Manu Abraham wrote: > Janne Grunau wrote: > >> On Tuesday 18 September 2007 01:41:04 Manu Abraham wrote: >> >>> Johannes Stezenbach wrote: >>> >>>> On Tue, Sep 18, 2007 at 02:50:09AM +0400, Manu Abraham wrote: >>>> >>>>> Johannes Stezenbach wrote: >>>>> >>>>>> 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 >>> >> right the software decoder needs cpu power. >> >> >>> and then the options what you can look at >>> is cutting whatever overheads it is. >>> >> Wrong, you would start optimizing parts with take significant time. I >> can record 20mbps streams on a machine capable of decoding H264 1080p >> video with more than 99 percent idle. So even if you can optimize >> capturing the stream to taking zero cpu cycles (and you can't) you will >> see at most 1% increase in decoding speed. >> > > > The case of a 20Mbps stream getting recorded is not a great thing. when > you have a TS with symbol rate 27.5Msps, (capturing the complete TS) the > normal TS itself is about 27Mbps (in a very crude rounded off case) > > So, the situation that you have isn't larger than a situation having a > normal single DVB-S card. > > A single DVB-C card can go up to about 55Mbps when using QAM256... And more and more operators are now using QAM256 on cable. Cheers, Rudy _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
