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Updated TrueHD and AC3 (markdown)

Moritz Bunkus 2016-04-22 18:36:20 +02:00
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TrueHD-and-AC-3.md Normal file

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# How does mkvmerge handle TrueHD tracks with embedded AC-3 data?
## The problem
I'd like to keep thd+ac3 in a single track.
## The answer
If a TrueHD track contains AC-3 data then both data sets are completely decodable independently from another. The AC-3 part is present so that if that track is output to a hardware decoder that doesn't know about TrueHD then that hardware decoder can still decode the AC-3 part. The only difference between the two is that TrueHD is a lossless codec while AC-3 isn't – but they've both been done from the same source material.
The Matroska specs state that one track must only contain data for one codec. Therefore mkvmerge cannot keep the AC-3 interleaved with the TrueHD part in a single track.
Starting with release 7.7.0 mkvmerge's solution is to [present the AC-3 core as an additional track](/mbunkus/mkvtoolnix/issues/1107). This applies to TrueHD tracks read from any source file, be it from e.g. a raw TrueHD file, from a Matroska file or a MPEG transport stream. Before release 7.6.0 mkvmerge was silently discarding the AC-3 core.
Categories: [merging](FAQ#category-merging)

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TrueHD-and-AC3.md

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# How does mkvmerge handle TrueHD tracks with embedded AC3 data?
## The problem
I'd like to keep thd+ac3 in a single track.
## The answer
If a TrueHD track contains AC3 data then both data sets are completely decodable independently from another. The AC3 part is present so that if that track is output to a hardware decoder that doesn't know about TrueHD then that hardware decoder can still decode the AC3 part. The only difference between the two is that TrueHD is a lossless codec while AC3 isn't – but they've both been done from the same source material.
The Matroska specs state that one track must only contain data for one codec. Therefore mkvmerge cannot keep the AC3 interleaved with the TrueHD part in a single track.
Starting with release 7.7.0 mkvmerge's solution is to [present the AC3 core as an additional track](/mbunkus/mkvtoolnix/issues/1107). This applies to TrueHD tracks read from any source file, be it from e.g. a raw TrueHD file, from a Matroska file or a MPEG transport stream. Before release 7.6.0 mkvmerge was silently discarding the AC3 core.
Categories: [merging](FAQ#category-merging)