SKLSDJASFG y r u using 5.1 FLAC?

Most people’s reaction to seeing surround (5.1 or better) FLAC used in releases tends to be something like “lol wut”. Therefore I’m gonna go ahead and write up a small explanation that I can link people to so I don’t have to repeat myself over and over on IRC all the time.

If you see 5.1 FLAC in some HD release it most likely means that the release in question is a Bluray rip and the source had Dolby TrueHD audio. TrueHD is the successor to AC3; unlike AC3 and DTS it is a lossless audio codec. In theory it can have up to 14 channels (max on a Bluray is 8), but most Blurays only use 6 (front left, front right, center, rear left, rear right, subwoofer). Since it’s nice to keep the original audio and TrueHD currently cannot be muxed into MKV, the easiest option is just to use eac3to to transcode it to another lossless codec, namely FLAC, which is open source and fairly well supported in most places that support MKV. Incidentally FLAC compresses better than TrueHD does anyway.

tl;dr: TrueHD is lossless but doesn’t fit in MKV, so some people who like keeping the audio untouched use FLAC instead, which compresses better (and does fit in MKV).

Comments (17)

  1. lol wut


    is there any noticeable difference between flac and, say, q1.0 aac? (with ABX preferred)
    IMO the only reason for me to keep lossless is to enable me converting it to lossy format without much loss in quality… and the only time I need that is when converting music, not omgwtfbbqanimeepisode

    or course, there’s good reason… the video file is large enough already and adding few hundred megabytes for audio won’t effect anything. lol

    Sunday, November 9, 2008 at 11:54 #
  2. Anon Encoder wrote:

    Lately I’ve been wondering if I should bother using a lossless audio codec(and which) for those R2 DVDs which come with LPCM audio. I don’t see many people doing that(even if it would probably be the right thing to do), the reason is probably because in the past people were concerned with fitting their encodes to standard sizes to care about lossless audio enough, but nowadays when more and more encoders aim to achieve/transparent/constant quality, we should probably give this a try. Seeing FLAC used in today’s gg’s BD release brought it to my attention again.

    Sunday, November 9, 2008 at 12:43 #
  3. TheFluff wrote:

    edogawaconan: no, to any sane listener there is no difference. This is mostly a principle thing.

    Anon Encoder: DVD’s aren’t high quality enough to bother with that, I’d say.

    Sunday, November 9, 2008 at 17:00 #
  4. Nichorai wrote:

    Aren’t most of them are just taking the LPCM track and encoding that to FLAC. The players (both BD and HD DVD) at least mandate that they must support LPCM, and I think its on a fair amount of the discs.

    Monday, November 24, 2008 at 07:19 #
  5. I rage every time I see an HD encode where over 50% of the bitrate is spent on fucking lossless 5.1/6.1/7.1/9000.1 audio.

    1. I only have two ears.
    2. Nobody gives a shit if your audio is lossless.

    Just re-encode to AAC or Vorbis or something. Your downloaders will thank you from the bottom of their hearts.

    Friday, December 26, 2008 at 19:15 #
  6. TheFluff wrote:

    even on my 720p releases that use this (not to mention the 1080p ones), the video bitrate is well over twice that of the audio (and even 6.1 FLAC usually uses less bitrate than 1536kbps 5.1 DTS) but have fun raging I guess

    Friday, December 26, 2008 at 23:27 #
  7. Raziel666 wrote:

    With the release of zx’s and THORA’s GitS 2.0, I was wondering how does the TrueHD->FLAC compare to TrueHD->DTS in terms of quality/compressibility.
    I haven’t downloaded THORA’s version yet and I see no point in doing so to be honest, but I suspect that the 1GB+ bigger THORA file has something to do with the audio being DTS (I’m talking about the 720p versions).
    Of course THORA are known for their more-than-needed-bitrate encodes! :p

    Saturday, December 27, 2008 at 19:38 #
  8. TheFluff wrote:

    The ZX release uses 1323kbps for lossless 6.1.

    The THORA release uses 1536kbps for lossy 6.1.

    Draw your own conclusions.

    Saturday, December 27, 2008 at 19:47 #
  9. lmm wrote:

    So is there a good reason why MKV doesn’t support TrueHD?

    Tuesday, December 30, 2008 at 02:02 #
  10. TheFluff wrote:

    AFAIK the reason is “noone got around to specifying how it should work and implementing it yet”.

    Tuesday, December 30, 2008 at 03:21 #
  11. delacroixp wrote:

    @ 1. Sure there is a difference in bits, bytes, 0’s and 1’s.
    Maybe there is one person out there with super-senses who can hear better than the rest and has a ‘supercomputer hifi’ to boot.
    However, for most people over 30 … any kind of exceptional hearing and a level of appreciation to notice the difference … is a thing of the past !
    IMAX is better than Blu-ray, DVD, Xvid, et al but the screen wont fit into your living room … unless you’re Bill Gates or an oil sheik/baron with your own private Boeing 747 as daily transport.
    Encoding rocks 4 99% of the planet !!!

    Thursday, January 1, 2009 at 22:52 #
  12. Anon Encoder wrote:

    If someone’s downloading a huge transparent 1080p BD Rip, it’s safe to assume he has a very fast pipe and the extra bitrate spent on lossless audio won’t increase the download times by much

    Saturday, January 3, 2009 at 16:58 #
  13. fanboi wrote:

    …and what if I want to have lossless sources to faithfully duplicate the original with a Bluray burner?
    That idea makes me agree with lossless preservation, even if it means huge-ass downloads.

    Thursday, January 15, 2009 at 18:57 #
  14. rager wrote:

    Goddamn, not more lossless codecs. They all are the same shit, and compress withing a few percent of each other. Since transcoding is harmless, just use FLAC. Or WavPack. But that’s it, PLEASE. No need for that TrueSHIT nonsense.

    Friday, January 30, 2009 at 01:19 #
  15. Sephirotic wrote:

    I tottaly agree with Dark Shikari, i would really prefer to see 1mbps extra on the video encode than on a Lossless audio wich 99,99% of the world population wouldnt be able to discern from an 384kbs AAC. How many ppl in fact have 6.1 or even 7.1 suber speakers home theaters that wont buy the original blu-ray anyway? I download 7,9gb reencodes because blu rays are too expensive in my country and i want the best quality vs size wize setting possibly. Lossless ISNT wize for good sake. WHAT I RAGE even more than dark shiraki is when someone makes thanks to those stupid FLAC audio movies that doesnt fit a DVD9 midia by only 500~1000mb. For god sake, if in japan eua and half europe DVD9s are outdated in the rest of the fucking world ISNT! i cant afford a 16gb pen drive just for 1 stupid movie downloaded in the internet, why botter reencode it?!?!! GEEZ.

    BTW, i downloaded one of those stupid encodes with a 6.1 FLAC audio, now i cant transcode it neither with eac3 or megui, anyone can give me a hint how to reprocess 6.1 FLAC audio to AC3 ou AAC multichannel? I already extracted (after some pain in the ass) it with mkvextract with the no-ogg parameter. Thanx a lot in advance (btw, my email/msn is

    Tuesday, June 9, 2009 at 13:06 #
  16. Nathan McDaniel wrote:

    Sephirotic – DVD9s are outdated everywhere. Get a portable hard disk. You’ll pay half the cost per gigabyte with a 1TB disk than with 110 DVD9 discs, and it takes up a lot less physical space and is 10x faster too.

    Anything that will play a 1080p encode will have a USB port to plug that disk into too.

    Friday, November 27, 2009 at 17:00 #
  17. Akujin wrote:

    Your argument is not valid because if you want to keep the output exactly the same as the original you shouldn’t re-encode at all. And yet this is precisely what people do with the video while claiming to be all holier than thou about quality by transferring the audio from one lossless codec to another lossless codec. If you want to keep the highest level quality you might as well rip the Bluray and upload the ISO and stop wasting people’s bandwidth.

    Sunday, June 24, 2012 at 07:04 #