BCF2000 units and recalling Scenes with fade times

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BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Sat Jul 14, 2012 11:57 pm

So I have a new system with 3 BCF2000 units for a SAC control surface. I have been using this for two productions now and so far they have worked out pretty well. But on the last production I did run into an issue. I was writing a scene where I wanted to fade some input and output faders over a period of a few seconds. In the past this has always worked just fine when using old Yamaha digitals for a control surface.

However this time around, when I would do this, the faders on the screen would fade in the time frame specified (and the audio in SAC would follow suit luckily). But the faders on the BCF units would sputter and jerk around and take anywhere from 30 seconds to sometimes a couple of minutes before they would inch their way to the correct fader position. Obviously this was worthless to me so at the time I just set the fade time back to zero and dealt with it and in one case made a special submaster fader that was not controlled by the surface so I could fade a couple of things up and down over set times.

I have these units all hooked up via USB by the way. I am using MIID-Ox to combine the USB MIDI ports and send them all to SAC via a virtual MIDI cable. And then another virtual MIDI cable out of SAC is split in MIDI-Ox and sent to all the surfaces.

I emailed Bob about the issue and he said that the MIDI messages were probably not being sent in the correct order and so the surface is fighting with itself. In my little bit of detective work I've done so far that made some sense as I saw he was using NRPR messages so he could get greater than 128 step resolution when using BCF faders. So it makes sense that if those messages are not sent in just the right pattern then it could lead to issues. I guess I will have to do some more experiments and see if I can figure out a solution. Maybe try one surface first and maybe try it all hooked up to a MIDI interface rather than USB as well. Or I could use the mode that lets you daisy chain multiple BCF units and that way I could perhaps not need MIDI-Ox as the surface will present itself as a single USB MIDI port.

Anyway, I'm mostly just posting to see if others have run into this issue and as a word of warning for others that may run into this. I suspect there is no real solution other than maybe tinkering with different modes and ways of getting the MIDI data in and out of SAC.

If anyone has any brilliant solutions I am of course all ears...

Hope everyone's summer is going well. I have finally had some time to come up for air.

Richard
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Re: BCF2000 units and recalling Scenes with fade times

Postby Kmoor » Mon Jul 16, 2012 8:06 pm

I have 2 bcf units...#1 is USB, #2 is chained through #1 via midi. I gave up with slow fader movements with multiple faders in scenes long ago. I had the same problem you described.
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Re: BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Wed Jul 18, 2012 5:25 pm

I think I have tracked my issue down to MIDI-Ox. If I just have one unit hooked up via USB, directly to SAC it works as expected. But as soon as I route that through MIDI-Ox, even as just a basic pass thru, it messes things up. I'm working on some other soultiouns on my test machine at home. Probably going to break out an old MOTU MIDI Time Piece AV and use that to merge the BCF MIDI outputs and split SAC's MIDI Output and run the BCF units in stand alone mode with no USB connection to the SAC system.
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Re: BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Wed Jul 18, 2012 7:34 pm

So maybe at some point I will find a fix, but honestly I think this is either a bug in SAC or just poorly implemented, you can choose which wording suits your fancy.

But I have just finished doing some basic tests. With only a single unit mind you. I was trying to keep it as simple as possible for testing, plus I only have one spare unit right now anyway. The other 3 are in a show and I'm not touching them until the show comes down in another month or so.

Anyway, I basically get poor results no matter what I try when I write a scene that "fades" the faders in a scene recall. If the fade time is zero, all it fine. If it's anything more than that (OK, I didn't bother trying values less than 250 ms, but really why is the fade time in ms and not seconds with a single decimal point anyway?) the faders will misbehave. I get various results based on my set up, but at best, I get jerky movements in approx the same rate they are fading on the screen (which is the correct time value) with one or two faders that don't move the correct position. They move close, but they are still off by several db. To worst case, the hardware faders take two to threee times longer than the fade time specified and with the same results, very jerky fader moves with one or two faders that are not in the correct position at the end of the fade.

Unfortunatly I hate to say it, but for me this puts the number of MIDI control surfaces that are properly supported and don't have issues... Zero.

Mackie, only one unit allowed. (not a bug, but not great either)
Motormix, works for 2 units, but 3 units don't work even though it's supposed to
Behringer, see above
Yamaha ProMix 01, works decent but only has 60mm faders and there is an unfixed bug dealing with the master fader
Korg 168RC, sometimes stops working until you go into the MIDI menu and turn send and recieve off and then turn them back on again...

Ugh! Oh well..... I'll just have to work around the timed fade issue. Fade Groups or something else up and down I guess that is not being controled on the control surface.... sigh... :(
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Re: BCF2000 units and recalling Scenes with fade times

Postby jlepore » Wed Jul 18, 2012 8:25 pm

Richard,

I am sure the problem is in the way he has implemented the controller code. When doing the time fades, he is moving everything a bit at a time each time through the engine loop. He must be sending TONS of fader move messages (for single point moves) and that has to be flooding the MIDI buffers on your controllers. The real solution would have to come from coding the interface differently, but we both know the chances of that ever happening.

Perhaps if MixiOX could throw away redundant messages, or some other process buffer them up and throw out the in-between movement messages it would help. If you do a trace on the MIDI port, you should see traffic go absolutely WILD during the fades. The problem is probably even worse with the larger controllers (Mackie / motormix) since he sends so much data per channel, and it seems he sends each channel - every time.
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Re: BCF2000 units and recalling Scenes with fade times

Postby TomyN » Thu Jul 19, 2012 12:08 pm

Does the situation improve if only one fader 'fades' ?

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Re: BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Sat Jul 21, 2012 1:54 am

TomyN wrote:Does the situation improve if only one fader 'fades' ?

Tomy


Don't know. I didn't think to try that. I will when I get time. But I am away from all my gear right now and won't be able to test again for anothe week or so.

I have been talking with Bob about this issue and we have been going back and forth to try and figure it out. I suspect it all has to do with the NRPN messages. In fact I'm pretty sure of that because I never had this issue when using my ProMix 01 and I've done dozens of productions with that surface.
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Re: BCF2000 units and recalling Scenes with fade times

Postby Glass50 » Mon Jul 23, 2012 11:45 am

Have just registered with SAC Talk. I to regret Bob's decision to shut down his forum.

With respect to using fades with scenes, I used scenes for a two SAC system Scottish Festival last May. Each stage had four rotating acts over three days, it was a natural for scenes. I tried fade down & up for 24 channels over 2 sec. Got same stuttering unsure results described below. Funny thing, fades worked fine when not LIVE. Bob (by phone) said there was not enough tcp/ip bandwidth to handle traffic since fade is commanded step by step. CAT5 remote improved over wireless but not by much. I rethought, decided to implement fade on break music only, had five scenes, act 1 to 4 plus break music. Going to break scene muted 23 channels and fade up winamp music on spdif ( ch25/26) 24 was left up for announcers wireless. Going to an act's scene recalled all settings and labels then faded music down. Worked well and smooth for me with 24 channels and 6 monitor mixes.

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Re: BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Tue Jul 24, 2012 1:30 am

Glass50 wrote:Have just registered with SAC Talk. I to regret Bob's decision to shut down his forum.

With respect to using fades with scenes, I used scenes for a two SAC system Scottish Festival last May. Each stage had four rotating acts over three days, it was a natural for scenes. I tried fade down & up for 24 channels over 2 sec. Got same stuttering unsure results described below. Funny thing, fades worked fine when not LIVE. Bob (by phone) said there was not enough tcp/ip bandwidth to handle traffic since fade is commanded step by step. CAT5 remote improved over wireless but not by much. I rethought, decided to implement fade on break music only, had five scenes, act 1 to 4 plus break music. Going to break scene muted 23 channels and fade up winamp music on spdif ( ch25/26) 24 was left up for announcers wireless. Going to an act's scene recalled all settings and labels then faded music down. Worked well and smooth for me with 24 channels and 6 monitor mixes.

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I am fairly convinced after playing with this for quite some time that basically it's just a bug in the way SAC deals with NRPN MIDI messages Bob implemented for use with the BCF units. The nice thing about going that route is that it gives you a lot more fader resolutions, since a standard MIDI continuous controller will only give you 128 steps between full on and full off or whatever the two extremese are of the parameter you are controlling. So with the NRPN messages (which is basically a series of 3 MIDI CC messages bundled togetehr to form a single MIDI command) you get thousands of steps rather than 128. The down side is that when you send these kind of messages if they get out of order at all then all hell can break loose. It must be something with the way Bob has SAC spitting out these strings of MIDI commands.

In thinking about it, it doesn't surprise me really because in order to make it work you would have to make sure your software never sent commands for two difference paremeters at the exact same time. So for example if I was fading 8 faders, SAC would need to make sure it sent a fader postion update for 1 thru 8 in the exact correct order and not try to send all 8 at one time. and you would have to do that for every time you want to update those fader positions, which could be several hundred times over the course of a few second fade.

I understand it's not trivial. But I'm still surprised it never came up as an issue sooner. ;) One would have thought that funcionality would have been tested long ago....

I say it doesn't surprise me because I can make the same thing happen on an M7 or LS9. Those consoles use NRPN messages to control the conslese via MIDI from other applications. I did the same basic thing using an LS9 or M7 with SFX software sending MIDI commands to manipulate things within the console directly. (often times easier than writing a lot of scenes to the internal meemory of the console. So when I first worked with the M7, I freaked it out in the same manner when I tried to send multiple channels worth of NRPN data all simultaneously. Now in SFX it was really easy to just make the software send the MIDI commands one at a time really fast one right after the other. But of course if you're moving a lot of parameters like this, it can take a second or two for more complext MIDI commands to complete.
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Re: BCF2000 units and recalling Scenes with fade times

Postby RBIngraham » Sun Jul 29, 2012 6:12 pm

TomyN wrote:Does the situation improve if only one fader 'fades' ?

Tomy


So mostly just for the sake of it, I did some more testing today. I did try with only a single fader moving as you suggested (thanks for that idea by the way). And big shock (not) it works as one would expect. So as I figured, it's the implementation of the NRPN that is causing the real issue here. Just for fun I reprogrammed a BCF to work with the general MIDI template. And now it can fade up and down just fine with a scene because it's just using standard MIDI CC#7 messages for the faders. It works just fine with the USB MIDI interface and it works find when plugged into a stock MIDI port. So it has nothing to do with MIDI bandwidth or TCP/IP bandwidth at all. It simply has to do with a poor choice to implement the BCF template using NRPN. It's nice in that you get more than 128 steps of fader resolution, but not being able to make an automation fade is a borderline show stopper at least in my book.

Oh well, I'm probably going to figure out a way to make it work using an alternate template and reprogram all my BCF units. The faders are still noisy and chatter when doing a longer fade but that is too be expected with these el cheapo units. Luckily that is not my biggest worry except in a few venues where the FOH position is practically in the lap of some audience members. (and I am only slightly exaggerating)

Thanks for the suggestions folks. But I'm chalking this one up as basically a bug or at least a poor idea. We'll see what the official response is from headquarters.
Richard B. Ingraham
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