windows XP BDA (Broadcast Data Architecture) where the full MPEG2 TS is fed
> out of the tuner to the software decoder there is no PID limit beside your
> available memory.

just a remark: there are also capable implementations for other OSes out there.

filtering itself is not a problem with memory.

quick calculation:
	2^13 PIDs. - so a lookup table would have 2^13bits, which is 1KB.
	(most current computers have more then that :)

	... also if you have a table with one byte per PID (because you
	want to lookup a specific encapsulation, which you're binding
	to the PIDs, this shouldn't be a problem (8KB))

the only problem you could have with memory is if you have all the datastreams
interleaved on all the PIDs (for simplicity assume we're using all the PIDs
for network data), also another thing we will not account is the overhead
for encapsulation (and TS headers)

worst case memory usage for reassembling/decapsulation:

	(MTU-184)*2^13	... around that at least.

and with an MTU of 64K this would lead to 64M if i'm correct. - this
could well be some problem, but with a smaller MTU=1500, we need 10M
for reassembling the data. (worst case)

	++Thomas	

-- 
in some way i do, and in some way i don't.