2015-04-01, 21:03
(2015-03-31, 20:58)halfgaar Wrote: In making that clip of Terminator 2, mplayer kept starting with the audio commentary track. In it, it's interesting to hear that James Cameron explaining how important dynamic range is. I think he would think his artistic expression is compromised if people play his films with DRC on. Just like David Lynch hates it when people watch films on phones.
Fair enough, but what does he think about people who may have to cover his carefully crafted scene with subtitles on as they couldn't hear dialogue at a "normal" volume level :-)
More seriously I wonder whether he put lfe in the DTS downmix meta for your film - if you could upload a snippet I could tell you.
Maybe you just used 2ch for your graphs and have 5.1, but if not you will AFAIK get different results from kodi compared to other players with DTS when downmixing, as I don't think kodi asks the codec for 2ch.
I dug out an old debugging patch I had and Toy story 3 DTS core from MA uses ( C L R Ls Rs LFE) -
Code:
[dca @ 0x2478fc0] Stereo downmix coeffs:
[dca @ 0x2478fc0] L, input channel 0 = 0.501190
[dca @ 0x2478fc0] R, input channel 0 = 0.501190
[dca @ 0x2478fc0] L, input channel 1 = 0.707092
[dca @ 0x2478fc0] R, input channel 1 = 0.000000
[dca @ 0x2478fc0] L, input channel 2 = 0.000000
[dca @ 0x2478fc0] R, input channel 2 = 0.707092
[dca @ 0x2478fc0] L, input channel 3 = 0.415680
[dca @ 0x2478fc0] R, input channel 3 = 0.000000
[dca @ 0x2478fc0] L, input channel 4 = 0.000000
[dca @ 0x2478fc0] R, input channel 4 = 0.415680
[dca @ 0x2478fc0] L, input channel 5 = 0.446686
[dca @ 0x2478fc0] R, input channel 5 = 0.446686
This does not get normalised any further - and hardly clips at all, 2k samples out of the whole movie IIRC, which I suppose sounds a bit off, but if you look (audacity) at the unmixed 5.1 the Center is clipped a bit anyway, so I guess the mixer didn't mind pushing it volume wise. Although ac3 does have, and can use mixdown meta I don't think there is provision for any LFE and the codec does normalise fully after applying.
Another advantage of requesting 2ch for TrueHD is that you can get a downmix that is in someways embedded - it's the way the codec works - higher channel counts are sort of mixed up from the 2ch using further substreams (that in the event you only want 2ch can be totally skipped). No DRC with current ffmpeg on TrueHD.
The two DTS-HD/MA decs that just appeared don't do this yet, but in time it should also be possible (stream layout permitting) to get a "studio" 2ch mix straight out of the codec.