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Thread: Aac 7.1 ??

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  1. Member cjbrown80's Avatar
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    Hey gang,

    Sometimes I like to take a movie file to watch at my other location (work) and I like to bounce my bluray backup rips into MP4 with ripbot264 or handbrake. I prefer Handbrake because it has some better audio options for the aac (i.e. up to 768kbps, etc..) I also usually knock the video bitrate down to 8kbps and use two-pass and you can barely tell the difference from the original .m2ts file and it reduces the file size by at least half. I just got Tron Legacy on tuesday and I realized the audio is 7.1 channel and that made me think, I could use MKV to preserve the original DTS HD audio, but my machine at work can't have any codecs installed on it (for several reasons, none of them good). So what I'm wondering is, in Handbrake, you can only select 6 channel discrete for audio (5.1) but is it possible to make an 8 channel discrete audio file to handle the 7.1? I'm assuming it would need to be written into the software in a future update if it's at all possible. Also, if I select 6 channel discrete, what does faac do with the other two channels? I'm assuming maybe they're either truncated entirely or just dumped in with the rear channels.

    As always, thanks in advance for your input.
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  2. vanished El Heggunte's Avatar
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    1) decode the DTS-HD source to a 7.1 WAV file

    2) encode the 8-channel WAV with faac, or maybe with Nero AacEnc
    (not sure about this latter)

    3) don't use GUIs that cripple the functionality of the actually-used applications
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  3. Member cjbrown80's Avatar
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    Thanks for the input. I'm too lazy and stupid to use anything other than GUIs, i.e. I don't have the time or desire to learn all the CLI crap for every little utility I use. But if you could point me in the direction of an easy to understand guide, I would definitely check it out. Basically, I need to be able to convert blu-ray rip m2ts files into h.264 video, discrete multi channel aac, in an MP4 container. It would be really nice if the AAC could be kept at 1500kbps for the DTS files as well. If there exists a guide so I could learn to setup a CLI type thing and run it from a queu, please let me know.
    Thanks,
    Chris
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  4. Member cjbrown80's Avatar
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    Still looking for an answer to my question about 7.1 -> 5.1 aac audio. What does Handbrake do with the other two audio channels? Are they discarded or mixed in with the rear channels?
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    Bumping this thread because I know the answer but still have questions.

    Originally Posted by cjbrown80 View Post
    Still looking for an answer to my question about 7.1 -> 5.1 aac audio. What does Handbrake do with the other two audio channels? Are they discarded or mixed in with the rear channels?
    It down mixes 7.1 to proper 5.1 by mixing in the rear channel(s) into the side channels. Discarding them all together would be a bad idea, of course the DTS-HD core of a 7.1 mix already has the 7.1 down mixed properly and in the case of some DTS-HD 6.1 tracks sometimes you get a matrixed core. Of course I'm assuming you'd prefer to use the entire thing which is the best way to get the whole shebang.

    Now I've got a question for you guys....I use MakeMKV on a friends computer to get my TrueHD or DTS-HD-MA/HR sound into 6 channel discrete FLAC to export as .WAV and re-encode to whatever I like...so far all my sources have been 5.1...I recently borrowed The Expendables from a friend for a little project! I want to rip this bad ass movie (the sound track is meant to kick your teeth in as one reviewer put it!) and throw it in a discrete DTS 6.1, AAC 7.1 or other codec because I don't like DPLIIx when I know the movie has discrete 7.1 but my MacBook can't bitstream DTS-HD, TrueHD, DD+ or even 8 channel L-PCM (the latter of which I was really hoping) over HDMI! However I can output DTS-ES Discrete with no trouble and my receiver registers just that! The 7.1 AAC would be for the PS3 though I have no idea if the PS3 can handle 7.1 AAC, I've seen it bitstream 6.1 AAC though. Is their any compressed 8 channel discrete codecs that will pass over HDMI to a receiver to be decoded? My 7.1 set up is itching to be tested! (BTW I have software to encode DTS-ES Discrete so that is not an issue).

    BTW: to the OP, I'm planning on getting Tron Legacy because the sound is amazing! I want to preserve the true surround experience and not "cut it short".
    Last edited by nateo200; 23rd Apr 2012 at 16:36.
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  6. Member cjbrown80's Avatar
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    Thanks for the input.

    Your Mac is the problem.... the weak link.... (jk )
    My understanding is that HDMI 1.3 and up can pass DTSHD, TrueHD and Linear PCM in 7.1 channels. That's it. AAC has to be decoded to PCM before it can pass over HDMI.
    Not sure if you care, but since I originally started this thread, I've actually abandoned the idea of storing my movies in x264/aac MP4 files. My biggest reason was the lack of options for the aac audio. The way Windows Media Center decoded them and passed the PCM audio along to my A/V receiver was kooky, to say the least. The center channel seemed lower than it should be, the LFE seemed way higher and the 768kbps maximum bitrate was just not good enough. I now store everything with it's original HD audio from the BluRay, and for the video I still use x264, but I run them down to CRF 20 usually to save space. I might start adding a second 2.0 audio track to each file (down-mixed from the original primary track) to assist in streaming playback from my Windows home server, if I can't get the DTSHD and TrueHD content to stream properly (WHS uses a Silverlight portal to stream over the web... awesome for movie watching at work through a simple browser window ).
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    Originally Posted by cjbrown80 View Post
    Thanks for the input.

    Your Mac is the problem.... the weak link.... (jk )
    My understanding is that HDMI 1.3 and up can pass DTSHD, TrueHD and Linear PCM in 7.1 channels. That's it. AAC has to be decoded to PCM before it can pass over HDMI.
    Not sure if you care, but since I originally started this thread, I've actually abandoned the idea of storing my movies in x264/aac MP4 files. My biggest reason was the lack of options for the aac audio. The way Windows Media Center decoded them and passed the PCM audio along to my A/V receiver was kooky, to say the least. The center channel seemed lower than it should be, the LFE seemed way higher and the 768kbps maximum bitrate was just not good enough. I now store everything with it's original HD audio from the BluRay, and for the video I still use x264, but I run them down to CRF 20 usually to save space. I might start adding a second 2.0 audio track to each file (down-mixed from the original primary track) to assist in streaming playback from my Windows home server, if I can't get the DTSHD and TrueHD content to stream properly (WHS uses a Silverlight portal to stream over the web... awesome for movie watching at work through a simple browser window ).
    Yeah I don't use Multichannel AAC at all let alone 7.1 since NOTHING decodes it properly, theoretically it can be passed properly un decoded but no AV receivers in the US support it...I have DTS-HD Master Audio Suite at my fingertips to encode any DTS codec so what I do for 5.1 movies that tend to play much better when matrixed is just use compressed DTS-ES for Matrixed 6.1 or in the case of 7.1/6.1 discrete movies Ill use DTS-ES Discrete which is no bigger than standard DTS and I can get the bit rate as low as 768kbps and it sounds excellent as DTS MAS is for professional mastering...just have to watch out for Dialog norm movie sound tracks for whatever reason. My mac can't bit stream anything above 2.0 LPCM for whatever reason....I can decode TrueHD but it only goes out at 2.0 LPCM and whatever bit depth and sample rate the original source was at...Good for music I guess... :/

    EDIT: Just realized Apples 7.1 AAC is in Sony SDDS format with no rear channels....6.1 AAC is still a go though, Ive seen it decoded as LPCM on a friend PS3 straight to my 7.1 HDMI receiver
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  8. Member cjbrown80's Avatar
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    Interesting... I know the PS3 is able to either pass the DTS or Dolby straight thru the HDMI (bitstreaming) or decode it to PCM and pass that to most receivers. That's the way both my Sony and HK receivers have worked at least, but without the funny business on the dialog channel or LFE channel that WMC causes. Again, I still don't think there's any other codec you can use to run it from your MacBook via HDMI, but only being able to do 2 channels is odd. I'm assuming it's a driver or hardware issue with the audio chipset in that particular computer. The HDMI connections on the ATI HD5550 and nVidia GTX550 Ti graphics cards I've had in my media center PC have all been able to bitstream DTS-HD MA and Dolby TrueHD up to 7.1 at 96kHz/24bit to both of those receivers. I also have another little mini-ITX machine that has an Intel board with an i5 661 cpu that runs the onboard Intel graphics, and even that was able to bitstream the HD codecs via the HDMI built into the mobo. About 5 years ago when I started tinkering with this stuff, my machine only had DVI outputs which coudn't carry the audio like HDMI, but the soundcard in that machine had an optical output which, if I recall correctly, was able to carry Linear PCM, DTS and Dolby Digital, but not the TrueHD or DTS-HDMA. Not sure if that helps.
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  9. Member Atak_Snajpera's Avatar
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    my 5 cents. frauthofers aac encoder is alooot better than faac.

    64kbps per channels is enough for transparent quality.
    for example no need to use more than 320kbps for 5.1.
    therefore 768kbps or even 1536kbps is simply stupid. ripbot tries to eliminate user's lack of basic knowledge. aac stands for advanced audio compression if you haven't noticed.
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  10. vanished El Heggunte's Avatar
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    First of all, apologies for having forgotten this thread

    Originally Posted by nateo200 View Post
    ...

    EDIT: Just realized Apples 7.1 AAC is in Sony SDDS format with no rear channels....6.1 AAC is still a go though,
    Are you sure of that ??? Unless I'm very-misinformed, there is no such thing as 6.1 AAC, and Sony SDDS is ATRAC version "oldest"

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  11. Member cjbrown80's Avatar
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    Couple things:
    1)Aren't you the creator of RipBot? (One of my favorite apps, btw, many huge thanks for all your effort with that!)
    2)I disagree that 320 kbps is enough for 5.1... to my ear. Maybe for most, but I'm a professional audio engineer, (not a pretend engineer, like sitting at home with some software and plugins... but an actual, working engineer in the television/broadcast industry, I suspect nateo200 might be as well if he has access to the DTS-HD Master Audio suite... or a hacker... ) Not trying to sound like a jerk, but I can absolutely hear the difference between 320 and 640 kbps and especially between DD at 640kbps and TrueHD, and DTS at 768kbps and HDMA. I know the HD codecs can see bitrates over 4000k at peak, and those really do sound amazing. I also have a very high quality surround system so I'm sure that helps... to me the higher bitrates are totally worth it.
    Last edited by cjbrown80; 23rd Apr 2012 at 19:11.
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    Interesting... I know the PS3 is able to either pass the DTS or Dolby straight thru the HDMI (bitstreaming) or decode it to PCM and pass that to most receivers. That's the way both my Sony and HK receivers have worked at least, but without the funny business on the dialog channel or LFE channel that WMC causes. Again, I still don't think there's any other codec you can use to run it from your MacBook via HDMI, but only being able to do 2 channels is odd. I'm assuming it's a driver or hardware issue with the audio chipset in that particular computer. The HDMI connections on the ATI HD5550 and nVidia GTX550 Ti graphics cards I've had in my media center PC have all been able to bitstream DTS-HD MA and Dolby TrueHD up to 7.1 at 96kHz/24bit to both of those receivers. I also have another little mini-ITX machine that has an Intel board with an i5 661 cpu that runs the onboard Intel graphics, and even that was able to bitstream the HD codecs via the HDMI built into the mobo. About 5 years ago when I started tinkering with this stuff, my machine only had DVI outputs which coudn't carry the audio like HDMI, but the soundcard in that machine had an optical output which, if I
    Yeah I can bitstream Dolby Digital, DTS 96/24, DTS standard, DTS-ES Discrete 6.1 and 2 channel L-PCM over optical and obviously HDMI. You need a graphics card that can handle it, pretty sure nearly any graphics card can decode and TrueHD/DTS-HD if it can handle FLAC :O BUT the new HD codecs have "anti-piracy" security features in place...can't explain it off the top of my head but basically you need special drivers to decode these codecs and only high end discrete graphics cards where you pay good money has this. I don't get the sense in this because allot of computers can only play the core of TrueHD (yes TrueHD does in fact have AC-3 as a core many times) or DTS-HD...My MacBook will basically decode TrueHD and down mix to stereo and output it as 2 channel L-PCM over HDMI and it will only play the core of DTS-HD...I'm pretty sure I should still be able to pass multichannel L-PCM from a .wav or .aiff file though but so far no one can give me a solution for that...my receiver will pop up with "Multichannel L-PCM" when I set a PS3 to PCM output or set my BluRay player to PCM (internal decoding) but when I try to play a 5.1 L-PCM file with my MacBook Pro it still down mixes to stereo L-PCM....I know the TrueHD/DTS-MA issue is Dolby/DTS being pricks with their "protected audio path" or whatever its called BS but mini display port is able to carry 8 channel uncompressed L-PCM @ 24bit/96khz and so are the cables I use (1.3a HDMI)! I like to play with this type of stuff allot so I've created test AV files with pretty much every codec I can think of too...

    Originally Posted by El Heggunte View Post
    First of all, apologies for having forgotten this thread

    Originally Posted by nateo200 View Post
    ...

    EDIT: Just realized Apples 7.1 AAC is in Sony SDDS format with no rear channels....6.1 AAC is still a go though,
    Are you sure of that ??? Unless I'm very-misinformed, there is no such thing as 6.1 AAC, and Sony SDDS is ATRAC version "oldest"

    Do you have Compressor 4 available? Under some "advanced" settings after 5.1 AAC 6.1 AAC is listed as L R C LFE Ls Rs Cs (in standard AAC/DTS channel mapping of course), when it hits 7.0 and over the channels switch to L R Lc Rc LFE Ls Rs or something like that. I meant SDDS order style where you have more front screening channels than rears. Let me stop talking and upload some screen shots
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  13. Member Atak_Snajpera's Avatar
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    what encoder have you used for AAC?
    Like I said FAAC still sucks. The best implementations are from Apple and from Frauthofer (this one is used by ripbot).
    Personally I cann't hear difference between 2.0 FhG AAC 128 kbps and CD (FLAC). Tests done on very good headphones.
    With 5.1 is even harder to spot difference.
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  14. vanished El Heggunte's Avatar
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    @ nateo200: Thanks for the screenshot

    It means I have to harder
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    Originally Posted by El Heggunte View Post
    @ nateo200: Thanks for the screenshot

    It means I have to harder
    No problem. Its a relatively rare setting as I haven't seen it in any other encoder but compressor....I dug for it after I ran across a BluRay rip that was encoded in 7.1 AAC with nero! I was more interested in the audio codec than the movie at first haha.

    what encoder have you used for AAC?
    Like I said FAAC still sucks. The best implementations are from Apple and from Frauthofer (this one is used by ripbot).
    Personally I cann't hear difference between 2.0 FhG AAC 128 kbps and CD (FLAC). Tests done on very good headphones.
    With 5.1 is even harder to spot difference.
    I'm assuming the question isn't directed at me but I use Compressor and Handbrake mostly. Anyways I agree....But listening to DTS-MA and TrueHD on the right movies I found my perception of quality was completely blown sky high! 128kbps AAC sounds fine from a standard Dolby or DTS source or something that doesn't have more than dialogue but something like The Expendables in DTS-HD 7.1 sounds INSANE! The highs and lows of sound and range are crisp but with lower bit rate AAC the range suffers....fine for dialogue but a heavy action movie will suffer. Besides I like to preserve multichannel sources in their original channels....I'm more about good to very good quality in multichannel vs insane quality lossless uncompressed multichannel (aka DTS-MA) with movies......Only problem I'm running into is making compressed and discrete 7.1 surround sound..Highest I can get is DTS-ES 6.1 Discrete.
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  16. vanished El Heggunte's Avatar
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    Hmmm, I've studied a bit more, and I don't like what I've read

    Short explanation: AAC is as good as FLAC for multichannel audio
    ( i.o.w., it suxxx as much as FLAC )

    Long explanation (according to ISO/IEC 13818-7):

    8.5.3.2 Explicit channel mapping using a program_config_element()

    Any possible channel configuration can be specified using a program_config_element().There are 16 available PCE’s, and each one can specify a distinct program that is present in the raw data stream.

    <SNIPP>

    8.5.3.3 Implicit channel mapping

    If no explicit channel mapping is given, the following methods describe the implicit channel mapping:

    1) Any number of SCE's may appear (as long as permitted by other constraints, for example profile). If this
    number of SCE's is odd, then the first SCE represents the front center channel, and the other SCE's represent L/R pairs of channels, proceeding from center front outwards and back to center rear.
    If the number of SCE's is even, then the SCE's are assigned as pairs as center-front L/R, in pairs proceeding out and back from center front toward center back.
    2) Any number of CPE's or pairs of SCE's may appear. Each CPE or pair of SCE's represents one L/R pair,
    proceeding from where the first sets of SCE's left off, pairwise until reaching either center back pair.
    3) Any number of SCEs may appear. If this number is even, allocating pairs of SCEs Left/Right, from 2), back to center back. If this number is odd, allocated as L/R pairs, except for the final SCE, which is assigned to center back..
    4) Any number of LFEs may appear. No speaker mapping is defined in case of multiple LFEs.
    As already expected, most encoders and decoders use only the "implicit channel mapping" –.–
    Last edited by El Heggunte; 28th Apr 2012 at 11:41. Reason: formatting
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    Originally Posted by El Heggunte View Post
    1) decode the DTS-HD source to a 7.1 WAV file
    How?
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  18. vanished El Heggunte's Avatar
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    Originally Posted by maxrockpro View Post
    Originally Posted by El Heggunte View Post
    1) decode the DTS-HD source to a 7.1 WAV file
    How?
    With eac3to, of course.
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