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.     let initSegment = shaka.util.BufferUtils.toUint8(initSegmentBuffer);
  40.     let isEncrypted = false;
  41.     /** @type {shaka.extern.ParsedBox} */
  42.     let stsdBox;
  43.     const ancestorBoxes = [];
  45.     const onSimpleAncestorBox = (box) => {
  46.       ancestorBoxes.push(box);
  47.       shaka.util.Mp4Parser.children(box);
  48.     };
  50.     const onEncryptionMetadataBox = (box) => {
  51.       isEncrypted = true;
  52.     };
  54.     // Multiplexed content could have multiple boxes that we need to modify.
  55.     // Add to this array in order of box offset.  This will be important later,
  56.     // when we process the boxes.
  57.     /** @type {!Array.<{box: shaka.extern.ParsedBox, newType: number}>} */
  58.     const boxesToModify = [];
  60.     new shaka.util.Mp4Parser()
  61.         .box('moov', onSimpleAncestorBox)
  62.         .box('trak', onSimpleAncestorBox)
  63.         .box('mdia', onSimpleAncestorBox)
  64.         .box('minf', onSimpleAncestorBox)
  65.         .box('stbl', onSimpleAncestorBox)
  66.         .fullBox('stsd', (box) => {
  67.           stsdBox = box;
  68.           ancestorBoxes.push(box);
  69.           shaka.util.Mp4Parser.sampleDescription(box);
  70.         })
  71.         .fullBox('encv', onEncryptionMetadataBox)
  72.         .fullBox('enca', onEncryptionMetadataBox)
  73.         .fullBox('dvav', (box) => {
  74.           boxesToModify.push({
  75.             box,
  76.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  77.           });
  78.         })
  79.         .fullBox('dva1', (box) => {
  80.           boxesToModify.push({
  81.             box,
  82.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  83.           });
  84.         })
  85.         .fullBox('dvh1', (box) => {
  86.           boxesToModify.push({
  87.             box,
  88.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  89.           });
  90.         })
  91.         .fullBox('dvhe', (box) => {
  92.           boxesToModify.push({
  93.             box,
  94.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  95.           });
  96.         })
  97.         .fullBox('hev1', (box) => {
  98.           boxesToModify.push({
  99.             box,
  100.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  101.           });
  102.         })
  103.         .fullBox('hvc1', (box) => {
  104.           boxesToModify.push({
  105.             box,
  106.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  107.           });
  108.         })
  109.         .fullBox('avc1', (box) => {
  110.           boxesToModify.push({
  111.             box,
  112.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  113.           });
  114.         })
  115.         .fullBox('avc3', (box) => {
  116.           boxesToModify.push({
  117.             box,
  118.             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
  119.           });
  120.         })
  121.         .fullBox('ac-3', (box) => {
  122.           boxesToModify.push({
  123.             box,
  124.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  125.           });
  126.         })
  127.         .fullBox('ec-3', (box) => {
  128.           boxesToModify.push({
  129.             box,
  130.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  131.           });
  132.         })
  133.         .fullBox('ac-4', (box) => {
  134.           boxesToModify.push({
  135.             box,
  136.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  137.           });
  138.         })
  139.         .fullBox('mp4a', (box) => {
  140.           boxesToModify.push({
  141.             box,
  142.             newType: ContentWorkarounds.BOX_TYPE_ENCA_,
  143.           });
  144.         }).parse(initSegment);
  146.     if (isEncrypted) {
  147.       shaka.log.debug('Init segment already indicates encryption.');
  148.       return initSegment;
  149.     }
  151.     if (boxesToModify.length == 0 || !stsdBox) {
  152.       shaka.log.error('Failed to find boxes needed to fake encryption!');
  153.       shaka.log.v2('Failed init segment (hex):',
  154.           shaka.util.Uint8ArrayUtils.toHex(initSegment));
  155.       throw new shaka.util.Error(
  156.           shaka.util.Error.Severity.CRITICAL,
  157.           shaka.util.Error.Category.MEDIA,
  158.           shaka.util.Error.Code.CONTENT_TRANSFORMATION_FAILED,
  159.           uri);
  160.     }
  162.     // Modify boxes in order from largest offset to smallest, so that earlier
  163.     // boxes don't have their offsets changed before we process them.
  164.     boxesToModify.reverse();  // in place!
  165.     for (const workItem of boxesToModify) {
  166.       const insertedBoxType =
  167.           shaka.util.Mp4Parser.typeToString(workItem.newType);
  168.       shaka.log.debug(`Inserting "${insertedBoxType}" box into init segment.`);
  169.       initSegment = ContentWorkarounds.insertEncryptionMetadata_(
  170.           initSegment, stsdBox, workItem.box, ancestorBoxes, workItem.newType);
  171.     }
  173.     return initSegment;
  174.   }
  176.   /**
  177.    * Insert an encryption metadata box ("encv" or "enca" box) into the MP4 init
  178.    * segment, based on the source box ("mp4a", "avc1", etc).  Returns a new
  179.    * buffer containing the modified init segment.
  180.    *
  181.    * @param {!Uint8Array} initSegment
  182.    * @param {shaka.extern.ParsedBox} stsdBox
  183.    * @param {shaka.extern.ParsedBox} sourceBox
  184.    * @param {!Array.<shaka.extern.ParsedBox>} ancestorBoxes
  185.    * @param {number} metadataBoxType
  186.    * @return {!Uint8Array}
  187.    * @private
  188.    */
  189.   static insertEncryptionMetadata_(
  190.       initSegment, stsdBox, sourceBox, ancestorBoxes, metadataBoxType) {
  191.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  192.     const metadataBoxArray = ContentWorkarounds.createEncryptionMetadata_(
  193.         initSegment, sourceBox, metadataBoxType);
  195.     // Construct a new init segment array with room for the encryption metadata
  196.     // box we're adding.
  197.     const newInitSegment =
  198.         new Uint8Array(initSegment.byteLength + metadataBoxArray.byteLength);
  200.     // For Xbox One, we cut and insert at the start of the source box.  For
  201.     // other platforms, we cut and insert at the end of the source box.  It's
  202.     // not clear why this is necessary on Xbox One, but it seems to be evidence
  203.     // of another bug in the firmware implementation of MediaSource & EME.
  204.     const cutPoint = shaka.util.Platform.isXboxOne() ?
  205.         sourceBox.start :
  206.         sourceBox.start + sourceBox.size;
  208.     // The data before the cut point will be copied to the same location as
  209.     // before.  The data after that will be appended after the added metadata
  210.     // box.
  211.     const beforeData = initSegment.subarray(0, cutPoint);
  212.     const afterData = initSegment.subarray(cutPoint);
  214.     newInitSegment.set(beforeData);
  215.     newInitSegment.set(metadataBoxArray, cutPoint);
  216.     newInitSegment.set(afterData, cutPoint + metadataBoxArray.byteLength);
  218.     // The parents up the chain from the encryption metadata box need their
  219.     // sizes adjusted to account for the added box.  These offsets should not be
  220.     // changed, because they should all be within the first section we copy.
  221.     for (const box of ancestorBoxes) {
  222.       goog.asserts.assert(box.start < cutPoint,
  223.           'Ancestor MP4 box found in the wrong location!  ' +
  224.           'Modified init segment will not make sense!');
  225.       ContentWorkarounds.updateBoxSize_(
  226.           newInitSegment, box.start, box.size + metadataBoxArray.byteLength);
  227.     }
  229.     // Add one to the sample entries field of the "stsd" box.  This is a 4-byte
  230.     // field just past the box header.
  231.     const stsdBoxView = shaka.util.BufferUtils.toDataView(
  232.         newInitSegment, stsdBox.start);
  233.     const stsdBoxHeaderSize = shaka.util.Mp4Parser.headerSize(stsdBox);
  234.     const numEntries = stsdBoxView.getUint32(stsdBoxHeaderSize);
  235.     stsdBoxView.setUint32(stsdBoxHeaderSize, numEntries + 1);
  237.     return newInitSegment;
  238.   }
  240.   /**
  241.    * Create an encryption metadata box ("encv" or "enca" box), based on the
  242.    * source box ("mp4a", "avc1", etc).  Returns a new buffer containing the
  243.    * encryption metadata box.
  244.    *
  245.    * @param {!Uint8Array} initSegment
  246.    * @param {shaka.extern.ParsedBox} sourceBox
  247.    * @param {number} metadataBoxType
  248.    * @return {!Uint8Array}
  249.    * @private
  250.    */
  251.   static createEncryptionMetadata_(initSegment, sourceBox, metadataBoxType) {
  252.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  253.     const sinfBoxArray = ContentWorkarounds.CANNED_SINF_BOX_.value();
  255.     // Create a subarray which points to the source box data.
  256.     const sourceBoxArray = initSegment.subarray(
  257.         /* start= */ sourceBox.start,
  258.         /* end= */ sourceBox.start + sourceBox.size);
  260.     // Create a view on the source box array.
  261.     const sourceBoxView = shaka.util.BufferUtils.toDataView(sourceBoxArray);
  263.     // Create an array to hold the new encryption metadata box, which is based
  264.     // on the source box.
  265.     const metadataBoxArray = new Uint8Array(
  266.         sourceBox.size + sinfBoxArray.byteLength);
  268.     // Copy the source box into the new array.
  269.     metadataBoxArray.set(sourceBoxArray, /* targetOffset= */ 0);
  271.     // Change the box type.
  272.     const metadataBoxView = shaka.util.BufferUtils.toDataView(metadataBoxArray);
  273.     metadataBoxView.setUint32(
  274.         ContentWorkarounds.BOX_TYPE_OFFSET_, metadataBoxType);
  276.     // Append the "sinf" box to the encryption metadata box.
  277.     metadataBoxArray.set(sinfBoxArray, /* targetOffset= */ sourceBox.size);
  279.     // Update the "sinf" box's format field (in the child "frma" box) to reflect
  280.     // the format of the original source box.
  281.     const sourceBoxType = sourceBoxView.getUint32(
  282.         ContentWorkarounds.BOX_TYPE_OFFSET_);
  283.     metadataBoxView.setUint32(
  284.         sourceBox.size + ContentWorkarounds.CANNED_SINF_BOX_FORMAT_OFFSET_,
  285.         sourceBoxType);
  287.     // Now update the encryption metadata box size.
  288.     ContentWorkarounds.updateBoxSize_(
  289.         metadataBoxArray, /* boxStart= */ 0, metadataBoxArray.byteLength);
  291.     return metadataBoxArray;
  292.   }
  294.   /**
  295.    * Modify an MP4 box's size field in-place.
  296.    *
  297.    * @param {!Uint8Array} dataArray
  298.    * @param {number} boxStart The start position of the box in dataArray.
  299.    * @param {number} newBoxSize The new size of the box.
  300.    * @private
  301.    */
  302.   static updateBoxSize_(dataArray, boxStart, newBoxSize) {
  303.     const ContentWorkarounds = shaka.media.ContentWorkarounds;
  304.     const boxView = shaka.util.BufferUtils.toDataView(dataArray, boxStart);
  305.     const sizeField = boxView.getUint32(ContentWorkarounds.BOX_SIZE_OFFSET_);
  306.     if (sizeField == 0) { // Means "the rest of the box".
  307.       // No adjustment needed for this box.
  308.     } else if (sizeField == 1) { // Means "use 64-bit size box".
  309.       // Set the 64-bit int in two 32-bit parts.
  310.       // The high bits should definitely be 0 in practice, but we're being
  311.       // thorough here.
  312.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_,
  313.           newBoxSize >> 32);
  314.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_ + 4,
  315.           newBoxSize & 0xffffffff);
  316.     } else { // Normal 32-bit size field.
  317.       // Not checking the size of the value here, since a box larger than 4GB is
  318.       // unrealistic.
  319.       boxView.setUint32(ContentWorkarounds.BOX_SIZE_OFFSET_, newBoxSize);
  320.     }
  321.   }
  322. };
  324. /**
  325.  * A canned "sinf" box for use when adding fake encryption metadata to init
  326.  * segments.
  327.  *
  328.  * @const {!shaka.util.Lazy.<!Uint8Array>}
  329.  * @private
  330.  * @see https://github.com/shaka-project/shaka-player/issues/2759
  331.  */
  332. shaka.media.ContentWorkarounds.CANNED_SINF_BOX_ =
  333.     new shaka.util.Lazy(() => new Uint8Array([
  334.       // sinf box
  335.       // Size: 0x50 = 80
  336.       0x00, 0x00, 0x00, 0x50,
  338.       // Type: sinf
  339.       0x73, 0x69, 0x6e, 0x66,
  341.       // Children of sinf...
  343.       // frma box
  344.       // Size: 0x0c = 12
  345.       0x00, 0x00, 0x00, 0x0c,
  347.       // Type: frma (child of sinf)
  348.       0x66, 0x72, 0x6d, 0x61,
  350.       // Format: filled in later based on the source box ("avc1", "mp4a", etc)
  351.       0x00, 0x00, 0x00, 0x00,
  352.       // end of frma box
  354.       // schm box
  355.       // Size: 0x14 = 20
  356.       0x00, 0x00, 0x00, 0x14,
  358.       // Type: schm (child of sinf)
  359.       0x73, 0x63, 0x68, 0x6d,
  361.       // Version: 0, Flags: 0
  362.       0x00, 0x00, 0x00, 0x00,
  364.       // Scheme: cenc
  365.       0x63, 0x65, 0x6e, 0x63,
  367.       // Scheme version: 1.0
  368.       0x00, 0x01, 0x00, 0x00,
  369.       // end of schm box
  371.       // schi box
  372.       // Size: 0x28 = 40
  373.       0x00, 0x00, 0x00, 0x28,
  375.       // Type: schi (child of sinf)
  376.       0x73, 0x63, 0x68, 0x69,
  378.       // Children of schi...
  380.       // tenc box
  381.       // Size: 0x20 = 32
  382.       0x00, 0x00, 0x00, 0x20,
  384.       // Type: tenc (child of schi)
  385.       0x74, 0x65, 0x6e, 0x63,
  387.       // Version: 0, Flags: 0
  388.       0x00, 0x00, 0x00, 0x00,
  390.       // Reserved fields
  391.       0x00, 0x00,
  393.       // Default protected: true
  394.       0x01,
  396.       // Default per-sample IV size: 8
  397.       0x08,
  399.       // Default key ID: all zeros (dummy)
  400.       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  401.       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  402.       // end of tenc box
  404.       // end of schi box
  406.       // end of sinf box
  407.     ]));
  409. /**
  410.  * The location of the format field in the "frma" box inside the canned "sinf"
  411.  * box above.
  412.  *
  413.  * @const {number}
  414.  * @private
  415.  */
  416. shaka.media.ContentWorkarounds.CANNED_SINF_BOX_FORMAT_OFFSET_ = 0x10;
  418. /**
  419.  * Offset to a box's size field.
  420.  *
  421.  * @const {number}
  422.  * @private
  423.  */
  424. shaka.media.ContentWorkarounds.BOX_SIZE_OFFSET_ = 0;
  426. /**
  427.  * Offset to a box's type field.
  428.  *
  429.  * @const {number}
  430.  * @private
  431.  */
  432. shaka.media.ContentWorkarounds.BOX_TYPE_OFFSET_ = 4;
  434. /**
  435.  * Offset to a box's 64-bit size field, if it has one.
  436.  *
  437.  * @const {number}
  438.  * @private
  439.  */
  440. shaka.media.ContentWorkarounds.BOX_SIZE_64_OFFSET_ = 8;
  442. /**
  443.  * Box type for "encv".
  444.  *
  445.  * @const {number}
  446.  * @private
  447.  */
  448. shaka.media.ContentWorkarounds.BOX_TYPE_ENCV_ = 0x656e6376;
  450. /**
  451.  * Box type for "enca".
  452.  *
  453.  * @const {number}
  454.  * @private
  455.  */
  456. shaka.media.ContentWorkarounds.BOX_TYPE_ENCA_ = 0x656e6361;