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2010-04-30T12:49:00.001+01:00

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Blackmagic Videohub & RS422

2010-04-19T13:03:00.007+01:00

I've talked about BlackMagic's router range - the VideoHub before but never installed one of the larger 72x144 models.
They are very thin! Where you'd expect the cables to terminate at the back of the bay these have to be long enough to terminate at the front of the cabinet.

Here are a few notes relating to it - it's amazing that you can buy a 3G-capable HD-SDi router (with RS422) for around ten grand. To do the same with Probel et al would be north of £50k. However - there are a few things you lose with your budget router.

Remotes control - although in the past I've mentioned how the VideoHub can't do the TX/RX crossover that all 'proper' matrices do (i.e. they know how to handle controlled/controlling devices) they have introduced this in v.4.3 of the control software (that runs on a USB-attached Mac or PC - can can even re-share control over a network so you can run the same control applet on your Avid/FCP workstation). In v.4.2 you had to declare what a device was - either a 'deck' (a controlled device) or a 'workstation' (a controller). This falls down when you think about doing two-machine front panel editing between two VTs - the recorder becomes the controller and so you have to go into the labels menu and temporarily declare that VT a 'workstation'. The reverse is true if you want to run your Avid in VTR-emulate mode (when the timeline can be controller like a piece of video tape). We thought 4.3 was the answer to all our RS422-payers but it doesn't work that well - and when it gets it wrong you have to keep making and breaking the route in the hope that it gets it right. So - we're sticking with v.4.2 (BlackMagic s/ware archive in the title link).
Touchscreen - our customer wanted a touchscreen to control the software which works quite well - I'd recommend at least a 19" 1280x1024 res screen as a 17" is fiddly.

Of course - in a non-TX environment these things may not matter. It really is a very good deal!

Why did late 60's/early 70's rock singers have two mics taped together?

2010-04-15T09:57:00.005+01:00

I've been enjoying "Guitar Heroes at the BBC" on BBC4 where they compile clips from Whistle Test, Rock goes to College, TOTP etc. I've always wondered why rock singers from a period of only a few years would have two mics taped together. By the time I was paying attention in the late 70's the practice seemed to have stopped so I suppose it was a technical development that made the change.
I asked the question on Twitter and Facebook and got great rock'n'roll answers; "...so they could take it to 11", "early form of stereo recording" etc. In fact when I went back over my old BBC notes I had been told why they did it but only a few weeks out of university I don't think I understood common mode rejection!

Ronnie Van Zant of Lynyrd Skynyrd c.1973 - two mics!

So - having re-read my notes and had a trawl around the web (my word, there is some awful rot spoken by people who know very little!) here are the two reasons (and I'll list them based on the technology that fixed the problem), they both rely on the fact that the two mics are wired anti-phase to each other and the assumption is the singer sings predominately into only one of them (doesn't matter which).

1. pre-compressor/limiters you needed a way of loosing some of the induced stage and line noise - this does it.

2. pre-parametric eq - you needed a way to reject howl-round and this does it.

So - you mix the anti-phase feeds in two channels on the desk and all noise/feedback etc gets canceled and the voice (predominantly coming down one feed) remains. Interestingly another technique to gate a mic is to have either an optical detector on the mic stand or a pressure mat in front of the mic which mutes the channel when nobody is near the microphone.

My blog is blocked in UAE!

2010-04-12T10:18:00.002+01:00

Fantastic - China as well - I'm kinda glad they don't want my kind of radical engineering ideas been seen there! Thanks to my good pal Tim Taylor (who's working out there at the moment).

I'm going to leave Virgin Media (and so should you)

2010-04-06T17:37:00.006+01:00

I've been with Virgin Media since they were Blue Yonder and then NTL and have consistently upgraded as faster cable connections arrive. I like lots of bandwidth because sometimes I need to download large files quickly but I find that for Skype, iPlayer and the plethora of other bandwidth hungry apps you can never have a big enough pipe.
Several times over the last couple of weeks my connection has slowed to a crawl. This screengrab from my 'phone is typical - unusable for anything other than email or IM. Eventually I called tech support (which is often a painful affair!) to be told that I'd fallen foul of the traffic management cap. All the details are in the title link. Bear in mind I never signed up for this - they introduced it without fanfare last summer and the details are show in the table below;

So let's take the slot between 16:00 and 21:00 - if you pull more than 3.5gigs across your connection you trigger the cap and they slow you for five hours. "Hang on, who downloads three and a half gigs of an evening?" you ask - but it's not the downloads that get you. We're talking about an 18,000 second slot which (do the calculation yourself) means that if you run your connection at two megabits per sec (it's actually a tad less) you fall foul of the cap - ten percent of what you pay for (on my twenty-meg connection) will give them the excuse to slow you down.
So - in a household of teenagers it is by no means unusual for more than one person to be watching the iPlayer (Sarah and I on the TV using the Wii, the boys of their computers) - so that's 2 or 3 x 800kBits per sec, maybe a bit of Skype (around 400 kBits per sec) and add to that a download or two and you've fallen foul - and over recent nights I have every evening!
Part of the problem has been the dodgy DVB-T tuner in my PVR - I've been downloading BBC shows in HD rather than recording them!

Virgin's response is one of fairness - why should some people hog all the bandwidth? The implication is that their network (the only one that is 100% fibre-to-the-cabinets as their adverts remind us) isn't up to delivering the bandwidth we have been sold. This is bogus because when I raised this with them their response was to try and up-sell me to the fifty-meg package which has no restrictions! It's a marketing strategy. I bet when they launch their 100meg connection the fifty meg one will suddenly have limits introduced to 'maintain a fair usage model'.

Again - DRM penalises legitimate users only

2010-03-15T09:50:00.005Z

Sarah works at Barnet Library on Saturdays and returned very excited this weekend as they've just introduced electronic loan of audio books and eBooks - fantastic you might think. Just download the book to your machine and then portable device and you save a visit to the library. Understandably they want DRM so that it mirrors the same service the library currently offers (you do have to return a physical book or CD after all).
So, Sarah installed the software on the media machine (which has a 10" 800x600 screen in the kitchen for iPlayer/iTunes etc and a second feed to the living room HD TV for Media Centre/Player - two sound cards mean you can be watching an HD recording in the living room and listening to/watching iPlayer in the kitchen). After she'd downloaded a book and tried to play it locally (which is entirely within the allowed behavior);

Quite why you need a hi-res screen for listening to an audio book is another matter. "No matter" I thought - I've got an old iPod kicking about, lets transfer it to that (again, OK in the EULA) and listen to it that way. Click the transfer button and you're in for an eight hour wait while it transcodes the WMA files to AAC. Also - it finds the iPod about one time in five (iTunes sees it every time) and so the chance of it working and you getting more than just a sample of chapters is remote. I did think about pulling out an old Windows Mobile 'phone but at that point I just torrented the book and it's good to go. You try and do the right thing but they make it impossible.

This all begs the question why public money has been spent on this very sub-optimal solution? If you don't want people to listen to these things then don't make them download'able - don't have an audio/eBook service. They will no doubt say that they can't make it easy as people can pirate/pass on the files. However - the OverDrive Media Console allows you to burn regular Red Book audio CDs - so they have NO trouble exposing the data un-DRM'ed! I despair. It reminded me of a time that I bought a couple of episodes of CSI from Channel Five's VOD service - they'd only play on the laptop I downloaded them on and not my media machine connected to the tele. Again - within half an hour I'd scored them off bittorrent (and in HD!)

JVC monitor calibration software

2010-03-11T10:01:00.007Z

Whilst at Channel Five recently I got to play with JVC's new monitor calibration software - it's for their DTV-series LCD panels and works using one of those little USB colourimeters (it supports several of the £150-gadget Tottenham Court Road specials). You use a DVI o/p from a PC to feed the monitor and hang the USB detector on the panel and via an RS232-USB connector the software models the monitor and uploads a 1D-LUT that makes the panel conform to a flat D6500 colour-space. Just the job for TV use.
There are a few caveats I can see;

The JVC monitors don't switch in a different colour matrix when you go between 601 and 709 working (i.e. SD and HD signal) - the monitor assumes you'll be wanting reliable colour at HD and any SD work is just for content. Previous posts on this here.
You calibrate the greys and whites using DVI (hence an RGB source) which only exacerbates my first point.
Those little USB gagdets are a couple of hundred quid against a proper colourimetry probe which is a few thousand and a photo-spectrometer which is many thousand. Given how sensitive your eye is (particularly in the blacks) I'm not sure I'd place a lot of faith in something you'd buy in the high street.
The software seems to do all it's modeling at 120Cd/m-sq - much hotter than you'd set the monitor for TV use and maybe twice as bright as if you were setting up a film grading display. This isn't as bad as HP's DreamColour range which start at 300Cd/m-sq!

Aside from those quibbles it looked quite good. I like the idea of being able to keep the LUTs for all your monitors and the fact that the software is looking to bring the display into compliance rather than "making it look good"(!)

Some more notes on Return Loss

2010-03-02T10:34:00.003Z

After my poor attempt at an explanation yesterday here is a page from Fluke's manual - much more concise.

Cause of return loss in cat5e cable

2010-03-01T18:09:00.003Z

One of our biggest suppliers asked us to test a sample of cat5e cable - we tried a couple of different RJ45 ends on the cable - a non-name one and Tyco. We ran the same 1000BaseT test on all six cores for both connector types and if you look you'll see that cores 2 & 4 consistently fail on return loss.
I initially thought it must be down to badly terminated ends but the DTX makes a distinction between return loss over the length of the cable and return loss at the remote end (how on earth it works that put is anyone's guess!) - generic RL is therefore all the reflections along the whole length of the cable that impede the transmitter's ability to send a strong signal.

Now then - it's the brown pair in every case - that suggests that the brown pair is sub spec. We didn't test to an ISO standard (because the cable isn't marked with one) so we used a generic gigabit Ethernet test which is a bit more tolerant.

I have to say I think the cable has a manufacturing fault in the brown pair.

With that in mind we stripped out some of the brown pair from core 2 (bad) and core 5 (good) and you can see the twist in the bad pair is much more variable than the twist ratio in the good pair.

So - it seems like the brown pair in cores 2 and 4 is inconsistently twisted compared to the brown in the other cores.

Understanding HD & 3G-SDI Video In HD

2010-02-11T08:50:00.004Z

I'm giving a talk at Broadcast Video Expo next week on HD infrastructure (10Gig Ethernet, OM3 fibre & 3G Video) and I was pleased to see several manufacturers are doing similair. The link is to Tektronix's 3G poster - all good stuff.

All your paywalls are belong to us!

2010-02-10T08:56:00.004Z

I subscribe to Broadcast (our industry's magazine) Tweet feed. Most of the tweets point to subscriber-only content which is annoying. I use a great site 'Be The Bot';

Have you ever been googleing something, and you see exactly what you need in the preview, but when you click the link it doesnt show you what you want to see? This is because the owners of the site are trying to trick you into buying something, or registering. It's a common tactic on the internet. When Google visits the site, it gives something called a "Header". This header tells the site who the visitor is. Google's header is "Googlebot". The programmers of the site check to see if the header says "Googlebot", and if it does, it opens up all of its content for only googles eyes.
Now, all we have to do is trick the site's headers, into thinking that we ARE google. That's what this site does. See the How to use box to the right for instructions on usage

It would appear that Broadcast don't even bother to do that - if you cut'n'paste the headline into Google and click the article you can read it all - it's the HREF tag they must be checking.

Cory Doctorow is a genius!

2010-02-09T14:16:00.003Z

Aside from him being an insightful writer and having some very intelligent things to say on the whole DRM/copyright/copyleft debate he seems to be a nice chap - my eldest boy, Joe, had him sign his copy of Makers at a recent book signing and he had the time to talk and be interested in a nervous sixteen year-old.

Anyhow - do email disclaimers annoy you? They do me. A lawyer friend told me that most of them are unenforceable because they assume the disclaimer can carry more legal weight than the contents of the email (which of course they can't, according to Contract Law 101). Cory has a fantastic email sig;

READ CAREFULLY. By reading this email, you agree, on behalf of your employer, to release me from all obligations and waivers arising from any and all NON-NEGOTIATED agreements, licenses, terms-of-service, shrinkwrap, clickwrap, browsewrap, confidentiality, non-disclosure, non-compete and acceptable use policies ("BOGUS AGREEMENTS") that I have entered into with your employer, its partners, licensors, agents and assigns, in perpetuity, without prejudice to my ongoing rights and privileges. You further represent that you have the authority to release me from any BOGUS AGREEMENTS on behalf of your employer.

1080/50 & 60P playback on a 2002-vintage PC? You betcha!

2010-02-04T11:33:00.002Z

Brian and I had six of these Compaq W8000 workstation which our tech support department were disposing of. This is the machine that was the penultimate Avid Meridien machine and eight years ago was a real killer workstation-class computer. It has dual 2.2Ghz P4s (so a lot less pokey than the laptop I'm writing this on!) but by gutting the six old machines we made two computers that were pimped out. Add to that a £30 Radeon 3650 AGP (remember that!) card from eBay and you've got a machine that can playback 50P H.264 at 1080 without a slip. This is going to be my new PVR machine (replacing an elderly 2Ghz P4 which has been fine for SD but can't handle HD).

Upturn?

2010-02-03T09:00:00.003Z

It's been years since I saw this many broadcast engineering jobs.

Glitch Takes Eutelsat W2 Out of Action

2010-01-29T11:54:00.002Z

I don't know if you noticed on Wednesday evening but Channel Five went off the air around eight-thirty. I was having breakfast with the Five engineers on Thursday and they mentioned that Eutelsat W2 carries their DTT distribution (so the feed to the various main-base Freeview transmitters around the UK). Arquiva must have quickly re-routed but it appears that as of today all Eutelsat have been able to do is move the bird to it's 'parking' orbit. It's quite an old satellite (launched in 1998) and was due to be decomissioned this year, but even loosing a few months must be costing a lot of money.

BT HomeHub madness!

2010-01-25T16:06:00.002Z

The new BT Homehub (their aDSL WiFi router) comes in a very sleek black, but apart from that seems to be the same gadget they've been hawking for a couple of years now. Anyway - I was visiting with Sarah's folks this weekend when her Dad mentioned how slow his Windows XP machine had got (three year-old Dell which I routinely remote desktop into to check-out - make sure his AV is up to date and Windows updat has run etc.). So - I fired it up and it crawled for the first ten minutes and then perked up. A quick run of MSCONFIG.EXE revealed a few start-up services that were taking an age to launch and (hiding inside svchost.exe) they turned out to be FOUR (yes, count 'em!) processes that the BT Homehub2 CD installs.

Now then, this is an ethernet-connected router - the only software you need to configure the router is a web browser but this had piled on a load of crap-ware. It reminded me of the state the machine was in when Dell shipped it! I got rid of all the BT stuff and the machine was back to it's nippy self without any trouble from the router.

The importance of a consistent earth with technical mains

2010-01-12T09:01:00.003Z

This is a paragraph from my standard Scope of Works document that goes to customers of build where I'm not responsible for the technical power;

Electrical requirements for all rooms part of the installation
We recommend an MCB-protected 16A mains feed terminated in a Commando connector. It is vital that the customer’s electrician runs the earths for the rooms back to the same earth bus-bar as the mains feeds to the bays thus creating a technical supply for all production/editing equipment. Failure to observe this request will cause mains hum on all video signal distribution around the new facility.

So we're quite explicit about the need for the need for a proper technical earth and what will probably happen if it's neglected. One of our recent builds has been having niggling problems with corrupt video captures and despite me having twice tested the physical layer performance of all the cabling (using the eye pattern on a Tek WFM7120) the attitude from the customer has been "…it must be the cabling or the routers you provided". After lots of haggling I was there recently and I measured a full 400mV of hum between the 'technical'(!) earth in the suites and the power distribution in the machine room. Given that an HD/SDi signal is only a volt I'm amazed they weren't seeing more corruption.
Now it's the inevitable "..why didn't you test for this and spot it earlier"? Perhaps there's a lesson here in not splitting the job up into many parts and using the cheapest contractor for each. If they'd been my electricians I'd have briefed them and made sure they ran proper tech earths - and I'd have made sure they tested them before handing over to the customer. That's why we'd have been a tad more expensive. As it is we'll no doubt wind up fixing this for free.

Two more hardware standards Apple play fast 'n' loose with - DVI and Display Port

2010-01-09T08:57:00.000Z

Another example of a customer splitting an equipment order into bits and not buying the monitors we recommended (saved a full fifty quid on each unit!) has combined with Apple's very poor implementation of 1920x1200 resolution to bit us in the backside.
The newest iteration of MacPro workstations ship with a display card that has a DVI and DisplayPort (with a DP->DVI breakout adapter). Aside from the problem of non-standard blanking as implemented in OS-X's drivers (see my blog entry about Kramer DVI routers) there is a very funny (but consistent effect) if you boot one of those computers with two monitors extended over fibre - you get one display at low-res and the procedure to get two monitors running at 1920x1200 is;

1. Boot the machine with a single monitor connected to the DVI port - increase resolution in increments to 1920x1200 @60hz
2. Reboot
3. Check the resolution sticks.
4. swap the monitor to the Display Port output
5. Reboot
6. Wind up the resolution as per 1. and if OS-X detects the extra monitor turn on display mirroring
7. Reboot
8. If both monitors come back up at 1920x1200 then turn off mirroring and ensure that both monitors are still at 1920x1200
9. Reboot
10. Make sure it's all sticking!

Compare this to the procedure for bringing up a PC-based Avid (running on an HP 8400/8600 workstation, nVidia card);

1. Set both displays for 1920x1200 @60hz

It is so clear that Apple assume you have the machine under your desk and you're using two of their monitors on the pre-made cables they supply. That's not how broadcast facilities are configured and if Apple wants to see FCP used more in film & TV they need to make their implementations of signal standards more robust.

Every Windows user to get pop-up menu of internet browsers

2009-12-17T01:00:00.001Z

Every person who owns a computer with Microsoft Windows is to be offered their choice of internet browsers in an automatic pop-up menu following an agreement today between the software company and the European Union.

I know liberals never like to see one sunflower grow any bigger than the others but this is plainly ridiculous - as one of the comments reads; "..when can I have a choice of a Ford engine in my Vauxhall car?" - and when has anyone ever been stopped from using whatever browser they want? Will Apple ever be obliged to let me use Windows Media Player to manage my iPhone? It seems wrong to punish a company for being successful when they behave exactly like everyone else. You know that if Steve Jobs ran a company with greater than 10% market share Apple would behave twice as aggressively.
I haven't used IE for six years but I don't think the EU should be able dictate to a company how they should configure their OS. Let's remember Microsoft are in the position they are because of market forces - they behave in a relatively ethical manner; they don't pollute, they don't use third-world slave labour and they don't do deals with brutal dictators.

Just sayin'.....

Day of the Triffids

2009-12-16T09:17:00.004Z

This is one of my favorite pieces of post-apocalyptic fiction. I read the book when I was a young teenager and really enjoyed the BBC production in my mid-teens. Good old Auntie Beeb have made the entire series available on YouTube (link above) at a very reasonable resolution. On my laptop the fullscreen playback is almost indistinguishable from the DVDs. Nice to see they've kept the 4x3 aspect that it was originally shot in.
Watch episode 2 - all the exteriors are shot in/around Primrose Hill near our workshop.

However, I read online this morning that the Beeb have a new production that they're showing over the holiday. From Wikipedia;

It is produced by Stephen Smallwood and directed by Nick Copus (EastEnders, The 4400). The script is by Patrick Harbinson, who has written episodes of the British dramas Soldier Soldier and Heartbeat, and the American series ER and Law & Order.

Filmed in the south-east of England, the new adaptation stars Dougray Scott as Dr Bill Masen; the confirmed supporting cast includes Joely Richardson as Jo Playton, Brian Cox as Dennis Masen, Vanessa Redgrave as Durrant, Eddie Izzard as Torrence and 90210 star Jason Priestley as Coker. Broadcast dates are 28 & 29 December 2009 on BBC1

So that's Christmas viewing for me sorted out!

Edit suite stories

2009-12-15T09:13:00.001Z

Just a great group on Facebook - a good read every day. I know not everyone does the Facebook thing but this really is a reason to start!

I am not a climate change denier

2009-12-07T10:50:00.007Z

The Climate Change Secretary Ed Miliband has acknowledged that there is "further to go" to persuade people in both the UK and around the world that global warming is man-made.

Interviewed by Today presenter on Humphreys on the opening day of the United Nations' climate change conference on Copenhagen, Mr Miliband said that those who denied the existence of a connection between human activity and global warming were "profoundly irresponsible".

And he said that the Copenhagen conference would be seen as successful if it led to "a deal consistent with science" which saw global emissions peaking in 2020.

Also - read this article on ScientificAmerican.com

Going to see Martyn Joseph tomorrow night

2009-12-02T16:34:00.002Z

It's been a couple of years but looking forward to seeing the "Welsh Springsteen/Dylan/Bragg"!

Why beauty in art is important

2009-11-29T17:13:00.006Z

Philosopher Roger Scruton presents a provocative essay on the importance of beauty in the arts and in our lives. In the 20th century, Scruton argues, art, architecture and music turned their backs on beauty, making a cult of ugliness and leading us into a spiritual desert. The link is to the page on the iPlayer.

Beauty is not popular among professional architects, just as the pursuit of beauty is not popular among visual artists: it suggests costly sacrifices, and a scaling down of pretensions for the sake of people whom they don't need to know. But the controversy over modern architecture remains real and important: for it reflects the need of ordinary people that appearances be respected, so that the place where they find themselves can also be shared as a home.

He crystallized some thoughts for me - I've always felt uneasy with art that has to assert it's own artistic relevance. I've always thought that true art doesn't need to be declared as such - a working man (who didn't go to St Martins!) should be able to recognize something that has artistic worth, he doesn't need Messrs Hirst and the Chapmans to tell him.
Whilst I was watching I did a Twitter search and was surprised how aggressive the people who disagreed with his thesis are - they just insult him rather than address what he's saying. I've stuck a quick sample at the end - some make for strong reading!
I suppose anybody who stands against an accepted orthodoxy gets flack - maybe it strengthens what he says!

emberson @Archispeak ....and as for Scruton and his cronies.....the talking dead?
sunwukung Roger Scruton in an unbearable old fart.
purpleparoxysm "as meaningless as a laugh, shout or smile" - i think that's your fundamental problem Scruton. What a twat and what an 'ugly' man & mind.
maty0609 Roger Scruton, get out of my face...This is rubbish you're saying...
Me-cold_2_normal Benjihotaylor Roger Scruton doesn't half talk a load of crap!
davidTrussler Ideas themselves cannot be beautiful, according to Roger Scruton, thus dismissing all Conceptual Art. Totally reactionary rubbish.
Daviesstock Watching some pretentious high-brow intellectual masturbating on the nature of Beauty, presented by Roger Scrotum, er, I mean Scruton...
NiteWaves roger scruton is a boring old cunt
danielnothing Roger Scruton: an arsehole?
unityzer0 fuck you Roger Scruton.
magnetite I think Duchamp's bog IS beautiful, Scruton you cock.

Quartz - excellent products AND tech support

2009-11-26T13:17:00.002Z

I was around at a customers' today - their Quartz 32x32 HD/RS422 Xenon router had stopped talking to it's control panels. Normally that is down to the coax 'QBus' cable that runs around all of the devices - like old-school 50ohm ethernet-over-coax - is prone to having a break in the middle or loosing a term from one end. However - this wasn't the case. A quick call to their tech support and you get an engineer who knows the products - can tell you what each board-LED means and what low-level commands you can send over the RS232 to illicit diagnostic information. In short order I re-loaded the configuration and the whole matrix was back up and running.