• Embedding frame ranges into Quicktime movies with FFmpeg

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    QuickTime (.mov) files are fundamentally time-based, not frame-based, and so don’t have a built-in, uniform “first frame/last frame” field you can set as numeric frame IDs. Instead, tools like Shotgun Create rely on the timecode track and the movie’s duration to infer frame numbers. If you want Shotgun to pick up a non-default frame range (e.g. start at 1001, end at 1064), you must bake in an SMPTE timecode that corresponds to your desired start frame, and ensure the movie’s duration matches your clip length.

    How Shotgun Reads Frame Ranges

    • Default start frame is 1. If no timecode metadata is present, Shotgun assumes the movie begins at frame 1.
    • Timecode ⇒ frame number. Shotgun Create “honors the timecodes of media sources,” mapping the embedded TC to frame IDs. For example, a 24 fps QuickTime tagged with a start timecode of 00:00:41:17 will be interpreted as beginning on frame 1001 (1001 ÷ 24 fps ≈ 41.71 s).

    Embedding a Start Timecode

    QuickTime uses a tmcd (timecode) track. You can bake in an SMPTE track via FFmpeg’s -timecode flag or via Compressor/encoder settings:

    1. Compute your start TC.
      • Desired start frame = 1001
      • Frame 1001 at 24 fps ⇒ 1001 ÷ 24 ≈ 41.708 s ⇒ TC 00:00:41:17
    2. FFmpeg example:
    ffmpeg -i input.mov \
      -c copy \
      -timecode 00:00:41:17 \
      output.mov
    

    This adds a timecode track beginning at 00:00:41:17, which Shotgun maps to frame 1001.

    Ensuring the Correct End Frame

    Shotgun infers the last frame from the movie’s duration. To end on frame 1064:

    • Frame count = 1064 – 1001 + 1 = 64 frames
    • Duration = 64 ÷ 24 fps ≈ 2.667 s

    FFmpeg trim example:

    ffmpeg -i input.mov \
      -c copy \
      -timecode 00:00:41:17 \
      -t 00:00:02.667 \
      output_trimmed.mov
    

    This results in a 64-frame clip (1001→1064) at 24 fps.

  • Scientists claim to have discovered ‘new colour’ no one has seen before: Olo

    https://www.bbc.com/news/articles/clyq0n3em41o

    By stimulating specific cells in the retina, the participants claim to have witnessed a blue-green colour that scientists have called “olo”, but some experts have said the existence of a new colour is “open to argument”.

    The findings, published in the journal Science Advances on Friday, have been described by the study’s co-author, Prof Ren Ng from the University of California, as “remarkable”.

    (A) System inputs. (i) Retina map of 103 cone cells preclassified by spectral type (7). (ii) Target visual percept (here, a video of a child, see movie S1 at 1:04). (iii) Infrared cellular-scale imaging of the retina with 60-frames-per-second rolling shutter. Fixational eye movement is visible over the three frames shown.

    (B) System outputs. (iv) Real-time per-cone target activation levels to reproduce the target percept, computed by: extracting eye motion from the input video relative to the retina map; identifying the spectral type of every cone in the field of view; computing the per-cone activation the target percept would have produced. (v) Intensities of visible-wavelength 488-nm laser microdoses at each cone required to achieve its target activation level.

    (C) Infrared imaging and visible-wavelength stimulation are physically accomplished in a raster scan across the retinal region using AOSLO. By modulating the visible-wavelength beam’s intensity, the laser microdoses shown in (v) are delivered. Drawing adapted with permission [Harmening and Sincich (54)].

    (D) Examples of target percepts with corresponding cone activations and laser microdoses, ranging from colored squares to complex imagery. Teal-striped regions represent the color “olo” of stimulating only M cones.