private static IEnumerable <byte[]> PsshBox(byte[] pssh)
{
// Pssh box specs:
// ISO IEC 23001-7 Cenc MP4
// Check box type, 'pssh'
if (pssh[4] != (byte)'p' ||
pssh[5] != (byte)'s' ||
pssh[6] != (byte)'s' ||
pssh[7] != (byte)'h')
{
yield break;
}
// ISO IEC 23001-7 8.1.1
// Check version. Must be > 0. Version 0 treat as:
// (...) "Boxes without a list of applicable KID values, or with an empty list,
// SHALL be considered to apply to all KIDs in the file or movie fragment"
if (pssh[8] == 0)
{
// push out master key id.
yield return(MasterKid);
yield break;
}
uint kidCount = BigEndian.AsUInt32(pssh, 28);
// 8.1.3 Semantics
// KID identifies a key identifier that the Data field applies to. If not set, then the Data array SHALL
// apply to all KIDs in the movie or movie fragment containing this box.
if (kidCount == 0)
{
// push out master key id.
yield return(MasterKid);
yield break;
}
var offset = 32;
for (var i = 0; i < kidCount; i++)
{
var uuid = new byte[16];
Array.ConstrainedCopy(pssh, offset, uuid, 0, 16);
offset += 16;
Logger.Info(KeyToUuid(uuid));
yield return(uuid);
}
}