RE: MTC and Time Code Types
RE: MTC and Time Code Types
- Subject: RE: MTC and Time Code Types
- From: "Cianflone, Chris" <email@hidden>
- Date: Sun, 6 Feb 2005 00:07:13 -0600
- Thread-topic: MTC and Time Code Types
Title: RE: MTC and Time Code Types
<<
30 versus 29.97 is the actual rate (fps, naturally).
Drop versus not is the counting method (i.e. how an actual frame number
is converted to hh:mm:ss:ff).
>>
That's what I was hoping and that is a nice explanation. I think I am getting more tripped up on what various sources are calling the various "frame rates" and "counting methods". For example, in my original e-mail I mentioned the MIDI Spec referring to the following:
> 0 = 24 fps
> 1 = 25 fps
> 2 = 30 fps (Drop Frame)
> 3 = 30 fps (Non-Drop Frame)
So if I am understanding this all correctly, shouldn't this simply be listed as
0 = 24 fps
1 = 25 fps
2 = 29.97 fps
3 = 30 fps
without any regard to drop/non-drop?
And then I tried a quick experiment in Digital Performer which lists the following SMPTE formats:
24 fps
25 fps
29.97 fps Drop
29.97 fps Non-Drop
30 fps
However, if I snoop on what MIDI data is getting sent in the above cases, it looks like this when shuttling to time 0:
24 fps : F0 7F 7F 01 01 00 00 00 00 F7, so 00 = "0 = 24 fps"
25 fps : F0 7F 7F 01 01 20 00 00 00 F7, so 20 = "1 = 25 fps"
29.97 fps Drop : F0 7F 7F 01 01 40 00 00 00 F7, so 40 = "2 = 30 fps (Drop Frame)"
29.97 fps Non-Drop : F0 7F 7F 01 01 60 00 00 00 F7, so 60 = "3 = 30 fps (Non-Drop Frame)"
30 fps : F0 7F 7F 01 01 60 00 00 00 F7, so 60 = "3 = 30 fps (Non-Drop Frame)"
So in the above, is the 4th line (29.97 fps Non-Drop) really supposed to be 30 fps Non-Drop? What am I missing here?
And sorry for the late reply. I got "dropped" by the flu late last week and am playing catch up on everything.
Thanks,
Chris
-----Original Message-----
From: kelly jacklin [mailto:email@hidden]
Sent: Thu 1/27/2005 9:25 AM
To: Cianflone, Chris
Cc: email@hidden
Subject: Re: MTC and Time Code Types
On Jan 26, 2005, at 7:10 PM, Cianflone, Chris wrote:
> So, what is kSMPTETimeType2997 and kSMPTETimeType2997Drop? I have
> been searching the web all day and not really finding a sufficient
> answer to this (although a few things I found made reference to these
> extra formats). Is there a more up-to-date MTC spec I should be
> reading?
30 versus 29.97 is the actual rate (fps, naturally).
Drop versus not is the counting method (i.e. how an actual frame number
is converted to hh:mm:ss:ff).
kelly
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden