Re: 1394 and compressing analog Re: [mythtv-users] Beginner Question
Ian Forde wrote: 1. HD2000/3000 with QAM drivers 2. Firewire Option 1 drivers don't exist yet, so test captures can't be done. Option 2? I can capture already. It's just not in Myth. It seems like a faster way of getting more HD users on myth in the short term until the (option 1) drivers are ready. As it turns out, they're also the only possibly likely ways to watch HD for those who can't put up antennae for HD. (ie - I live in an apartment!) The good news is that for someone with the hardware and some C++ experience, it should be simple to add this capability to MythTV. You just need code to change channels, grab data from the FireWire port, and spew it into the ringbuffer. You also have to watch the stream so you can mark keyframes into the database. hdtvrecorder is good example code, though it does more processing. It's possible the stream may need to be munged in some way -- you can test this now by doing a capture into a file, then do 'mythtv filename'. If it plays properly, the decoder is capable of playing the raw files, and you're good to go. -Doug signature.asc Description: OpenPGP digital signature ___ mythtv-users mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: 1394 and compressing analog Re: [mythtv-users] Beginner Question
On Sunday 19 December 2004 16:00, Brad Templeton wrote: The bad news is those firewire streams out of the cable box or satellite box are going to be encrypted and/or the box will refuse to send them to any device that doesn't have the authentication codes licenced from the oligopoly. (ie. 5C etc.) You won't get them for an open source box. I was under the impression that the FCC mandate meant that the FIreWire output had to be unencrypted, though it could be downsampled to a lower resolution. So, you couldn't get HD resolution out of the box, but you could at least get direct digital access to some form of the content, even if it is only 480i or 720p. Personally, I'd be reasonably happy with that, from a picture quality perspective. What really burns me up is the fact that in order to access all of the content I pay for, I'd *still* need to rent an additional box from the cable company per tuner (unless they're not encrypting any of it, which is unlikely with Comcast). Also, regarding the 'authentication'/5C stuff, etc., I thought that everything was required to work with pre-broadcast flag devices (i.e., devices manufactured sold before July 2005). -JAC ___ mythtv-users mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: 1394 and compressing analog Re: [mythtv-users] Beginner Question
On Monday 20 December 2004 12:54, Joe Barnhart wrote: --- Joseph A. Caputo [EMAIL PROTECTED] wrote: I was under the impression that the FCC mandate meant that the FIreWire output had to be unencrypted, though it could be downsampled to a lower resolution. So, you couldn't get HD resolution out of the box, but you could at least get direct digital access to some form of the content, even if it is only 480i or 720p. No. 720p IS a high def output. You would get 480 only. Oops. No matter, resolution isn't a big issue with me since I have a 60 projection TV with only composite and RF antenna inputs, so a high-def signal doesn't do much for me. It's not likely that I'll be in the market for a high-def set for some years. But I hear the cable systems are already playing fast and loose with their interpretation of the rules, i.e. encrypting some content (e.g. broadcast stations) that should not be encrypted. True. I'd suggest writing to or calling your cable provider if you find out that they're encrypting things they shouldn't (i.e., local broadcast stations). Let them know that doing so may violate FCC regulations and that you would like a response. If they don't respond to your satisfaction (or at all), report them to the FCC (not likely to produce results, but if everyone does it, it may get some attention). -JAC ___ mythtv-users mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: 1394 and compressing analog Re: [mythtv-users] Beginner Question
On Mon, Dec 20, 2004 at 01:19:46PM -0500, Joseph A. Caputo wrote: Oops. No matter, resolution isn't a big issue with me since I have a 60 projection TV with only composite and RF antenna inputs, so a high-def signal doesn't do much for me. It's not likely that I'll be in the market for a high-def set for some years. Better stay away from them. Like the PVR/Tivo/Myth, Hi-def is one of those hard to go back things. Once you watch a few shows in hi-def, your old TV and 480i shows in general look blurrier than they did before. Though I don't think it's as much of a must-have as a PVR (which is odd because it costs a lot more). It varies on the type of show. Watching sitcoms in hi-def is nice. Dramas are also nice. Shows with cinematography like nature shows and travel shows are a major difference. Sports can be a whole new experience especially if the camerwork is done assuming HDTV. ___ mythtv-users mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: 1394 and compressing analog Re: [mythtv-users] Beginner Question
On Monday 20 December 2004 15:08, Brad Templeton wrote: On Mon, Dec 20, 2004 at 01:19:46PM -0500, Joseph A. Caputo wrote: Oops. No matter, resolution isn't a big issue with me since I have a 60 projection TV with only composite and RF antenna inputs, so a high-def signal doesn't do much for me. It's not likely that I'll be in the market for a high-def set for some years. Better stay away from them. Like the PVR/Tivo/Myth, Hi-def is one of those hard to go back things. Once you watch a few shows in hi-def, your old TV and 480i shows in general look blurrier than they did before. Though I don't think it's as much of a must-have as a PVR (which is odd because it costs a lot more). It varies on the type of show. Watching sitcoms in hi-def is nice. Dramas are also nice. Shows with cinematography like nature shows and travel shows are a major difference. Sports can be a whole new experience especially if the camerwork is done assuming HDTV. For me the big difference would be end-to-end digital content (i.e., no issues with analog signal quality, luminance/chroma issues with TV tuner chips, faded analog TV-out... just MPEG source content and DVI-out, even at crappy ol' NTSC resolution would be a big step up for me. After that, HD content is just the icing on the cake :-) -JAC ___ mythtv-users mailing list [EMAIL PROTECTED] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
1394 and compressing analog Re: [mythtv-users] Beginner Question
On Sun, Dec 19, 2004 at 10:06:19AM -0800, Ian Forde wrote: On Sun, 2004-12-19 at 09:20 -0500, Joseph Caputo wrote: What you want to do *may* be possible, as the FCC has required cable operators to provide an enabled FireWire port that you may use to capture the digital (MPEG) data that your cable box has decrypted (but not decoded). The catch is the content accessed via FireWire will not be HD... any HD content will have been transcoded down to a lower resolution (say, 480p). In any event, Myth does not currently support capturing video over FireWire. Yep - about that - there's a new library called libiec61883 (available from www.linux1394.org in subversion) that supports firewire capture. I've been testing that capability with massive amounts of assistance from Dan Dennedy, it's author. (He also wrote ddr1394.) I've gotten it to capture HD streams with a sample program that he wrote, so a release may be soon forthcoming. I've got packages available too, if anyone wants to test the capability. What we need now is for someone to take a look at the sample capture code included in the package and adapt it for use within Myth. Anyone? Actually, I'm more interested in the reverse, having Myth stream the mpeg to the TV over 1394 or DTVLink as they now call it. I got some code from the linux 1394 guys that may be on the path to doing that. The reports are that dtvlink mpeg streaming is not a lot different from dv streaming for camcorders, which is what all the past linux projects have been doing with video. Also on the plus side, I believe that mpeg includes a bitmap overlay that can do on-screen-display -- is this what is already done when using xvmc and OSD? The one component that would be missing would be menus over firewire. You would need to write a framebuffer driver which took each frame and compressed it to dv format or mp2 format and streamed that out. Though who knows, perhaps you could fake something with a blank mpeg and the bitmap overlay? Alternately, I believe on many TVs they display a regular analog input until the mpeg comes and they switch to it and back. For extra credit you would interpret the remote control backchannel so the tv's remote control controlled myth. I don't know enough about firewire protocols to make this happen. The bad news is those firewire streams out of the cable box or satellite box are going to be encrypted and/or the box will refuse to send them to any device that doesn't have the authentication codes licenced from the oligopoly. (ie. 5C etc.) You won't get them for an open source box. On another note, the original question asked one of the most common mis-questions when it comes to HDTV. Analog, uncompressed HDTV could be captured by an analog capture card but probably not any of the ones people use for orindary NTSC TV which I doubt have the bandwidth. Even if they did have the bandwidth, you would need to convert it to a compressed form in real-time. Hardware to do that to mpeg-2 is thousands of dollars (though it might become cheaper.) In truth you probably would not use a capture card because it would make far more sense to record DVI, which is already digital, and for which decoding chips are available. It's possible you might be able to pull of something less ambitious than mpeg2 though, but it's hard to figure if it could be done in software with today's processors. Without compression the files would of course be giant. 186 megabytes per second at 8 bit per colour capture. 671 gigabytes per hour. Yikes... That is in fact beyond the capacity of your disk drive to write. You would need dedicated multiple spindles with striping. However, another option that might be possible is to figure out how much compression you _could_ pull off in real time with a fast CPU, such as a 3.4ghz P4. Say you could do a very basic compression in hardware or software and get it down to 100 gigs per hour (7 to 1). Then at least you can write it to your dedicated disk. And from there you could start up a thread on another processor to, in non-real time, compress it to mp2 or mp4. You might even take 2 stages, one that is fast but not quite real time, and another that is slow but much better compression. Why? Well, the problem is that if you are spitting out 100 gigs/hour, it will take a lot of disk space even to temporarily hold an hour. You probably can allocate a 400gb disk and hold 4 hours. Once that's full, you can't record any more, not until your compression threads can free up disk space. So if you have a long event or long movie you can't record anything else until the next morning. And of course 400gb disk drives are still somewhat expensive but that will drop. Forget about having 2 tuners without having 2 computers, each with a fast processor, giant disks and encoder card. It all depends on how much you can pull off with
