On Sun, 2007-06-24 at 07:15 +0100, Tore Sinding Bekkedal wrote: > > > " a lamp on the camera which says whether or not the cam's on " > > I have a pic programmed to do this, when faced with different characters > > at a serial port. > > As we've discussed on IRC, I myself don't see this as the right > solution. The use of a PIC is needlessly complicated, it introduces > cabling requirements (although the cabling requirements to make RS-232 > frames transmit correctly admittedly aren't stringent), there could be > serial port problems, you can only run one camera per serial port, > many machines nowadays dont even have serial ports.. > I suggest using a single I/O line off the parallel port, as it can be > programmed to act as an 8-bit general-purpose TTL-level output. Many machines don't have parallel ports either. I made a half-serious suggestion to Dave that the simplest way to attach a tally light would be to cannibalise a USB keyboard. (I believe all the lock lights are programmable.) But that is sick. As I said on IRC, Cypress has cheap microcontrollers[1],[2] with hardware USB and flash, but programming them may be difficult without a fairly expensive development kit[3]. However there is a fair amount of documentation on their web site and the only critical thing missing is the low-level flash programming protocol needed initially. (Reprogramming can be done under firmware control[4].) It might be worth asking for documentation of that. [1] http://www.cypress.com/portal/server.pt?space=CommunityPage&control=SetCommunity&CommunityID=209&PageID=259&fid=16&rpn=CY7C638xx&ref=pfm [2] http://www.arrownac.com/aws/pg_webc/0,4513,,00.html?application=SEARCH&event=1000&search_criteria=match_begins_with&search_token=CY7C638 [3] http://www.onfulfillment.com/cypressstore/Product.aspx?d=46&p=783&sid=205 [4] http://www.cypress.com/portal/server.pt?space=CommunityPage&control=SetCommunity&CommunityID=285&PageID=552&r_folder=Application%20Notes&r_title=AN6075&ref=prt > > However, tally lights go further than this; we should have preview (pvw) and > > programme "monitors" in dvswitch. When a camera is cut to a pvw monitor, > > the tally light should show green or amber; when the camera is cut to > > transmission (Tx); the tally light should be red. > > So, this is like A/B bus on the Helsinki video switch? Where one would > select a source for bus A, and a source for bus B, and switch between > them? The source for the inactive bus is the pvw source? It also means the cam-op has advance warning. > I'm not sure how useful this is for now. IMAO, buses only really make > sense if you're fading between the sources or making other > transitions. If you're just cutting between them, I don't see any > point at all... or am I wrong on this? We would like picture-in-picture. And maybe rapid fades. > > However, talkback is more important, as there have been several cases > > where a camera operator has not been able to produce a useful shot; and > > some direction would've been useful. > > I agree. In essence, tally lights would be only a very primitive talkback system. > > > We should be able to organise the talkback with asterisk next year > so it should be fine. > > Are you sure the added complexity of Asterisk is worth the > out-of-the-boxed-ness? It seems to be a very large system, with > transcoders and CPU-intensive things... Considering we'll have gigabit > between the machines, we could just write some near-zero-latency > program which will push 48KHz 16-bit PCM directly from the ADC of the > dvswitch box to the camop boxen... return comms could be largely > accomplished with hand gestures - having camops talking during a talk > is probably not the best thing. I would actually like to have talkback supported in dvswitch. It would need to mix talkback with monitoring in some way. But I know very little about the audio processing necessary to do this, and the latency between capture at the camera and processing in dvswitch could be a problem. Ben. -- Ben Hutchings compatible: Gracefully accepts erroneous data from any source
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