Monday, December 05, 2011

Subtitling software and my new Bluray player

Occasionally my PVR makes an incomplete recording of a film that Sarah and I wanted to watch. It was the case last week with the Italian film Couscous and so I didn't feel too bad snagging a copy from a torrent site. However, when we sat down to watch it I realised there were no subtitles (either burned into the video or as a separate text file). "Not a problem" I thought - straight to one of the many sites that carry subtitles for every film ever released and I grabbed a likely looking .sit file for the movie. After discovering that Microsoft have pretty much removed all subtitle support from Windows 7 (my PVR is MediaCentre) I tried watching it with that old faithful backup VLC player (an order of magnitude better than WMP12 in every respect!) - a good example of where open-source software makes the closed-source equivalent look very silly - but I discovered the subtitles in the file were a consistent twelve seconds late. I suppose the subtitler was working off a different version of the film, maybe he started his frame count with all the film and distribution company bumpers?

Again, no worries, I fired up my previous standby for manipulating subtitle files DivXLand Media Subtitler only to discover it can't slip ever sub in a file by a defined amount. In every other respect it s an excellent utility handling twenty-odd file formats and having auto-timing functionality as well as individual sub-sync features, but couldn't handle this problem easily.

So, bit of Googling revealed another free and excellent utility Subtitle Edit which offers pretty much the same toolset but with the ability to slip the sync on groups of subs. Just what I needed; it has a better preview facility as well so you can drop into various places of the video file to check the captions are consistently running to time and it will automatically pull captions a few frames either way when the audio waveform doesn't quite match with the start frame-code of the subtitle.

After this VLC played the .avi & .sit combo perfectly but not WMP12 or MediaCentre. At that point my thoughts turned to my new (2nd hand!) Bluray player; a Sony BDP-S370 which we've had for a week (£70 on the eBay) and have been mightily impressed with it's network video functionality. It's the best iPlayer machine I've found so far bar none (much better than the Wii, Virgin Media & Tivo) and it will happily play the file and display the subtitles either off a thumb-drive or via the network using DNLA.

Wednesday, November 23, 2011

RS422 / Sony P2 protocol and serial stuff!

When running P2 protocol over RS422 (i.e. Sony VTR remotes) there is no hardware handshaking so RTS and CTS (Request To Send and Clear To Send) aren’t used; a bit like the old 3-wire XModem/YModem/Kermit protocols used in RS232 (remember RS422 is just a balanced version of RS232).

We base our RS422 wiring on the Quartz remote standard (Quartz were one of the first firms to use RJ45s & cat5 for RS422 remotes):

However – I know for certain that Probel use a different standard and many places are wired to whatever the local standard is; remember – until ten years ago most places wired ‘422 on star-quad cable rather than cat5e/6. I don’t know if current model Evertz routers have maintained the Quartz standard – I bet they have given they bought Quartz for its router business.

Whatever wiring standard is used always make sure that pins 2 & 7 are a twisted pair and likewise 3 & 8 otherwise you lose all the advantage of common-mode noise rejection that balanced RS422 brings.

Finally you need to be certain if a place is wired for chassis earth (pin 1 on a 9-pin) or signal earth (pins 4 & 6 on 9-pin). Signal earth is best as there is always a chance of earth-hum between areas when you tie chassis earths together but hopefully properly designed kit with balanced lines have the signal earth floating WRT to power/chassis ground. BUT, you have to stick with the local standard; if the engineer has wired only chassis earths you need to continue using pin 1 or even shorting pins 1, 4 & 6 at the remote end.

Thursday, November 10, 2011

Remote control options

If (like me) you find yourself as the default tech support provider for friends and family you've no doubt wondered about remote desktop software - VNC, RDP, Apple remote desktop, or any of the paid-for managed services (Go To Assist, LogMeIn etc).

I think there are several things to bear in mind;
  1. NAT routers in the way? If you're merely using remote desktop to go between machines on the same LAN then this isn't an issue but if you have to take control of your Mum's laptop and you're both behind routers then you either have to have made a hole in her's or be using a protocol that supports NAT translation.
  2. IP address - again, the person you're trying to reach may well be on a dynamically assigned IP address.
  3. Bitmap vs remote GUI rendering; VNC sends a bitmap (admittedly compressed) and so maybe sluggish whereas Windows RDP or Apple remote desktop send GUI primatives which render at the remote end.
  4. What combination of OSes are you using? Running Windows but supporting someone on a Mac? The remote desktop client built into OS-X since Tiger falls back to VNC if the remote machine isn't a Mac - nice touch.
So - in the case of my Father-in-law's Windows XP desktop machine I use VNC every time - This is because I don't know if he's going to call me during the working day (when I'm using an OS-X laptop) or in the evening when I'm likely on a Windows 7 or XP desktop. Since his machine is fixed I had the liberty of installing a DynDNS account on his router (so I hit a address rather than trying to discover his internet-facing IP address) and I opened a hole in his routers firewall (so traffic on TCP port 5900 gets mapped through to his PC). With all that in place I know I can grab control of his desktop using TightVNC (my favorite VNC client) under Windows or the built-in remote desktop of Snow Leopard;

On the other hand my Mum has a laptop which may or may not be at her house. Since she is running Windows 7 and I can always get to a Win7 machine she Instant Messages me with a Windows RDP support request and after a bit of typing in confirming codes it works well without having to worry about IP addresses or NAT traversal.

That leaves the paid-for server-based systems like Log Me In and Go To Assist which require no software installed (it's done via a quick Java download) and take care of NAT traversal etc.

So - you pays for money, you takes your choice. I prefer VNC because it's open and works across OSes. It does require a bit of work to send it across the public internet. After that Windows RDP is fine if you have contemporary Windows boxes. I suspect at some point I'll sign up to Go To Assist and pay as it is very convenient and works entirely well across networks and OSes.

VNC connected to my home Windows 7 media machine, running inside a Windows 7 virtual machine on my Macbook Pro under OS-X

Friday, November 04, 2011

TCP/IP Congestion Avoidance

TCP/IP is a jolly clever protocol that now forms the bulk of the traffic that runs across the Internet. Given that routers and gateways along a packets route are entirely at liberty to drop packets without informing either the sender or the recipient (it's up to the client/server to figure out packet sequence and if any packets were lost) there is a very clever way that the IP stack in your computer does packet collision avoidance.
So when TCP establishes a connection it goes through an IP-slow-start. In essence the stack has to "sneak-up" on a transmission speed where packets are being lost faster than they're being sent; when that occurs the stack backs off until packet failure is happening less than new packets are being sent. The initial condition is that the stack can send two packets without getting a confirmation. For every confirmed packet the stack can increase the maximum segment size by one so that two packets can become three and so on. After that there are several commonly used strategies, most commonly "TCP Reno" and "TCP Tahoe". Tahoe reduces the congestion window to one MTU ("Maximum transmission Unit" - typically a 1550 byte packet in Windows) and then go back to the IP-slow-start. Reno halves the size of the congestion window and so backs off slower than Tahoe but hopefully the link has recovered fast enough to make that a better strategy than Reno.

Anyway - as ever the Wikipedia article is very comprehensive;

Friday, October 21, 2011

Bill Mallonee's new record

Best thing I've heard so far this year - full band/studio album from the most talented song-writer still working in the USA.

"...noisy, jangle-y, lush, passionate, Rickenbakers, hooks, '60's, '70's...cobalt blue skies;"

all songs by Bill Mallonee
released 02 October 2011
Bill Mallonee: vocals, guitars (electric, acoustic, hi-string) harmonicas
Muriah Rose: vocals, piano, organ, mellotron
Bert Shoaff: bass
Kevin Heuer: drums, percussion

Wednesday, October 19, 2011

Save us from Media Studies students!

I was on the train on the way up to Manchester this morning - on the next table along were four undergraduates on the way to the BBC for a recruitment day out and clearly part of their day was to propose potential new programme formats. Well - they spoke very loudly and earnestly about their ideas for radical new television shows and all made notes in their moleskin notebooks. Their ideas were so derivative and tired it made me chuck and I made a note of some of them;
  1. "Darts players - wives & girlfriends" - a reality show investigating the love lives of darts players. @bendavison tells me it's been done already, sigh.
  2. A series of documentaries that challenge racism by featuring the apparently growing Bollywood porn industry...!
  3. "Strictly come prancing"- reality show for jockeys.
  4. "Blaggers with attitude"; documentary series following people around the festivals who manage to score free stuff; t-shirts etc.
  5. "Bankrupt celeb finance boot-camp"; broke Z-listers learning how to manage the money they get from Heat Magazine.
  6. "Boyle Baron" - singer Susan Boyle learns the ins and outs of the oil industry.
  7. "The Grapes of Hoff"- David Hasselhoff becomes a vintner.
  8. "Frankie goes to Bollywood" - ex. members of the 80s band learn Indian dance moves; they also discussed if it should be for Comic Relief(!)
  9. "The Yids are alright" - Pete Townsend explores Jewish culture.
  10. "Train of thought"- a gameshow set on the West Coast Mainline. Different stations would signal different rounds. Would suit Alan Titchmarsh?
So - BBC, stop employing media-studies graduates and instead give English/History/Classics students a shot at making some original TV.
If you see any of these formats on BBC3 in eighteen months time you read it here first!

Friday, September 30, 2011

The Monty Hall problem

This is a scenario made popular by the American game-show "Let's make a deal"; The host, the eponymous Monty shows the contestant three doors and tells them there is a car behind one of the doors and booby prizes (typically goats) behind the other two. The contestant gets to choose a door and then Monty opens one of the doors they didn't choose showing them a goat. He then offers them the chance to change their mind. Initially most people say something like "'s fifty-fifty, so no, I won't change" - but it's not 50/50, changing your mind at this point doubles your chance of getting the car.

Possibly because I did a year of Game Theory on my degree the first thought I had when I initially heard this problem was "where are the odds invested?". When you pick your first door your odds are a third. However - two-thirds odds are invested behind the other two doors and when Monty shows you which of those doors has a goat you know that none of the odds are now behind the door he just showed you; the car can't be behind that door (Monty showed you the goat). Your original door still has a third of the odds and so now the final door MUST carry the two-thirds odds that you didn't choose initially. Changing your mind now doubles your odds.
It's not a straight fifty-fifty because Monty introduced some new information half-way through the game. He showed you which of the two-thirds doors don't have the car.

The Wikipedia article is very good - I nicked the picture from there.

The problem is interesting because it shows how little innate understanding of game theory (and statistics, and probability) most people have. You gotta trust the maths, not your instincts.

Thursday, September 29, 2011

Recovering corrupt flash memory cards

The good thing about paid-for photo-recovery software is that they have an easy trial-model; they show you the images and videos they can recover and you stump-up your $50 to register the software and get at your pictures. I've had varying success with a coule of paid-for apps but I came across PhotoRec yesterday (it's part of a larger suite of tools).
Now, granted, the pay apps have nice GUIs while PhotoRec runs in the UNIX shell in a text-based interface, but it requires little interaction and gets the job done. It also runs on just about any common OS platform from Mac OS X to Windows to Linux to Solaris, etc. Link in the title.

Wednesday, September 14, 2011

Things that peaked my interest at IBC

I spent just a couple of days over at the RAI in Amsterdam. It was splendid to catch up with some old pals and Bryant Broadcast do an excellent night out. My main observation is that 3D/stereoscopic was no where near as prominent as it was last year and as the number of network delivery solutions increases the number of 'proper' transmitter companies seems to drop.

Newtek - updates to TriCaster, new model & control panel. The new 450 is very similar to the 850 but has only four HD inputs (against eight). The other things that I think are significant;
  • 3Play - their "poor man's EVS" has been improved. Running on what looks like a Tricaster 850 chassis it now has eight inputs and can run two outputs simultaneously. For sports slow-mo it is an excellent quick turn-around solution at the fraction of the cost of EVS.
  • VTR-style control for the DDRs in Tricaster; might suite some people.
  • Tricaster Extreme upgrade - allows for eight ISO records (can be either cameras or other internal/external sources, at different rasters and codecs than the main record).
  • They fixed the AUX audio in embedded HD-SDi I'd been moaning about!
  • The network sources (iVGA feeds) can now carry audio as well.
VidCheck - file-based QC is getting good! In fact this one looks like it needs serious consideration! I have a demo license on the way and will report back. Along with being able to test all the usual codecs etc it does full ITU.1770 audio loudness AND has numerous correction facilities; Tektronix AND Eyeheight, you might say.
  • Containers: MPEG-2 TS, MPEG-2 PS, MXF, MP4, MOV, ASF, AVI, LXF, GXF, FLV, F4V
  • Formats: Web, SD, HD, D-Cinema and many custom formats
  • Video: MPEG-2, IMX, XDCAM, D10, HDV, DV25, DVCPro50, DVCPro100/HD, AVC/H.264, VC-1, ProRes, DNxHD/VC-3, MJPEG
  • Audio: MPEG, PCM, WAV, AAC, stereo, 5.1 / 7.1 Dolby, multiple different language tracks
The really significant thing is the price €5k with paid options (DolbyE, ProRes etc) in the hundreds rather than thousands of pound. It also seems to handle multi-core computers much better, a single instance scaling to 28 cores.

AutoQue - they make broadcast monitors, who would have thunk it? They seem to be pitching them very much against the JVC DT-V24 series at the bottom end (a grand cheaper) and the VuTrix at the edit suite/grade-1 end (again, a lot cheaper). I have demo stock coming so I will write a bit more when I've seen them.

Other things worthy of note - Tek now have all their 3D analysis tools in the WVR/WFM-8000 series 'scopes. I had a very informative half-hour with Lee Ballinger from Tektronix going over them.

Friday, September 09, 2011

Security and the Diginotar debacle

You might have been following the trouble that the Dutch SSL-certificate issuing firm Diginotar have been suffering recently. It transpires that Iranian hackers have got into their system and have spent several months issuing themselves wildcard certs for well known domains, most notably * - it essentially means these ne'er-do-wells can sign certificates that look like they have come from Google and your browser would be none the wiser. In fact it's not that severe unless you've been the victim of another attack;
  • Man-in-the-middle attack - you might be in a coffee shop where someone has managed to poison the ARP-table in the router and inserted themselves into your wireless comms. If they served up the fraudulent cert they could make any domain (especially there own server) look like you were securely connected to.
  • DNS-poisoning attack - as highlighted by Dan Kaminsky a couple of years ago it is possible to for elderly versions of BIND and more contemporary versions of IIS to incorrectly serve up DNS look-ups. Once this is in place the fraudulent cert on the same server would have you believing you had a secure connection.
  • Corporate decrypting proxies; many corporations install their own certificate on all client machines and essentially do a man-in-the-middle SSL intercept. Your traffic to is encrypted, but it goes via the proxy where it is momentarily decrypted for your boss to look at! If a corporate proxy was compromised dodgy SSL certificates could have you believing you had an encrypted connection to Amazon.
All of this raises issues with SSL - when I first started using an SSL browser (Netscape Navigator v.2 IIRC in '95!) there were around seven or eight trusted issuing CAs. Now there are hundreds (including the Hong Kong Post Office!) and it comes as no surprise that some of them get compromised sometimes. What I don't understand is why browsers don't keep a record of the CA associated with domains and when they see a change (particularly if a cert had time to run) inform the user? There is a plugin I use for Firefox called "Certificate Patrol" that does just that and it's easy to use and unobtrusive.
Now then - the whole Diginotar story started three months ago and they didn't spill the beans until last week; security is never served by secrecy. Also - it took Apple far to long to patch Safari. I think if you're concerned about network security then avoid Safari on OS-X.

Saturday, August 27, 2011

Sony BVM-E250 OLED broadcast monitor

I had an hour or so to set up a new Sony OLED grade-1 next to a Vutrix HD Pro-24 (their grade-1 LCD display which I like) - the Sony is twice as expensive as the Vutrix (£20k vs £10k). OLED as a technology is supposed to have a number of advantages over thin film transistor (TFT - the important bit of an LCD display. A few are;
  • In a TFT layer the polarisation of light is twisted through 90 degrees to allow the pixel to be illuminated by the virtue of the fact that the front filter is 90 degrees offset from the rear. In effect the transistor stops the light from the fluorescent (or nowadays LED) source. Since the light source is a few millimeters behind the pixel there are chromatic distortions inherent and since thin-film transistors don't shut-off all the light when turned off there are black-level issues. These are the two best known problems with LCD monitors in film & TV grading.
  • Thin-film transistors have a limit to how quickly they can be cycled - typ. 16ms at best (I know some manufacturers claim faster but it's smoke & mirrors). OLEDs can be cycled a lot quicker for better response.
  • In a TFT display the place where the colour is made (the three sub-pixel RGB transistors) is physically separate from the light source - not so with OLEDs where the illuminating LED is also the colour-maker.
So - with deeper blacks and fewer chromatic problems you'd think OLEDs were the way forward. The only thing to consider is the life-span. The blue OLED elements have an estimated life of 10k hours (around a third of the backlight of an LCD). Also - the metameristic character of OLEDs is different and so colour-management tools will need to be upgraded (I just spent £7k on a new LCD photometer!).

I thought out of the box the pictures on the BVM were very good - close to the VuTrix I'd just calibrated to illuminant-D (6504K at 80Cd/m2 for peak white). Response seemed as good with much better blacks, particularly from different angles. The monitor's de-interlacer didn't seem as good as I'd have expected for video-shot material but camera pans etc looked better than the VuTrix.

Overall I was impressed, but not an extra £10k impressed!

Friday, August 26, 2011

UPNP has always been a bad idea!

UPNP is a protocol that allows an application to open up ports on a router so that incoming packets from the Internet get to the correct IP address on the LAN. It's typically used to allow the XBox360 to set up open ports through your router to allow multi-player gaming. If both XBoxes are behind NAT routers there is no way that unsolicited traffic from one can make it to the other (hey, I never wanted your bullets to hit me!). Skype suffers thus if both callers are behind NAT routers (i.e. in most cases; who has an internet-facing IP address on their machine nowadays?) - details here). More recent versions of Skype will make use of UPNP if it's on the router.
You won't be surprised to learn that it's a Microsoft technology and I've always encouraged people to disable it on their routers. Any piece of malware inside your network can open ports and invite any other nasties in. In the case of XBox there are about four ports you need to open up for the Live! service to work. Anyhow - it turns out that Linksys routers have a bug that allows UPNP activation on the WAN side - that's right, with the correctly formatted packets you can open ports through a Linksys router from the Internet. Using something like UPNP Port Mapper will allow you to scan Internet IP addresses and open ports on those routers.

The title link is to the article on The H.

Thursday, August 25, 2011

Flame ain't all that

The facility that I'm building at the moment has a couple of Flame Premium suites - the very best version of Autodesk's TV and film compositing and finishing tool. Now I know very little about Autodesk products - I've never really worked in facilities where they were used. Flame, Smoke and the rest of them have been around for nearly twenty years and so you'd think they are what software people would describe as "mature products".
Anyway - a currently model Flame runs on an HP Z800 workstation with a Kona K3 card for video i/o (more about that in a minute!), an nVidia 4500 for desktop and their own proprietary fibre attached storage called "stone". They can typically handle two streams of 2k in realtime.
All very good, but everything is specified in a system - even down to the Eizo monitor you can use for the desktop display. This is because the SDi output for preview (which is not the output of the K3) is made by looping the 2nd DVI output of the graphics card into a daughter card that converts it to SDi. Consequentially you often see bits of the GUI on the HD video monitor. Now the reason for them specifying a certain model of GUI monitor becomes evident - they have to run the output at a rate near video for the DVI output to be convertible! This gets even more silly when you find out you have to use their own provided long DisplayPort cable to run it. We'd run in LC loose-tube fibre with DVI extenders which initially only worked whilst Linux was booting in text mode (i.e. before the X11 display subsystem could run). I had to throw in a Lindy EDID manager to fool Linux into thinking it really had the Eizo directly connected before we could run the desktop (and hence the Flame application).
This, along with a ton of little bits that the kit ships with; an 8-port ethernet hub, Lucid AES->analogue converters etc gives the impression they expect you to install the system on your dining room table rather than in a pro video facility. It really has the feel of a v.7 Avid from 1996! Cobbled together from third-party bits and only just running (everything on the hairy edge).
It reminds me of the Abekas DVEous (again, 1996) - one of the design engineers confided in me that if every bit of silicon on the video-processing board only performed to published spec then the system couldn't work. They relied on everything outperforming itself.

Thursday, August 18, 2011

Mute the TV automatically!

I've been a fan of ComSkip (a PVR plugin that automatically detects/removes TV adverts from recorded MPEG2 transport streams) and I firmly believe that technology will allow us to 'tame' various media sources - advert blocking in Firefox makes the web a nicer place, for example. Anyway - this is great, what a project;

Wednesday, August 17, 2011

iPhone 4 battery fault? NO!

Yesterday my iPhone 4 starting showing all the signs of a failed battery - the back of the 'phone was hot and it could hold a charge for around three hours. Darn - replacement handset with all the attendant messing around (although it a lot easier than it ever was on Windows Mobile!).
Anyhow - Googling around brought up a few sites with folks suggesting the mail daemon can get stuck trying to synchronise with Exchange and merely turning off push and letting the 'phone entirely discharge (or doing the hard-reset method of holding down the home and power buttons until the 'phone has powered off and restarted) and then re-enabling push sorts it.

settings>mail,contacts,calendar>fetch new data>advanced

By jove - it did the job. I can only assume the handset burns through the battery by keeping a data connection open continually.

I haven't blogged much recently because I've been on holiday. Pics here

Tuesday, July 19, 2011

Making iPhone ringtones from MP3s

1. Start iTunes and find the song you want to convert. (It must be an MP3.)
2. Right-click the song and choose Get Info.
3. Click the Options tab.
4. Check the Start Time and Stop Time boxes, then enter times for each (no more than 30 seconds apart, the maximum length for a ringtone). I used 0:00 and 0:30, respectively, as "Spit It Out" has a perfect ascending lead-in.
5. Click OK, then right-click the song again and choose Create AAC Version. You should immediately see a new 30-second version of the song. You need to make your import settings are set for AAC (I normally leave them as MP3).
6. Drag that version out of iTunes and into the folder of your choice.
7. Delete the 30-second version from iTunes and undo the Start Time/Stop Time changes to the original.
8. Open the folder containing the 30-second AAC file you dragged out of iTunes, then change the file extension from .m4a to .m4r. Double-click it and it immediately gets added to iTunes' ringtone library.
9. Finally, sync your iPhone. When it's done, you can head into the settings and select your new ringtone.

Couple of gems; Spanish Flea and Hawaii 5-0

Thursday, June 23, 2011

Two location-based things I'd like from my smartphone

  1. Location aware mute; I'd love to have a silent setting that unset itself when you moved more that (say) 50m from your current location. I have often put my iPhone into silent mode for a meeting and then noticed later in the day that I've missed several call because I forgot to take it out of that mode. Also - time-based silent-mode. I'd like my 'phone to auto-silence every Sunday 10:30 - 12:30 'cause I'm in church (for example).
  2. Location aware alarm; I've often missed a train stop because I've fallen asleep listening to a podcast or music. Why can't I set an alarm that rings in my earbuds when I get within five miles (say) of a location? Also - the ability to announce the time every ten minutes in the earbuds would be great.

Thursday, June 16, 2011


Unlike other digital currencies, Bitcoin avoids central authorities and issuers. Bitcoin uses a distributed database spread across nodes of a peer-to-peer network to journal transactions, and uses digital signatures and proof-of-work to provide basic security functions, such as ensuring that bitcoins can be spent only once per owner and only by the person who owns them.

My introduction to Bitcoin was via Steve Gibson's "Security Now" podcast; (check out episode 287 here). Along with the Wikipedia article my interest was peaked. Bitcoin seems to be a real, credible digital currency that is cryptographically secure. However - a currency needs to appeal to more than engineers and the economists are up in arms about it - read the very entertaining exchange here.

For the moment Bitcoins are trading for 1 BTC: 20$

Sunday, June 12, 2011

Estimating the time a job takes

For the last eight years I have spent a lot of my time quoting for broadcast installation builds. From small single edit suites to £1.5m broadcast editing centers I think I have a good feel for how long most jobs take. I recently did a search of my arrogated purchase orders folder and discovered I've bought more than 500 equipment cabinets, nearly 1000 video jackfields, and just over 100 kilometers of bulk fibre optic cable - all in the last eight years!
Anyhow - I often get quotes thrown back at me by chief engineers who assume I'm trying to fiddle them and they will typically say;
You've quoted ten days for a wiremen to wire those audio patch panels back to krone blocks; I'm sure my guy could do it in seven.
Even as a chief engineer he's probably only built one or two big machine rooms in his time. He might think he has experience of wiring technical facilities, but I've hired and paid wiremen to do many hundreds of audio panels in recent years. Possibly more than all the panels every chief engineer in Soho will oversee this decade! I know how long things take.

Anyway - for the last five years I've done an audit at the end of each year to compare the number of wiremen and engineer days each job used against what I thought when I quoted. It turns out that I naturally underestimate the time required by around 25% - If I quote 100 wireman days it'll be nearer to 130 when all is said and done. This isn't down to me not knowing how long each part of the job takes - it's a function of wasted time;

  • Client won't provide passes to everyone and so guys have to wait idle in rooms or go looking for the pass.
  • Deliveries are late, guys are idle
  • Customers change their mind, but not enough (or it isn't politic) to warrant a change order
  • Faulty parts - we always have to replace those for free!
  • Various other things you didn't expect.
So - I've made it my habit to still estimate the number of days as I think it should be and then add on the 25% extra. Consequently my quotes have been getting a lot more accurate over the last few of years. I also discovered the same effect with parts but in the other direction; I always over-estimate the amount of cable/connectors required by around 10%.

So far I haven't done anything about that!

Thursday, June 02, 2011

Tektronix WVR5200

During a manic day I was fortunate enough to bump into my old Tektronix mucker Tom Perry who had a new WVR5200 in his rucksack and gave me a quick in-the-street demo! It seems like a much more complete instrument than the current WVR5000 'scope and I can't believe it won't cannibalize their WVR7000 and 8000-series business. The things that stood out for me are:
  • Much improved four-tile monitoring with four inputs that can be configured as 4 x SDi (270M, 1.48G, or 3G - yes!) or 2 x dual-link. With four discrete inputs you can display all four at once.
  • An SDi o/p that can be any of the inputs OR a test output with bars or pathological signal.
  • Audio loudness - and up to 16 channels via embedded groups
  • Full Java control (the 5000 lacked this)

So I think this is excellent - the only thing missing is physical layer measurements. Some of the better features are paid-for upgrades (license key) but at £4.5k this represents superb value.
I shall write more when I've had one in to evaluate.

Tuesday, May 24, 2011

Tricaster tally-light interface for EX3s

One of my favorite parts of the job is prototyping and making little interface units so that equipment from different manufacturers can talk to each other.

This gadget allows the Tricaster TXCD850 studio production system to light the tallies on Sony EX3 cameras; although the Tricaster has "wet"-style GPI outputs it can drive the 12V needed for the lights. So, simple buffer circuit with relays to drive the studio tallies;

There are some photos in a Facebook album - click the title link.

Monday, May 23, 2011

Extending Sony 8-pin camera remotes

How far can the camera control signals from any smaller Sony camera go? If you talk to Mr Sony it's around 50m (the longest cable they sell) - but as the pictures (below) suggest it's at least the length of a box of cat5e cable! The CCA5 cable they sell is north of £500 so I recommend you hot-foot it over to RS, the Hirose ends are part numbers 685-1166 and 685-1163 for the lady and the gentleman and by consulting my scrappy wiring notes (above) you can brew your own for a tiny fraction of the cost. You can also adapt the cable to send down existing structured cable routes (cat5e / cat6 / cat7).

The title-link is to the F23's maintenance manual; that SR field-recorder has every Sony standard interface on it and so you can find the pinouts for whatever you might be using on your EX3 for example.
Rather splendidly the DC supply that runs back from the camera to the remote is the unregulated feed and so even if you loose a few volts down your home-brewed cable the regulator in the RM-B150 won't care; if you want to you can even power that device locally and not worry about volts coming back from the camera.

Tuesday, May 17, 2011

Old SVHS machines, the half line and archive ingest

As every superhero knows it's the second half of line 23, field one, that active content starts in a PAL signal yet come the start of field 2 line 336 starts as a full line with the corresponding half line at the end of field 2 on line 623. Consequently without a reference signal the only way to tell the difference between field one and two is by the half line at the top of field 1 (well, the broad pulses at line 3 vary but most equipment is field-locked by the time you get to that point in the scan).
We've been testing an ingest/archive solution at the workshop for an African state broadcaster who have a large analogue archive (SVHS and BetaSP). Capturing off the SVHS deck they'd provided for testing (a Panasonic AG-7550) we got some very strange effects. The route is this;

Analogue VT -> AJA FS/1 processor -> SDi into Content Agent uncompressed AVI

this is then compressed to 50 Mbit/s MPEG2 transport stream (I-frame only) and mux'ed into an MXF OP-1A and onto the shared storage. The file is then QC'ed on another machine with a Decklink SDi o/p running OpenCube MXF playback software. Both the input to the CA and the output of the QC are displayed on a JVC DT-V24 video monitor and Tek WVR5000 waveform.

All the clips captured off the SVHS were field-reversed by the time they got to the QC and so we assumed that there was some problem with the capture. After a lot of testing and head-scratching I discovered that the internal TBC on the Panasonic was removing the half-line at the start of field 1 and from then on the capture was marking F1 as F2 and vice-versa.

If you look at the output of the QC machine you can see the half line at the top of the frame, but the motion of the replaced video suggests the fields are reversed. In fact the fields are in the correct order but the capture card has marked them incorrectly and so by the time they are multiplexed and played out they are in the wrong order. The Tek shows the missing half-line at the start of field 1 (on input) and since there is a half line on replay it seems it must be there on field 2; hence the confusion by the capture card.

Turning off the AG-7550's TBC and relying only on the FS/1 showed the half line return to the start of field one and the problem disappeared.

Friday, May 13, 2011

Varying standards...!

Recently we installed five bays worth of equipment at a big facility - of course we did all the usual; Scope of Works, Method Statement, etc and when we'd finished all the usual test results - particularly electrical safety (since we all live in a 17th Edition world now). Now this machine room (one of several) was more than fifty cabinets and so you'd think they've sorted out all of their standards. However - when were handing over we were met with the following criticisms;
  • "You've mounted all the storage chassis flush with the front of the bays; our standard is that they are proud of the rack-strip". I went around the all other cabinets and they were an almost 50/50 mix of mounted proud and mounted flush...?
  • "You've attached the earthing straps to the front mounting-point of the bay, our standard is to the rear". I went around the all the other cabinets and discovered the only bays in the whole comms room with earthing straps were the ones we'd just installed.
  • "Our standard for PDUs is for 10-amp IEC outlets - even when they're feeding C19 (16A input) equipment, you've installed 16A PowerConn outlet PDUs" - we have to certify what we do to appropriate standards (that pesky 17th Edition again!) - no death-leads when you use us...
So I left confused, they'd taken us on to do a job they clearly didn't want/weren't able to do but they had nothing but ridiculous criticism by the end of the job. There doesn't seem to be any camaraderie amongst engineers anymore.

Saturday, April 23, 2011

iPhone vs Windows Mobile

I'm very pleased to have recently upgraded to an iPhone 4 handset. It really is much better at running the v.4 software than the iPhone 3 and reminded me of the reasons I was pleased to leave Windows Mobile behind and how some of those things are starting to bedevil Apple.
  1. Windows Mobile was effectively unsupported from the moment you owned the handset. In seven years and six handsets I never had a manufacturer-pushed upgrade. On a couple of occasions I managed to find slightly hookey versions (from other networks etc) than upgraded versions slightly but it never worked well. This seems to be playing out again with WM 'phone 7 for mobiles (or whatever they're calling it!); a year out of the gate and there has been one update that bricked a lot of handsets! MS are still asleep at the wheel when it comes to cell 'phones.
  2. With Windows mobile you have to hit the right hardware/OS version combo; A couple of handsets I owned were early in OS cycles (the first WM6 ones for example) and they weren't man enough for the new version of the OS. A couple (the HTC M1000 and the Vodafone V1615) were right before OS upgrades and worked brilliantly. The iPhone is starting to suffer this; nobody should run V4 on a v3 handset and expect the nice experience they remembered when they first got the iPhone.
It's an interesting time in smartphones; I wonder who will take third place after the iPhone and Android (or the other way around) - Blackberry or Nokia/Windows Mobile?

Thursday, April 21, 2011

"Schneier's Law"

Anyone can invent a security system that he himself cannot break. I've said this so often that Cory Doctorow has named it "Schneier's Law": When someone hands you a security system and says, "I believe this is secure," the first thing you have to ask is, "Who the hell are you?" Show me what you've broken to demonstrate that your assertion of the system's security means something.

Bruce Schneier is such an insightful chap - his blog is required reading if you have any interest in security or crypto; and really that should extend to anyone who is involved in networks. The grain of truth I take from this law is that you have to have to certain level of understanding of a subject to recognise your own ignorance. My dad had an expression "'re not even wrong" - being so far removed from the truth that you're not even on the same field as people who understand the problem (even if they've come to the right or wrong conclusion).

I'm so busy at work at the moment I'm not blogging to much.

Tuesday, March 29, 2011

Video post production a 'dying industry' - yikes!

This is a table nicked from the Wall Street Journal (via my pal Hugh - @hugh_waters on Twitter). On one hand it's very worrying but on the other hand it's what I've suspected.

  1. The equipment required for TV post production is now a £1.5k laptop and not a room that cost a million quid to install (twenty years ago). It's why audio still makes money (you still need an expensive room even thought the equipment is cheap) and why OBs, studios etc will always be profitable.
  2. Post production is largely run by owner-operators; folks who have an emotional attachment to it and will do work at a loss for the love of it and have a far too optimistic view of the future.
I don't know what the answer is - I'm going to try and concentrate on designing/building audio suites, TV studios etc and avoid edit rooms!

Monday, March 21, 2011

Side channel attacks with encrypted data

In cryptography, a side channel attack is any attack based on information gained from the physical implementation of a cryptosystem, rather than brute force or theoretical weaknesses in the algorithms. For example, timing information, power consumption, electromagnetic leaks or even sound can provide an extra source of information which can be exploited to break the system.

Several examples that I think are interesting are;
  • Secure web applications; Bruce Schneier's excellent blog (which is required reading if you have any interest in security/crypto) describes the attack carried out on the IRS's (what they call the Inland Revenue in the US) online tax form site; leaks a fairly accurate estimate of your Adjusted Gross Income (AGI). This happens because the exact set of questions you have to answer, and the exact data tables used in tax preparation, will vary based on your AGI. To give one example, there is a particular interaction relating to a possible student loan interest calculation, that only happens if your AGI is between $115,000 and $145,000 -- so that the presence or absence of the distinctively-sized message exchange relating to that calculation tells an eavesdropper whether your AGI is between $115,000 and $145,000. By assembling a set of clues like this, an eavesdropper can get a good fix on your AGI, plus information about your family status, and so on.
  • Compromise of HDCP; The encryption used over HDMI displays is industrial strength and cannot be broken by brute force methods (not in this universe, anyway!) - instead by freezing the memory used by a software BluRay player you can be assured that the volume-key is somewhere in memory. By stepping through 128-bits at a time and having a try at decrypting the first few frames of video (which are very clear when they are decrypted) you quickly find the key for that BluRay or HD-DVD disk.
  • The use of 'cribs' when decrypting Enigma traffic; Bletchley Park had typically less than a day to decrypt most traffic captured from German wireless telegraphy as they changed the rotor-positions in the Enigma machines every twenty-four hours. Apparently the intelligence gained by the French who were experts at recognizing the morse-key style of German operators (and hence were able to track which army group Fritz or Herman worked for) along with a knowledge the ten most profane German swear words and ten most common German girl's names meant they code-breakers had a head-start with seed-words which cut down the key-space to a manageable size that was process-able by 1942 mechanical computers!

Interesting though these examples are, the one that really peaked my fancy this week was the side-channel attach described by the Associated for Computing Machinery on the encryption used in VOIP systems. It turns out that most VOIP systems (Skype included) use variable-bitrate compression ahead of the encryption process (typ. AES at 128-bits). It turns out that by training a Markov Model with the encrypted data (yet knowing what the words spoken were) you can subsequently get around 50% accuracy with data streams from unknown talkers. Given that English has a lot of redundancy you could glean most of what was being said!

Read all about it here.

Thursday, March 17, 2011

Blackmagic, have the courage of your convictions!

I've often bad-mouthed Blackmagic as they often build to price rather than spec. In the past when I've complained about their interpretation of the SDi spec they've always said that so long as they can light-up a monitor they're 'democratizing digital video' or some such(!) Anyhow - Joel showed me that they are now featuring screen-grabs from a Tek rasteriser on their website; they weren't so keen on it five years ago!

Saturday, March 12, 2011

People's expense accounts depend on their unquantifiable skills!

In 1999 the Super Audio CD format was released - higher sampling rate and longer word-length than the venerable 44.1Khz/16-bit Red Book standard that traces it lineage back to the late seventies and the Sony F1 digital audio system.
I've spoken to audio engineers who have made a very good career out of there being a benefit in re-mastering recordings to this newer standard. Their contention is that the difference is "night and day" (please go back and read that post).
Anyway - in 2007 a couple of chaps from the AES did a double-blind test to see if audio professionals could tell the difference - it turns out they can do no better than random. Remember - that was audio engineers, dubbing mixers, and other people who know what to listen for in properly recorded audio. Mix Magazine did a very good write-up under the title of The Emperor's New Sampling Rate!

This all reminded me of a project I was involved in at Oasis TV in the late nineties where we were home-brewing an audio-FX server for the dubbing suites. At the time 9 gigabyte SCSI drives were £1,500 and so compression was implied! None of the dubbing mixers liked this idea and so I made up a CD of various recordings; spot-effects, different music styles, dry vocal recordings and finished mixed programme. The compression we were using was MP2 (so not as good as the now-ubiquitous MP3) at 128, 164, and 192 kBits per sec (as well as uncompressed).
Remember - these were the golden-ears listening on £10k matched amp/speaker combos. It turns out that somewhere between 164 and 192kBits per sec these guys dropped to about 50% accuracy in discerning the compressed audio from the original.
Actually I think it's a bit more complicated than what these two double-blind tests suggest; I store all my music at 192kbit MP3 encoded using LAME 3.9 - for 99% of my music I can't hear the difference. However;
  • On some passages (typ. splash cymbals and some acoustic guitar parts) I am aware of compression artefact's.
  • An old VT editor once told me (around fifteen years ago) that although he liked the look of (the then new) DV format he felt more tired after a day of editing DV footage compared to BetaSP - the differences aren't immediately clear but over time one is better (in some way?) than the other.

I do believe that you can only get to the truth of these things by statistical analysis - I place no faith in audio professionals who expect their view to be taken seriously without the numbers to back it up. Their salaries depend on them being able to 'hear' the differences - if they are there or not.

Friday, March 11, 2011


I've been following the Stuxnet worm in the technical press and it is fair to say that this is probably the world's first weaponised computer worm. In a very real sense this is cyberwar.
From Bruce Schneier's excellent blog;
Stuxnet was expensive to create. Estimates are that it took 8 to 10 people six months to write. There's also the lab setup--surely any organization that goes to all this trouble would test the thing before releasing it--and the intelligence gathering to know exactly how to target it. Additionally, zero-day exploits are valuable. They're hard to find, and they can only be used once. Whoever wrote Stuxnet was willing to spend a lot of money to ensure that whatever job it was intended to do would be done.

Symantec's report is very thorough but somewhat long!
The best expose on the whole subject is Steve Gibson's podcast on the subject;

Tuesday, March 01, 2011

Tony Drummond-Murray presents...!

This talk will start with the early methods of TV recording using film (Telerecording) and will briefly touch on some of the problems associated with TV cameras of this era. From there it will move on to Videotape recording (VTR), and will be illustrated with a few historical slides showing the early equipment. "VTR" is a vast field in this context, covering Recording, Playback, Editing (physical cutting and electronic splicing), Transverse and Helical scan tape formats, slow-motion and freeze-frame, and so on....

I've known Tony for many years, he is a great guy and a good speaker. We have staff meeting that night so I'll miss this unfortunately.

Thursday, February 24, 2011

Ever need to slow down ethernet?

I've had a few occasions when I've had to force gigabit down to 100BaseT or even 100 down to 10BaseT. My preferred method is to force the NIC down to the appropriate speed but if you aren't using Windows (OS-X, Linux or an embedded device) then a hardware solution is needed.

  • Distance - 100BaseT only goes 100m over cat5e but 10BaseT goes 300m; If you find yourself in that situation then an old 10BaseT hub at the far end does the job.
  • Equipment reports 100BaseT but is only reliable at 10BaseT; my Squeezebox network MP3 player is running a hacked OS and works a lot more reliably at 10BaseT. I achieved this by swapping the green/white and orange cores in the network cable. This degrades the common-mode rejection performance of the cable and means the ethernet switch ramps the circuit down to 10BaseT.
  • Gigabit too fast? Just make off a cable with the blue and brown pairs excluded. Gigabit needs all four pairs and if the switch only sees the Green and Orange pairs it will assume 100BaseT.

Thursday, February 17, 2011

My Presentations at BVE 2011

I've been representin' at the Broadcast Video Expo show in Earls Court. I'll blog about some of the things I've seen at the show later this week but in the meantime here are the slides from my three seminars;

These are all tasters for the training days I run at root6.

Friday, February 04, 2011

Rise times in HD TriSyncs

To my shame I haven't blogged for a month! We are starting to pick up at work with projects on the go and the BVE trade show at Earls Court in just over a week (I'm presenting each day - will post my slides next week).

These are two traces from two separate TriSync generators - The blue trace represents a correct waveform and as every superhero will realise you're looking at the line timing pulse. Here is the diagram from rec-709 (the spec for HD video);

It clearly shows that rise time is to be equal between the start, middle and end of the line-sync pulse. The rep from the manufacturer of the green pulse insisted that his waveform was a lot sharper - but given the ringing on it I think they just aren't filtering it properly to comply with the rise time spec - seen here (again from rec-709) as being 4 clock cycles +/- 1.5

Thanks to an unnamed ex-colleague(!) for engaging me in this conversation! The link in the title is to the summary document PDF of rec-709.

Tuesday, January 04, 2011

Hopes for 2011

  1. Teradici PCoIP starts working with Snow Leopard - Apple broke USB HIDs in 10.6 and so standard USB cards (which the Teradici HBA looks like to the OS) are not recognised (as they were in Leopard and are in XP, Win7 & any Linux).
  2. Someone launches a USB DVB-T2 adaptor - seriously, I want to upgrade my PVR to FreeviewHD!
  3. The industry starts to pick up; at some point effort for the BBC move to Salford and the Olympics have to trickle down to London-based SIs
  4. The Dolby PRM-4020 monitor starts to ship in the UK - see here.
  5. UK broadcasters start to take HD seriously before getting all excited about 3D
  6. UK broadcasters start to treat SD channels with some technical quality before getting too excited about HD!
  7. 3D in the cinema dies on the vine - the number of folks choosing to pay for it when they have a choice dropped off consistently throughout 2010 and so presumably at some point it will become economically nonviable.
  8. The root6 tech podcast eventually takes off (watch this space!).