Your info is not quite exact or authoritative. > -----Original Message----- > From: Matt Hallacy [mailto:poptix at poptix.net] > Sent: Wednesday, October 07, 2009 6:39 PM > To: Chuck Cole > Cc: TCLUG List > Subject: Re: [tclug-list] OT channel frequencies > > > Chuck, > > You're going well beyond trolling here. Let me break it down for you > into something so simple you can't possibly feign ignorance. > > There is a magical piece of coax with multiple signals on it, they could > be NTSC, PAL, HDTV, FM, AM, etc. utilizing one of many "channel plans". > > The TV tuner card is connected to the coax and is capable of providing a > digital representation of various analog signals, most importantly in > this case, NTSC. He never said any of that was within his question. THAT was part of my inquiry. > There are drivers in Linux for these TV tuner cards, they use a > standardized API called Video4Linux. > > VLC has support for Video4Linux. > > To tune into a *channel*, you must tell the TV tuner card (and thus, > VLC) what *frequency* to tune. This value is expressed in kilohertz > because that is the resolution a lot of 'tuner cards', which Video4Linux > supports, are capable of. Mine are already channelized and frequency is not explicit. Further, tuners and analog frequency are not within VLC as was originally the ONLY context. > Now for your various comments: > > "Capturing from a "TV tuner" would be an analog video baseband signal. > Capturing from a tuner card in a PC would be digitized after > A/D conversion. Neither of those signal types match your descriptions. > Neither has channels in the signal, or mere kilohertz > bandwidth." > > The TV tuner card provides a digital representation of the analog signal > (or in the case of an HD capable tuner card, the raw signal). To be just > as pedantic as you are, those signals are fully capable of supporting > channels inside the stream (most HD channels do). Nobody said it was > less than 999 KHz of bandwidth either, only that the channel center > frequency must be expressed in KHz for precision. The analog signals have that capability, but the digital VLC interface of this question does not have anything but digital data. > > "Much better answer, but does he really have a tuner which indicates TV > channels in kilohertz? I seriouly doubt that any of us have > such an animal. I have tuner cards, fancy USB connected tuners, and > Slingplayer as well as ordinary TVs and VHS tape machines with > tuners that are all interfaced and none has any mention of actual TV > frequencies." > > Every TV tuner card I've ever owned (and I have owned at least 30) has > required that the software tune it into a frequency. You cannot simply > say 'channel 23, GO!' and have the hardware understand *which* channel > 23 you mean. "Channel 23" in the USA alone can be at least four > different frequencies (217,250, 216,010, 217,262 and 525,250 KHz) > depending on the source of the signal. You may have had *software* that > made an educated guess about which channel plan you're using based on > questions it asked you, but in the end the software was telling the > hardware to tune into a specific frequency. Mine select TV channel numbers and their drivers do the rest. That is 100% digital and never touches analog frequencies except by the way chips in the tuners translate digital commands to tuner parameters within those chips. > > I have no idea what your hang up is with KHz vs. MHz, it's the same > frequency, just with less decimal places. Didin't ask your opinion of that. He mentioned very low kilohertz for some reason when the much higher megahertz range seemed more relevant. Yu could try reading the context and threads of this before pontificating. > "No: frequency selection in that is ONLY by choosing digital data, but > not handling actual analog signals in any direct way. It's > only a digital data format issue, and the data would be in some psuedo-code. Frequency per se is not an issue, but > digital encoding > format for that data type or the data format to read brand and model of tuner would be relevant." > > I hope you realize how incredibly ignorant this statement was by now. Not ignorant, it's 100% accurate for what VLC itself does, and THAT was the question. Apparently you are out to lunch on what this thread actually stated. Much of your peripheral data is valid, just outside this specific scope of discussion. Chuck