The reason for that is that the start of every stream always has what's called a major sync. We also know that we can cut the very last TrueHD frame off a stream without consequences. 129 of those contain duplicate audio frames, which means that by the end of the movie your audio would be 107 ms late! That's noticeable. But Monsters University is special in that it consists of 135 segments, or 134 segment boundaries. If we just naïvely append two tracks together, like MakeMKV does here, we'll accumulate desync at each boundary and we run the risk of introducing a "pop" caused by the discontinuity of the audio signal. It turns out that blu-ray TrueHD tracks can have an overlapping frame at the segment boundary. It's the smallest unit of audio we can add or delete.) You might already be able to see the problem - the audio frames at either ends of the original TrueHD streams are identical! (A TrueHD frame is always 1/1200 seconds, or just under 1ms, long. Track 4 is the audio demuxed with MakeMKV 1.15.1.Track 3 is the (start of the) unmodified TrueHD stream of 00056.m2ts.
Track 1 is the audio demuxed with this tool.We're looking at the boundary between segments 55 and 56.
This is the TrueHD audio of Monsters University, downmixed to one channel for better illustration. The following image is a screenshot from Audacity: I'm glad you asked! For that, we'll need to inspect the generated TrueHD streams on the level of individual audio samples. Notably, however, MakeMKV 1.15.4 and newer joins TrueHD streams flawlessly as well. This tool aims to be a perfectly accurate TrueHD demuxer that doesn't produce invalid, broken, or out-of-sync streams. However, all of them fail in different ways on TrueHD streams, especially on discs that contain a large number of segments, which has resulted in desync and noticeable audio artifacts. FAQ Aren't there already other demuxing tools out there?Ībsolutely. Mlp demux segments -s "F:\BDMV\STREAM " -o "out.thd " -l "55,56 " -stream 2Įvery command supports -v or -vv for more verbose output. Mlp demux playlist "F:\BDMV\PLAYLIST\00800.mpls " -output "out.thd " -stream 1
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