Rudy Zijlstra wrote: > Manu Abraham wrote: >> Georg Acher wrote: >> >>> On Tue, Sep 18, 2007 at 02:50:09AM +0400, Manu Abraham 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 >>>> >>> I have h.264 playback running on a really slow Geode with 300MHz. For a >>> 15Mbit/s stream, the TS path from the DMA buffers into user space needs >>> about 5% CPU with traditional memcpy(). I wouldn't call that >>> optimization >>> worthy... What really counts is the postprocessing in user space >>> (remuxing, >>> repacking, etc.). The API may support this with single PIDs per >>> read filedescriptor, but I don't think it makes a difference where >>> the data >>> is actually filtered... >>> >>> >> >> You are looking at a single DVB-S2 demod. There are dual S2 demods in a >> single chip config. >> Consider that with multiple adapters, even if you ignore post processing. >> >> If you have a larger number of adapters and you have to do post >> processing, there is quite a large unnecessary overhead, even if you >> don't do software decoding. >> >> Are there only a very few people having multiple DVB adapters in a PC ? >> (I guess people having dual and quad demods (single demod/chip) on an >> adapter and having multiple adapters can be quite a small fraction) >> > 2 systems with each 4 DVB tuners. test system has 3 DVB-S + 1 DVB-C. > operational its 4x DVB-S > > The DVB-C is capturing H.264 though.... and not problems in capturing. > > capturing and demux is not the problem. Displaying it (postprocessing) is. True, the issue with post processing seems to be open ended. _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
