» Dezrann corpus/developer documentation

Dezrann displayed sychronized images. The synchronisation is done through a position file that allows Dezrann to associate musical time with a position in the image. A synchronized image is described as a source:

  // Any image (scan, score, piano roll, diagram...), with positions
  {
    "images": [
        "http://bli/scan-07-page1.jpg", 
        "http://bli/scan-07-page2.jpg" 
    ],
    "positions": "http://bli/positions-07.json"
  }

A position file is a JSON tree structure that can either be stored in a file (here http://bli/positions-07.json) or computed on-the-fly by some view when loading the source. In both cases, its format follows the positions.schema.json schema, as for example: :

{
  "$schema": "https://doc.dezrann.net/schemas/positions.schema.json",
  "pages": [
    {
      "image": "http://bli/scan-07-page1.jpg",
      "rows": [
        {
          // y positions
          "y": 96,
          "height": 214,
          "staves": [
            {
              "top": 96,
              "bottom": 258
            },
            {
              "top": 270,
              "bottom": 310
            }
          ],

          // x positions
          "start-x": 35,
          "end-x": 1465,
          "onset-x": [
            {
              "onset": 0,
              "x": 115.91
            },
            {
              "onset": 1.5,
              "x": 157.51
            },
            ...
          ]
        },
       ... // possibly other rows
      ]
    },
    ... // possibly other pages
  ]
}

Structure.

• The top-level object contains only a pages field, which is an array of pages.
• For each page, the URL of the corresponding image is specified in the image field. (If the source image is generated on-the-fly, any value can be used in this field.)
• Each page consists of rows, declared in the rows field.

For many applications, one single page with one single row is enough, yielding to a “linear” source (as a piano roll or a “linear score”). (Historically, there were different formats for linear sources and so-called ‘3D’ sources. Today, the ‘3D’ format is the format to use in all cases.)

The y positions are given with y and height, here between 96 and 310=96+214. In this vertical space, there may be one or several staves, here two. The staves have to be included in that space. For an image without any specific staff, there could be just one staff taking the full height, or even no staff.

The x positions are given by:

• the first and last x position (start-x and end-x).
• a number of synchronization points, given by onset-x, linking musical onsets (or seconds, if there is no score) and x positions. There could be just two synchronisation points, if the image flows linearly with the music time, or many of them.

Examples

There is here 1 page, composed of 4 rows, each composed of 3 staves: