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src/remux/aac-helper.ts

  1. /**
  2.  *  AAC helper
  3.  */
  4.  
  5. class AAC {
  6.   static getSilentFrame(
  7.     codec?: string,
  8.     channelCount?: number
  9.   ): Uint8Array | undefined {
  10.     switch (codec) {
  11.       case 'mp4a.40.2':
  12.         if (channelCount === 1) {
  13.           return new Uint8Array([0x00, 0xc8, 0x00, 0x80, 0x23, 0x80]);
  14.         } else if (channelCount === 2) {
  15.           return new Uint8Array([
  16.             0x21,
  17.             0x00,
  18.             0x49,
  19.             0x90,
  20.             0x02,
  21.             0x19,
  22.             0x00,
  23.             0x23,
  24.             0x80,
  25.           ]);
  26.         } else if (channelCount === 3) {
  27.           return new Uint8Array([
  28.             0x00,
  29.             0xc8,
  30.             0x00,
  31.             0x80,
  32.             0x20,
  33.             0x84,
  34.             0x01,
  35.             0x26,
  36.             0x40,
  37.             0x08,
  38.             0x64,
  39.             0x00,
  40.             0x8e,
  41.           ]);
  42.         } else if (channelCount === 4) {
  43.           return new Uint8Array([
  44.             0x00,
  45.             0xc8,
  46.             0x00,
  47.             0x80,
  48.             0x20,
  49.             0x84,
  50.             0x01,
  51.             0x26,
  52.             0x40,
  53.             0x08,
  54.             0x64,
  55.             0x00,
  56.             0x80,
  57.             0x2c,
  58.             0x80,
  59.             0x08,
  60.             0x02,
  61.             0x38,
  62.           ]);
  63.         } else if (channelCount === 5) {
  64.           return new Uint8Array([
  65.             0x00,
  66.             0xc8,
  67.             0x00,
  68.             0x80,
  69.             0x20,
  70.             0x84,
  71.             0x01,
  72.             0x26,
  73.             0x40,
  74.             0x08,
  75.             0x64,
  76.             0x00,
  77.             0x82,
  78.             0x30,
  79.             0x04,
  80.             0x99,
  81.             0x00,
  82.             0x21,
  83.             0x90,
  84.             0x02,
  85.             0x38,
  86.           ]);
  87.         } else if (channelCount === 6) {
  88.           return new Uint8Array([
  89.             0x00,
  90.             0xc8,
  91.             0x00,
  92.             0x80,
  93.             0x20,
  94.             0x84,
  95.             0x01,
  96.             0x26,
  97.             0x40,
  98.             0x08,
  99.             0x64,
  100.             0x00,
  101.             0x82,
  102.             0x30,
  103.             0x04,
  104.             0x99,
  105.             0x00,
  106.             0x21,
  107.             0x90,
  108.             0x02,
  109.             0x00,
  110.             0xb2,
  111.             0x00,
  112.             0x20,
  113.             0x08,
  114.             0xe0,
  115.           ]);
  116.         }
  117.  
  118.         break;
  119.       // handle HE-AAC below (mp4a.40.5 / mp4a.40.29)
  120.       default:
  121.         if (channelCount === 1) {
  122.           // ffmpeg -y -f lavfi -i "aevalsrc=0:d=0.05" -c:a libfdk_aac -profile:a aac_he -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
  123.           return new Uint8Array([
  124.             0x1,
  125.             0x40,
  126.             0x22,
  127.             0x80,
  128.             0xa3,
  129.             0x4e,
  130.             0xe6,
  131.             0x80,
  132.             0xba,
  133.             0x8,
  134.             0x0,
  135.             0x0,
  136.             0x0,
  137.             0x1c,
  138.             0x6,
  139.             0xf1,
  140.             0xc1,
  141.             0xa,
  142.             0x5a,
  143.             0x5a,
  144.             0x5a,
  145.             0x5a,
  146.             0x5a,
  147.             0x5a,
  148.             0x5a,
  149.             0x5a,
  150.             0x5a,
  151.             0x5a,
  152.             0x5a,
  153.             0x5a,
  154.             0x5a,
  155.             0x5a,
  156.             0x5a,
  157.             0x5a,
  158.             0x5a,
  159.             0x5a,
  160.             0x5a,
  161.             0x5a,
  162.             0x5a,
  163.             0x5a,
  164.             0x5a,
  165.             0x5a,
  166.             0x5a,
  167.             0x5a,
  168.             0x5a,
  169.             0x5a,
  170.             0x5a,
  171.             0x5a,
  172.             0x5a,
  173.             0x5a,
  174.             0x5a,
  175.             0x5a,
  176.             0x5a,
  177.             0x5a,
  178.             0x5a,
  179.             0x5a,
  180.             0x5a,
  181.             0x5a,
  182.             0x5e,
  183.           ]);
  184.         } else if (channelCount === 2) {
  185.           // ffmpeg -y -f lavfi -i "aevalsrc=0|0:d=0.05" -c:a libfdk_aac -profile:a aac_he_v2 -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
  186.           return new Uint8Array([
  187.             0x1,
  188.             0x40,
  189.             0x22,
  190.             0x80,
  191.             0xa3,
  192.             0x5e,
  193.             0xe6,
  194.             0x80,
  195.             0xba,
  196.             0x8,
  197.             0x0,
  198.             0x0,
  199.             0x0,
  200.             0x0,
  201.             0x95,
  202.             0x0,
  203.             0x6,
  204.             0xf1,
  205.             0xa1,
  206.             0xa,
  207.             0x5a,
  208.             0x5a,
  209.             0x5a,
  210.             0x5a,
  211.             0x5a,
  212.             0x5a,
  213.             0x5a,
  214.             0x5a,
  215.             0x5a,
  216.             0x5a,
  217.             0x5a,
  218.             0x5a,
  219.             0x5a,
  220.             0x5a,
  221.             0x5a,
  222.             0x5a,
  223.             0x5a,
  224.             0x5a,
  225.             0x5a,
  226.             0x5a,
  227.             0x5a,
  228.             0x5a,
  229.             0x5a,
  230.             0x5a,
  231.             0x5a,
  232.             0x5a,
  233.             0x5a,
  234.             0x5a,
  235.             0x5a,
  236.             0x5a,
  237.             0x5a,
  238.             0x5a,
  239.             0x5a,
  240.             0x5a,
  241.             0x5a,
  242.             0x5a,
  243.             0x5a,
  244.             0x5a,
  245.             0x5e,
  246.           ]);
  247.         } else if (channelCount === 3) {
  248.           // ffmpeg -y -f lavfi -i "aevalsrc=0|0|0:d=0.05" -c:a libfdk_aac -profile:a aac_he_v2 -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
  249.           return new Uint8Array([
  250.             0x1,
  251.             0x40,
  252.             0x22,
  253.             0x80,
  254.             0xa3,
  255.             0x5e,
  256.             0xe6,
  257.             0x80,
  258.             0xba,
  259.             0x8,
  260.             0x0,
  261.             0x0,
  262.             0x0,
  263.             0x0,
  264.             0x95,
  265.             0x0,
  266.             0x6,
  267.             0xf1,
  268.             0xa1,
  269.             0xa,
  270.             0x5a,
  271.             0x5a,
  272.             0x5a,
  273.             0x5a,
  274.             0x5a,
  275.             0x5a,
  276.             0x5a,
  277.             0x5a,
  278.             0x5a,
  279.             0x5a,
  280.             0x5a,
  281.             0x5a,
  282.             0x5a,
  283.             0x5a,
  284.             0x5a,
  285.             0x5a,
  286.             0x5a,
  287.             0x5a,
  288.             0x5a,
  289.             0x5a,
  290.             0x5a,
  291.             0x5a,
  292.             0x5a,
  293.             0x5a,
  294.             0x5a,
  295.             0x5a,
  296.             0x5a,
  297.             0x5a,
  298.             0x5a,
  299.             0x5a,
  300.             0x5a,
  301.             0x5a,
  302.             0x5a,
  303.             0x5a,
  304.             0x5a,
  305.             0x5a,
  306.             0x5a,
  307.             0x5a,
  308.             0x5e,
  309.           ]);
  310.         }
  311.         break;
  312.     }
  313.     return undefined;
  314.   }
  315. }
  316.  
  317. export default AAC;