112 lines
3.0 KiB
JavaScript
112 lines
3.0 KiB
JavaScript
|
import { bytesMatch, toUint8 } from './byte-helpers.js';
|
||
|
|
export var NAL_TYPE_ONE = toUint8([0x00, 0x00, 0x00, 0x01]);
|
||
|
|
export var NAL_TYPE_TWO = toUint8([0x00, 0x00, 0x01]);
|
||
|
|
export var EMULATION_PREVENTION = toUint8([0x00, 0x00, 0x03]);
|
||
|
|
/**
|
||
|
|
* Expunge any "Emulation Prevention" bytes from a "Raw Byte
|
||
|
|
* Sequence Payload"
|
||
|
|
*
|
||
|
|
* @param data {Uint8Array} the bytes of a RBSP from a NAL
|
||
|
|
* unit
|
||
|
|
* @return {Uint8Array} the RBSP without any Emulation
|
||
|
|
* Prevention Bytes
|
||
|
|
*/
|
||
|
|
|
||
|
|
export var discardEmulationPreventionBytes = function discardEmulationPreventionBytes(bytes) {
|
||
|
|
var positions = [];
|
||
|
|
var i = 1; // Find all `Emulation Prevention Bytes`
|
||
|
|
|
||
|
|
while (i < bytes.length - 2) {
|
||
|
|
if (bytesMatch(bytes.subarray(i, i + 3), EMULATION_PREVENTION)) {
|
||
|
|
positions.push(i + 2);
|
||
|
|
i++;
|
||
|
|
}
|
||
|
|
|
||
|
|
i++;
|
||
|
|
} // If no Emulation Prevention Bytes were found just return the original
|
||
|
|
// array
|
||
|
|
|
||
|
|
|
||
|
|
if (positions.length === 0) {
|
||
|
|
return bytes;
|
||
|
|
} // Create a new array to hold the NAL unit data
|
||
|
|
|
||
|
|
|
||
|
|
var newLength = bytes.length - positions.length;
|
||
|
|
var newData = new Uint8Array(newLength);
|
||
|
|
var sourceIndex = 0;
|
||
|
|
|
||
|
|
for (i = 0; i < newLength; sourceIndex++, i++) {
|
||
|
|
if (sourceIndex === positions[0]) {
|
||
|
|
// Skip this byte
|
||
|
|
sourceIndex++; // Remove this position index
|
||
|
|
|
||
|
|
positions.shift();
|
||
|
|
}
|
||
|
|
|
||
|
|
newData[i] = bytes[sourceIndex];
|
||
|
|
}
|
||
|
|
|
||
|
|
return newData;
|
||
|
|
};
|
||
|
|
export var findNal = function findNal(bytes, dataType, types, nalLimit) {
|
||
|
|
if (nalLimit === void 0) {
|
||
|
|
nalLimit = Infinity;
|
||
|
|
}
|
||
|
|
|
||
|
|
bytes = toUint8(bytes);
|
||
|
|
types = [].concat(types);
|
||
|
|
var i = 0;
|
||
|
|
var nalStart;
|
||
|
|
var nalsFound = 0; // keep searching until:
|
||
|
|
// we reach the end of bytes
|
||
|
|
// we reach the maximum number of nals they want to seach
|
||
|
|
// NOTE: that we disregard nalLimit when we have found the start
|
||
|
|
// of the nal we want so that we can find the end of the nal we want.
|
||
|
|
|
||
|
|
while (i < bytes.length && (nalsFound < nalLimit || nalStart)) {
|
||
|
|
var nalOffset = void 0;
|
||
|
|
|
||
|
|
if (bytesMatch(bytes.subarray(i), NAL_TYPE_ONE)) {
|
||
|
|
nalOffset = 4;
|
||
|
|
} else if (bytesMatch(bytes.subarray(i), NAL_TYPE_TWO)) {
|
||
|
|
nalOffset = 3;
|
||
|
|
} // we are unsynced,
|
||
|
|
// find the next nal unit
|
||
|
|
|
||
|
|
|
||
|
|
if (!nalOffset) {
|
||
|
|
i++;
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
nalsFound++;
|
||
|
|
|
||
|
|
if (nalStart) {
|
||
|
|
return discardEmulationPreventionBytes(bytes.subarray(nalStart, i));
|
||
|
|
}
|
||
|
|
|
||
|
|
var nalType = void 0;
|
||
|
|
|
||
|
|
if (dataType === 'h264') {
|
||
|
|
nalType = bytes[i + nalOffset] & 0x1f;
|
||
|
|
} else if (dataType === 'h265') {
|
||
|
|
nalType = bytes[i + nalOffset] >> 1 & 0x3f;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (types.indexOf(nalType) !== -1) {
|
||
|
|
nalStart = i + nalOffset;
|
||
|
|
} // nal header is 1 length for h264, and 2 for h265
|
||
|
|
|
||
|
|
|
||
|
|
i += nalOffset + (dataType === 'h264' ? 1 : 2);
|
||
|
|
}
|
||
|
|
|
||
|
|
return bytes.subarray(0, 0);
|
||
|
|
};
|
||
|
|
export var findH264Nal = function findH264Nal(bytes, type, nalLimit) {
|
||
|
|
return findNal(bytes, 'h264', type, nalLimit);
|
||
|
|
};
|
||
|
|
export var findH265Nal = function findH265Nal(bytes, type, nalLimit) {
|
||
|
|
return findNal(bytes, 'h265', type, nalLimit);
|
||
|
|
};
|