feat: add Dolby TrueHD SampleEntry and ConfigurationBox

[jamrial]

As the PR subject says, this add supports for Dolby TrueHD specific sample entry and configuration box.

The only issue is that samplerate in MLPSampleEntry, despite being an extension of AudioSampleEntry, is defined as a 32bit unsigned value instead of a 16.16 fixed point value as in the main spec. The idea was to support sample rates higher than 48Khz, but clearly people at Dolby did not realize that the srat box exists for this same purpose, and came up with this hack.

I don't know how to make the aforementioned change.

mp4box.js/src/boxes/sampleentries/base.ts

Line 257 in 9925057

this.samplerate = stream.readUint32() / (1 << 16);

This should somehow check that the class extending AudioSampleEntry is MLPSampleEntry and then parse samplerate in a different way, probably in a similar fashion to the existing isQT check. Do you know how this could be done?

And then

mp4box.js/src/boxes/sampleentries/base.ts

Line 301 in 9925057

stream.writeUint32(this.samplerate << 16);

Should do the same for writing.

[changeset-bot]

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