View Source Vtc.FilmFormat (vtc v0.17.5)
Functions and types for working with physical film data.
Link to this section Summary
Perfs
Perforations are the holes that run along the sides of a strip of film, and are used by the camera's sprocket to physically pull the film in place to be exposed. For more information, see this Wikipedia article.
Perforation count in a single frame of film.
Link to this section Types
@type t() :: :ff35mm_4perf | :ff35mm_2perf | :ff16mm
Enum-like type of supported film formats for Vtc.
ff35mm_4perf
ff35mm_4perf
35mm 4-perf film (16 frames per foot). ex: '5400+13'.
what-it-is
What it is
On physical film, each foot contains a certain number of frames. For 35mm, 4-perf film (the most common type on Hollywood movies), this number is 16 frames per foot. Feet-and-frames was often used in place of Keycode to quickly reference a frame in the edit.
where-you-see-it
Where you see it
For the most part, feet + frames has died out as a reference, because digital media is not measured in feet. The most common place it is still used is Studio Sound Departments. Many Sound Mixers and Designers intuitively think in feet + frames, and it is often burned into the reference picture for them.
- Telecine.
- Sound turnover reference picture.
- Sound turnover change lists.
ff35mm_2perf
ff35mm_2perf
what-it-is-1
What it is
35mm 2-perf film records 32 frames in a foot of film, instead of the usual 16. This creates a negative image with a wide aspect ratio using standard spherical lenses and consumes half the footage per minute running time as standard 35mm, while having a grain profile somewhat better than 16mm while not as good as standard 35mm.
where-you-see-it-1
Where you see it
35mm 2-perf formats are uncommon though still find occasional use, the process is usually marketed as "Techniscope", the original trademark for Technicolor Italia's 2-perf format. It was historically very common in the Italian film industry prior to digital filmmaking, and is used on some contemporary films to obtain a film look while keeping stock and processing costs down.
16mm
16mm
what-it-is-2
What it is
On 16mm film, there are forty frames of film in each foot, one perforation per frame. However, 16mm film is edge coded every six inches, with twenty frames per code, so the footage "1+19" is succeeded by "2+0".
where-you-see-it-2
Where you see it
16mm telecine, 16mm edge codes.
Link to this section Perfs
@spec perfs_per_foot(t(), [{:physical?, boolean()}]) :: pos_integer()
Perforations are the holes that run along the sides of a strip of film, and are used by the camera's sprocket to physically pull the film in place to be exposed. For more information, see this Wikipedia article.
By default, returns the count in a 'logical' foot.
logical-feet-and-16mm
Logical feet and 16mm'Logical foot' means each time
XXrolls over when annotated in theXX+YYformat. There are 40 perfs in a foot of 16mm film, but when annotated asXX+YY,XXrolls over every 6 inches rather than every foot.
options
Options
physical?: Return the physical number of feet rather than the logical number.
@spec perfs_per_frame(t()) :: pos_integer()
Perforation count in a single frame of film.