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Support Matroska stream #766

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merged 1 commit into from
Feb 25, 2021
Merged

Support Matroska stream #766

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44 changes: 34 additions & 10 deletions lib/matroska/MatroskaParser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,9 @@ export class MatroskaParser extends BasicParser {

private parserMap = new Map<DataType, (e: IHeader) => Promise<any>>();

private ebmlMaxIDLength = 4;
private ebmlMaxSizeLength = 8;

constructor() {
super();
this.parserMap.set(DataType.uint, e => this.readUint(e));
Expand Down Expand Up @@ -132,12 +135,21 @@ export class MatroskaParser extends BasicParser {
private async parseContainer(container: IContainerType, posDone: number, path: string[]): Promise<ITree> {
const tree: ITree = {};
while (this.tokenizer.position < posDone) {
const element = await this.readElement();
let element: IHeader;
try {
element = await this.readElement();
} catch (error) {
if (error.message === 'End-Of-Stream') {
break;
}
throw error;
}
const type = container[element.id];
if (type) {
debug(`Element: name=${type.name}, container=${!!type.container}`);
if (type.container) {
const res = await this.parseContainer(type.container, this.tokenizer.position + element.len, path.concat([type.name]));
if (type.multiple) {
const res = await this.parseContainer(type.container, element.len >= 0 ? this.tokenizer.position + element.len : -1, path.concat([type.name]));
if (type.multiple) {
if (!tree[type.name]) {
tree[type.name] = [];
}
Expand All @@ -164,25 +176,27 @@ export class MatroskaParser extends BasicParser {
return tree;
}

private async readVintData(): Promise<Buffer> {
private async readVintData(maxLength: number): Promise<Buffer> {
const msb = await this.tokenizer.peekNumber(Token.UINT8);
let mask = 0x80;
let ic = 1;
let oc = 1;

// Calculate VINT_WIDTH
while ((msb & mask) === 0) {
++ic;
if (oc > maxLength) {
throw new Error('VINT value exceeding maximum size');
}
++oc;
mask >>= 1;
}

const id = Buffer.alloc(ic);
const id = Buffer.alloc(oc);
await this.tokenizer.readBuffer(id);
return id;
}

private async readElement(): Promise<IHeader> {
const id = await this.readVintData();
const lenField = await this.readVintData();
const id = await this.readVintData(this.ebmlMaxIDLength);
const lenField = await this.readVintData(this.ebmlMaxSizeLength);
lenField[0] ^= 0x80 >> (lenField.length - 1);
const nrLen = Math.min(6, lenField.length); // JavaScript can max read 6 bytes integer
return {
Expand All @@ -191,6 +205,16 @@ export class MatroskaParser extends BasicParser {
};
}

private isMaxValue(vintData: Buffer) {
if (vintData.length === this.ebmlMaxSizeLength) {
for (let n = 1; n < this.ebmlMaxSizeLength; ++n) {
if (vintData[n] !== 0xff) return false;
}
return true;
}
return false;
}

private async readFloat(e: IHeader) {
switch (e.len) {
case 0:
Expand Down
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