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Posts: 2

GoPro Metadata question

So...I am parsing the GoPro Metadata (delivered to me from ffmpeg). I get the following "stream" of data concerning the onboard accelerometer:

 ('STRM', '\x00', 1, 1372) 
 ('TSMP', 'L', 4, 1) [4665]
 ('STNM', 'c', 1, 14) ['Accelerometer']
 ('TMPC', 'f', 4, 1) [25.0]
 ('SIUN', 'c', 4, 1) ['m/s²']
 ('SCAL', 's', 2, 1) [418]
 ('MTRX', 'f', 4, 9) [0.0, 0.0, 1.0, 0.0, -1.0, 0.0, 1.0, 0.0, 0.0]
 ('ORIN', 'c', 1, 3) ['YxZ']
 ('ORIO', 'c', 1, 3) ['ZXY']
 ('ACCL', 's', 6, 204) 612 [-1171, -1063, 4519]

from: GoPro's Github of GPMF:

STRM marks the begiining of the stream and total number of bytes.

TSMP is number of samples (not sure how they compute this)

STNM is the stream name: Accelerometer

TMPC is the temperature of the sensor(s) in deg C: 25

SIUN are the units for the samples: m/s^2

SCAL is a divisor by which to scale down the raw data: 418

and ACCL is the raw data in this case 612 'tuples' the first of which is: [-1171, -1063, 4519]

The question is: What are ORIN, ORIO and MTRX. I am assuming that MTRX is a 3x3 matrix to transform the raw data tuples, but how? ORIO and ORIN are 'orientations' but of what? Situation is very similar for gyroscope.