Dan, On Thu, 2009-10-01 at 23:20 -0400, Daniel Flesner wrote: > Andy Walls <[email protected]> writes: .
> i turned on more debug info and only got a single warning on the > recording tonight. OK. CPU and interrupt performance are not your problem. > >> > >> was wondering what else i can do to fix or help fix the problem, the > >> jitter can get annoying and sometimes mplayer crashes with corrupted > >> video and/or audio packets from the capture file. > > > > > > This sounds like a cable signal level problem. When capturing, please > > run femon in a terminal window and look for periods where the > > uncorrectable block count increases. If you get those, and the > > correspond roughly to when the artifacts occur, then cable TV signal is > > the problem. > > i ran femon during the capture tonight and did get what looks like some > bit errors. it ran predominately with the ber 0's messages, but once in > a while with the ber set to a non 0 value as below: > > status 1f | signal 013a | snr 0138 | ber 00000000 | unc 00000000 | > FE_HAS_LOCK > status 1f | signal 013a | snr 013a | ber 00000000 | unc 00000000 | > FE_HAS_LOCK > status 1f | signal 0138 | snr 0138 | ber 00000000 | unc 00000000 | > FE_HAS_LOCK > status 1f | signal 013a | snr 013a | ber 00000276 | unc 00000276 | > FE_HAS_LOCK > > so it appears it is a signal quality issue. Yup. Granted the mxl5005s tuner driver needs some tweaking (it's got 3 dB of loss for cable that we could probably get back, if I had access to MaxLinear datasheets and programming manuals), but there are other steps to take. BTW, the s5h1409 driver shouldn't be erasing the unc block count back to 0 after every read. If it is, I'll have to fix it. > i need an external amplifier > then i suppose? i did add a splitter and an extra line for the digital > input when i got the hvr1600 so maybe that is the issue. the splitter is > rated to 2300Mhz so that is fine right? Please read: http://www.ivtvdriver.org/index.php?title=Howto:Improve_signal_quality&action=history and remember that overdriving the tuner's front end with too much amplification can also degrade reception. 2.3 GHz should be fine (above L-band for sure, into S-band (?)). I don't know what your cable company uses for channel allocation, but I doubt they go that high. > what are acceptable values for > the signal and/or snr above? It depends. First I have to see what the values the mxl5005s and the s5h1409 driver are putting out mean, then I'll have to look up the theoretical SNR for QAM-256 an quasi-error free reception (BER < 10^-12) at various data rates. It may take me a few days. > > > > You should also be using the "-cache 8192" option with mplayer to > > mitigate the effects of any buffer delivery jitter or TS stream > > corruption. > > i do run mplayer with the cache flag. OK. You simply have a signal quality problem that results in corrupt packets that mplayer chokes on. > thanks again, > dan You're welcome. Andy _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
