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Some lessons from MythTV
Your editor's eighth-grade son was looking around for an end-of-year school
project. Fearing the alternatives (most of which seemed to involve
explosives), your editor made the logical suggestion: let's build a MythTV box together. That project looked
like a good Linux learning project which might just yield a device which
would be useful around the house. Plus, with what he thought was expert
Linux guidance (kids are so gullible sometimes), the project couldn't
fail.
Well, it didn't fail, but it was not always clear that a successful outcome was in the works. For the benefit of others who may be considering the creation of such a box, here's a few things your editor learned on the way. Do not expect it to be easy. Contemporary Linux users tend to be a spoiled bunch. For the most part, any of thousands of programs can be installed by way of a single package manager operation. Often these programs come pre-configured in some sort of minimally working way; finishing the job is just a matter of making a few tweaks. So what could be so hard about installing MythTV? After all, there are packages for many distributions just waiting to be used. Even with pre-built packages, installing MythTV reminds your editor of installing Linux back in 1993. Remember trying to come up with an XFree86 configuration file for a previously unknown monitor? MythTV is somewhat like that. There's a great deal of configuration to perform, and a lot of parameters to tweak. Get one wrong, and the whole thing fails in mysterious ways. Anybody who is not up for a long setup experience would be well advised to stick with simpler tasks - like writing new sendmail rulesets. Choose your hardware with care. MythTV requires a fairly strong system in general; it's not a suitable application for that Pentium 100 system gathering dust in the basement. A capable (but supported!) video card is required. Then, there is the issue of choosing a TV card.
And it does work, once one gets it configured correctly. That involves tracking down the firmware and putting it in the right place, ensuring that the correct modules get loaded (something that doesn't seem to happen by default), and going through a lengthy process of figuring out which stations can actually be tuned and carefully instructing MythTV to avoid all the others. That last step, incidentally, requires a development version of the dvb-apps package obtained from CVS. Then one finds out that, in order to cope with a high-definition signal, one needs a seriously fast processor; that 1.8GHz Athlon you have gathering dust in the basement just won't cut it. Meanwhile, getting plain old, low-resolution TV out of the card, while said to be possible, has proved to be a challenge in real life. Expect pitfalls. One of the many MythTV configuration screens is for setting up the TV card(s). One of the options given there is the pcHDTV HD3000. Every day, some well-meaning MythTV user probably tells the system that his or her pcHDTV HD3000 is a pcHDTV HD3000, while a hundred experienced users, if they only knew, would be shouting "NO, YOU FOOL! It's a trap!" at the top of their lungs. This poor user is heading for some significant pain; MythTV will never work in that configuration. As the battle-hardened veterans know, an HD3000 card should be configured as a DVB device (described in the documentation as "a video standard primarily found in Europe"). Then it will work. One can only imagine a legion of sadistic MythTV hackers leaving the pcHDTV-HD3000 option on the menu as a way of ensuring that beginning users spend more time staring at Google than watching TV. The allegedly easy path isn't necessarily so. Part of the work plan involved researching the best distribution for the creation of a MythTV box. What better way for an eighth grader to learn about how Linux systems are created? He quickly settled on KnoppMyth, which comes with claims like:
KnoppMyth can be installed in as little as 10 minutes (depending
upon your hardware speed) then all you have to wait for is the
first week of TV scheduling to be downloaded. If all your hardware
is supported under Linux, you may not have to edit any
configuration files.
Why bother with anything else when you can get all of the pieces off a single disk? KnoppMyth does not appear to be a project which receives a great deal of development time; the 5.0 release has been in the works for quite a while. A number of the download links on the main page are dead. It still uses version 0.18 of MythTV. More to the point, however: while one may not have to edit configuration files, nothing gets one out of the need to go through a couple dozen MythTV setup and configuration screens. There are dozens of operating parameters to tweak. TV cards must be set up. A separate step is required to set up video sources. Yet another step exists just to connect the configured TV cards with the configured video sources. Then there's the set of channel configuration screens. One has to figure out where the programming information will come from and set that up. Then one has to actually make the resulting combination work - something your editor never succeeded in doing. Among other things, KnoppMyth did not set up the video card (a Radeon 9250-based card) correctly in its XFree86-based graphics system, with the result that the XVideo extension was not available. Suffice to say that MythTV (along with lower-level tools like mplayer) is not happy without XVideo. So your editor dumped the whole mess and installed Fedora Core 4, which had no trouble figuring out the video configuration. The excellent Fedora Myth(TV)ology document made most of the rest of the setup relatively easy - modulo the level-60 secret incantations required to make the HD3000 work properly. Don't expect it to tell you anything.. The MythTV setup program will not work properly if the MythTV backend daemon is running. But it won't check for said daemon, and it won't say why it is failing. MythTV has a built-in logging system with eight log levels, but your editor has yet to find anything of interest there. Other things just fail silently, with no indication of why, for example, an attempt to watch TV in real time yields a black screen for ten seconds before returning to the menu. In summary: MythTV may have a lot of things to recommend it, but there is some work to be done to make it installable by normal people. Today's MythTV reminds your editor of installing early Slackware releases: a long and fiddly process with the occasional trap to avoid. The Linux installation problem has been nicely solved; if the target hardware is supported, putting together a Linux system to use that hardware is usually a straightforward task. What has been done for Linux as a whole can certainly be done for MythTV. Until it has been done, MythTV is likely to be inaccessible to many who would like to use it. Having written the summary, your editor would like to briefly touch on two other lessons. It's seriously cool. Once the system works, it does just what it is claimed to do. It can watch and record television, skip over advertisements, move around quickly in the program, handle multiple tuners, juggle conflicting recording schedules, work with a wide variety of remote controls, browse the web, play games, etc. Packaged in a suitably powerful and quiet box, MythTV could be a welcome part of one's larger entertainment complex. We may not be able to build MythTV boxes for much longer. The capabilities provided by MythTV go against everything the Powers That Be in the entertainment industry want us to have. As they continue to push for hostile legislation and DRM-encumbered hardware, they will eventually make the creation of a MythTV box impossible. Hardware which can tune in tomorrow's signals, and which makes the result available to software that doesn't know the secret handshakes, will be unavailable. MythTV is a powerful - if rough-edged - tool; it's how access to video programming should be. It would be a shame if MythTV were to smooth out the setup experience, only to be obliterated by legal systems worldwide. (Log in to post comments)
TV? What's that? Posted Mar 9, 2006 9:31 UTC (Thu) by dion (subscriber, #2764) [Link] I've been researching a MythTV box for years now, initially I wanted a box with one analog tv tuner (with mpeg encoder) and two DVB-s tuners for the rest of the channels, but without any luck.
The analog tuner is easy the PVR-250 fits the bill nicely.
The digital sattelite tuner, however, is impossible to get, as all interesting channels are encrypted and no support exists for cards with the needed decryption hardware.
If only supported dvb-s cards existed which could take a CAM module and an original smartcard then everything would work perfectly and several cards have come close.
In the last year or so the anti-customer antics of Viasat and Canal Digital have heated up and it's now impossible to buy a smartcard for either of those networks if you don't have an approved tuner.
I can't legally build a receiver and the approved ones are too limited for what I want to do (build a mythtv box) so I have concluded that TV is dead for me.
From now on it's DVDs and Internet all the way for me.
TV? What's that? Posted Mar 9, 2006 10:20 UTC (Thu) by drag (subscriber, #31333) [Link] Generally what people do for stuff that requires a seperate 'set top box' is to setup a irblaster doo-dad and program Mythtv to act as a remote control. This is fairly common thing to do.
Here is a inexpensive commercial one, but it's a favorite project for do-it-yourself'rs and there are plans aviable online for it.
This allows you to record encrypted stuff as well as possibly access 'premium' stuff such as pay-per-view and other items. I am not sure of all the capabilities of Mythtv, but I wouldn't be suprised if it supported stuff like that.
Also there are a very small number of set-top boxes that have firewire-out that is supported by Linux. I don't know much about those.
But I find that a bit distasteful. Screw the tv companies who don't respect their own customers.
TV? What's that? Posted Mar 9, 2006 13:11 UTC (Thu) by NightMonkey (subscriber, #23051) [Link] My serial IR blaster is this one: http://www.mytvstore.com/product_id_004.html
Works great, and they host a F/OSS MythTV-ready control code script. Very lirc-friendly... since it doesn't need lirc at all! That leaves LIRC to only handle your MythTV box's remote control.
Had this MythTV box with IR Blaster, PVR-350 (all S-VIDEO inputs and outputs, crystal clear), AMD Athlon 1600, 350 GB LVM2 partition for recordings (2x200GB 7200 RPM IDE Segate Barracudas), and Dish Network in a Shuttle SN41G2V2 (very quiet) running smoothly since August of 2004. Still waiting for some more bug fixing before making the jump to 0.19. Only pain is when Zap2It adds a channel to your channel list that you haven't subscribed to, and that channel has a show that you have a recording set for, you can lose any shows after that to hours of recordings of the "Subscribers only..." notice. I've got to figure out a way to mitigate that.
Some lessons from MythTV Posted Mar 9, 2006 10:42 UTC (Thu) by evgeny (guest, #774) [Link] I wholeheartedly agree with most of the article. A couple of months ago, I tried to setup a home-video PC. Having seen a rather positive media coverage ("MythTV is not a myth" or like in LJ etc), I expected it to be a reasonably easy task after some 10+ years of Linux administration experience. Alas! KnoppMyth was a complete disaster. Some directory paths were preconfigured wrong, MySQL authorization failed, etc etc. Given the general weakness of Knoppix-based distros to deal with normal Debian way of doing updates, I soon ditched it off the harddisk and installed Ubuntu with the corresponding MythTV packages. That was better, though I had to compile the newest (by then) kernel in order for the card (AVerTV Go 007) to work properly - this isn't a MythTV fault, of course. Then, many hours were spent on configuring the whole thingy (part done as root, another as the mythtv user, and yet another as the real user). In all the config screens, the mouse cursor was invisible, so I had to navigate using the keyboard (with rather weird keybindings). Probably this is specific to the video card; but all normal X apps didn't have a problem with the cursor. The setup... OK, I won't repeat what's said by our editor. Only a special twist: when finally presented with a non-blank screen, the picture was jumpy and interlaced in an exotic way (seemed like even and odd strokes came from different frames with some half a second delay). At first I blamed the driver, but xawtv worked flawlessly (BTW, why can't MythTV start with a _working_ zero-level "Watch TV" configuration like xawtv?). The reason was a wrong ALSA capture setting. Apparently, MythTV didn't get the audio bits, resulting in a buffer underflow, entering an error recovery loop breaking the smooth capture etc.
IMHO, the whole client/server separation is an overkill for 99% of usage cases. And then that MySQL. Why, or why should I run a full-blown SQL server in order to watch and record TV?! What's wrong with an embedded DB engine, let it be sqlite if SQL is a must?
Some lessons from MythTV Posted Mar 9, 2006 20:52 UTC (Thu) by NightMonkey (subscriber, #23051) [Link] Hmm... From the SQLite FAQ:
"Multiple processes can have the same database open at the same time. Multiple processes can be doing a SELECT at the same time. But only one process can be making changes to the database at an given moement in time, however."
This means that even on one box, every database transaction must be done serially. The mythtv backend would then have a difficult time spawning commerical-flagging and other child processes that need to update the database with new information, while keeping database access regimented. Not to mention having multiple frontends running concurrently - as I sometimes do when I want to watch TV from my laptop or desktop. Yes, just watching a recording might just be a matter of a few SELECTs, but what about deleting shows, scheduling programs, even changing channels on Live TV, etc. A networked database engine is the answer...
I appreciate your pain, though. :)
Some lessons from MythTV Posted Mar 9, 2006 21:52 UTC (Thu) by evgeny (guest, #774) [Link] Unless I'm mistaken, it's the mythtv-backend that talks to the database. So it _is_ a single process anyway.
Some lessons from MythTV Posted Mar 9, 2006 22:14 UTC (Thu) by NightMonkey (subscriber, #23051) [Link] Well, we were both slightly incorrect. :) After some grepping through the code, I found that mythbackend does process most MythTV database UPDATEs statements, with one apparent exception: mythfilldatabase, which populates the program information. This is on 0.18, however - 0.19 might do some things differently.
Multiple backends allowed Posted Mar 19, 2006 23:44 UTC (Sun) by lisch (subscriber, #36574) [Link] You can setup MythTV with more than one backend, so you can still have theproblem of multiple processes writing simultaneously to the database. In case anyone wondered, there are many reasons to have multiple backend servers. You might have many tuner cards, and you maxed out the available PCI slots in one server. I put the tuner cards in a slave backend, so I can reboot the system with the tuners without affecting playback (which is handled by the master backend).
Multiple backends allowed Posted Mar 20, 2006 8:31 UTC (Mon) by evgeny (guest, #774) [Link] Oh... Are talking about a home user???
Some lessons from MythTV Posted Mar 16, 2006 16:47 UTC (Thu) by quintesse (subscriber, #14569) [Link] The strange keybinding have to do with the fact that you are supposed to be controlling MythTV, including it's setup, using a remote control with only a limited number of useful buttons.
Don't blame me if you think that is silly, I'm just telling you what the devs decided on. (Which is a pity because MythTV can be very useful on a desktop machine but it doesn't lend itself very well for that).
Some lessons from MythTV Posted Mar 9, 2006 10:51 UTC (Thu) by wookey (subscriber, #5501) [Link] All I can really say is 'hear hear'. I already had a media box (for playing DivX and DVDs) which had been quite painless to set up using GeexBox, but when I tried to add a DVB-T receiver (USB NOva_T 2) and a hardware MPEG decoder to speed up my underpowered EPIA 800Mhz box (HOllywood+) I entered a whoile world of pain from which I have still not emerged, some 3 months after Xmas.
I did quite a lot of research in order to work out what I actually needed and what was reasonably possible with given hardware, and that bit seems to have worked out OK, but the whole process of getting it working is indeed highly reminiscent of the old days when everything was hard and cryptic and you spend your entire life wandering the web, mailing lists and web forums looking for little crumbs of clues that might help you on your way.
So far I've got very slow (3 frames/sec) video out of the DVB card and the hollywood card will only ever show me the picture in the left half of the screen, in the wrong colours, despite many hours of dicking about with module loading options, geexbox, debian, dvr, and xine.
Anyone who didn't do this sort of thing 'for fun' would have given up a long time ago. I also jealously note the Windows docs for my TV device which clearly shows that the software does the region-setting and scanning for you - you don't have to find out which transmitter you live near, the frequencies it transmits on, get config files containing the relevant info and then issue myterious commands to get it to search the frequencies in question for channels in order to generate another config file (in one of 3 possible formats) which you can copy to the right places before it will tune anything. I'm quite sure this bit is just a matter of writing some software which ecapsulates the config data and expert knowledge required, like all those installers and hardware detection routines which have made Linux-installations so generally painless these days. But that would be 3 evenings saved.
Hopefully I'll get it all working before _next_ christmans. And if anyone knows the answer to the Hollywood+ half-screen problem, I'd love to hear from them :-)
Some lessons from MythTV Posted Mar 9, 2006 14:09 UTC (Thu) by bronson (subscriber, #4806) [Link] The HD3000, last I checked, didn't offer hardware mpeg compression. That's folly, especially when trying to capture high definition! Only the very fastest computers (expensive with hungry power supplies) can transcode to decent MPEG2 in realtime. I wish I could support the HD3000 guys but I just don't have that kind of compute power in my living room. I ended up buying 2 Hauppauge cards instead.
And, I found that Knoppmyth is a myth. It didn't save me any time at all. I had a textbook setup: Epia M10000 with Hauppauge PVR350. How long did it take me to get everything working? Three days, off and on. I had to patch and re-compile LIRC to get the remote working. Then I found that the .lircrc shipped with Knoppmyth is totally broken. That took hours to fix. Then I ran out of disk space. Disk space? But 85 GB are still free! Turns out KnoppMyth creates partitions with barely any inodes to try to save a few hunnert MB. Lovely. Repartition hard drive, create filesystems by hand, re-configure mythtv... Finally, I ended up with a barely working system that I can never apt-get upgrade for fear of KnoppMyth vs. Debian package dependency hell. I should have just installed Fedora Core. It would have taken the same amount of time and, at the end, I'd have TV *and* a full Red Hat box in my living room.
A few weeks ago I dumped KnoppMyth for Ubuntu. Ubuntu boots WAY faster, has newer LIRC, and is much nicer to work with. I did have to compile the IVTV drivers but it turns out that's not too hard. I suppose KnoppMyth may have been good once but it's sure looking dusty to me.
Some lessons from MythTV Posted Mar 9, 2006 14:59 UTC (Thu) by Robin.Hill (subscriber, #4385) [Link] Isn't HDTV broadcast in MPEG2 format anyway? In which case there's no need for any compression at all - you just need to dump the stream directly to disk. That's certainly how it works for standard definition digital TV.
Some lessons from MythTV Posted Mar 16, 2006 22:55 UTC (Thu) by barrygould (guest, #4774) [Link] HDTV is closer to MPEG4 than MPEG2. (it uses H.264 encoding, fwiw)
Yes, it can be dumped to the harddrive, but if you want to watch it, it needs a lot of CPU time, especially if it's a 1080i signal.
The latest video cards have hardware acceleration for H.264 decoding, but I doubt there is linux support for that yet... it's only been around for a few months.
Barry
Some lessons from MythTV Posted Mar 9, 2006 15:47 UTC (Thu) by rknize (guest, #6917) [Link] Yes, the stream is already MPEG2, so there is nothing to compress. You do need some hefty CPU power to decode the HD stream, however. Also, the MPEG2 stream uses a lot of disk space, so some folks transcode the programming to MPEG4. MythTV lends it self well to doing these jobs in the background quite seemlessly. Again, a fairly powerful machine is needed to do this quickly.
I've been using Myth since 2002 when I dropped a $10 eBay frame grabber card in my old Dual P2 333 server box. Later I won a free XBox at work and that became the living room frontend. My wife was hooked within a week and soon and I had buy a second card (PVR-250). I probably spent about a week's worth of evening setting it all up (including modding the XBox).
My Dual P2 was huffing and puffing, but it could do it. Later I got a 2nd SqueezeBox and that forced me to upgrade the processors (Dual 850 P3s now). I guess what I am trying to say is that you don't need that much processor power if you are not doing HD, especially if you buy the Hauppage cards.
I've just recently picked up a pcHD3000 and built a powerful slave backend for it (which will double as the frontend, as it is located next to my HDTV). Everything he said about this card is true. It's been a week now and I still can't get it to tune QAM properly. Ugh.
Some lessons from MythTV Posted Mar 9, 2006 20:45 UTC (Thu) by HappyCamp (subscriber, #29230) [Link] As others have said. HDTV is already transmitted via ATSC as MPEG2. There is NO need for hardware MPEG compression in the card. All you need to do is transfer the data you receive to the disk.
Now the card does also have an NTSC tuner on it, and there is NO hardware MPEG encoding for that. But if you are buying the HD3000 you really should only be buying it for its HDTV capabilities and not for NTSC.
If you want NTSC then do buy a Hauppauge card (PVR-150, PVR-250, PVR-350, or PVR-500 are good choices).
Some lessons from MythTV Posted Mar 10, 2006 16:08 UTC (Fri) by arafel (subscriber, #18557) [Link] I don't know if there are any terrestrial free-to-air AVC channels yet, but I can't imagine they'd be too far away. Certainly the satellite companies have started AVC broadcasts already.
Some lessons from MythTV Posted Mar 16, 2006 14:59 UTC (Thu) by scharkalvin (guest, #7372) [Link] I have a pvr250 in a 933mhz PIII box which should be fast enough for analog stuff. I'd like to try the HD3000 if I can at least get the broadcast channels off my cable without having to un=encrypt them. I would not expect to be able to get the premium channels of course.
As for horsepower, I have a box with an Athlon64 at 2200mhz. Athlon64 systems should have enough horsepower, and are not too expensive. The low end dual core cpus are slowly dropping in price and should provide the required power for most applications. But I agree, that leftover box in the closet won't cut it, but you shouldn't need to go to something like Alienware unless you want to watch HDTV while compiling a new Linux kernel.
Some lessons from MythTV Posted Mar 9, 2006 14:31 UTC (Thu) by pbardet (guest, #22762) [Link] I'm not sure I completely agree with the way the information is provided. Sure, MythTV is hard to set up, but let's not forget that the current release is 0.19, which is far from a 1.00 release that is usually called user-friendly. BTW, 0.18 release is just 2 releases before the current one and published a year before. At this rate, we're far from a 1.00 release (never?).
I think that the KnoppMyth release (and other resources) make it sound like it's easy to use/setup MythTV when it's far from being the case. We're still dealing with "beta" software in which all the features are not setup completely.
I sure hope MythTV can soon access the 1.00 stage so that it can be a lot more widespread and people can realize the power of open-source when it comes to TV/entertainment, compared to a Vista enabled HTPC...
An alternative experience Posted Mar 9, 2006 16:42 UTC (Thu) by a9db0 (subscriber, #2181) [Link] My experience with Myth and Knoppmyth is quite different.
My initial install of Knoppmyth is on a PII 400 with 512mb ram and an nvidia video card, and a Hauppauge 250 as the video source and a Sound Blaster for audio. Not a powerhouse machine by any stretch of imagination. The install was surprisingly straightforward. Yes, I did have to go through dozens of config screens, but no real heavy tweaking was required. And it works. Now, WATCHING TV on this is a bit beyond its capabilities but it can be done. Audio is a bit choppy, but video is acceptable. The system works wonderfully as a backend. CPU utilization while recording is moderate (<30% on average). One reason for this is that the Hauppauge does MPEG in hardware, so the CPU doesn't have to. Video is stored on an 100GB partition NFS mounted off my file server.
I've got two frontends configured - both based on Kubuntu. Configuration there is simple - add the repositories, apt-get install mythfrontend, go through the config screens, and on the database page point the frontend to the system running mythbackend. Voila. Strong CPU / video helps here - one is an Athlon XP2500 with nvidia and it rund Myth in a window on my KDE desktop. The other is a PIII733 laptop, and I had to revert to the fluxbox window manager to free up the CPU and memory resources used by KDE to get smooth playback.
Frankly, I spent far more time and frustration trying to get the Thinkpad T21 to support TV-Out than I did on the entire Myth setup.
Some lessons from MythTV Posted Mar 9, 2006 18:25 UTC (Thu) by yohan555 (guest, #4253) [Link] I can feel the pain of the autor, I went pretty much through the same experiences. However, I was a bit more "lucky" in the choice of the hardware because I spent some time browsing through some user comments on the myth listserv archives. Because of that I ended up buying the Hauppage PVR 350 and I scrapped the ideo of using the TV-Out of any videocard and went with a VGA-to-TV converter instead. I also went with a fairly powerful machine, 2.5 GHz P-4, 1 GB Mem, 205GB SATA Harddrive. On the distribution side I again must have gotten lucky, because I picked Fedora, which is the distro I run on most of my machines anyway. Nevertheless, there was quite a bit of fiddling with the module settings in modprobe.conf involved until I finally got the tuner to work and the entire process from buidling to installation of the base system to configuration took an entire weekend. And yes, installation of the correct ivtv firmware was very important, a fact that took me a while to realize.
BUT: once I had the box up an running, I was extremely happy. It works really well and does everything that people promise. I watch a lot of AVI videos through the box and use it also to play music that's stored on my home server in addition to recording TV shows. So, is it worth it? I definitely think so. Rather then being locked into a vendor solution that may not exactly fit my needs AND is associated with a monthly fee, I have now retained the ability to both easily upgrade hardware and software. The new version of MythTV now also has a Netflix module, which is quite neat if you are a subscriber of Netflix.
Some lessons from MythTV Posted Mar 11, 2006 22:52 UTC (Sat) by giraffedata (subscriber, #1954) [Link] What does the Netflix module do?
Some lessons from MythTV Posted Mar 11, 2006 23:28 UTC (Sat) by pivot (guest, #588) [Link] Why didn't you try VDR? If the DVB driver is set up properly, then VDR, with the softdevice plugin, will be running in no time.
http://www.cadsoft.de/vdr/
I've been waiting for a grumpy editors guide to HTPC setups..
Some lessons from MythTV Posted Mar 15, 2006 21:33 UTC (Wed) by jeskritt (guest, #4092) [Link] I setup a mythtv box over a year ago using a WinTV-PVR 350 and an nvidia card for tv output following the instructions at Fedora Myth(TV)ology it was pretty easy. Only took an afternoon to get setup and running nice.
It's worth the pain Posted Mar 19, 2006 23:51 UTC (Sun) by lisch (subscriber, #36574) [Link] I agree that setting up MythTV can be difficult. I spent a lot of timetrying to get my setup working the way I like. Now that it works, however, I must say that it was worth the effort. I have two HD-3000 tuners, and a 300 GB hard drive to store recordings. HDTV is glorious to watch. My wife and I can watch different shows on our respective computers. I organized the recordings to keep children's programming separate, so the kids can watch only programs that I have approved. The only problem is that we find ourselves watching more TV than we used to...
Some lessons from MythTV Posted May 15, 2006 3:10 UTC (Mon) by Andyt123 (guest, #37747) [Link] Im not one to add my 2cents but reading this makes me want to comment. Ivebeen using Mythtv for around 3 years, I think they were around the .14 release then. I use to upgrade to cvs once a week. Things were good then, it was still hard to setup but was not to bloated like it is today. I dont use Mythtv anymore, why? because there is no direction, what do the developers want in the end? a full blown window manager with multimedia capabilities? Useless features keep getting added and the things that matter get left out. Who needs opengl effects like fading? What about when it comes to actually watching TV? First it takes upto 10secs to start playing and on an interlaced TV, like most people use the picture is no where near as good as the cheapest stb's on the market. The dependencies the program relies on is a joke, Mysql? wtf??!! then you got X servers, Window manages, QT ect.... Does mythtv really need to be so bloated to watch TV, movies, play music ect ? Look at vdr, I can run vdr on a 600mhz celeron with 64meg of ram with software decoding and it all fits on a 128mb flash disk with room to spare. Look at the dreambox, 200mhz ppc cpu, 32mb ram, I know it has a hardware decoder but all the osd and graphics are done by cpu, its not as pretty as mythtv but it work and who need pretty to watch TV. The Mythtv GUI should be smaller, and have no X dependency. DirectFB is a perfect output method for Mythtv, even though there is allready support for DirectFB its quite old, doesnt work with the gui and will no longer compile with latest svn. What about supporting some hardware mpeg cards ? As of the last 3 months I do not use Mythtv anymore. Ive made the switch to VDR and am happy with the features it supplys. With VDR's Softdevice output you can software decode mpeg2 ( actully any codec ffmpeg supports )and output the decoded frames to directfb with sync on Vblank so you get good motion with no tearing. If a Matrox G4x0 is used with interlaced TV you have an allmost perfect picture with no scaling and good motion ( no jerking and tearing ) and you dont have to run the deinterlacer to make it look good because the output method cant interlace properly. I know Mythtv is only at .19 and vdr has beed in development much longer and is at a stable 1.4.0 but can you see how large it will be when it gets to 1.0.0. I just think the Mythtv developers need to take a good look at the video output methods, shouldnt this be number 1 on the list? I guess when everyone has got progressive scan TV's the problems with interlaced TV will go away, but its going to be some years yet. Dont get me wrong, I like Mythtv, I wouldnt comment if I didnt but I also want to watch TV and Mythtv doesnt let me do that with ease. What I would like to see is the frontend gui to cater for embedded systems. I would like to run mythtv frontend on top of DirectFB with no X server on the system, take out the Mysql database and go for something lite, have a builtin db or even just a config file. Some support for hardware mpeg decoders like DXR3, FF DVBS and PVR350. Ok PVR350 works allready but you still need bloody X!!!!!! as Mythtv svn wont compile with qt embedded anymore! DXR3 and FF DVBS are only decoders so you cant run GUI on then even though xine manages to put its gui on dxr3. By losing X and Mysql you can customise your system to startup in under 10 secs instead of the nearly 60+secs it needs. Then Mythtv will be like usefull PVR. I could go allday but I dont have time. Just my 2c
Some lessons from MythTV Posted Jun 21, 2006 6:45 UTC (Wed) by Cal (guest, #38536) [Link] After spending well more than 50 hours messing with Myth (installing, studying, tweaking), I agree with most of what's said here. I'm on my 3rd Myth OS, Fedora Core 5.
I now have a reasonably functional Mythtv system, but the end result still has a few glitches and lacks some important video features, compared to a Windows PVR. Without my many hours invested in tweaking, the performance would not be acceptable at all to me.
Many of the Myth deficiencies should be blamed on the poor video card support for Linux. Nvidia is the card of choice for Myth because ATI does not support mpeg2 decoding features like XvMC (Linux) or DxVA (Windows) under Linux. I'm amazed no one has filed suit or a complaint with the FTC against the preference given to Microsoft by ATI and Nvidia. Even though Nvidia chips support XvMC, they lack some desirable features like progressive decoding of mpeg2 source containing RFF (repeat first field) flags to produce 24 fps "film" output. Most HD movies and shows aired on HBO, Showtime, Starz, etc. are actually progressive video with the 3:2 pulldown encoded in the mpeg2 stream. This is not possible with Myth.
The second major shortcoming of an Nvidia graphics card under Linux is the lack of a video overlay when running twin or "cloned" displays. The overlay under Windows is also limited to one display but Windows solves the problem with a high performance non-overlay render/mixer, VMR9 (Video Mixing Renderer 9). On a mid to high-end ATI card, VMR9 provides performance at least as good as the older overlay mixer, but allows such performance on multiple displays to be realized. DxVA performance isn't half bad with an Nvidia based card either.
The alternative to the video overlay under Linux just doesn't hack it and,with Myth as you must accept some level of video "tearing" or audio/video sync problems when running multi displays. I've found that without OpenGL sync and the overaly, you'll have tearing on a single display too. Not all Nvidia cards support and overlay; the 6xxx series does not, I understand. OpenGL sync works with multi displays and the blitter, but some programs exhibit A/V sync problems instead.
Even worse are the "prebuffering pause" stutters but, with settings tweaks, the problem can be confined to unobjectionable and brief periods after channel changes --at least I think so; I'm always surprised to find some program that doesn't play well with my settings after I think I've found perfection! Not all mpeg2 transport streams are alike. :(
So, with a single display, I've triumphed over most of the problems. One nasty problem remains, however--a seek bug. Myth often fails to seek (fast forward, typically) and either advances the timeline display, but not the video; pauses for a very long time; or locks completely. Some recordings exhibit this behavior and some don't but it's very repeatable with the recalcitrant recordings. I think Myth is confused with some mpeg stream timestamps. Perhaps it will be fixed one day. Maybe Myth will support analog and digital from the same card too, one day.
Cal
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