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Support of an unique SMPTE ST 12 Timecode in track header #684

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JeromeMartinez
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Several container formats, e.g. MXF or QuickTime, don't have SMPTE ST 12 Timecode values per frame, they have a start time code and a frame rate, then other time codes are computed from that.

This PR adds the support of a similar way to store timecodes in Matroska.

As SMPTE ST 12 does not indicate the corresponding frame rate, we provide it in the private data. frame rate num/den is preferred over an integer because we need the precise source (constant) frame rate for computing the corresponding timecode.

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definition:
If present, indicates that Block Additional Mapping is not present and that the stored bytes represent the start timcode.
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nit: timcode > timecode

@hubblec4
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It seems to me you want add two new elements which are a Rational number.

Should we first implement the EBML Rational type?
ietf-wg-cellar/ebml-specification#164

@JeromeMartinez
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Should we first implement the EBML Rational type?

Would be better, for sure.

@robUx4
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robUx4 commented Feb 25, 2023

Should we first implement the EBML Rational type?

This might be a while. And since there's no agreed technical solution, you should not create such a file for now.

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4 participants