I have been preparing a DTS-HD 6.1 source for an editing project and I just wanted to check my process and get feedback. I'm happy with the results, but confused about what exactly is happening.
1. Rip bluray to .m2ts file with DVDFab
2. Extract DTS-HD 6.1 from .m2ts file using eac3to. I have Arcsoft DTS installed. I use -down6 to remix the 6.1 to 5.1. Eac3to is using Arcsoft for the decode and I output to a .raw file.
My assumption is that I getting all of the DTS-HD material in my .raw output?
3. I use an avs script to frameserve the .raw file with NicAudio to FFMPEG. Libav encodes the .raw into AC3 5.1.
My understanding is that Libav is a more uptodate AC3 encoder and slightly better than Aften. The version of Libav contained in eac3to has to be modified to work with eac3to so is slightly behind the latest Libav build in FFMPEG?!
Q. What confuses and concerns me is that the end file is the exact same file size if I use eac3to with Libav decoding the DTS core and converting to AC3 5.1 with Aften all in one step. I assumed that because Arcsoft is decoding the DTS-HD in addition to the Core, the end file would be a different size?
Q. Is the -down6 command in eac3to causing Arcsoft only to decode the Core?
*Edit: I did another extract with eac3to, this time DTS-HD to a .RAW file without using the -down6 switch. The output file was 2gb larger. When this was run using my avs script to FFMPEG the resulting file was the same size as previous encoded.
What I'm going to try next is splitting the DTS-HD into 8 wavs, discard the rear centre channel and see if this results in a different sized output file. My assumptions is that the information in the rear centre channel should be reflected by the -down6 switch, but I'm still curious to understand this better, based on the experience with the libav decode.