id3-helpers.js 1.2 KB

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  1. "use strict";
  2. Object.defineProperty(exports, "__esModule", {
  3. value: true
  4. });
  5. exports.getId3Offset = exports.getId3Size = void 0;
  6. var _byteHelpers = require("./byte-helpers.js");
  7. var ID3 = (0, _byteHelpers.toUint8)([0x49, 0x44, 0x33]);
  8. var getId3Size = function getId3Size(bytes, offset) {
  9. if (offset === void 0) {
  10. offset = 0;
  11. }
  12. bytes = (0, _byteHelpers.toUint8)(bytes);
  13. var flags = bytes[offset + 5];
  14. var returnSize = bytes[offset + 6] << 21 | bytes[offset + 7] << 14 | bytes[offset + 8] << 7 | bytes[offset + 9];
  15. var footerPresent = (flags & 16) >> 4;
  16. if (footerPresent) {
  17. return returnSize + 20;
  18. }
  19. return returnSize + 10;
  20. };
  21. exports.getId3Size = getId3Size;
  22. var getId3Offset = function getId3Offset(bytes, offset) {
  23. if (offset === void 0) {
  24. offset = 0;
  25. }
  26. bytes = (0, _byteHelpers.toUint8)(bytes);
  27. if (bytes.length - offset < 10 || !(0, _byteHelpers.bytesMatch)(bytes, ID3, {
  28. offset: offset
  29. })) {
  30. return offset;
  31. }
  32. offset += getId3Size(bytes, offset); // recursive check for id3 tags as some files
  33. // have multiple ID3 tag sections even though
  34. // they should not.
  35. return getId3Offset(bytes, offset);
  36. };
  37. exports.getId3Offset = getId3Offset;