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Could I Run a TV Station on Linux?
JesusQuintana asks: "I'm working with a low-power television station to update their playback system. Currently they're using tape and I've been tasked to move them to computerized playback (MPEG-2, etc.) There are proprietary solutions (very expensive) and there are companies that bundle software with Windows and standard x86 hardware. Overall, they are generally unimpressive and won't sell the software without bundling it with their own hardware. (They won't let us buy our own storage.) We have the expertise to build our own infrastructure (NAS, redundancy, etc.), but really just need the equivalent of iTunes for high quality video. There are lots of other pieces needed to complete the work-flow (such as encoding the media), which could be accomplished on Mac or Windows or even Linux. But what about playback? We need something that will play back these files at their scheduled times (perhaps scheduling cron jobs to change playlists) to broadcast quality hardware (SDI or YUV video). Could we run a TV station on Linux?"
With Linux, all you have to do is concatenate 6 strings on the command line and edit 3 configuration files and you can accomplish anything!
There some pretty good information about TV station automation here
It wouldn't even be all that complex.
MySQL database that indexes all content.
Also have a table for the schedule.
Batch job queues up content. As one piece of content finishes, next piece is queued up and plays.
All of this can be made fairly redundant without too much effort. Setting up your schedule can be point & click.
The real work will be if you want to make it fancier to give the advertising department more direct control over what ads run when, as opposed to having the programming manager schedule all of that.
All of this can pretty easily give you a very detailed automated log of what content played when, when you gave your station ID's, what ads played, etc.
Pick one good well known scripting language, learn it well, and use it. I'm not going to enter the holy war of telling you which one to use.
MySQL can be replaced with PostgreSQL if you prefer. Doesn't matter which. You're not keeping your content in the database, just an index of where to find the content on the filesystem plus the broadcast schedule.
The REAL work in all of this is making it resilient so you don't hit dead air. Redundant systems with automated failover, etc. And the cost of entry may be high, but I can't recommend highly enough that your content be stored on a redundant SAN or NAS infrastructure. Most of my long nights repairing things have dealt with failed hard disks. A decent SAN or NAS will allow you to rest easily at night.
Additionally a system like this will allow you to have a much more intelligent content-rich web site.
And I'm also sure there are people at Google who would love to talk to you about your ad delivery system if you put something like this in place. You would like to increase your ad revenue, wouldn't you? Google is working on breaking into this space in a big way. It would be worth making a few calls.
But implimentation is left as an exercise for the student.
KFG
Not to be a technology nay-sayer, but does this low-power TV station need all of this high-faluting stuff?
Sometimes I have visions of throwing a load of technology at a problem, and then leaving someone with a solution they can't run, maintain, or understand. And then they've leaped back even further in technology when it all becomes inoperative.
The thing you have to ask yourself, is do they really need it, and can they be updated to it without damaging them in the long run?
[ No, I'm not a complete luddite, I just wonder if this is a step they might actually be ready to take ]
Cheers
Lost at C:>. Found at C.
Everyone seems to be forgetting the little part about translating the MPEG compressed video into a broadcast quality NTSC signal, preferrably without noticable artifacting and color problems. Depending on the equipment, a simple TV-OUT port could be used, but would that really give the results a television station needs?
Also, let's not forget that he needs to future-proof his solution for digital transmissions. While there's tons of NTSC equipment on the market, what does one use to broadcast in digital? Presumably, he'll need encoders that are well suited to broadcast technology and an advanced digital to analog signal coverter at a minimum. He'll also need to understand whether he will have to support SDTV broadcasts, HDTV broadcasts, or both. If it's both, does his software support anamorphic encoding? If not, what is the hit from multi-encoding?
I'm barely even scratching the surface of the problems he's going to have. Right now, Linux has media software intended for home use. Setting things up for a professional television station is a whole other ball of wax that probably hasn't been considered yet.
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You can even write the entire program to run the station itself in a mere 11 characters of APL code.
Where were you when the voynix came?
If you're running off remote disks, then the NAS MUST be capable of greater output than is required to transmit, as you absolutely must allow for dropped packets and other glitches that force a retransmit. If there's not enough time to fix the problem, then you're going to transmit a picture with noise.
ALWAYS work ahead and cache pre-processed frames. There should be enough processed frames (encoded, digested and all ready to blast to the mast) that in the event of a failover (you DO have failover, don't you?
Your NAS should use a striped RAID array (although each stripe may also be mirrored). Striping is essential in keeping the data flowing fast, and your hardware should be geared to maximizing that throughput. Let the realtime handle the scheduling.
Don't bother using cron, or some other such userland service to start things. Exploit the FIFO queue. It won't run the next thing in the queue until the previous thing is finished. So long as you guarantee the stop time, you implicitly guarantee the next start time. You can then use cron to kill programs that overrun.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
In a way you are asking two different questions here, due to the technical difficulties involved with a TV station playback. So, lets put it this way then:
Do you require Frame Accurate playback? The reason that the profesional solutions you briefly mentioned are expensive and require their own storage are that they Garuntee frame accurate playback, no droped frames and everything else needed to playback everything flawlessly. One thing to remember about that, though. So long as you only keep the current days video on the server, you can stick with a video server with under 1/4 terrabyte of storage space (12Mbps vid+aud=~128GB) and have a seperate NAS for the next days video that just gets moved onto the video server throughout the day as what has already been played gets deleted.
The main problem with most consumer video playback I have seen is that it is not frame accurate. Even on a decent computer, most video programs don't run at exactly the framerate of the video using consumer playback programs. Also, unlike the profesional hardware, the consumer programs don't pre-buffer the next file for playback so that there is a delay between the end of one file and the beginning of the next.
We're also going to need to know what kind of outputs you want. Analog? What kind? SDI? HD-SDI What does your video router handle? Theoretically you could use a VGA/DVI output to a VGA/DVI-SDI adapter, if that's what you use. You'd also need to run it through a frame sync, but that's pretty standard for most stations anyway. Most likely you will not want to use the video card ouput of a PC, VGA/DVI/S-Video due to the need for then having a consumer program play it out.
For proffesional level playout you're going to want a card with hardware playback. SkyMicro and ViewCast make some playback cards that will run under linux that it looks like you could use. I'm just listing them as an example that showed up after a quick googling. These capture/playback cards are essentially going to become the heart of your system if you want something resembling a cheap profesional system.
So, as I said. It depends on how high end a system you want. However, it looks like it is possible to get a decent one going. One thing to remember, and I state it as habit, trial test whatever cards you are looking at before buying. Some of these cards can run to $2000 a piece and you're probably going to want redundancy.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
If you want to do it for real, take a look at the MLT project: http://mlt.sourceforge.net/
That has support for for example the Bluefish444 SDI cards, and do playout of real broadcast formats, such as DVCPRO, but also regular MPEG formats.
It also provides ShotCut, a really competent Non-linear editor, that can send edited clips directly to playout.
I know it is in use in one of Indias largest broadcasters, and they transmit to millions of viewers. So it would definitely be good enough for a small station like the one you are talking about.
Well, I've never run Linux for "years" but I'll share my experiences.
I think in the end it is about setting up any computer system to do the job it is designed for in a way that will continue until hardware wears out or power dies. Kernel patches and Security Updates are the exceptions. Windows has more critical patches but probably doesn't affect me as much as a lot of people, since I pair down my servers to not run software they don't need. For stability I usually use an enterprise system with security updates enabled which translates to almost never needing to reboot for security updates. Almost every security update is about software, not kernels in Windows, Unix, xBSD and Linux as long as you start out with a stable kernel.
Cliff probably would be well served by whatever OS he chooses as long as it supports the choice of software well. The trick will be finding software that serves the purpose well. My approach is to see first if there is OSS that meets the need well and then to look at commercial options if not or if they offer something that offers enough service or time savers to offset the cost. I think that the question that Cliff needs to be asking isn't about the OS but rather about what OSS software is out there for specific tasks and how it compares to propritary offerings.
B) Eliminate all the stupid users. This is frowned upon by society.
I wrote a long response to this, but screwed up and hit command-Q. I won't retype all of that, but here's a much more concise version.
The things you need are a scheduler (to determine which commercials air when), a program format spec file (to tell where in a program file the actual video begins and ends so you don't end up unnecessarily airing several seconds of black as you might if you just paused the playback of a TV show), and a mechanism for crossfading the audio between spots to handle the case where people run it right up to the wire. You need a switcher for the video---the ability to quickly change from one foreground full-screen video window to another without any glitching. This is a lot harder than it sounds. Finally, you need a player that can start pretty much instantaneously and without glitch in the middle of a program. I haven't found that to be true of VLC at all in my experience, but maybe it has improved a lot in the last few months....
For a possible controller UI, you might check out SongCue on SourceForge. I designed it for radio automation, but combine that UI with a preview pane above each controller and show a still frame from 5 seconds into a segment, and you have a UI that would work pretty well for what you're doing, too. Maybe even show live video in the preview panes during playback. (I wouldn't recommend the code from SongCue, though, as it's pretty much raw Xlib, not for the faint of heart.)
If I were writing such a thing, I'd start with a Mac OS X (10.4 Server) box. Xsan provides a supported mechanism for handling your storage needs. QTKit can do your playback, and Quartz Composer should make switching the foreground full screen movie pretty easy. The only potential snag I can think of would be that if you aren't careful, you could mouse over onto the live output signal, but all things considered, it's probably the easiest way to build an app that does what you want, IMHO.
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I know you didn't ask for any composting, editing, or formatting software. And I know you plainly asked for Linux. But you should really check out Final Cut Pro. It doesn't do what you want and doesn't run on the platform you suggested, but I used it once and it was great.
Mod me up informative!