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Old 2nd June 2009, 22:42   #1  |  Link
Karkas
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FLAC vs HD audio questions

I tried searching google and here, but can't seem to shake the needle out of the search result haystack.

Can someone explain or point me to where FLAC is compared and contrasted with DD-TrueHD & DTS-HDMA. I understand they are all lossless, but I assume FLAC is inferior in some way?

Thanks in advance, and I apologize if this is a stupid/common question.

Thanks
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Old 2nd June 2009, 22:53   #2  |  Link
Inspector.Gadget
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I understand they are all lossless, but I assume FLAC is inferior in some way?
Lossless is lossless. A sample encoded to DTS-HD MA, TrueHD, FLAC, ALAC, WAVPack Lossless, etc. will sound exactly the same on decoding.
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Old 2nd June 2009, 22:58   #3  |  Link
Atak_Snajpera
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FLAC has better compression versus TrueHD and probably DTS-HD as well
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Old 2nd June 2009, 23:01   #4  |  Link
tetsuo55
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FLAC has better compression versus TrueHD and probably DTS-HD as well
How much better do you guestimate ??

Do you think it would be worth converting to flac container purely for the MB's?
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Old 2nd June 2009, 23:21   #5  |  Link
Karkas
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Thanks for the responses guys.

I figured the output would be the same since they are all supposed to be "lossless."

What about bitrates? all 7.1 channel support? What about cable (FLAC limited in some way over spdif like HD audio).

If FLAC has better compression than the non-free options why are the paid ones used at all?

Last edited by Karkas; 2nd June 2009 at 23:31. Reason: EDIT: Realised my example was incorrect, SPDIF can only carry core audio from HD audio
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Old 2nd June 2009, 23:56   #6  |  Link
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If FLAC has better compression than the non-free options why are the paid ones used at all?
Because Dolby and whoever owns DTS spend lots of money marketing their standards, and these standards are part of the BluRay spec, whereas FLAC is just an open standard with little to no hardware support.

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Old 3rd June 2009, 00:17   #7  |  Link
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Originally Posted by tetsuo55 View Post
Do you think it would be worth converting to flac container purely for the MB's?
I think it is worth it for the freedom, but is it possible?
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Old 3rd June 2009, 00:36   #8  |  Link
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Originally Posted by Atak_Snajpera View Post
FLAC has better compression versus TrueHD and probably DTS-HD as well
Yeah, DTS-HD has the inefficiency of its core / extension structure so FLAC should out-compress it every time (at best compression). It certainly should for 16 bit DTS-HD MA with a 1.5 Mbit/s core.

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How much better do you guestimate ??
This really depends on the source bitdepth and number of channels. An extreme example is 16 bit, 2 channel DTS-HD MA, which would compress a lot with FLAC, down to perhaps less than half of the original size. With 24 bit 5.1 or 7.1 I've found there isn't always much of a saving - maybe 10% or so. I haven't yet found a lossless audio track though that's bigger as FLAC than whatever it was originally.

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What about bitrates? all 7.1 channel support? What about cable (FLAC limited in some way over spdif like HD audio).
FLAC supports eight channels and any sample rate. Actually there is a maximum sample rate but I forget what it is - it's really high. FLAC is limited in the sense that you can't transmit it over S/PDIF. So it has to be decoded at source and then only stereo PCM can get sent over S/PDIF. It also can't be sent over HDMI but of course it can be decoded and all channels sent as PCM.
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Old 3rd June 2009, 00:38   #9  |  Link
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Originally Posted by Blue_MiSfit View Post
Because Dolby and whoever owns DTS spend lots of money marketing their standards, and these standards are part of the BluRay spec, whereas FLAC is just an open standard with little to no hardware support.

~MiSfit
But that doesn't make any sense. While I could expect consumers to be duped into paying for TrueHD or HDMA over free FLAC; I can't imagine publicly traded companies like Sony (Blu Ray) or Toshiba & co. (HD-DVD) to be cutting into their bottom line by paying to adopt inferior or even equivalent codec support.

Correct me if I am wrong, but I thought TrueHD & HDMA are not mandatory part of the specs for BR & formerly HD-DVD.
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Old 3rd June 2009, 00:43   #10  |  Link
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It also can't be sent over HDMI but of course it can be decoded and all channels sent as PCM.
HDMI can carry PCM, but NOT FLAC? If your player can not decode FLAC it can not pass it along to the reciever to decode??
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Old 3rd June 2009, 02:30   #11  |  Link
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But that doesn't make any sense. While I could expect consumers to be duped into paying for TrueHD or HDMA over free FLAC; I can't imagine publicly traded companies like Sony (Blu Ray) or Toshiba & co. (HD-DVD) to be cutting into their bottom line by paying to adopt inferior or even equivalent codec support.

Correct me if I am wrong, but I thought TrueHD & HDMA are not mandatory part of the specs for BR & formerly HD-DVD.
No they're not mandatory for blu-ray, but Dolby Digital and DTS are. So blu-ray authors are already doing Dolby Digital or DTS encoding anyway. TrueHD and DTS-MA are only inferior to FLAC in terms of compression, and often by not very much. I think that DTS-HD is superior to FLAC for blu-ray because of its backwards compatiblity with older hardware. Same with the pairing of TrueHD and DD. LPCM is always freely available for lossless, although the bitrate's a bit of a killer for multiple LPCM tracks.

Maybe FLAC will get used in the future though? I suspect it's lack of backwards compatibility ruled it out this time, if it was ever considered. I don't know how long it had been around when the new HD formats were being decided on. Maybe it wasn't mature enough.

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HDMI can carry PCM, but NOT FLAC? If your player can not decode FLAC it can not pass it along to the reciever to decode??
There's no hardware support for FLAC in the home cinema area. At least none that I know of. So even if you could coax your player to pass FLAC out over HDMI, or S/PDIF for that matter, there aren't any decoders available to plug in at the other end.
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Old 3rd June 2009, 02:32   #12  |  Link
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HDMI can carry PCM, but NOT FLAC? If your player can not decode FLAC it can not pass it along to the reciever to decode??
There is no standard way of putting a FLAC stream on HDMI or SPDIF. Even if you could output FLAC, what receiver can decode it?
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Originally Posted by Karkas View Post
But that doesn't make any sense. While I could expect consumers to be duped into paying for TrueHD or HDMA over free FLAC; I can't imagine publicly traded companies like Sony (Blu Ray) or Toshiba & co. (HD-DVD) to be cutting into their bottom line by paying to adopt inferior or even equivalent codec support.

Correct me if I am wrong, but I thought TrueHD & HDMA are not mandatory part of the specs for BR & formerly HD-DVD.
Choosing Dolby and DTS makes sense. Blu-ray manufacturers already have to license the core formats, the studios do not have to produce a soundtrack in yet another format, and consumers get lossless tracks that are backwards compatible with the equipment they own.
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Old 3rd June 2009, 02:35   #13  |  Link
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I haven't yet found a lossless audio track though that's bigger as FLAC than whatever it was originally.
I did not know it was possible to transcode.
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Old 3rd June 2009, 02:47   #14  |  Link
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I did not know it was possible to transcode.
eac3to
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Old 3rd June 2009, 02:54   #15  |  Link
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This really depends on the source bitdepth and number of channels. An extreme example is 16 bit, 2 channel DTS-HD MA, which would compress a lot with FLAC, down to perhaps less than half of the original size. With 24 bit 5.1 or 7.1 I've found there isn't always much of a saving - maybe 10% or so.
TrueHD should be able to give good compression with 5.1 content. It has more complex channel weighting matrixes that allow for better decorrelation. FLAC only does this for stereo, and even that is more simplistic. Also, TrueHD has smaller latency, better error recovery, and more error resilience, which makes it better-suited to broadcast transmission and for storage on fragile media.

That said, it sucks that they decided to use proprietary audio codecs. I'm glad there are people out there who enjoy reverse-engineering.

Last edited by jruggle; 3rd June 2009 at 02:58. Reason: channel mixing -> channel weighting
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Old 3rd June 2009, 03:15   #16  |  Link
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Choosing Dolby and DTS makes sense. Blu-ray manufacturers already have to license the core formats, the studios do not have to produce a soundtrack in yet another format, and consumers get lossless tracks that are backwards compatible with the equipment they own.
Good point. That actually makes sense.

Thanks!
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Old 3rd June 2009, 23:12   #17  |  Link
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Originally Posted by tetsuo55 View Post
How much better do you guestimate ??

Do you think it would be worth converting to flac container purely for the MB's?
On this 100 minute movie i just checked out:

DTS-MA: 1.97GB
TrueHD+AC3: 2.2GB
flac: 1.3GB
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Old 4th June 2009, 09:30   #18  |  Link
tetsuo55
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On this 100 minute movie i just checked out:

DTS-MA: 1.97GB
TrueHD+AC3: 2.2GB
flac: 1.3GB
For that sample the difference is huge!! 5.1 or 7.1 audio?
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Old 4th June 2009, 15:49   #19  |  Link
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For that sample the difference is huge!! 5.1 or 7.1 audio?
...and was it 16 or 24 bit?

Here's an example I've just done. Source is 24 bit 5.1 DTS-HD MA, 1:36:56 long.

Source 2.73GB
FLAC 2.35GB

So a 14% saving converting to FLAC.

Converting a 24 bit source to 16 bit FLAC offers really big space savings, although it's not lossless obviously. Good enough for me though - I can't tell the difference. In this case the above audio can be reduced to a 0.88GB 16 bit FLAC track, making it a third of its original size. In fact it's smaller than the DTS core (1.02GB).
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Old 4th June 2009, 20:47   #20  |  Link
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Wow, I had no idea FLAC produced such good compression when compared to the big name lossless ones.
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