Source: lib/media/content_workarounds.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.media.ContentWorkarounds');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.log');
  11. goog.require('shaka.util.BufferUtils');
  12. goog.require('shaka.util.Error');
  13. goog.require('shaka.util.Lazy');
  14. goog.require('shaka.util.Mp4Parser');
  15. goog.require('shaka.util.Platform');
  16. goog.require('shaka.util.Uint8ArrayUtils');
  19. /**
  20.  * @summary
  21.  * A collection of methods to work around content issues on various platforms.
  22.  */
  23. shaka.media.ContentWorkarounds = class {
  24.   /**
  25.    * Transform the init segment into a new init segment buffer that indicates
  26.    * encryption.  If the init segment already indicates encryption, return the
  27.    * original init segment.
  28.    *
  29.    * Should only be called for MP4 init segments, and only on platforms that
  30.    * need this workaround.
  31.    *
  32.    * @param {!BufferSource} initSegmentBuffer
  33.    * @param {?string} uri
  34.    * @return {!Uint8Array}
  35.    * @see https://github.com/shaka-project/shaka-player/issues/2759
  36.    */
  37.   static fakeEncryption(initSegmentBuffer, uri) {
  38.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  39.     const initSegment = shaka.util.BufferUtils.toUint8(initSegmentBuffer);
  40.     let modifiedInitSegment = initSegment;
  41.     let isEncrypted = false;
  42.     /** @type {shaka.extern.ParsedBox} */
  43.     let stsdBox;
  44.     const ancestorBoxes = [];
  46.     const onSimpleAncestorBox = (box) => {
  47.       ancestorBoxes.push(box);
  48.       shaka.util.Mp4Parser.children(box);
  49.     };
  51.     const onEncryptionMetadataBox = (box) => {
  52.       isEncrypted = true;
  53.     };
  55.     // Multiplexed content could have multiple boxes that we need to modify.
  56.     // Add to this array in order of box offset.  This will be important later,
  57.     // when we process the boxes.
  58.     /** @type {!Array.<{box: shaka.extern.ParsedBox, newType: number}>} */
  59.     const boxesToModify = [];
  61.     new shaka.util.Mp4Parser()
  62.         .box('moov', onSimpleAncestorBox)
  63.         .box('trak', onSimpleAncestorBox)
  64.         .box('mdia', onSimpleAncestorBox)
  65.         .box('minf', onSimpleAncestorBox)
  66.         .box('stbl', onSimpleAncestorBox)
  67.         .fullBox('stsd', (box) => {
  68.           stsdBox = box;
  69.           ancestorBoxes.push(box);
  70.           shaka.util.Mp4Parser.sampleDescription(box);
  71.         })
  72.         .fullBox('encv', onEncryptionMetadataBox)
  73.         .fullBox('enca', onEncryptionMetadataBox)
  74.         .fullBox('dvav', (box) => {
  75.           boxesToModify.push({
  76.             box,
  77.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  78.           });
  79.         })
  80.         .fullBox('dva1', (box) => {
  81.           boxesToModify.push({
  82.             box,
  83.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  84.           });
  85.         })
  86.         .fullBox('dvh1', (box) => {
  87.           boxesToModify.push({
  88.             box,
  89.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  90.           });
  91.         })
  92.         .fullBox('dvhe', (box) => {
  93.           boxesToModify.push({
  94.             box,
  95.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  96.           });
  97.         })
  98.         .fullBox('hev1', (box) => {
  99.           boxesToModify.push({
  100.             box,
  101.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  102.           });
  103.         })
  104.         .fullBox('hvc1', (box) => {
  105.           boxesToModify.push({
  106.             box,
  107.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  108.           });
  109.         })
  110.         .fullBox('avc1', (box) => {
  111.           boxesToModify.push({
  112.             box,
  113.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  114.           });
  115.         })
  116.         .fullBox('avc3', (box) => {
  117.           boxesToModify.push({
  118.             box,
  119.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  120.           });
  121.         })
  122.         .fullBox('ac-3', (box) => {
  123.           boxesToModify.push({
  124.             box,
  125.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  126.           });
  127.         })
  128.         .fullBox('ec-3', (box) => {
  129.           boxesToModify.push({
  130.             box,
  131.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  132.           });
  133.         })
  134.         .fullBox('ac-4', (box) => {
  135.           boxesToModify.push({
  136.             box,
  137.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  138.           });
  139.         })
  140.         .fullBox('mp4a', (box) => {
  141.           boxesToModify.push({
  142.             box,
  143.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  144.           });
  145.         }).parse(initSegment);
  147.     if (isEncrypted) {
  148.       shaka.log.debug('Init segment already indicates encryption.');
  149.       return initSegment;
  150.     }
  152.     if (boxesToModify.length == 0 || !stsdBox) {
  153.       shaka.log.error('Failed to find boxes needed to fake encryption!');
  154.       shaka.log.v2('Failed init segment (hex):',
  155.           shaka.util.Uint8ArrayUtils.toHex(initSegment));
  156.       throw new shaka.util.Error(
  157.           shaka.util.Error.Severity.CRITICAL,
  158.           shaka.util.Error.Category.MEDIA,
  159.           shaka.util.Error.Code.CONTENT_TRANSFORMATION_FAILED,
  160.           uri);
  161.     }
  163.     // Modify boxes in order from largest offset to smallest, so that earlier
  164.     // boxes don't have their offsets changed before we process them.
  165.     boxesToModify.reverse();  // in place!
  166.     for (const workItem of boxesToModify) {
  167.       const insertedBoxType =
  168.           shaka.util.Mp4Parser.typeToString(workItem.newType);
  169.       shaka.log.debug(`Inserting "${insertedBoxType}" box into init segment.`);
  170.       modifiedInitSegment = ContentWorkarounds.insertEncryptionMetadata_(
  171.           modifiedInitSegment, stsdBox, workItem.box, ancestorBoxes,
  172.           workItem.newType);
  173.     }
  175.     // Edge Windows needs the unmodified init segment to be appended after the
  176.     // patched one, otherwise video element throws following error:
  177.     // CHUNK_DEMUXER_ERROR_APPEND_FAILED: Sample encryption info is not
  178.     // available.
  179.     if (shaka.util.Platform.isEdge() && shaka.util.Platform.isWindows() &&
  180.         !shaka.util.Platform.isXboxOne()) {
  181.       const doubleInitSegment = new Uint8Array(initSegment.byteLength +
  182.         modifiedInitSegment.byteLength);
  183.       doubleInitSegment.set(modifiedInitSegment);
  184.       doubleInitSegment.set(initSegment, modifiedInitSegment.byteLength);
  185.       return doubleInitSegment;
  186.     }
  188.     return modifiedInitSegment;
  189.   }
  191.   /**
  192.    * Insert an encryption metadata box ("encv" or "enca" box) into the MP4 init
  193.    * segment, based on the source box ("mp4a", "avc1", etc).  Returns a new
  194.    * buffer containing the modified init segment.
  195.    *
  196.    * @param {!Uint8Array} initSegment
  197.    * @param {shaka.extern.ParsedBox} stsdBox
  198.    * @param {shaka.extern.ParsedBox} sourceBox
  199.    * @param {!Array.<shaka.extern.ParsedBox>} ancestorBoxes
  200.    * @param {number} metadataBoxType
  201.    * @return {!Uint8Array}
  202.    * @private
  203.    */
  204.   static insertEncryptionMetadata_(
  205.       initSegment, stsdBox, sourceBox, ancestorBoxes, metadataBoxType) {
  206.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  207.     const metadataBoxArray = ContentWorkarounds.createEncryptionMetadata_(
  208.         initSegment, sourceBox, metadataBoxType);
  210.     // Construct a new init segment array with room for the encryption metadata
  211.     // box we're adding.
  212.     const newInitSegment =
  213.         new Uint8Array(initSegment.byteLength + metadataBoxArray.byteLength);
  215.     // For Xbox One & Edge, we cut and insert at the start of the source box.
  216.     // For other platforms, we cut and insert at the end of the source box. It's
  217.     // not clear why this is necessary on Xbox One, but it seems to be evidence
  218.     // of another bug in the firmware implementation of MediaSource & EME.
  219.     const cutPoint =
  220.       (shaka.util.Platform.isXboxOne() || shaka.util.Platform.isEdge()) ?
  221.         sourceBox.start :
  222.         sourceBox.start + sourceBox.size;
  224.     // The data before the cut point will be copied to the same location as
  225.     // before.  The data after that will be appended after the added metadata
  226.     // box.
  227.     const beforeData = initSegment.subarray(0, cutPoint);
  228.     const afterData = initSegment.subarray(cutPoint);
  230.     newInitSegment.set(beforeData);
  231.     newInitSegment.set(metadataBoxArray, cutPoint);
  232.     newInitSegment.set(afterData, cutPoint + metadataBoxArray.byteLength);
  234.     // The parents up the chain from the encryption metadata box need their
  235.     // sizes adjusted to account for the added box.  These offsets should not be
  236.     // changed, because they should all be within the first section we copy.
  237.     for (const box of ancestorBoxes) {
  238.       goog.asserts.assert(box.start < cutPoint,
  239.           'Ancestor MP4 box found in the wrong location!  ' +
  240.           'Modified init segment will not make sense!');
  241.       ContentWorkarounds.updateBoxSize_(
  242.           newInitSegment, box.start, box.size + metadataBoxArray.byteLength);
  243.     }
  245.     // Add one to the sample entries field of the "stsd" box.  This is a 4-byte
  246.     // field just past the box header.
  247.     const stsdBoxView = shaka.util.BufferUtils.toDataView(
  248.         newInitSegment, stsdBox.start);
  249.     const stsdBoxHeaderSize = shaka.util.Mp4Parser.headerSize(stsdBox);
  250.     const numEntries = stsdBoxView.getUint32(stsdBoxHeaderSize);
  251.     stsdBoxView.setUint32(stsdBoxHeaderSize, numEntries + 1);
  253.     return newInitSegment;
  254.   }
  256.   /**
  257.    * Create an encryption metadata box ("encv" or "enca" box), based on the
  258.    * source box ("mp4a", "avc1", etc).  Returns a new buffer containing the
  259.    * encryption metadata box.
  260.    *
  261.    * @param {!Uint8Array} initSegment
  262.    * @param {shaka.extern.ParsedBox} sourceBox
  263.    * @param {number} metadataBoxType
  264.    * @return {!Uint8Array}
  265.    * @private
  266.    */
  267.   static createEncryptionMetadata_(initSegment, sourceBox, metadataBoxType) {
  268.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  269.     const sinfBoxArray = ContentWorkarounds.CANNED_SINF_BOX_.value();
  271.     // Create a subarray which points to the source box data.
  272.     const sourceBoxArray = initSegment.subarray(
  273.         /* start= */ sourceBox.start,
  274.         /* end= */ sourceBox.start + sourceBox.size);
  276.     // Create a view on the source box array.
  277.     const sourceBoxView = shaka.util.BufferUtils.toDataView(sourceBoxArray);
  279.     // Create an array to hold the new encryption metadata box, which is based
  280.     // on the source box.
  281.     const metadataBoxArray = new Uint8Array(
  282.         sourceBox.size + sinfBoxArray.byteLength);
  284.     // Copy the source box into the new array.
  285.     metadataBoxArray.set(sourceBoxArray, /* targetOffset= */ 0);
  287.     // Change the box type.
  288.     const metadataBoxView = shaka.util.BufferUtils.toDataView(metadataBoxArray);
  289.     metadataBoxView.setUint32(
  290.         ContentWorkarounds.BOX_TYPE_OFFSET_, metadataBoxType);
  292.     // Append the "sinf" box to the encryption metadata box.
  293.     metadataBoxArray.set(sinfBoxArray, /* targetOffset= */ sourceBox.size);
  295.     // Update the "sinf" box's format field (in the child "frma" box) to reflect
  296.     // the format of the original source box.
  297.     const sourceBoxType = sourceBoxView.getUint32(
  298.         ContentWorkarounds.BOX_TYPE_OFFSET_);
  299.     metadataBoxView.setUint32(
  300.         sourceBox.size + ContentWorkarounds.CANNED_SINF_BOX_FORMAT_OFFSET_,
  301.         sourceBoxType);
  303.     // Now update the encryption metadata box size.
  304.     ContentWorkarounds.updateBoxSize_(
  305.         metadataBoxArray, /* boxStart= */ 0, metadataBoxArray.byteLength);
  307.     return metadataBoxArray;
  308.   }
  310.   /**
  311.    * Modify an MP4 box's size field in-place.
  312.    *
  313.    * @param {!Uint8Array} dataArray
  314.    * @param {number} boxStart The start position of the box in dataArray.
  315.    * @param {number} newBoxSize The new size of the box.
  316.    * @private
  317.    */
  318.   static updateBoxSize_(dataArray, boxStart, newBoxSize) {
  319.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  320.     const boxView = shaka.util.BufferUtils.toDataView(dataArray, boxStart);
  321.     const sizeField = boxView.getUint32(ContentWorkarounds.BOX_SIZE_OFFSET_);
  322.     if (sizeField == 0) { // Means "the rest of the box".
  323.       // No adjustment needed for this box.
  324.     } else if (sizeField == 1) { // Means "use 64-bit size box".
  325.       // Set the 64-bit int in two 32-bit parts.
  326.       // The high bits should definitely be 0 in practice, but we're being
  327.       // thorough here.
  328.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_,
  329.           newBoxSize >> 32);
  330.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_ + 4,
  331.           newBoxSize & 0xffffffff);
  332.     } else { // Normal 32-bit size field.
  333.       // Not checking the size of the value here, since a box larger than 4GB is
  334.       // unrealistic.
  335.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_OFFSET_, newBoxSize);
  336.     }
  337.   }
  338. };
  340. /**
  341.  * A canned "sinf" box for use when adding fake encryption metadata to init
  342.  * segments.
  343.  *
  344.  * @const {!shaka.util.Lazy.<!Uint8Array>}
  345.  * @private
  346.  * @see https://github.com/shaka-project/shaka-player/issues/2759
  347.  */
  348. shaka.media.ContentWorkarounds.CANNED_SINF_BOX_ =
  349.     new shaka.util.Lazy(() => new Uint8Array([
  350.       // sinf box
  351.       // Size: 0x50 = 80
  352.       0x00, 0x00, 0x00, 0x50,
  354.       // Type: sinf
  355.       0x73, 0x69, 0x6e, 0x66,
  357.       // Children of sinf...
  359.       // frma box
  360.       // Size: 0x0c = 12
  361.       0x00, 0x00, 0x00, 0x0c,
  363.       // Type: frma (child of sinf)
  364.       0x66, 0x72, 0x6d, 0x61,
  366.       // Format: filled in later based on the source box ("avc1", "mp4a", etc)
  367.       0x00, 0x00, 0x00, 0x00,
  368.       // end of frma box
  370.       // schm box
  371.       // Size: 0x14 = 20
  372.       0x00, 0x00, 0x00, 0x14,
  374.       // Type: schm (child of sinf)
  375.       0x73, 0x63, 0x68, 0x6d,
  377.       // Version: 0, Flags: 0
  378.       0x00, 0x00, 0x00, 0x00,
  380.       // Scheme: cenc
  381.       0x63, 0x65, 0x6e, 0x63,
  383.       // Scheme version: 1.0
  384.       0x00, 0x01, 0x00, 0x00,
  385.       // end of schm box
  387.       // schi box
  388.       // Size: 0x28 = 40
  389.       0x00, 0x00, 0x00, 0x28,
  391.       // Type: schi (child of sinf)
  392.       0x73, 0x63, 0x68, 0x69,
  394.       // Children of schi...
  396.       // tenc box
  397.       // Size: 0x20 = 32
  398.       0x00, 0x00, 0x00, 0x20,
  400.       // Type: tenc (child of schi)
  401.       0x74, 0x65, 0x6e, 0x63,
  403.       // Version: 0, Flags: 0
  404.       0x00, 0x00, 0x00, 0x00,
  406.       // Reserved fields
  407.       0x00, 0x00,
  409.       // Default protected: true
  410.       0x01,
  412.       // Default per-sample IV size: 8
  413.       0x08,
  415.       // Default key ID: all zeros (dummy)
  416.       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  417.       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  418.       // end of tenc box
  420.       // end of schi box
  422.       // end of sinf box
  423.     ]));
  425. /**
  426.  * The location of the format field in the "frma" box inside the canned "sinf"
  427.  * box above.
  428.  *
  429.  * @const {number}
  430.  * @private
  431.  */
  432. shaka.media.ContentWorkarounds.CANNED_SINF_BOX_FORMAT_OFFSET_ = 0x10;
  434. /**
  435.  * Offset to a box's size field.
  436.  *
  437.  * @const {number}
  438.  * @private
  439.  */
  440. shaka.media.ContentWorkarounds.BOX_SIZE_OFFSET_ = 0;
  442. /**
  443.  * Offset to a box's type field.
  444.  *
  445.  * @const {number}
  446.  * @private
  447.  */
  448. shaka.media.ContentWorkarounds.BOX_TYPE_OFFSET_ = 4;
  450. /**
  451.  * Offset to a box's 64-bit size field, if it has one.
  452.  *
  453.  * @const {number}
  454.  * @private
  455.  */
  456. shaka.media.ContentWorkarounds.BOX_SIZE_64_OFFSET_ = 8;
  458. /**
  459.  * Box type for "encv".
  460.  *
  461.  * @const {number}
  462.  * @private
  463.  */
  464. shaka.media.ContentWorkarounds.BOX_TYPE_ENCV_ = 0x656e6376;
  466. /**
  467.  * Box type for "enca".
  468.  *
  469.  * @const {number}
  470.  * @private
  471.  */
  472. shaka.media.ContentWorkarounds.BOX_TYPE_ENCA_ = 0x656e6361;