atem-connection/dist/lib/converters/rle.js

Typescript Node.js library for connecting with an ATEM switcher.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.decodeRLE = exports.encodeRLE = exports.RLE_HEADER = void 0;
exports.RLE_HEADER = 0xfefefefefefefefen;
function encodeRLE(data) {
    const result = Buffer.alloc(data.length);
    let lastBlock = data.readBigUInt64BE();
    let identicalCount = 0;
    let differentCount = 0;
    let resultOffset = -8;
    for (let sourceOffset = 8; sourceOffset < data.length; sourceOffset += 8) {
        const block = data.readBigUInt64BE(sourceOffset);
        if (block === lastBlock) {
            ++identicalCount;
            if (differentCount) {
                data.copy(result, resultOffset + 8, sourceOffset - 8 * (differentCount + 1), sourceOffset - 8);
                resultOffset += differentCount * 8;
                differentCount = 0;
            }
            lastBlock = block;
            continue;
        }
        if (identicalCount > 2) {
            result.writeBigUInt64BE(exports.RLE_HEADER, (resultOffset += 8));
            result.writeBigUInt64BE(BigInt(identicalCount + 1), (resultOffset += 8));
            result.writeBigUInt64BE(lastBlock, (resultOffset += 8));
        }
        else if (identicalCount > 0) {
            for (let i = 0; i <= identicalCount; ++i) {
                result.writeBigUInt64BE(lastBlock, (resultOffset += 8));
            }
        }
        else {
            ++differentCount;
        }
        lastBlock = block;
        identicalCount = 0;
    }
    if (identicalCount > 2) {
        result.writeBigUInt64BE(exports.RLE_HEADER, (resultOffset += 8));
        result.writeBigUInt64BE(BigInt(identicalCount + 1), (resultOffset += 8));
        result.writeBigUInt64BE(lastBlock, (resultOffset += 8));
    }
    else if (identicalCount > 0) {
        for (let i = 0; i <= identicalCount; ++i) {
            result.writeBigUInt64BE(lastBlock, (resultOffset += 8));
        }
    }
    else {
        ++differentCount;
        data.copy(result, resultOffset + 8, data.length - 8 * differentCount, data.length);
        resultOffset += differentCount * 8;
    }
    return result.slice(0, resultOffset + 8);
}
exports.encodeRLE = encodeRLE;
function decodeRLE(data, fullSize) {
    const result = Buffer.alloc(fullSize);
    let resultOffset = -8;
    for (let sourceOffset = 0; sourceOffset < data.length; sourceOffset += 8) {
        const block = data.readBigUInt64BE(sourceOffset);
        // read a header, start a repeating block
        if (block === exports.RLE_HEADER) {
            // Read the count
            sourceOffset += 8;
            const repeatCount = Number(data.readBigUInt64BE(sourceOffset));
            // Read the repeated sample
            sourceOffset += 8;
            const repeatBlock = data.readBigUInt64BE(sourceOffset);
            // Write to the output
            for (let i = 0; i < repeatCount; i++) {
                result.writeBigUInt64BE(repeatBlock, (resultOffset += 8));
            }
        }
        else {
            // No RLE, repeat unchanged
            result.writeBigUInt64BE(block, (resultOffset += 8));
        }
    }
    return result;
}
exports.decodeRLE = decodeRLE;
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