parse-tfhd.js
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var tfhd = function(data) {
var
view = new DataView(data.buffer, data.byteOffset, data.byteLength),
result = {
version: data[0],
flags: new Uint8Array(data.subarray(1, 4)),
trackId: view.getUint32(4)
},
baseDataOffsetPresent = result.flags[2] & 0x01,
sampleDescriptionIndexPresent = result.flags[2] & 0x02,
defaultSampleDurationPresent = result.flags[2] & 0x08,
defaultSampleSizePresent = result.flags[2] & 0x10,
defaultSampleFlagsPresent = result.flags[2] & 0x20,
durationIsEmpty = result.flags[0] & 0x010000,
defaultBaseIsMoof = result.flags[0] & 0x020000,
i;
i = 8;
if (baseDataOffsetPresent) {
i += 4; // truncate top 4 bytes
// FIXME: should we read the full 64 bits?
result.baseDataOffset = view.getUint32(12);
i += 4;
}
if (sampleDescriptionIndexPresent) {
result.sampleDescriptionIndex = view.getUint32(i);
i += 4;
}
if (defaultSampleDurationPresent) {
result.defaultSampleDuration = view.getUint32(i);
i += 4;
}
if (defaultSampleSizePresent) {
result.defaultSampleSize = view.getUint32(i);
i += 4;
}
if (defaultSampleFlagsPresent) {
result.defaultSampleFlags = view.getUint32(i);
}
if (durationIsEmpty) {
result.durationIsEmpty = true;
}
if (!baseDataOffsetPresent && defaultBaseIsMoof) {
result.baseDataOffsetIsMoof = true;
}
return result;
};
module.exports = tfhd;