83 lines
2.5 KiB
JavaScript
83 lines
2.5 KiB
JavaScript
var parseSampleFlags = require('./parse-sample-flags.js');
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var trun = function(data) {
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var
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result = {
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version: data[0],
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flags: new Uint8Array(data.subarray(1, 4)),
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samples: []
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},
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view = new DataView(data.buffer, data.byteOffset, data.byteLength),
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// Flag interpretation
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dataOffsetPresent = result.flags[2] & 0x01, // compare with 2nd byte of 0x1
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firstSampleFlagsPresent = result.flags[2] & 0x04, // compare with 2nd byte of 0x4
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sampleDurationPresent = result.flags[1] & 0x01, // compare with 2nd byte of 0x100
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sampleSizePresent = result.flags[1] & 0x02, // compare with 2nd byte of 0x200
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sampleFlagsPresent = result.flags[1] & 0x04, // compare with 2nd byte of 0x400
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sampleCompositionTimeOffsetPresent = result.flags[1] & 0x08, // compare with 2nd byte of 0x800
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sampleCount = view.getUint32(4),
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offset = 8,
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sample;
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if (dataOffsetPresent) {
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// 32 bit signed integer
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result.dataOffset = view.getInt32(offset);
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offset += 4;
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}
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// Overrides the flags for the first sample only. The order of
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// optional values will be: duration, size, compositionTimeOffset
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if (firstSampleFlagsPresent && sampleCount) {
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sample = {
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flags: parseSampleFlags(data.subarray(offset, offset + 4))
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};
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offset += 4;
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if (sampleDurationPresent) {
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sample.duration = view.getUint32(offset);
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offset += 4;
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}
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if (sampleSizePresent) {
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sample.size = view.getUint32(offset);
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offset += 4;
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}
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if (sampleCompositionTimeOffsetPresent) {
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if (result.version === 1) {
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sample.compositionTimeOffset = view.getInt32(offset);
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} else {
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sample.compositionTimeOffset = view.getUint32(offset);
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}
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offset += 4;
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}
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result.samples.push(sample);
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sampleCount--;
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}
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while (sampleCount--) {
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sample = {};
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if (sampleDurationPresent) {
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sample.duration = view.getUint32(offset);
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offset += 4;
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}
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if (sampleSizePresent) {
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sample.size = view.getUint32(offset);
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offset += 4;
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}
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if (sampleFlagsPresent) {
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sample.flags = parseSampleFlags(data.subarray(offset, offset + 4));
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offset += 4;
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}
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if (sampleCompositionTimeOffsetPresent) {
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if (result.version === 1) {
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sample.compositionTimeOffset = view.getInt32(offset);
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} else {
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sample.compositionTimeOffset = view.getUint32(offset);
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}
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offset += 4;
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}
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result.samples.push(sample);
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}
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return result;
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};
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module.exports = trun;
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