shaka-player
Version:
DASH/EME video player library
519 lines (465 loc) • 18.1 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.media.ContentWorkarounds');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.Error');
goog.require('shaka.util.Mp4BoxParsers');
goog.require('shaka.util.Mp4Generator');
goog.require('shaka.util.Mp4Parser');
goog.require('shaka.util.Platform');
goog.require('shaka.util.Uint8ArrayUtils');
/**
* @summary
* A collection of methods to work around content issues on various platforms.
*/
shaka.media.ContentWorkarounds = class {
/**
* Transform the init segment into a new init segment buffer that indicates
* encryption. If the init segment already indicates encryption, return the
* original init segment.
*
* Should only be called for MP4 init segments, and only on platforms that
* need this workaround.
*
* @param {!shaka.extern.Stream} stream
* @param {!BufferSource} initSegmentBuffer
* @param {?string} uri
* @return {!Uint8Array}
* @see https://github.com/shaka-project/shaka-player/issues/2759
*/
static fakeEncryption(stream, initSegmentBuffer, uri) {
const ContentWorkarounds = shaka.media.ContentWorkarounds;
const initSegment = shaka.util.BufferUtils.toUint8(initSegmentBuffer);
let modifiedInitSegment = initSegment;
let isEncrypted = false;
/** @type {shaka.extern.ParsedBox} */
let stsdBox;
const ancestorBoxes = [];
const onSimpleAncestorBox = (box) => {
ancestorBoxes.push(box);
shaka.util.Mp4Parser.children(box);
};
const onEncryptionMetadataBox = (box) => {
isEncrypted = true;
box.parser.stop();
};
// Multiplexed content could have multiple boxes that we need to modify.
// Add to this array in order of box offset. This will be important later,
// when we process the boxes.
/** @type {!Array<{box: shaka.extern.ParsedBox, newType: number}>} */
const boxesToModify = [];
const pushEncv = (box) => {
boxesToModify.push({
box,
newType: ContentWorkarounds.BOX_TYPE_ENCV_,
});
};
const pushEnca = (box) => {
boxesToModify.push({
box,
newType: ContentWorkarounds.BOX_TYPE_ENCA_,
});
};
new shaka.util.Mp4Parser()
.box('moov', onSimpleAncestorBox)
.box('trak', onSimpleAncestorBox)
.box('mdia', onSimpleAncestorBox)
.box('minf', onSimpleAncestorBox)
.box('stbl', onSimpleAncestorBox)
.fullBox('stsd', (box) => {
stsdBox = box;
ancestorBoxes.push(box);
shaka.util.Mp4Parser.sampleDescription(box);
})
.fullBox('encv', onEncryptionMetadataBox)
.fullBox('enca', onEncryptionMetadataBox)
.fullBox('dvav', pushEncv)
.fullBox('dva1', pushEncv)
.fullBox('dvh1', pushEncv)
.fullBox('dvhe', pushEncv)
.fullBox('dvc1', pushEncv)
.fullBox('dvi1', pushEncv)
.fullBox('hev1', pushEncv)
.fullBox('hvc1', pushEncv)
.fullBox('avc1', pushEncv)
.fullBox('avc3', pushEncv)
.fullBox('ac-3', pushEnca)
.fullBox('ec-3', pushEnca)
.fullBox('ac-4', pushEnca)
.fullBox('Opus', pushEnca)
.fullBox('fLaC', pushEnca)
.fullBox('mp4a', pushEnca)
.parse(initSegment);
if (isEncrypted) {
shaka.log.debug('Init segment already indicates encryption.');
return initSegment;
}
if (boxesToModify.length == 0 || !stsdBox) {
shaka.log.error('Failed to find boxes needed to fake encryption!');
shaka.log.v2('Failed init segment (hex):',
shaka.util.Uint8ArrayUtils.toHex(initSegment));
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MEDIA,
shaka.util.Error.Code.CONTENT_TRANSFORMATION_FAILED,
uri);
}
// Modify boxes in order from largest offset to smallest, so that earlier
// boxes don't have their offsets changed before we process them.
boxesToModify.reverse(); // in place!
for (const workItem of boxesToModify) {
const insertedBoxType =
shaka.util.Mp4Parser.typeToString(workItem.newType);
shaka.log.debug(`Inserting "${insertedBoxType}" box into init segment.`);
modifiedInitSegment = ContentWorkarounds.insertEncryptionMetadata_(
stream, modifiedInitSegment, stsdBox, workItem.box, ancestorBoxes,
workItem.newType);
}
// Edge Windows needs the unmodified init segment to be appended after the
// patched one, otherwise video element throws following error:
// CHUNK_DEMUXER_ERROR_APPEND_FAILED: Sample encryption info is not
// available.
if (shaka.util.Platform.isEdge() && shaka.util.Platform.isWindows() &&
!shaka.util.Platform.isXboxOne()) {
const doubleInitSegment = new Uint8Array(initSegment.byteLength +
modifiedInitSegment.byteLength);
doubleInitSegment.set(modifiedInitSegment);
doubleInitSegment.set(initSegment, modifiedInitSegment.byteLength);
return doubleInitSegment;
}
return modifiedInitSegment;
}
/**
* @param {!BufferSource} mediaSegmentBuffer
* @return {!Uint8Array}
*/
static fakeMediaEncryption(mediaSegmentBuffer) {
const mediaSegment = shaka.util.BufferUtils.toUint8(mediaSegmentBuffer);
const mdatBoxes = [];
new shaka.util.Mp4Parser()
.box('mdat', (box) => {
mdatBoxes.push(box);
})
.parse(mediaSegment);
const newSegmentChunks = [];
for (let i = 0; i < mdatBoxes.length; i++) {
const prevMdat = mdatBoxes[i - 1];
const currMdat = mdatBoxes[i];
const chunkStart = prevMdat ? prevMdat.start + prevMdat.size : 0;
const chunkEnd = currMdat.start + currMdat.size;
const chunk = mediaSegment.subarray(chunkStart, chunkEnd);
newSegmentChunks.push(
shaka.media.ContentWorkarounds.fakeMediaEncryptionInChunk_(chunk));
}
return shaka.util.Uint8ArrayUtils.concat(...newSegmentChunks);
}
/**
* @param {!Uint8Array} chunk
* @return {!Uint8Array}
* @private
*/
static fakeMediaEncryptionInChunk_(chunk) {
// Which track from stsd we want to use, 1-based.
const desiredSampleDescriptionIndex = 2;
let tfhdBox;
let trunBox;
let parsedTfhd;
let parsedTrun;
const ancestorBoxes = [];
const onSimpleAncestorBox = (box) => {
ancestorBoxes.push(box);
shaka.util.Mp4Parser.children(box);
};
const onTfhdBox = (box) => {
tfhdBox = box;
parsedTfhd = shaka.util.Mp4BoxParsers.parseTFHD(box.reader, box.flags);
};
const onTrunBox = (box) => {
trunBox = box;
parsedTrun = shaka.util.Mp4BoxParsers.parseTRUN(box.reader, box.version,
box.flags);
};
new shaka.util.Mp4Parser()
.box('moof', onSimpleAncestorBox)
.box('traf', onSimpleAncestorBox)
.fullBox('tfhd', onTfhdBox)
.fullBox('trun', onTrunBox)
.parse(chunk);
if (parsedTfhd && parsedTfhd.sampleDescriptionIndex !==
desiredSampleDescriptionIndex) {
const sdiPosition = tfhdBox.start +
shaka.util.Mp4Parser.headerSize(tfhdBox) +
4 + // track_id
(parsedTfhd.baseDataOffset !== null ? 8 : 0);
const dataview = shaka.util.BufferUtils.toDataView(chunk);
if (parsedTfhd.sampleDescriptionIndex !== null) {
dataview.setUint32(sdiPosition, desiredSampleDescriptionIndex);
} else {
const sdiSize = 4; // uint32
// first, update size & flags of tfhd
shaka.media.ContentWorkarounds.updateBoxSize_(chunk,
tfhdBox.start, tfhdBox.size + sdiSize);
const versionAndFlags = dataview.getUint32(tfhdBox.start + 8);
dataview.setUint32(tfhdBox.start + 8, versionAndFlags | 0x000002);
// second, update trun
if (parsedTrun && parsedTrun.dataOffset !== null) {
const newDataOffset = parsedTrun.dataOffset + sdiSize;
const dataOffsetPosition = trunBox.start +
shaka.util.Mp4Parser.headerSize(trunBox) +
4; // sample count
dataview.setInt32(dataOffsetPosition, newDataOffset);
}
const beforeSdi = chunk.subarray(0, sdiPosition);
const afterSdi = chunk.subarray(sdiPosition);
chunk = new Uint8Array(chunk.byteLength + sdiSize);
chunk.set(beforeSdi);
const bytes = [];
for (let byte = sdiSize - 1; byte >= 0; byte--) {
bytes.push((desiredSampleDescriptionIndex >> (8 * byte)) & 0xff);
}
chunk.set(new Uint8Array(bytes), sdiPosition);
chunk.set(afterSdi, sdiPosition + sdiSize);
for (const box of ancestorBoxes) {
shaka.media.ContentWorkarounds.updateBoxSize_(chunk, box.start,
box.size + sdiSize);
}
}
}
return chunk;
}
/**
* Insert an encryption metadata box ("encv" or "enca" box) into the MP4 init
* segment, based on the source box ("mp4a", "avc1", etc). Returns a new
* buffer containing the modified init segment.
*
* @param {!shaka.extern.Stream} stream
* @param {!Uint8Array} initSegment
* @param {shaka.extern.ParsedBox} stsdBox
* @param {shaka.extern.ParsedBox} sourceBox
* @param {!Array<shaka.extern.ParsedBox>} ancestorBoxes
* @param {number} metadataBoxType
* @return {!Uint8Array}
* @private
*/
static insertEncryptionMetadata_(
stream, initSegment, stsdBox, sourceBox, ancestorBoxes, metadataBoxType) {
const ContentWorkarounds = shaka.media.ContentWorkarounds;
const metadataBoxArray = ContentWorkarounds.createEncryptionMetadata_(
stream, initSegment, sourceBox, metadataBoxType);
// Construct a new init segment array with room for the encryption metadata
// box we're adding.
const newInitSegment =
new Uint8Array(initSegment.byteLength + metadataBoxArray.byteLength);
// For Xbox One & Edge, we cut and insert at the start of the source box.
// For other platforms, we cut and insert at the end of the source box. It's
// not clear why this is necessary on Xbox One, but it seems to be evidence
// of another bug in the firmware implementation of MediaSource & EME.
const cutPoint = (shaka.util.Platform.isApple() ||
shaka.util.Platform.isXboxOne() || shaka.util.Platform.isEdge()) ?
sourceBox.start :
sourceBox.start + sourceBox.size;
// The data before the cut point will be copied to the same location as
// before. The data after that will be appended after the added metadata
// box.
const beforeData = initSegment.subarray(0, cutPoint);
const afterData = initSegment.subarray(cutPoint);
newInitSegment.set(beforeData);
newInitSegment.set(metadataBoxArray, cutPoint);
newInitSegment.set(afterData, cutPoint + metadataBoxArray.byteLength);
// The parents up the chain from the encryption metadata box need their
// sizes adjusted to account for the added box. These offsets should not be
// changed, because they should all be within the first section we copy.
for (const box of ancestorBoxes) {
goog.asserts.assert(box.start < cutPoint,
'Ancestor MP4 box found in the wrong location! ' +
'Modified init segment will not make sense!');
ContentWorkarounds.updateBoxSize_(
newInitSegment, box.start, box.size + metadataBoxArray.byteLength);
}
// Add one to the sample entries field of the "stsd" box. This is a 4-byte
// field just past the box header.
const stsdBoxView = shaka.util.BufferUtils.toDataView(
newInitSegment, stsdBox.start);
const stsdBoxHeaderSize = shaka.util.Mp4Parser.headerSize(stsdBox);
const numEntries = stsdBoxView.getUint32(stsdBoxHeaderSize);
stsdBoxView.setUint32(stsdBoxHeaderSize, numEntries + 1);
return newInitSegment;
}
/**
* Create an encryption metadata box ("encv" or "enca" box), based on the
* source box ("mp4a", "avc1", etc). Returns a new buffer containing the
* encryption metadata box.
*
* @param {!shaka.extern.Stream} stream
* @param {!Uint8Array} initSegment
* @param {shaka.extern.ParsedBox} sourceBox
* @param {number} metadataBoxType
* @return {!Uint8Array}
* @private
*/
static createEncryptionMetadata_(stream, initSegment, sourceBox,
metadataBoxType) {
const ContentWorkarounds = shaka.media.ContentWorkarounds;
const mp4Generator = new shaka.util.Mp4Generator([]);
const sinfBoxArray = mp4Generator.sinf(stream, sourceBox.name);
// Create a subarray which points to the source box data.
const sourceBoxArray = initSegment.subarray(
/* start= */ sourceBox.start,
/* end= */ sourceBox.start + sourceBox.size);
// Create an array to hold the new encryption metadata box, which is based
// on the source box.
const metadataBoxArray = new Uint8Array(
sourceBox.size + sinfBoxArray.byteLength);
// Copy the source box into the new array.
metadataBoxArray.set(sourceBoxArray, /* targetOffset= */ 0);
// Change the box type.
const metadataBoxView = shaka.util.BufferUtils.toDataView(metadataBoxArray);
metadataBoxView.setUint32(
ContentWorkarounds.BOX_TYPE_OFFSET_, metadataBoxType);
// Append the "sinf" box to the encryption metadata box.
metadataBoxArray.set(sinfBoxArray, /* targetOffset= */ sourceBox.size);
// Now update the encryption metadata box size.
ContentWorkarounds.updateBoxSize_(
metadataBoxArray, /* boxStart= */ 0, metadataBoxArray.byteLength);
return metadataBoxArray;
}
/**
* Modify an MP4 box's size field in-place.
*
* @param {!Uint8Array} dataArray
* @param {number} boxStart The start position of the box in dataArray.
* @param {number} newBoxSize The new size of the box.
* @private
*/
static updateBoxSize_(dataArray, boxStart, newBoxSize) {
const ContentWorkarounds = shaka.media.ContentWorkarounds;
const boxView = shaka.util.BufferUtils.toDataView(dataArray, boxStart);
const sizeField = boxView.getUint32(ContentWorkarounds.BOX_SIZE_OFFSET_);
if (sizeField == 0) { // Means "the rest of the box".
// No adjustment needed for this box.
} else if (sizeField == 1) { // Means "use 64-bit size box".
// Set the 64-bit int in two 32-bit parts.
// The high bits should definitely be 0 in practice, but we're being
// thorough here.
boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_,
newBoxSize >> 32);
boxView.setUint32(ContentWorkarounds.BOX_SIZE_64_OFFSET_ + 4,
newBoxSize & 0xffffffff);
} else { // Normal 32-bit size field.
// Not checking the size of the value here, since a box larger than 4GB is
// unrealistic.
boxView.setUint32(ContentWorkarounds.BOX_SIZE_OFFSET_, newBoxSize);
}
}
/**
* Transform the init segment into a new init segment buffer that indicates
* EC-3 as audio codec instead of AC-3. Even though any EC-3 decoder should
* be able to decode AC-3 streams, there are platforms that do not accept
* AC-3 as codec.
*
* Should only be called for MP4 init segments, and only on platforms that
* need this workaround. Returns a new buffer containing the modified init
* segment.
*
* @param {!BufferSource} initSegmentBuffer
* @return {!Uint8Array}
*/
static fakeEC3(initSegmentBuffer) {
const ContentWorkarounds = shaka.media.ContentWorkarounds;
const initSegment = shaka.util.BufferUtils.toUint8(initSegmentBuffer);
const ancestorBoxes = [];
const onSimpleAncestorBox = (box) => {
ancestorBoxes.push({start: box.start, size: box.size});
shaka.util.Mp4Parser.children(box);
};
new shaka.util.Mp4Parser()
.box('moov', onSimpleAncestorBox)
.box('trak', onSimpleAncestorBox)
.box('mdia', onSimpleAncestorBox)
.box('minf', onSimpleAncestorBox)
.box('stbl', onSimpleAncestorBox)
.box('stsd', (box) => {
ancestorBoxes.push({start: box.start, size: box.size});
const stsdBoxView = shaka.util.BufferUtils.toDataView(
initSegment, box.start);
// "size - 3" is because we immediately read a uint32.
for (let i = 0; i < box.size -3; i++) {
const codecTag = stsdBoxView.getUint32(i);
if (codecTag == ContentWorkarounds.BOX_TYPE_AC_3_) {
stsdBoxView.setUint32(i, ContentWorkarounds.BOX_TYPE_EC_3_);
} else if (codecTag == ContentWorkarounds.BOX_TYPE_DAC3_) {
stsdBoxView.setUint32(i, ContentWorkarounds.BOX_TYPE_DEC3_);
}
}
}).parse(initSegment);
return initSegment;
}
};
/**
* Offset to a box's size field.
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_SIZE_OFFSET_ = 0;
/**
* Offset to a box's type field.
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_OFFSET_ = 4;
/**
* Offset to a box's 64-bit size field, if it has one.
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_SIZE_64_OFFSET_ = 8;
/**
* Box type for "encv".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_ENCV_ = 0x656e6376;
/**
* Box type for "enca".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_ENCA_ = 0x656e6361;
/**
* Box type for "ac-3".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_AC_3_ = 0x61632d33;
/**
* Box type for "dac3".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_DAC3_ = 0x64616333;
/**
* Box type for "ec-3".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_EC_3_ = 0x65632d33;
/**
* Box type for "dec3".
*
* @const {number}
* @private
*/
shaka.media.ContentWorkarounds.BOX_TYPE_DEC3_ = 0x64656333;