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. Cheers, Rudy _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
