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.