|
|
No amount of caffeine is getting me through my morning, and I've found a bug in my MidiSlicer app. It's not a show stopper, but it's annoying. There are two ways to fix it, and one way is a dastardly hack. The other is complicated, but the Proper Way(TM) to do things.
The problem is such: In the MidiSlicer app you can modify a file while it is playing. However, since playback merges all of the tracks together for playback since they all must play at once, if you "mute" a track by removing it from playback, it changes the number of "events" in the stream. So your current cursor position during playback is now invalid.
Say for example we're playing a track with the following layouts
Drums: 50 events
Bass: 35 events
Guitar: 60 events
Total that's 145 events. So let's say I'm playing back and I'm near the end of the loop, and I remove the bass track. Well I'm on position 140, but it doesn't exist anymore now, because there are only 110 events in the stream now. Make sense?
The dumb way to fix it: Add a "dummy" NOP midi message to the API that never gets played or saved to disk. Replace any events i remove with a dummy event.
The right way to fix it: Before modification, get the absolute time of the cursor position. This should be expressed basically as system ticks or a timespan. After modifying the events, seek back within the event stream to that same *time* based position, wrapping if needed. and get the actual position within the event stream from that.
The latter way is preferable for many reasons, but while I've written code to convert from the current position to an absolute time based position, I do not have the code to go the other way around.
It sounds like a simple computation of time - basically the time each quarternote takes in system ticks, and then measure the score as quarter notes - which is simplified from what i'm actually doing but close. However, it won't work because the tempo can change throughout the track, meaning the duration of a quarter note can change throughout the score.
Measuring it involves starting at 0 and moving through the track, counting up times at the current tempo, and then recomputing durations whenever the tempo changes. That's what I do going the first direction. Converting from Time to position should be roughly the same thing but my brain isn't working this morning.
Real programmers use butterflies
|
|
|
|
|
honey the codewitch wrote: No amount of caffeine is getting me through my morning,
Have you tried with bacon? 
M.D.V. 
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpful answers is nice, but saying thanks can be even nicer.
|
|
|
|
|
i really should.
Real programmers use butterflies
|
|
|
|
|
Why not just find the first previous non-muted object, storing its 'this', as well as the current offset tick, then recreating the vector without shuffling, finding that 'this', setting the container's location to 'that', and then playing the next object in the list at the appropriate time?
Or something like that.
|
|
|
|
|
It's more complicated than it sounds because i'm not working on the merged tracks. I only see the individual tracks separated at that point.
They get merged only at the last second.
I'd have to show you the code, but putting in dummy messages is the easiest, if not the cleanest solution. It's far easier than recomputing all the delta times in each of the events in each of the tracks.
Real programmers use butterflies
|
|
|
|
|
If you are creating a pure MIDI stream and sending it to some process that only works in MIDI diff-times, then you will have to do something like you are stating. If not, you can just add a check to the C# object in the container when it reaches play time, and if it's track is muted simply don't play it.
|
|
|
|
|
It doesn't work they way, because the driver takes events with deltas attached to them. You queue them up with the deltas attached and it plays them when the time indicated by the delta comes up. It does this in the background. All the deltas are relative to each other, so if you remove an event, it shifts all the notes that follow it back by whatever it's delta was. So I'd have to recompute all the deltas any time i remove an event.
Real programmers use butterflies
|
|
|
|
|
Is it your driver or something you're using? If yours, maybe a change to absolute time (since the start of the piece), or even bar plus beat offset, would make this easier.
|
|
|
|
|
No, I don't have control over that. It's part of the MIDI spec, and the win32 driver API doesn't do translation
Real programmers use butterflies
|
|
|
|
|
I should add, I do actually, use the absolute time technique when I'm doing non-streaming playback, but that doesn't do background playback. It blocks the thread and just chews up CPU. It uses no waits, no timers, nothing, except querying the current system ticks and playing the event stream in a tight loop.
Real programmers use butterflies
|
|
|
|
|
If you can't do as Greg says, then it is a matter of going through each non-muted track individually, and finding the last non-muted event played. Recreate the new container without the muted events, find that last event played, and do the corresponding finagling. Unless I'm missing something.
|
|
|
|
|
> find that last event played, and do the corresponding finagling
That's the trick.
Real programmers use butterflies
|
|
|
|
|
You control all of the data structures at that point. Just add an 'absoluteTick' value to the struct and keep it up to date. Then finding things becomes easy.
|
|
|
|
|
i'm not adding one member i only ever use for one purpose, and then greatly complicating the code.
For example, what does my code do if both are set?
Nah. I think I'll solve this by thinking my way through it.
Real programmers use butterflies
|
|
|
|
|
|
Should dead HDD's be encrypted?
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
OK, I'DE be willing to take a big FAT byte. Just, when you answer, please avoid unnecessary spin or platter-tudes.
| Ravings en masse^ |
|---|
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
|
|
|
|
|
I was making tracks in that direction, but I'll head off home instead.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
Do you ruin an HDD by beheading or by splattering?
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
|
|
|
|
|
Let's see how you spin this one...
I'm not sure how many cookies it makes to be happy, but so far it's not 27.
JaxCoder.com
|
|
|
|
|
This question is pretty solid - state your reasoning behind this idea so we can speed things up around here.
If you can't laugh at yourself - ask me and I will do it for you.
|
|
|
|
|
OK - I have a garden that is mainly Eggplant and Hot peppers. All sorts of hot peppers. The point of all this, of course, is to get as much fruit as possible (otherwise I'd just look at pictures of them in seed catalogs).
Well - it started with some indoor hot banana peppers that survived well over a year in a sunny window at work. To get peppers from them, since there was a shortage of bees and other pollinators, I took upon myself the task of giving them the finger - or more precisely, the back of my thumbnail. For peppers, even without other pepper flowers available, this was enough to cause fruiting. Still, it was rather crude.
So now I've gotten a small soft paint brush - a tiny version of the ones used by humans during what is oft called 'foreplay'. Here's the plan:
I figure that if even a fingernail gets the flowers to go to fruit, imagine how much the yield will improve if the plants enjoy the experience even more with gentle and genteel brush strokes! As I only just started this method, there is an obvious induction period before any results are observable.
I'll update the lounge, if there is the expected clamor for the results, when the upcoming developments are manifest, so stay tuned !
| Ravings en masse^ |
|---|
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
|
|
|
|
|
We really need to bring back the Soapbox. 
Social Media - A platform that makes it easier for the crazies to find each other.
Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
