Surprisingly they stay in sync even though they are just free-wheeling. Good point! Based on my tests of a month or so ago, multiple timing sources is indeed an issue. That worked for midi. Though I do have an old cassette deck and tapes with a sync track, I didn't try that, either. The Cakewalk reference guide and the on-line help pages state that audio and midi may not be in sync "Digital audio will play back, but not necessarily in sync. I was thinking that your external sync data would be constant as opposed to my wanting to vary the BPM from the external midi clock and that with the right settings you might be able to get both audio and midi to track well together based on a non-varying external sync.
I think I saw some video tutorials recently that showed how to create a tempo map based on an audio track. Maybe that might be an alternative to using the external sync track if the free-wheeling method is less than satisfactory. Yes, the days of the Sansui 6 track! I have two I slaved together but I want to transfer to CbB. If the bits are "10" 2 decimal , the frame rate is "drop 30" or If the top two bits are "11", then the frame rate is 30 frames per second.
The frame byte takes values which range depends on the frame rate specified in the hour byte. For example, if the frame rate is 24 frames per second, then the frame byte takes values between 0 and The sub-frame byte takes values between as there are always sub-frames in a frame.
The status byte is 0xFF which means that this is a meta message. The third byte shows that 5 bytes follow. The fourth byte is 0x01 which has the binary form and hence the frame rate is "00" or 24 frames per second. Thus this message means that the track should start 1 hour after the beginning of the sequence. Skip to main content.
A chunk is simply a group of related bytes. Each chunk begins with a 4 character ie, 4 ascii bytes ID which tells what "type" of chunk this is. The next 4 bytes all bytes are comprised of 8 bits form a bit length ie, size of the chunk.
All chunks must begin with these two fields ie, 8 bytes , which are referred to as the chunk header. It simply tells you how many bytes of data are in the chunk following this header. Note that the first 4 bytes make up the ascii ID of MThd ie, the first four bytes are the ascii values for 'M', 'T', 'h', and 'd'.
The next 4 bytes tell us that there should be 6 more data bytes in the chunk and after that we should find the next chunk header or the end of the file. NOTE: The 4 bytes that make up the Length are stored in Motorola byte order, not Intel reverse byte order ie, the 06 is the fourth byte instead of the first of the four. The first two data bytes tell the Format which I prefer to call Type. There are actually 3 different types ie, formats of MIDI files.
A type of 0 means that the file contains one single track containing midi data on possibly all 16 midi channels. A type of 1 means that the file contains one or more simultaneous ie, all start from an assumed time of 0 tracks, perhaps each on a single midi channel. Together, all of these tracks are considered one sequence or pattern. If your sequencer separates its midi data i.
A type of 2 means that the file contains one or more sequentially independant single-track patterns. The next 2 bytes tell how many tracks are stored in the file, NumTracks. Of course, for format type 0, this is always 1. For the other 2 types, there can be numerous tracks. The last two bytes indicate how many Pulses i. For example, if your sequencer has 96 ppqn, this field would be in hex :. Alternately, if the first byte of Division is negative, then this represents the division of a second that the time-stamps are based upon.
The first byte will be , , , or , corresponding to the 4 SMPTE standards representing frames per second. The second byte a positive number is the resolution within a frame ie, subframe. After the MThd chunk, you should find an MTrk chunk , as this is the only other currently defined chunk.
If you find some other chunk ID, it must be proprietary to some other program, so skip it by ignoring the following data bytes indicated by the chunk's Length. An MTrk chunk contains all of the midi data with timing bytes , plus optional non-midi data for one track. The Length will likely be different for each track. After all, a track containing the violin part for a Bach concerto will likely contain more data than a track containing a simple 2 bar drum beat.
Think of a track in the MIDI file in the same way that you normally think of a track in a sequencer. A sequencer track contains a series of events. For example, the first event in the track may be to sound a middle C note. The second event may be to sound the E above middle C.
These two events may both happen at the same time. The third event may be to release the middle C note. This event may happen a few musical beats after the first two events ie, the middle C note is held down for a few musical beats. Each event has a "time" when it must occur, and the events are arranged within a "chunk" of memory in the order that they occur. In a MIDI file, an event's "time" precedes the data bytes that make up that event itself.
In other words, the bytes that make up the event's time-stamp come first. A given event's time-stamp is referenced from the previous event. For example, if the first event occurs 4 clocks after the start of play, then its "delta-time" is If the next event occurs simultaneously with that first event, its time is So, a delta-time is the duration in clocks between an event and the preceding event. NOTE: Since all tracks start with an assumed time of 0, the first event's delta-time is referenced from 0.
A delta-time is stored as a series of bytes which is called a variable length quantity. So, if you have a bit delta-time, you have to unpack it into a series of 7-bit bytes ie, as if you were going to transmit it over midi in a SYSEX message. Of course, you will have a variable number of bytes depending upon your delta-time. To indicate which is the last byte of the series, you leave bit 7 clear. In all of the preceding bytes, you set bit 7. So, if a delta-time is between , it can be represented as one byte.
Here are examples of delta-times as bit values, and the variable length quantities that they translate to:. The first 1 to 4 byte s in an MTrk will be the first event's delta-time as a variable length quantity. The next data byte is actually the first byte of that event itself. I'll refer to this as the event's Status. For example, if the byte is hex 90, then this event is a Note-On upon midi channel 0. If for example, the byte was hex 23, you'd have to recall the previous event's status ie, midi running status.
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