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19th April 2012, 18:18 | #1 | Link |
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TrueHD to PCM / DTS-HDMA not the same
Hi,
It seems TrueHD and PCM are not equal after all. I am trying to convert the Transformers 3 TrueHD track to DTS-HDMA (eac3to + DTS HD Encoder Suite). The resulting DTS-HDMA track is not the same. Some sounds have less emphasis (for example the intro voice is stronger, more defined compared to the environmental sounds with the TrueHD track). When converted to PCM and DTS-HDMA these sounds which are emphasized in the TrueHD track sound muffled as they get lost in the environmental sounds. The only explanation I find is that TrueHD applies effects like dialnorm and DRC. So while this doesn't change the compressed PCM contained within the TrueHD track, the decoders (Hardware receiver or PowerDVD) will modify the output by applying these effects on the different channels (as per the meta data contained in the TrueHD track). So the TrueHD output is different. Question: is it possible to convert the TrueHD track to DTS-HDMA that will playback the same sound? |
19th April 2012, 22:58 | #4 | Link | |
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The problem seems to be the DRC in TrueHD. PCM and DTS-HDMA don't have the meta data to apply these effects on the sound.
It seems the people who think TrueHD and PCM/DTS-HDMA are equal are wrong. Quote form wikipedia: Quote:
This is the first time I see this (Transformers 3). Someone tells me Iron Man is also doing this (?). Question: how can I extract the TrueHD to PCM (wav) with the DRC applied? (I see no setting in eac3to). (Furthermore, the open source decoders don't seem to be decoding this properly; I don't seem to hear a difference between the original TrueHD and my DTS-HDMA encode when playing back on Media Player Classic HC (needs further testing). But with PowerDVD 12 the difference is there: the TrueHD track is better). Thanks. Last edited by Bigmango; 19th April 2012 at 23:27. |
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19th April 2012, 23:20 | #5 | Link | |
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PowerDVD does it right. The open source decoders don't seem to do this properly (?). Does anyone know how I can extract the whole sound (including DRC) to keep the TrueHD experience? |
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20th April 2012, 09:42 | #6 | Link | |
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Dynamic Range Compression make the audio less dynamic and is only recommended to listen the audio in difficult ambiences (problems with neighborg, children sleeping, car, ...) Like modern receivers have already a equivalent filter, Night mode, that can be applied to all audio not only AC3/TrueHD, the use of DRC became obsolete.
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20th April 2012, 20:58 | #7 | Link | |
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Look at the names of the format: DTSHD-MA. MA = Master Audio, it's meant to be a perfect copy of the original master tapes (or whatever format) delivered from the studio (I believe you can trigger things like normalization and such in DTS, but even DTS themselves don't recommend it. They are of the opinion that the audio should be left alone, as mixed by audio engineers hired by the studio). TrueHD still likes to tweak things since Dolby has always done that since the days of AC3 on DVD (and probably earlier), so people with Dolby setups expect it... This causes problems with people these days that have one system that does both formats and either don't, or can't, adjust levels separately for each format. The same audio encoded in both formats will sound different. It _shouldn't_, but many people find that it does... And, naturally, they prefer one over the other and complain about it... |
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21st April 2012, 14:25 | #8 | Link | |
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@ rik1138: Thanks for the clarifications
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=> What I experience with the eac3to extracted lossless Transformers 3 source is that at some times there's so much going on (explosions, movements, etc...) that the sound becomes a "flat mess" (it's badly worded I know, but I think you get what I mean). When this happens, the TrueHD track will give some more presence to specific sounds (For example actions with explosions all over are going on, and suddenly a sports car passes by and it's sound will become more defined - this makes the sound more dynamic and doesn't happen with the extracted source). So far, the open source decoders (libav, MPC,...) don't seem to be able to decode these TrueHD tracks correctly (they only play the lossless source without the added effects). PowerDVD 12 plays them fine, but it only outputs 16bit (the TF3 track is 24bit). Does anyone know of a tool that will allow me to save the TrueHD track to wavs with the TrueHD effects applied? Thanks for the feedback. |
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21st April 2012, 22:42 | #9 | Link | ||
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22nd April 2012, 12:00 | #10 | Link | |
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1) DialNorm is not a problem for quality, is only a global attenuation (-4 dB most the times) and can be compensate with the volume control. 2) Dynamic Range Compression work attenuating high volumes (until -20 dB sometimes), then low volumes are more audibles (dialogs, the sport car, ...). Don't exist: "multiband compression" (=can give some control over specific instruments in a mix) or something else. But audio engineers don't want so, they want explosions with full volume. BTW, you are free to save the original TrueHD audio. I can't recommend recode TrueHD applying DRC, this is a lossy conversion, you can't recover the original audio data. If you apply DRC you losse much more than 24 -> 16 bits precission.
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