MPC-BE x64 Settings: Audio: Sound Processing: Channel Mixing - Stereo - Stereo Upmix in Decoder
When downmixing from 7.1 or 5.1 to 2.0 stereo, matrix normalisation does not work with the DTS MA format. Downmixing currently works for TrueHD and AC3; E-AC3 always works. Please add downmixing support for DTS, DTS MA and DTS X. Subject: Incorrect downmix normalization and clipping when downmixing DTS-HD MA 7.1, or 5.1 to stereo Hello FFmpeg developers, I have encountered an issue with downmix normalization when converting or playing DTS-HD MA 7.1 audio tracks to stereo. Compared to Dolby formats (AC3, E-AC3, TrueHD), the DTS-HD MA downmix output is noticeably louder, which often leads to severe audio clipping. Additionally, ffplay reports an "Invalid downmix layout" warning during playback. Steps to reproduce / commands tested: 1. ffplay -downmix 2 input.mkv 2. ffmpeg -i input.mkv -ac 2 output.wav Stream details: - Audio: dts (dca) (DTS-HD MA), 48000 Hz, 7.1, s32p (24 bit) Observed behavior: - AC3, E-AC3, and TrueHD 7.1 streams downmix correctly with proper normalization. - DTS-HD MA 7.1 output is too loud and clips. - ffplay console output shows: "[dca @ ...] Invalid downmix layout" Environment: - FFmpeg version: 8.1.1 essentials build (Windows) - The issue is also reproducible in MPC-BE player (which relies on FFmpeg decoders internally). I suspect that the dca decoder either misinterprets the 7.1 channel layout during downmixing or does not apply the correct attenuation coefficients compared to the Dolby decoder implementations. Thank you for your time and for maintaining this great project! _______________________________________________ ffmpeg-user mailing list -- [email protected] To unsubscribe send an email to [email protected]
