[linux-dvb] DVB API update

Manu Abraham abraham.manu at gmail.com
Tue Sep 18 01:41:04 CEST 2007


Johannes Stezenbach wrote:
> On Tue, Sep 18, 2007 at 02:50:09AM +0400, Manu Abraham wrote:
>> Johannes Stezenbach wrote:
>>
>>>> If you would like to fix that in V3, i would much appreciate. If you
>>>> would just like to keep talking only, maybe lets then not talk too much
>>>> about it.
>>> The recording filters are exactly the piece from V4 which has the
>>> "mmap DMA buffers" zero copy API. But to be honest, I don't think
>>> it's important on a PC which can copy > 1GByte/s in RAM. More
>>> interesting would be the ability to have multiple independant filtered
>>> TS outputs instead of just one dvr device.
>> Currently have you tried playing back a High Bit rate H.264 stream
>> default of a DVB-S2 stream ? I guess not.
>>
>> If you have had, you will see my reasons why i am trying to optimize the
>> overheads.
>> BTW: it is not RAM that matters here, but CPU horsepower
> 
> A demux doesn't decode, and what matters is memory bandwidth.

Try running a software decoder alongwith and tell me that that decoding
doesn't need CPU and then the options what you can look at is cutting
whatever overheads it is.

Finally even memory bandwidth comes to a bottleneck at the CPU FSB. Try
capturing a High bit stream while playing along. After a while, you will
also think in the same lines of optimizations.
The problems arise when one person just talks without doing anything.
This is the root cause of all problems.

Some people call it: It's all fart and no shit (about just talking along
and doing nothing)

Manu




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