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Old Jan 10, 2013, 01:05 PM   #1
Superfly611
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Handbrake 5.1 audio (Dolby Pro Logic II)

i am trying to encode a video file that has 5.1 audio For my Apple TV first generation and i have the audio set to dolby pro logic ii from an apply tv preset but when i check the file with a program called videospec it shows up as 2ch stereo. what am i doing wrong? isnt dolby pr logic ii actually 5.1 surround sound? Should I set it to six channel discrete? any help would be appreciated. Thank you in advance.
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Old Jan 10, 2013, 01:12 PM   #2
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You need to make two audio output settings.

The second one should be AC-3 passthrough for the 5.1 audio.
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Old Jan 10, 2013, 01:37 PM   #3
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Pro Logic is not true 5.1

You need to have an AC3 (Dolby Digital) track to have true discrete surround sound and a receiver that can decode it after the ATV passes it through.
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Old Jan 10, 2013, 03:42 PM   #4
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Dolby pro logic is not true surround sound, it is faux surround. It is a set of audio algorithms that help receivers decode stereo sound and make it into surround sound. If you want true surround sound you need an AC3 (ffmpeg) track selected as 6-channel discrete. The Apple TV 3 preset will automatically make both tracks.
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Old Jan 10, 2013, 03:52 PM   #5
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Originally Posted by Pyromonkey83 View Post
The Apple TV 3 preset will automatically make both tracks.
In fairness all three atv presets as well as other apple device presets will use this track layout identically.
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Old Jan 10, 2013, 03:59 PM   #6
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In fairness all three atv presets as well as other apple device presets will use this track layout identically.
This is good to know since I have never used the other presets! =D
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Old Jan 10, 2013, 04:19 PM   #7
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Originally Posted by micrors4racer View Post
Pro Logic is not true 5.1

You need to have an AC3 (Dolby Digital) track to have true discrete surround sound and a receiver that can decode it after the ATV passes it through.
Agreed, to get just a touch more specific .. in fact HB's dpl2 is in fact 5.0 as the LFE channel in DPL2's phasing is flawed as per dolby labs (we tested the specs and in fact was better without the lfe channel phasing). Now, that said ... it is yes listed as a 2 channel track in fact since it is but on a good receiver dpl2 sounds pretty darned good tbh. No, it isn't the same as 6 discrete channels (FR,C,FL,RR,RL,LFE) but its a pretty decent reproduction given only 2 channels of sound which of course many device can only do.
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Old Jan 10, 2013, 05:37 PM   #8
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I have an onkyo 7.2 ch receiver but I only have it set up for 5.1. So I should be set there.I've been using the Apple TV first-generation preset which sets up AAC (coreaudio)-dolby pro logic ii and AC3 ffmpeg. if I change the second one to ac3 passthru will that track be selected automatically by my Apple TV and played through my receiver?
I did take a look at my program videospec and I figured out why it keeps saying two channel stereo. It only tells you the first channel in the basic mode. Plus I'm assuming because I'm playing it on my iMac which only has stereo that's the channel that is selected. I changed the view of the program and it shows you both channels. Dumb mistake on my part. Anyway the second channel is showing up as six channels ac3. So which will Apple TV?

Thanks for all the answers
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Old Jan 10, 2013, 05:46 PM   #9
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If I change the second one to ac3 passthru will that track be selected automatically by my Apple TV and played through my receiver?
Yes, as long as the aTV audio preferences are set to Dolby Digital: ON (instead of AUTO)
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Old Jan 10, 2013, 05:54 PM   #10
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if I change the second one to ac3 passthru will that track be selected automatically by my Apple TV and played through my receiver?
You do not need to select passthru to have the Apple TV play it. Passthru means that during the encoding process it will just copy the AC3 track exactly rather than re-encode it for a lower bitrate (assuming the settings have it set to a lower bitrate than the original). I have never used a first generation Apple TV so I am not sure what to do to have it play the AC3 track by default. It is more than likely in the Apple TV's settings under "Dolby Digital" which needs to be set to "ON".
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Old Jan 11, 2013, 09:10 AM   #11
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Okay. Cool. I'll give it a try. Hopefully I'll be able to tell if it's playing the 5.1 audio. I'm not the best one to be able to differentiate between surround sound and not. is there a way to tell on the receiver what type of audio it's receiving that anyone knows of?
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Old Jan 11, 2013, 09:15 AM   #12
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Okay. Cool. I'll give it a try. Hopefully I'll be able to tell if it's playing the 5.1 audio. I'm not the best one to be able to differentiate between surround sound and not. is there a way to tell on the receiver what type of audio it's receiving that anyone knows of?
Generally it will change to say Dolby Digital or DD5.1 or something like that depending on your brand of receiver. If you have a Denon, Yamaha, Onkyo, or Sony, they all have a specific mode for Dolby Pro Logic. Therefore, if you do NOT see Dolby Pro Logic on the front and you have one of those 4 brands, you are more than likely on 5.1 surround.
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Old Jan 13, 2013, 12:01 PM   #13
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what should i do when theres no option for ac3 passthru? theres only dts passthru and ac3 ffmpeg.
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Old Jan 13, 2013, 12:12 PM   #14
mic j
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what should i do when theres no option for ac3 passthru? theres only dts passthru and ac3 ffmpeg.
If you have a dts track, you should select:
DTS
ffmpeg
6-channel discrete

That will convert you DTS to a DD 5.1.
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Old Jan 14, 2013, 11:21 AM   #15
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so not dts passthru? whys that?
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Old Jan 14, 2013, 11:23 AM   #16
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Old Jan 14, 2013, 11:29 AM   #17
Superfly611
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i only see aac (coreaudio), he-aac (coreaudio), aac (faac), aac (ffmpeg), ac3 (ffmpeg), dts passthru, mp3 lame, auto passthru.
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Old Jan 14, 2013, 11:44 AM   #18
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so not dts passthru? whys that?
AppleTV will not play back DTS. As told above it will go to AC3 (ffmpeg).
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Old Jan 14, 2013, 12:02 PM   #19
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Originally Posted by Superfly611 View Post
i am trying to encode a video file that has 5.1 audio For my Apple TV first generation and i have the audio set to dolby pro logic ii from an apply tv preset but when i check the file with a program called videospec it shows up as 2ch stereo. what am i doing wrong? isnt dolby pr logic ii actually 5.1 surround sound? Should I set it to six channel discrete? any help would be appreciated. Thank you in advance.
OP: You're not doing anything wrong. Dolby ProLogic is not a discrete 6 channel format. It's a two channel format, and other external programs will only ever recognize it as such.

To be a little more technical, Dolby ProLogic II is not really a format so much as it's a decoding method designed for Dolby Surround. But I won't bother you with the extremely technical details unless you really want to know.

The default behavior of Handbrake is that it'll create an AC-3 track and an AAC track that's ProLogic compatible. This is a bit of handwaving since the Handbrake encoder doesn't actually downmix anything... the Dolby Surround mix already exists in the front left and front right channels of any program that has a Dolby Digital track, and a ProLogic/ProLogic II decoder decodes the matrixed surround out of those two channels. How it does it is a longer, more boring discussion.... but no format analyzer will really recognize it as anything but stereo because digitally speaking there are only two channels.

If your version of handbrake presets isn't automatically selecting "ProLogic II downmix" in the audio settings, change those settings to show what that guy above, Peace, had taken a screenshot of.
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Last edited by Avatar74; Jan 14, 2013 at 12:07 PM.
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Old Jan 14, 2013, 12:06 PM   #20
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so not dts passthru? whys that?
Dynaflash is correct regarding DTS passthru. However, I include a DTS passthru audio track as a third option on all my HD conversions for the AppleTV. The ATV just ignores them and plays the DD5.1 track, but I like having the DTS there for other medai players. (Also hope Apple will someday support it as well.)

I usually select the High Profile preset, then add in a second audio file (ffmeg 5.1) and then a DTS pass thru as the third. That's my default setup.
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Old Jan 14, 2013, 06:06 PM   #21
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Okay. Being that AC3 passthru does not always show up I'm assuming ac3 ffmpeg is the same so that's what I will put. Hope that is what I understood from you guys And it is right.

thanks again
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Old Jan 14, 2013, 06:32 PM   #22
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Okay. Being that AC3 passthru does not always show up I'm assuming ac3 ffmpeg is the same so that's what I will put. Hope that is what I understood from you guys And it is right.

thanks again
It is, HB will encode the DTS 5.1 track to an AC3 5.1 track. The atv will pass it through just as if it was a source AC3 track.
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Old Jan 15, 2013, 10:48 AM   #23
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Very good. You all have very helpful. Thank you for all your help. I still have to connect Apple TV to my receiver and make sure everything is good and shows up. I'll keep you posted.
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