The above will result in correct steering when played back using any matrix based surround decoder like Dsur or DTS Neural.ĭVDfab incorrectly merges the two surround channels to the total front channels. Suppose you have 5.1 channels of Front Left (FL), Front Right (FR), Center (C), Left Surround (LS), Right Surround (RS) and LFE (S), then this should be the correct DPL2 encoding:

Here is the problem: To correctly down-mix 5.1 channels, the channels must be matrix-encoded into 2 channels, called Left Total (LT) and Right Total (RT). In the handbrake result, left and right surround test tones are heard from the corresponding left and right surround speakers, while in the DVDfab result, they are heard only from the left and right FRONT speakers!!! This is a major bug and very disappointing, coming from a commercial software. Please try to play and compare results while you AV receiver surround mode is set to Dolby Prologic 2 (or Dsur, or DTS Neo 6, or DTS Neural X). Now, this is the same video again with 2.0 downmix handeled by DVDfab (sellecting DPL2 option and AAC audio): This is the same video with 2.0 downmix handled correctly by Handbrake: This is a sample test video - the original video with DTS-MA 5.1 soundtrack: Unlike Handbrake's DPLII mixing, which is implemented correctly, DVDfab's DPL2 mixing is actually a simple stereo mixing! I'm used to the open source software Handbrake and decided to give DVDfab a try because it can use CUDA for processing.Īlthough video encoding works fast and great, I discovered a serious bug when down-mixing a video with discrete 5.1 to 2.0 audio with matrix surround encoding.

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Handbrake dolby surround vs 5.1