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Messages - Deltafire

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MilkyTracker Support / FAQ: BPM/SPD/Rows/Ticks etc
« on: March 07, 2010, 10:48:04 »
People are often asking how these 4 are related, so I thought I'd type up a quick forum post to explain:

In ye olde days back on the Amiga, trackers used the VBL interrupt for timing (the Vertical BLank is the time in which a CRT has finished drawing the image and is resetting the beam position back to the top-left of the screen).  In Europe, the VBL interrupt was effectively a nice stable 50Hz timer.

So, a player routine would use this 50Hz timer to update the values in the Amiga's sound chip (named Paula): frequency, sample address & volume.  This was the shortest amount of time in which these parameters could be modified and was known as a 'tick'.  On the Amiga, a tick occurs at 50Hz and therefore has a duration of 20ms.

Obviously this is much too fast to playback a song (50Hz = 3000bpm!) so it had to be subdivided.  This is where the SPD (speed) parameter comes in, this controls the number of ticks that occur before the pattern advances to the next row.  Typically this is set to 6, meaning that 6 ticks will occur for every row of a pattern.  Using 4 rows per beat, this equates to 4 X 6 = 24 ticks per beat.  We know that the standard tick duration is 20ms (for a 50Hz timer), so 24 X 20 = 480ms per beat, translating this to Beats Per Minute:

60 / 0.480 = 125BPM

Which coincidently, is the default BPM setting of Milkytracker :)

Later versions of Amiga trackers added an option to use the Amiga's CIA timer interrupt instead of the VBL, this could be programmed to different frequencies enabling the tick duration to be altered.  Altering the tick duration allows the BPM to be set to user defined values instead of being fixed at 125BPM, therefore the BPM setting was added.  The Fasttracker II manual explains it thus:

The BPM setting defines how fast (ticks/second) the music player will run. 125 BPM<-> 50 Hz. Number of player ticks/second = BPM*2/5

Converting this value to a duration is easy:  Tick duration (ms) = 2500/BPM.


In Europe, Amiga's were designed for the PAL TV standard which updates at 50Hz.  In America, the NTSC standard was used at 60Hz.

Milkytracker does not use a fixed timer interrupt like the Amiga players do, instead it updates the tick value every x samples (where x is a calculated value that corresponds to the equivalent timer frequency).  Due to the granularity of both timer interrupts and sample speeds, the BPM value is almost never 100% accurate; there is usually an error of <1BPM.  This can cause problems when using trackers with other music software which may have a true BPM setting.

Bug Report Archive / Re: Audio sample generation problem.
« on: March 06, 2010, 15:00:26 »
This isn't a bug.

The value for 'Samples' is the amount of samples to allocate for a new sample (a sample consists of multiple samples!).  There's another thread on this board which has more information including what length sample to use so that one period = C4.

The mixer output is 16-bit, which is simply converted to a float for the JACK driver.  Feel free to improve on this if you wish :)

Not sure why the player is unresponsive to input - perhaps there is just not enough CPU time to process the input events at high sample rates?


This was fixed in release 0.90.85.

MilkyTracker Community / Re: MilkyTracker Wikipedia Entry
« on: February 21, 2010, 11:49:26 »
Deleted.  There were 4 votes to delete and only 2 (DasKreestof and myself) voted to keep it.

Btw, it has been deleted because it is deemed not notable, there are a lack of secondary reliable sources (sources not affiliated with MilkyTracker).  I could only find two secondary sources, and I don't think they were classed as 'reliable' sources according to Wikipedia's guidelines.

MilkyTracker Community / Re: MilkyTracker Wikipedia Entry
« on: February 11, 2010, 20:47:01 »
Click on the "edit this page" tab at the top.

MilkyTracker Community / Re: MilkyTracker Wikipedia Entry
« on: February 10, 2010, 17:39:19 »
I don't think an article on modarchive would help much - they could argue that modarchive is a primary source being the forums are hosted here.
[ Edit: "Primary sources or sources affiliated with the subject are generally not sufficient for a Wikipedia article" ]

Milkytracker has been mentioned in some hard-copy music magazines and PC magazines also as DasKreestof has mentioned on that discussion page, however I can't remember the magazine names and have no idea if there is an online copy that can be referenced.

Wikipedia has a blind spot for anything that could be considered 'underground' such as the tracker scene, IRC, anything that doesn't obtain main-stream media attention (for example, look up the page on Idle-RPG, a 'game' that appears on virtually every IRC network but which Wikipedia refuse acknowledge existence of!).  Really, it annoys me - we have a well-written and useful page for Milkytracker, but all that can be gone on the whim of a few arrogant Wikipedia editors.


MilkyTracker Support / Re: sample problem
« on: February 03, 2010, 23:12:28 »
Milkytracker adjusts the frequency of a sample by playing it faster or slower.  If the sample is playing too fast for you, use a lower note - for instance try a C-3 instead of a C-4.

You can also fine-tune a sample using the instrument editor.

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