Friday, March 30, 2007

Unit Post and JVC monitors

This from
Tim Burton, Technical Manager, Unit Post Production, explains, "The MCR has enabled us to keep the edit suites cutting 100% of the time, and streamline how we execute ancillary tasks. The biggest gains have been in digital delivery and rendering times, by moving these tasks from the workstations to a 20 processor cluster we have seen a 5 fold increase in speed. Root6 completed the installation to an extremely high standard and It was a pleasure to work with Phil Crawley as he took the concept and helped develop it into a rounded solution within weeks. We have only scratched the surface of what this technology can offer and are continuing to expand and refine our systems and workflows."

I like those guy! I was back there today helping them out with some colour issues in their grading room. I discovered a few things about JVC SD/HD monitors - specifically;

  • If you use one of their HD-SDi, SD, or mixed-mode cards you only get the Rec601 matrix. This means that when you calibrate for the tube for correct illuminant-D you wind up with a monitor that shifts either green or magenta (depending on which way you calibrated).

  • If you install a component input card the colourimetry doesn't shift in this way - BUT the change in the raster causes the monitor to sit the picture down (the blacks get crushed) and you get a slight yellow cast in the white.
So, with all this in mind I've taken to calibrating those displays for HD and SD and handing the customer a set of instructions of changing the numbers when they start a new job.

Thursday, March 29, 2007

Celebrities - just like the rest (or worst!) of us.

I was working in an edit suite recently and overheard a well known TV personality making a call to book train tickets. They wanted to go to Glasgow first class (hey, if you've got the cash why not travel in comfort?) but booking four tickets (around the same table) so that...
...I don't have to sit next to any common people

Now, this person has a column in The Independent and presents themselves as fair-minded, liberal, person-of-the-people in their writing/TV presenting!

One celeb I've got a bit of experience of is Jeremy Paxman - In the late eighties I was working as a maintenance engineer in BBC Television News and was doing the late shift one night (essentially what was the Nine O'clock News and then Newsnight) and was on the studio floor in Studio Two, BBC Television Centre trying to fix Paxman's 'cought-cut' (a button on a long cable that the newsreader keeps to hand to momentarily mute his microphone if he has a coughing fit). Not really noticing the time and my brain having long blanked out the seemingly unending re-cueing of the theme music over the studio's monitors I didn't realise that while scrabbling about under the programme desk the Studio Manager had counted the crew down for the live transmission. As I emerged from under the desk by Paxman's legs he put a gentle yet very firm hand on my head and pushed me back under the table-top and as he finished delivering his piece to camera introducing the first report on video tape he let go and said with a broad grin "you didn't know we were on the air, did you?" - what a gentleman! Not at all like the media-types I have to deal with nowadays.

Paxman anecdote no.2

One of the guys who was an engineer on my team used to do a monthly comic strip featuring the adventures of "Paxman" - a caped crusader who always won the day with his hard-questioning of politicians(!) - The strip would get photo-copied and put up on staff noticeboards around the building (the days before the web!) - eventually the weight of 'stop abusing the noticeboards' emails meant my colleague stopped the cartoon. One day a few months later another colleague had to go and fix the vt100 terminal in Paxman's office and noticed the complete set of cartoons on his pinboard.

Wednesday, March 28, 2007

Adrienne Electronics

Do you remember a BBC2 late-night show called Diners - back in 2002 anything that had the reality label attached to it got commissioned (although admittedly on very late in the evening). If you Google for it now there is scant evidence of it! I did find a John Walsh article from The Independent. Anyhow - one of the problems I had to solve for that show was using cheap Avids (software-only versions - ExpressDV back then) to capture or log live feeds with timecode. Of course the studio or OB sends you audio timecode (the kind that sounds like a fax and comes down a twisted pair cable) but all hardware-less edit stations assumed the timecode comes down the RS422 line as part of the machine control.
Adrienne Electronics do a range of really useful boxes to address these kind of problems - the AEC-Box-2 takes in audio code and has a 9-pin connector. It emulates a VTR but (being a solid box) doesn't actually play or rewind tape - it just tells the Avid it is doing so (in this case it's an Avid MCSoft with SDi Mojo). The really cool thing is that when the Avid asks for timecode down the RS422 the box returns what it is receiving on it's input. It's the ideal solution for using cheap workstations to log or capture proper studio or OB type material.
Now I'd been puzzling about this for ages last night (got home late from the studio where I was working) and it was only over my tea that I remembered solving the problem five years before - kinda like how everyone has forgotten Diners!

Tuesday, March 27, 2007

ITU Rec 601 vs Rec 709 colourspace

Every superhero knows that in transitioning from standard definition television to high def we've adopted a different matrixing function for component to/from RGB conversion. The numbers for (old-skool) Rec 601 are thus;
Y = 0.299R +0.587G +0.114B
Cb = 0.564(B-Y) + 350mV
Cr = 0.713(R-Y) + 350mV

And the new kids on the block (Rec 709);
Y = 0.213R +0.715G +0.072B
Cb = 0.539(B-Y) + 350mV
Cr = 0.635(R-Y) + 350mV

So, not only has the weighting of the colours that make up the luminance path changed but the weighting of the colour difference signals is different. I've heard varying accounts of why they felt the change was necessary - I think it's probably to do with cameras and telecines (now be entirely CCD-based as opposed to the ubiquity of tubes when 601 was being formulated) and display devices (are we going to be able to buy a tube'd monitor by the end of this year?!). The new values better reflect the tri-stimulus nature of human vision and are less bound by the very noisy response of the blue-tube in image acquisition devices of yester-year.

However, one of the upshots of this is that digital devices that can receive an SD/HD-SDi bitstream have to be able to switch in the appropriate matrix. If that isn't the case then you'd notice a green cast on pictures if you switched between standards (going from HD to SD) or a magenta error going the other way. In the case of a monitor you'd have to re-calibrate the white point to D65.

The reason this has cropped up is that a facility (where I've just started to offer them colour calibration advice) has noticed that a monitor that was lined up correctly for HD working is showing the wrong colourimetry when being sent an SD feed. It's gone green (and not with envy! - oh, and that isn't the facility in case you're wondering!). It's a JVC DTV1700 series monitor which (although a cheapie at <£2k) has an EBU-phosphored tube (so you can calibrate it to 6500k at the white point). It looks like JVC's input card doesn't do the matrix switch. So, I'm wondering what other monitors do - I was sure the Sony BVM-D range did (but those monitors started in the mid-teen thousands of pounds). Any comments from people who've hit this before? As an aside the image (right - click it!) is from a very good Tektronix poster entitled Understanding Colors and Gamut - I have many copies (along with the equally exciting Understanding High Definition Video!) - give me a yell if you want one.

Monday, March 26, 2007

Mark Russinovich: From Winternals to Microsoft

All Windows users owe Russinovich a huge debt;

Sunday, March 25, 2007

Cerberus and FTP minucea

Having written about Cerberus FTP server in the past I did notice that after I upgraded to v 2.43 on my Windows server I was experiencing some delays when publishing from Blogger. Now I don't know about the finer points of FTP (despite it being the protocol I've used on an almost daily basis since 1985!) but a quick tweak of Cerberus's passive FTP settings made things good - see the screen-shot.
As an aside one of the other nice features of Cerberus is that it handles IP banning automatically. Whereas IIS will happily sit there letting a Chinese hacker run a password generator on you for days (it takes about three hours to fill your system even log over a cable-modem connection) Cerberus will (by default) lock out an IP address for three hours once it's got it's login wrong ten times - very cool. It means your FTP server suddenly isn't vulnerable - why has Microsoft never got wise to this kind of thing?

Friday, March 23, 2007

Zoo animals 'may jump into park'

Oh dear! According to BBC News the tigers at Regents Park Zoo could leap the fence and start roaming the surrounding area! The workshop is only a few hundred yards from the Zoo and so I'm thinking the bars I had put on the windows last year might have been a wise precaution!

Thursday, March 22, 2007

UnDead pixel

This program helps to locate and fix LCD screens dead pixels.
You can fix the stuck pixels by calling them to do rapid changes. You need to run this program for a couple of hours. There is no warranty on the result, but you don't really have anything to lose trying it out.

Wednesday, March 21, 2007


mp3DirectCut is a fast and extensive audio editor and recorder for compressed mp3. You can directly cut, copy, paste or change the volume with no need to decompress your files (e.g. to wav format) for audio editing. This saves encoding time and preserves the original quality, because nothing will be re-encoded.

Sunday, March 18, 2007

More4 - Live from Abbey Road

Having vented my spleen a couple of days ago against Channel Four I thought I'd give credit where it's due to their music show 'Live from Abbey Road' - it's superb. Each hour long programme features three acts performing and speaking. As well as some superb performances the show looks great from a production pount of view. The recent Wynton Marsalis set was graded to look just like the late sixties and suited the music exactly. I've also been enjoying Muse's set - so much so I stuck all three numbers on YouTube (link in the right hand bar).

Friday, March 16, 2007

Extending DVI over fibre

I've spent the last couple of weeks designing and supervising the install of Optomen Television's new editing facilities in Kentish Town, North London. I decided this time to try extending all the DVI feeds over fibre - I've done it before on more expensive projects but up until now it's been prohibitively expensive for SD-only Avid rooms. However, Lindy are now carrying extenders that look remarkably like the ones I've used in DI projector rooms before. In fact Lindy are sourcing them from the same OEM as others (Gefen for example) but selling them for sensible money. They have proved good - there are a couple of things worth noting;

  • Pay attention to the fibre allocation - you need two duplex multi-mode circuits (which we ran in loose-tube cable terminating it in dedicated wallboxes) - on the receiver the inputs are crossed-over WRT the transmitter - they presume a TX-RX cross-over (but the manual makes no mention!).

  • The nVidia FX1500 cards that ship with the Avids have both RGB (SVGA) and DVI on their 29-pin DVI-I connectors but the card detects if a monitor is connected and mutes it's other output - so you can't used these splitters as the card doesn't support simultaneous analogue and digital output - bummer!
So I'd recommend these (with the normal warning about doing the fibre properly!)

Wednesday, March 14, 2007

RIP incandescent bulbs

Being a global warming denier is currently a bit fashionable. It's all tied up with people thinking they have a better handle on the subject than professionals who know several orders of magnitude more about it than they do. Just because a Channel Four documentary digs up some renegade (failed!) researcher who has a theory it doesn't mean there is any truth in it. George W. Bush depends on this kind of double-think when he says 'science is divided'- well, it is divided if you think the opinion of a tiny minority (in the pay of the petro-chemical industry) holds weight against 99% of climatologists. The fact that the vast majority of scientists have come to the conclusion that man-made CO2 is responsible is not proof, anyone that suggests that is wrong. But it does imply a very high-probability that it is the cause. To not accept that high-probability is to pick your science like a sweet in a sweet-shop to suit your own taste.
To a degree I blame Kuhn, or rather the poor half-baked understanding lots of folks have of the nature of scientific revolutions. They have the notion that scientific advances always come from mavericks who tirelessly labour outside the mainstream. People like to think that they too 'just might have something there' and produce something valuable even though they have no scientific training - well it isn't true - it never happens!
Anyhow, the Aussies have done it, and now Europe is going to use legislation to phase out incandescent bulbs - good stuff.
Interesting take on the programme here and Marcus Brigstock had a brilliant rant (2.9 megabyte MP3, 7 minutes) on The Now Show where producer Martin Durkin gets some of the heat he deserves.

In the end you have to remember that all programmes on Channel Four (in common with all commercial television) are the loss-leaders for the commercials. The channel wants you to watch the ad breaks and so will make programmes that play fast and easy with the truth so long as it gets people watching them. The BBC is the only place you find accurate science programmes.

Tuesday, March 13, 2007

MP3s, DRM & The Zune

I listened to Paul Thurrot's podcast - Windows Weekly - which is always interesting, especially with Vista upon us. Episode seventeen features an interview with David Caulton of the Microsoft Zune team. Although it isn't yet launched here in the UK there are several retailers that carry it. A couple of the guys who I work with have them and I have to say they are pretty sweet.
I have been pretty negative about iPods in the past and to be honest I don't see any reason to change my view. Apple need competition and I think the Zune is the gadget to do it - as long as they let it connect over 802.11 to a network rather than just peer-to-peer - having to hook something up with a cable to get content onto it seems very 20th century! The screen on the Zune is lovely - definately superior to the video iPod. The GUI is tasty as well (although missing any direct podcasting support!).

So, it got me thinking about buying music etc. and I realised that with the exception of a couple of quite niche music stores (including the splendid BillTunes) I still buy all my music as CDs. It seems that an industry that has spent a quarter of a century selling digital music without DRM (the compast disc) is now bleeting about how users can only use music they've paid for as the industry sees fit. I have several digital music players - car HD player, couple of cheap flash-based players, my PDA/'phone, and PCs running several different OSes - the only format they all support is MP3 and so I'm never going to download DRM-crippled music from an online store who haven't taken the care to compress the music properly. The 128kBit files from iTunes aren't HiFi (and they wouldn't play on ANY of my hardware!) and, in fact, there is no alternative for someone who (a) cares about the music, and (b) cares about how they spend their cash to buying CDs and ripping them yourself - you at least have a chance of making decent sounding MP3s at an acceptable bitrate (192kbits VBR - all the way baby!).

Friday, March 09, 2007

Two steps back, one forward.

I noticed that over the last few weeks a couple of machine rooms I designed and built have closed. Oasis has gone under but it appears Sanctuary are taking it on. The basement machine room (thirty-eight racks, Phillips 64x64 matrix) was build over Christmas 1995 when we took over the building. My old mucker Chris Clegg was the project engineer (I was the chief engineer at the time) and they seemed to have got lots of value from that install. O2 - the duplication machine room on the 2nd floor (seventeen racks, BTS 128x128 matrix) was designed and built by me at the end of 1998.
Resolution's Old Street building - I designed and built that facility in the summer of 1999 - twenty-four Avids and a twenty-two rack machine room. I had a lot of fun there although endless re-versioning of Pet Rescue took it's toll!
On a more positive note we've recently built The Farm's new facility in Soho Square - Corner. It all went very well, it was the first time we did a system build for those guys and they were nice people to work for.

Wednesday, March 07, 2007

Got my Mojo working

I did investigate this the Production Show before last (2005) - I thought I'd so this but include balancing for the audio to make it a bit more pro - XLRs & BNCs on the back. I got Bryant to do me a quote for the metalwork and adding in the cost of a buffer card to balance/level match the audio brought it to about £250 cost to us. With that in mind I asked maybe a dozen people at the show who were looking at ExpressPro/Mojo if they'd consider it and what price - they ALL thought £250 would be a waste of cash.

Now - what with SDi Mojo maybe it's worth re-investigating. MC Soft (the current less-than-£5k Avid package) appeals not only to wedding videographers but broadcasters and serious facilities people. In fact, Root6 have asked my to prototype one up - watch this space.

Saturday, March 03, 2007

Hard Drive Reliability

I love the Security Now! podcast - episode eighty-one this week was a corker. Leo and Steve discuss the distressing results and implications of two recent very large population studies (more than 100,000 drives each) of hard drive field failures. Google and Carnegie Mellon University (CMU) both conducted and submitted studies for the recent 5th USENIX conference on File and Storage Technologies.
Since I have a modest amount of experience with hard drive reliability I thought I'd drop Steve the following;
For the last twenty years I've been working in broadcast engineering and the track of my career has mirrored the uptake of commodity computers over bespoke television equipment.
I had a couple of points - one interesting and one informative that I thought you might enjoy;

  • In the mid-nineties the whole industry was switching over from editing video-tape to cutting shows on workstations. Consequently large and fast hard-drives were needed and Micropolis (now out of business) was one of the manufacturers of choice for most TV facilities. They'd launched a nine gig model (big full-height 5 1/4¨ device!) that the company I was working for was buying in number - even at $2,500 a pop they were thought to be good value! After about six months a number of these drives started to fail. The manufacturer had given us a SCSI utility to see which sectors had failed and it appeared to be the same ones on each drive. In a couple of cases we did a low-level format of the drives (which mapped out the bad sectors) and continued to use them. Those drives then showed problems and when analysed their sectors were clearly failing in very similar patterns. In the end the representative from Micropolis told us that in the case of that series of drives the lubricant they used would leak from the spindle-bearings and spread out across the platters, getting progressively more spread from the centre of the disk.

  • The company I currently work for specialises in editing systems, particularly for film and high-definition television. In the case of HD the data rate off of the videotape is either 1.48 or 3 gigabits per second (unlike the domestic HDV format that manages to compress the video to a paltry 18 megabits per second!). In the case of film (either from a digital film camera or telecine film scanner) the data rate can be much higher. The upshot of all this is that the stand-alone storage systems and SANs (storage area networks) have to stripe many drives together to achieve the required through-put. We are very used to having ten or more drives with data striped across them and the dirty little secret we shy away from is that the mean-time between failure of a ten-way drive set is only one tenth of a typical drive. Consequently our tech-support department is always trying to resurrect dead fibre-channel drives. We tell (or even try and bully) customers into keeping backups but with many terabytes of data it is a hard thing to enforce. This is why mixed striped/mirrored drive sets are becoming popular. Anyhow - one of the things I have found to be useful in temporarily reviving a dead drive (and I've done it maybe a dozen times) is to freeze a disk. It might sound crazy but it you consider that the most common reason for mechanical failure in a drive is the bearings becoming loose and the drive spinning eccentrically you can see the reason. The cold temperature tightens everything up as it shrinks and (temporarily) allows the thing to work at specification. The only option is to clone the drive and then throw the suspect one away.

Friday, March 02, 2007

MediaPortal v0.2.2.0

This is an image I took on my 'phone - a panorama of Alexandra Palace on what is first really bright day we've had this year.
Anyhow - pressure of work and having taken a couple of days to go and visit my Dad in hospital has meant I've been a bit low on blog posts recently. Last night I re-paved my PVR - running the mighty MediaPortal and I have to say I am very impressed with the current build. I took the chance to repave Windows as well. Here are a few thoughts;

  • Follow the recommendations on the requirements page to the letter - the MS HotFixes really do help! KB entry 896626 was en eye-opener! Apparently the DirectShow filter that extracts an MPEG2 transport stream from the 38meg Mux (as captured by the DVB-T card) has an issue if the PSI header is greater than 255 bytes. In the case of BBC2 and Channel Five (from the Crystal Palace transmitter) they are - something to do with the payload size of the interactive application. I'd got to the point were I'd lost count of the number of times I'd have to give up watching University Challenge because to a corrupt, stuttering file. I should have checked the updates pages more often!

  • Try and keep your media drive on a separate IDE/SATA bus to your system drive and DVD drive. You want the maximum uninterrupted data rate to that drive.

  • If (like me) you use a mouse-type remote then you need to find the right skin that supports both the extended OSD (on screen display) AND the top-bar. The best one I found was BlackTwo

  • nVidia 5600 graphics card - most of the reason for upgrading was that the old Riva128 card I had was DirectX 7 only and the recent builds require a DX9 card. However - although the 5600 has excellent video-rate output (720x576 at 50 interlaced fields) the analogue video signal (both SVideo & RGB) is noisy. Strangely it is fine when in NTSC mode. Since my TV is dual-standard it makes little difference, but worth knowing about.
So, if you want a PVR then save yourself some cash and home-brew one with an old machine and base it around MediaPortal. It is faster, more stable, more fully-featured than Windows MediaCenter edition and because it's open source it's free. I've been using my rig to watch the test HD transmissions from Crystal Palace and am very impressed. You could also look at MythTV.