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Many videos files are now beyonds 30fp. For example 50fps or 60fps. MTC only supports up to 30fps,
isn't it time to update the MTC specification to support higher frame/sec ? The first MTC byte uses two bits now to specify the frame rate and the others bits are unused. Modern DAWS support MTC, but can't sync the new video files due to MTC's limitation.
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Happy Accepted Answer Pending Moderation
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This has absolutely nothing to do with the speed of MIDI. (except that there will be about twice as many MTC messages over the wire)

MTC byte 3, 000fffff: Frame (0–29, or less at lower frame rates)
THUS MTC CAN ONLY SELECT FRAME 0 to 29, NOT BEYOND THAT.

MTC can only address/select these frames
0rrhhhhh: Rate (0–3) and hour (0–23).
rr = 00: 24 frames/s
rr = 01: 25 frames/s
rr = 10: 29.97 frames/s (SMPTE drop-frame timecode)
rr = 11: 30 frames/s

The unused bits in minute and seconds could be used to extend the frame rate bits for "HFR" because the unused bits 6 and 7 in frame# will need to be used for the selected frame (127 max)

One bit could mean to double the frame rate. That is to 48, 50 and 60 and using the seconds bit to go to maximum of 120fps. (The hobbit was shot in 48fps and many MP4 files are in 50fps, and some really high end media goes up to 120fps)

The request for change is thus as follows:

HFR (High Frame rate) support
minute bit 6 - seconds bit 6
0 0 = standard
0 1 = 2x fps (48, 50, 60)
1 0 = 4x fps (96, 100, 120)
1 1 = Not usable because frame maximum is 127

The use case is that software and hardware with MTC can control the playback of video without first having to down convert the video to lower fps rates.

Sure all applications that send and receive MTC will need to be updated. But it's 2017, it's time.

The MMC Locate command will also have to be updated and it has unused bits as well in the frame byte


https://www.smpte.org/atc2012/symposium
https://www.smpte.org/sites/default/files/22-1445-CH6-MASTERING.Mitchell-Wilson-Claydon.pdf
https://en.wikipedia.org/wiki/High_frame_rate
https://en.wikipedia.org/wiki/MIDI_Machine_Control
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  1. more than a month ago
  2. MIDI Specifications
  3. # 1
Geoff Accepted Answer Pending Moderation
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Is the problem with the MTC Spec?

A quick read via Google suggests that the 30 fps limit is imposed by the SMPTC (?) protocol, not by midi. I'm sure the midi clock/time codes can run at quite enough resolution to handle 60fps? Midi runs at 32k bps (or so). I'd assume that USB emulations of midi could run at even higher rates (and so be capable of higher resolution)?

Geoff
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  1. more than a month ago
  2. MIDI Specifications
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