I am working on a MIDI project using mido library in Python. I see in the manual a meta message for time signature with value: notated_32nd_notes_per_beat which has a default value of 8.
<meta message time_signature numerator=4 denominator=4 clocks_per_click=24 notated_32nd_notes_per_beat=8 time=0>
Which makes sense. However, can I define it like:
<meta message time_signature numerator=4 denominator=4 clocks_per_click=24 notated_32nd_notes_per_beat=32 time=0>
Does this increase the display resolution when shown in a score/typesetting software? What is the usage of this please?
time_signature (0x58) meta message in midi files
The file header specifies the number of ticks per beat, and the tempo messages specify the length of a beat, in microseconds. These value are needed to correctly play back the file.
The last field of the time signature message specifies how the tick values in the MIDI file relates to notes in a score. It does not affect at what time events are sent (so a pure playback program will ignore this message), but how notes are displayed.
For example, if the header says there are 100 ticks per beat, and the time signature has the default of 8 32th notes per beat, then a note-on/note-off pair with a distance of 100 ticks is displayed as a quarter note. If you change the time signature to 32 32th notes per beat, then a length of 100 ticks corresponds to a whole note.
Related
I have fragmented mp4 which I want to send users through HLS. It's ok if I just send it as is. But I need opportunity to reorder fragments in this video.
For example initial video, which looks like this:
original video format
I want reorganize fragments and get this:
expected video format
I try make it locally, and it's work in VLS player (HLS). For this I modified sequence number for fragments in moof (mfhd). But when I try play it remotely (HLS) it does not work. I think, that some players (js) expect some additional information from each fragment, probably for example time offset. But I can not find which atom (box) contain this information. I spent a lot of time searching and I'm still at the very beginning of the problem.
I tried to modify the fragment sequence number, but it doesn't work.
The "Track Fragment Media Decode Time Box" (tfdt) stores the baseMediaDecodeTime which is the accumulative decode time.
Consider the following...
baseMediaDecodeTime must increase monotonically for each chunk.
This means you must update (replace) the tfdt entry of chunk with expected next tftd entry.
When you naively reorder the chunks, the baseMediaDecodeTime will be invalid.
The "Track Fragment Media Decode Time Box" (tfdt) is located inside each moof header at:
moof --> traf --> tfdt
According Chrome DevTools Protocol viewer the value of requestTime is a baseline in seconds. To understand it I took this value from few web pages and for all of them the value of requestTime was unexpectedly large. For example one of them was 13133423 seconds. Does anyone know why the value of requestTime is too large? And what requestTime value mean?
Quoting the source code:
We want to present a unified timeline to Javascript. Using walltime is
problematic, because the clock may skew while resources load. To prevent
that skew, we record a single reference walltime when root document
navigation begins.
All other times are recorded using
monotonicallyIncreasingTime().
When a time needs to be presented to
Javascript, we build a pseudo-walltime using the following equation
(m_requestTime as example): pseudo time = document wall reference + (m_requestTime - document monotonic reference)
All values from monotonicallyIncreasingTime(), in base::TimeTicks.
More info on monotonicallyIncreasingTime: https://stackoverflow.com/a/39634132
I have the Panasonic MN63Y1210 tag. I have read it with different phones and always I see that the ID is 0x00000000
I've made a program with Arduino and Adafruit's PN532 shield and I have that response too, in ATQB, the PUPI appears like 0x00000000, but when I read the ISO 14443-3 I read this:
A Pseudo-Unique Identifier (PUPI) is used to differenciate PICCs
during anticollision. This 4-byte number may be either a number
dinamically generated by the PICC or a diversified fixed number. The
PUPI shall only be generated by a state transition form the POWER-OFF
to the IDLE state.
For the transition from POWER OFF to IDLE, we need a field, so, I expect that when I try to read the tag this is not in POWER OFF, because I'm applying a field, but I think it is strange to have that PUPI of 0x00000000. I've tested with another tag (same Panasonic model) and I get the same PUPI...
Is this normal? Or what do you think about it?
I would suggest that you start by looking into the datasheet of the MN63Y1210:
On page 26 (table 3-13) you will find that the default value this chip uses for the PUPI is 00000000. You can configure that value, for instance, over the serial interface.
I'm using an ElNet energy&power meter that communicates with my processor via Modbus RTU protocol.
There are two 16-bit ElNet registers that contain information about the Date and Time (separately) in a Win Format (registers 85-86, page 6 of this document). I'm able to read these two registers. However, I'm unable to extract information about the Date and Time.
For example, Date register contains decimal value of 17841 for today's date (31/07/2015). Is there any person willing to explain me how to convert 17841 into 31/07/2015?
I have the same problem with the time. My time register contains a decimal value of 55296. Can you help me extract the time from this number?
This thread addresses the same problem:
HEX/Decimal to date and time from modbus
However, I'm not sure I understand the extraction algorithm applied there. My point of operation is processor with the code written in C or C++.
Thank you very much for your time and effort to help me.
Sincerely,
Bojan.
The MS-DOS date/time format is described here: https://archive.is/2bVlz (was http://proger.i-forge.net/MS-DOS_date_and_time_format/OFz but is gone)
It makes sense for the 17256 value mentioned in the other question, as it translates to 2013-11-08. See here how to do it:
Register bit description: 0bYYYYYYYMMMMDDDDD
Registervalue: 17256 0b0100001101101000
Yearmask: 0b1111111000000000
Yearpart: 0b0100001000000000
Yearpart rightshifted 9 steps: 0b0000000000100001 = 33 years after 1980
Monthmask: 0b0000000111100000
Monthpart: 0b0000000101100000
Monthpart rightshifted 5 steps: 0b0000000000001011 = 11
Daymask: 0b0000000000011111
Daypart: 0b0000000000001000 = 8
Unfortunately your register value 17841 does not make sense, as it translates to 2014-13-17 (That is month 13).
Are you sure that:
you read the correct register? (change the time setting in the instrument, and see what happens to the register value)
you do not mix up the two bytes in the register?
the time setting is correct?
How do I interpret dwParam1 from the midiInProc delegate into midi status message like note-off, or note-on, control change?
Because as long i try dwParam1 is 254, and is not equal to note-off or anything else.
You won't necessarily receive note-offs from every input device. IIRC it is legal for a device to send a note-on with volume=0 as a substitute for note-off. Also a drum stream (from a drum machine and/or on MIDI channel 10) I believe commonly contains only note-ons, no note-offs.
Given that your question mentions dwParam1 and midiInProc, I'm assuming this is for Windows. When you receive MIM_DATA in your midiInProc, you can parse dwParam1 as follows:
For the status byte (command and channel), use LOBYTE(dwParam1).
For the first data byte, use HIBYTE(dwParam1).
If applicable, for the second data byte, use LOBYTE(HIWORD(dwParam1)).
I'm not entirely sure what you are asking, but I think you are trying to figure out how to interpret MIDI data.
I suggest this resource:
http://www.midi.org/techspecs/midimessages.php
MIDI messages related to notes are differentiated by the first 4 bits, not by the whole byte. The last four bits of the first byte specify the channel.
The answer by #Conrad Albrecht is mostly right, but I wanted to chip in with an answer (instead of a comment), as I think that the original poster is probably being confused by MIDI running status.
If you are seeing bytes which don't resemble normal MIDI status bytes, you can assume that they are of the same type as the previous byte which you received. Therefore it is not only legal, but very common, to use MIDI note on events with velocity of 0 as a substitute for MIDI note offs.
You should just interpret these bytes as the normal second two bytes of a MIDI note on event.