- Broadcast engineering and IT related links and stuff. Maybe some music, films and other things.
Friday, December 30, 2005
Tuesday, December 20, 2005
Happy Christmas to you!
If you want to see our family Christmas newsletter see here.
Oh, the link above is to the Podsafe For Peace record which has a great back-story (courtesy of the Daily Source Code - see the link in the Podcast section, right). The song is cheesy as a big omelet but I love it!
Causes of colour
Monday, December 19, 2005
"The perils of colour-space conversion" - an article for the Root6 Dr. Watson newsletter
An important aspect of the production/post-production chain is maintaining correct colourimetry. If the director of photography or the lighting-cameraman want that certain shade of red to be correctly delivered to the viewer then attention needs to be paid to the correct representation from the camera (be it standard or high definition or even film) through all transfer operations (potentially going between resolutions, YUV/RGB colour spaces and bit depths) to the final display surface (be it a CRT, LCD or even cinema screen). In truth colour-space management for film is a complex issue best handled by specialists like Filmlight (who are represented in the UK by Root6) and is perhaps beyond the scope of some technical notes in a newsletter! That said there are many points worth making if you are acquiring or delivering for high definition television and worried about going between colour spaces.
The CIE Chromaticity diagram (first published in 1931!) shows the gamut of human vision – essentially any display surface is a subset of this diagram and will be a triangle with red, green and blue apexes and white (actually monochrome – as the luminance of the image is reduced it tends through grey to black) in the centre. In the case of “illuminant D” (AKA “D6500” or “EBU phosphors”) – the standard definition colour standard used since the sixties in Europe we enjoy a slightly wider red range than our colonial cousins but every gamut (television, film or print) is a poor compromise on what your eyes can handle. This is where the problem begins – you have a very critical instrument at your disposal to see these differences.Part of the problem is that all of our machines acquire images in the RGB space (TV cameras, Telecines, graphics workstations etc.) but for the most part we post-produce in a YUV space (with the exception of Sony’s new HDCam SR format, an RGB high-definition VTR) which represents an immediate lowering of the colour space. This has been the case for a long time and is well understood. Manufacturers have agreed a common “matrix” for transcoding. To make the luminance portion of the component signal the following is used:
y = 0.299 * r + 0.587 * g + 0.114 * b
Well, this is the case for standard definition (AKA “601”), but for high-def (AKA “709”):
y = 0.213 * r + 0.715 * g + 0.072 * b
Which, even if you’re not so into the maths, will give different values for the luminance (the overall level and hence look of the picture). This makes it doubly important that you get your cameraman to record some colour bars at the head of each rushes tape and that your editor checks alignment on his scope before he starts adding captions etc. The best of breed digital picture instruments are from Tektronics who Root6 are pleased to represent.
If you find you have a colour space issue (particularly going between standard and high definition formats) then the Belle Nuit Montage test chart is a good starting point. It can highlight all the common transcoding errors – be it the limited 8-bit range of old D1 videotape to some of the sub-sampling issues associated with HDCam. You can download the file at various resolutions from their website and by injecting it at the start of your workflow any inadequacies are quickly revealed and can be corrected.Friday, December 16, 2005
DVS in Hannover
Stephan & Emanuelle from Post Logic, Chia from DVS (our trainer), myself and Ben (Root6) who enjoyed the fact that we got to hire a 5-series BMW!
We also got taken through the hardware of the Clipster from a maintenance point of view and spent the last day doing SAN configuration. Their SAN is based around ADIC's StoreNext file system and as such allows you to have clients using all the common OSes - Windows, Linux, Unix (variants as well as IRIX for SG) as well as OS-X Tiger. They use X24 raidheads to control the array and so the system is not burdened with RAID operations (unlike a Unity).
Wednesday, December 07, 2005
Colourise black and white images
This is a very cool little freeware app that allows you to just mark an image with a few colour swipes and it does a very creditable job of colouring it. Do you remember when SG workstations first allowed people to colour black & white video? Popular for three weeks in about 1985!Anyhow - I thought an application for this (other than making Stan Laurell look unwell!) would be to give a new look to digital images that you'd previously made monochrome.
Tuesday, December 06, 2005
Engineering page at suitetv.com
...numerous awards for their work in commercials, short-form and broadcast programming, and their creativity is reflected in the company's impressive client base. No matter how complex your post production problem, you can be sure it will be....blah blah blahYou get the pictures.
Anyhow - The Suite (in Newman Street) have a really cute engineering page - just a bunch of pictures captured from the CCTV and looped in high speed - I was entranced - you see a guy fixing a VTR, them someone drinking tea, then someone installing something on a PC - it's great!
Monday, December 05, 2005
Saturday, December 03, 2005
If I got a tattoo.....
Yes indeed - if there is one thing that I wish the whole world would remember is that there are well defined relationships between analogue and digital audio levels. PLEASE - if you are (or have any influence with) a manufacturer of professional television equipment then align your A->D and D->A converters appropriately for your market, which is the case of Europe is -18dBfs for 0dBu.I installed a new v7 Protools on Friday - wrong (set for -14dBfs), Avid still ship set for -20dBfs and countless other bits of kit come in at -24dBfs. Perhaps these people just don't understand (or can't be bothered!).
Friday, December 02, 2005
Leitch routers and inheriting old gear
Anyhow - back to the Leitch - I could get the video level control panel to talk to the chasis and route but every time I attached an audio panel it wouldn't route both sides of the stereo pair - in the end I set the audio panel to issue commands on all levels bar the video and that did the trick. It's a bit of a bodge but works - until they try and attach an RS422 level (and then I'll get the call - probably at night!). I'm thankful I paid attention to the ESAM protocol when I was building Oasis's machine room - once you have a feel for how that works you can pretty much understand how any modern router's control system operates.
Back to inheriting old gear - monitors are the worst because the client expects them to look as good as the rest of the install - even with soft ten-year-old tubes they think the new setup will bring life back to those displays that should either be re-tubed or retired! A job we did earlier this year was a good example - the client had origional series 16x9 PVMs - even when new they weren't colour accurate but ten years down the track - well. Suffice to say Sony no longer make the SDi input board for that monitor and so we had to feed them analogue component (which in most instances is my prefered method - the analogue output of an Adrenaline BOB, for example, is a better picture than the 8-bit conversion done in the monitor input card) but the YUV was from a Decklink card! I'll stop now before my blood boils!
Friday, November 25, 2005
VideoReDo
I used to have an app that came with a Hauppage capture card called something like MPEG Razer (might have remembered that wrongly) which was ideal for chopping out ad breaks from TV shows captured on the PC. The application was keyed to the card and so once I upgraded to a DVB capture card (see here) I couldn't use it - it was such a good idea - letting you chop the MPEG stream only at I-frames, thus avoiding breaking the GOP structure and meaning you could re-save the cut very fast and no loss of quality from decompressing / re-compressing. Anyhow - I recently discovered VideoReDo which is superb. As well as super-fast MPEG editing it has a really good audio-sync tool which allows you to slip sync as the clip plays. The thumbnail and waveform display is very helpful for that and the real killer feature is that it can automatically detect ad breaks and mark them for removal (subject to your approval). If you really want to frame-accurately cut the GOP it only re-compresses the sequence back to the I-frames either side of the cut. Very clever. It also has tools for fixing non-compliant streams.Guess what show I was cutting when I grabbed that screenshot!
Thursday, November 24, 2005
What the Dell's going on?!
This got me wondering about the larger relationship between software and hardware and I pondered back to twenty years ago when I was doing a degree in maths and programming. At the time object-orientated languages were thin on the ground (Smalltalk was the only one I had any exposure to) and so working with either a procedural language (C, Pascal, COBOL etc.) or a functional language (LISP, Prolog) the developer could see how the abstraction applied to the final assembled code. All the programmers I graduated with (for example) could also code in Z80 and x86 assembler - not too many programmers can do that today. There was even the idea of induction to prove code. This was an idea that came from defense contracting that allowed you to show that a routine (typically in LISP) was good for every case by showing it worked for the specific case of n=1 and then for the general n+1 case. You could have confidence that a subroutine or even a whole program would work properly every time. Shoot forward to a few years ago when I was still running engineering for Resolution and I had to commission a database application that would support a 24-7 reality TV show and the programmer refused to stand by what he wrote - there was no way he'd be on call-out to fix any bugs we discovered down the line. It seems that as software development has moved into the realms of bolting objects together the idea of robustness has gone (get a programmer to explain the idea of garbage collection and why it is necessary in modern languages).
This is well illustrated if you compare the state of the two biggest NLE applications in the late 90's - Avid and Lightworks.
- Avid v.7, which if you used/installed/fixed it you'll know, was a capable application that needed a 300Mhz computer to run on a typically required 256megs of memory. It crashed often and took many minutes to boot. Judging by the multitude of error messages I got familiar with it was written in at least four languages and had components in it that hadn't been re-written in a decade (I know v.1 came out in 1991 but even today it has elements of EditDroid, the Lucas Film application that Avid acquired in the late 80's).
- Lightworks v.6, by comparison was a stable product that crashed once a month (on average), booted in under thirty seconds (due in part to DTX - they wrote their own disk handler rather than rely on an off-the-shelf OS!) and had an incredibly modest hardware requirement - a 66Mhz '486 with 64megs of RAM! It also came on three floppies!
Compare all this to how far hardware has come - back when I was doing that degree the 25Mhz '386 was the fastest cheap processor around and even then people were sounding the death-knell for the CISC architecture. The Von Neumann bottlekneck was perceived as a real problem for traditional processor design and RISC chips (especially the T800 series of transputers) were going to save IT. BUT, hardware design got better and all those problems haven't held back the Moore's Law express-train.
Tuesday, November 22, 2005
Tri Level Syncs
I get loads of people asking me about Tri-level syncs - they are becoming more significant in this HD-world and so here is a quick note - the link is a good explanation on the Extron website.The thing to remember is that unlike HD-SDi video tri-syncs can be distributed much like normal black & burst - the same cables, jackfields, and even DAs and routers can be used to carry them. Equipment that uses tri-syncs will often need it's reference input switched (one day it's a 24P job, the next it's a 1080i (50 field) one) and so small composite routers and multi-o/p SPGs are a good idea.
The horizontal timing reference point for a standard bi-level sync signal is defined as the 50% point of the falling edge of the horizontal sync pulse. In order to ascertain this point precisely, it is necessary to clamp both black-level and sync-tip level and derive a value half way between. If the signal is in any way distorted, this will give H timing inaccuracy. With a relatively pedestrian standard def signal (line rate in the province of 15 Khz) this isn't such a big deal, but with 1080 lines per frame this becomes more significant and with a tri-level sync signal, the timing reference point is the rising edge of the sync signal as it passes through the black-level. This point is much easier to determine accurately, and can be implemented relatively easily. It is also more immune to signal distortion.
Monday, November 14, 2005
Sony's DRM "Root Kit" controversy
Anyhow - a very funny post on Sysinternal (who broke the story origionally):
f you want a more concrete proof, try to rename your favourite ripping software as $sys$whatever.exe and then run it again. You'll notice that the DRM system can no longer detect it, and thus you'll get good copy of the track you try to rip instead of one filled with noise.There is a worry that virus and other malware authors can exploit this loophole - but the idea that the very thing that Sony were trying to prevent now gets easier is funny.
Thats just hilarious. I think everyone should simply not worry about removing the rootkit, as this is too difficult, and then just do at Matti says, and use the rootkit to make your favorite ripping tool immune to the DRM. On second thought, is their software breaking the DMCA? It provides a method to bypass copyright protection that they install? Hmm...
A list of Sony/BMG disks that you should avoid.
23rd November update: It now appears that Sony had bundled the open source Lame encoder as part of the XCP install - in clear violation of the GNU public license. It seems it's OK for Sony BMG to install software on your PC that stops you from making legitimate use of the music you purchased and at the same time they're ripping off other people's IP!
You couldn't make it up!
Sunday, November 13, 2005
"He's running a bit rich"
Thursday, November 10, 2005
Operation Christmas Child
There is an anti-American undercurrent in the newspapers aimed at the chattering classes and I don't like it. Every American I've met (here and in the States) has been an entirely reasonable person. Surely you can hold a view that you dissapprove of Bush and the war and yet still feel affectionate towards normal Americans.
Anyhow - it's not too late - the couple of hours it'll take you to fill a shoebox with some goodies (and maybe £10 out of your Christmas budget) will be time and cash better spent than you'll ever realise.
Wednesday, November 09, 2005
Mix tapes!
Saul put me on to this site that just has pictures of audio cassette stock. I remember my Dad making mix tapes (I'm sure the expression then was "compilation"!) for car journeys onto this type. This is great - a website that actually bought back some childhood memories very vividly.Tuesday, November 08, 2005
Cerberus FTP server
It transpired that there was a hotfix over the weekend that "...addresses some compatibility issues with IIS and passive FTP transfers" - well, if the issue was it used to work then they have indeed addressed it with the now it doesn't solution! I suppose I could un-install IIS and re-install (not forgetting to disable auto-hotfix!) and spend half a day getting the configuration right but I tried Cerberus (Rupert mentioned it yesterday) and was amazed - installed and configured in twenty minutes and all my users are happy again. Yet another one of those cases of grasping the nettle and realising how easy it is to break away from Microsoft and how much better things seem to work afterwards.
Monday, November 07, 2005
Virtual desktop PPMs
Paul Marshall is a very clever chap - he often posts on uk.tech.broadcast (Google Groups link in menu bar, right hand side). Here are a few stand-alone audio meter apps that just look at the o/p level on the system sound card - you tell it what zero level is (typ. -18dBfs for TV work) and it makes an animated meter (VU, Digital, BBC PPM) that has all the ballistics of the real thing. I've had his dual-PPMs up on screen all day for spoken as well as music content and they are the business!
11th Nov Update - Rupert has got this working with ExpressPro - very neat. In Settings you need to tell the audio tool to use the system mixer - select "mix" or "wave mix" in your Windows mixer tool record setting and you'll be off to the races!
Friday, November 04, 2005
Audiophile at I-Like-Jam
The Intelligent Chip is a one inch square, bright orange plastic wafer that, when placed on top of a compact disc player for 2-3 seconds, upgrades the disc (CD, DVD or SACD) being played at the time. The sound of the upgraded disc has more detail and articulation, better dynamics and an absence of "digital harshness." Voices are more human-sounding and less synthetic. The upgrade is permanent. Inside the white translucent Intelligent Chip case are two ultrathin, clear polycarbonate sheets, one on each side of the Chip. The manufacturer's product brochure states, "The Intelligent Chip should be put back into the packing case after using, because the packing case can protect the quantum material of the Intelligent Chip, preventing them from leaking."The nonesense goes on with reference to Schrodinger's cat and other quantum ideas, the summary is the best;
The Intelligent Chip works via coherent quantum superposition and quantum entanglement, in which two coherent light sources - the CD laser and the quantum dot laser in the chip - interact strongly with the atoms and molecules in the CD's polycarbonate layer to produce long-lasting, superior transparency for better optical signal to noise ratio (SNR). Laser light escapes the player via a number of small holes and gaps in the player case. The emitted light from the quantum dot laser instantly comingles with the CD laser light in the room and inside the player.Now what has escaped these people's attention is that with some CD players you can get the CD to show the number of errors in the bitstream (the Red Book standard specifies Miller Coding so errors are easy to spot). I used to have a Sony machine in the early nineties that had a maintenance mode that would make the display show the error count rather than track number etc. I had several disks that could play end to end with no errors - so, how can improving the s/n of the bitstream signal improve the final analogue sound if the digital signal wasn't noisey enough to give errors in the first place?!
However - the $1,500 power cord really got my goat! I wrote an email to the dude;
Hi,I'll let you know what comes back!
I just read your review of this power cable - did you write this for a joke or is it a paid-for "advertorial" for the company concerned?
If this power cable produced a measurable difference in sound reproduction why didn't you include some measurements (Total Harmonic Distortion, bandwidth figures, signal-to-noise etc.)? - Would you know how to measure these things?
"...like most other AC products, it will undergo changes in sound for three to five days after its application to a component. Judging the absolute merits of any AC product within this "settling period" will most often prove misleading. "
What, precisely, happens to a power cord during this "bedding in" period? For such a high sum you'd expect the manufacturer to burn the cable in for you!
What, in your view, makes this a good power cord? What was the impedance per metre? What about the capacitance? Do they make a different design for 50hz users? If it is so optimised the difference between 50 and 60Hz is surely significant.
Surely improvements and order of magnitude more significant than this could be achieved by hard-wiring the amp's mains input to the incoming mains feed from the street - even then they have merely used copper cabling for the mile back to the substation.
Regards,
Phil Crawley,
I really feel it's important to stand up against this pseudo-science and trickery.





