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ATV4 Surround Sound Issues
- Thread starter iphonetravel
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Oh yeah right. It's 7.1 PCM but my receiver converts its to 5.1 (I have a 5.1 System).
But this is not a problem for me.Before TVOS 9.0.1 I got 2.0 PCM instead of 7.1 PCM when I choosed auto.
Cool, thanks for clarifying that. Glad it's an improvement for you and hopefully TVOS 9.1 will bring further fixes.
I assume the "Auto" setting depends on the HDMI sink advertising its surround sound capabilities, most likely via E-DDC. If it doesn't speak E-DDC or doesn't announce the ability to decode Dolby Digital the the ATV4 will probably do the decoding and send multi-channel PCM.
An interesting question (to which I have no answer) is: what happens if the HDMI sink is a chain of devices (as in ATV4 -> AVR -> TV). Where does the E-DDC response come from?
I have a feeling it might come from the TV, which would be bad, since many TVs don't decode Dolby Digital. I'm thinking this because once I had everything hooked up my (rather ancient) Sony Bravia TV showed up as volume control device in the ATV4 menu, and the Siri remote could change the TV volume without any input from me. The ATV4 did not see my (latest generation) Sony AVR, I had to do the IR learning step.
If in fact E-DDC responses come from the last link in the HDMI chain then the manual override will be required in many cases. In any case, setting the Dolby Digital setting to "On" instead of "Auto" doesn't mean the ATV4 encodes everything as DD.
An interesting question (to which I have no answer) is: what happens if the HDMI sink is a chain of devices (as in ATV4 -> AVR -> TV). Where does the E-DDC response come from?
I have a feeling it might come from the TV, which would be bad, since many TVs don't decode Dolby Digital. I'm thinking this because once I had everything hooked up my (rather ancient) Sony Bravia TV showed up as volume control device in the ATV4 menu, and the Siri remote could change the TV volume without any input from me. The ATV4 did not see my (latest generation) Sony AVR, I had to do the IR learning step.
If in fact E-DDC responses come from the last link in the HDMI chain then the manual override will be required in many cases. In any case, setting the Dolby Digital setting to "On" instead of "Auto" doesn't mean the ATV4 encodes everything as DD.
Maybe but. When set to Auto the ATV 4 is sending 7.1 PCM, the TV might not be able to decode DD but it definitely can't handle 7.1 channels of audio, if it was using E-DDC to detect the last links capabilities I'd expect it to send only 2 channel stereo.
I think it sending PCM is by design, so that it can mix in its own sounds.
Setting the ATV 4 to Dolby Surround results in everything being sent as DD with only the main two channels active for non surround sources, for me at least.
Only thing that worked for me is selecting DD Surround. If I use Auto I get zero surround no matter what I select on my Sony Receiver. On my own ripped movies, I do have to go in and select 2nd track and then it decodes DD surround at 5.1 or 7.1. If I listen to music it auto detects it is stereo and only the left right and sub plays. So, with these setting the only thing I have to change is when viewing my own ripped movies and change to the 2nd track.
I had the ATV2, I never upgraded to the ATV3 and never had these issues before. But for now I seem to have found the work around for my setup. I am going to test some setting on my ripper this weekend to see if I can make it push that 2nd track as the 1st track, so I don't have to change anything.
I had the ATV2, I never upgraded to the ATV3 and never had these issues before. But for now I seem to have found the work around for my setup. I am going to test some setting on my ripper this weekend to see if I can make it push that 2nd track as the 1st track, so I don't have to change anything.
I'm not a movie sound engineer, but I believe that in a multi-channel audio signal the surround, back and LFE channels are purely optional. A 2-channel device receiving 7.1 channel audio can simply throw away everything but the front left and right channels, and will be fine.
My AVR does in fact have 7.1 channels, maybe that's why the ATV4 chooses to send 7.1 PCM instead of 5.1 DD when on "Auto"?
Wouldn't it be great if there were a KB article explaining exactly what the ATV4 does here?
No, if the signal contains 8 discrete channels then that's how the audio has been mixed. Different sounds through all the discrete channels. If you throw away all but the front two you will miss out on all that audio.
If you play a video with DD 5.1, it should feed your AVR with DD 5.1 and not PCM 7.1 no matter what your AVR supports.
Sure, but all that audio is just surround sound and LFE effects. You can still watch a 5.1 DVD on a stereo TV set and not miss much (except for surround sound and deep rumble).
Should it? AVRs up-mix the 5.1 sound to 7.1, too. Should they also not do that? (Mine doesn't because I only connect 4.1 speakers.)
However, the question what does the ATV4 do, and why? It would be silly to assume that Apple engineers have not thought long and hard about this.
That's not correct. The 5.1 mix is a specific mix, the centre channel handles most of the dialogue the LFE channel most of the bass, but important sounds could come from any channel. When a 5.1 mix is sent to a piece of equipment that can't handle it, say a TV that can only handle 2 channel stereo, it is remixed to 2.0, that is the sound allocated to the surround channels is repositioned into the stereo sound field, usually on the original decoding device say a dvd player. You can't just throw away the channels that the TV can't use. Either that or a specific 2 channel mix is provided on the Disc .
The AVR can up mix to 7.1 because it already has all the available audio information from the 5.1 mix, it uses algorithms to reposition those sounds into a 7.1 sound field.
"Not miss much"...well, the fact that you do miss out on audio is enough.
If it mixes it up to 7.1 then it does that based on certain algorithms, nothing out of the ordinary. It's a setting you choose in your AVR, how it should act in certain situations.
But if you have the standard setup, if you play a video with DD 5.1 audio on your ATV4, it should feed your AVR with DD 5.1. Not PCM 7.1.
Well, Apple has failed here. No doubt about that. What the ATV4 does? See below:
AUTO: When playing 2.0 Stereo, it feeds your AVR with 2.0 Stereo. When playing multichannel audio, no matter what audio, it feeds your AVR with PCM 7.1.
DOLBY SURROUND: No matter what you play on your ATV4, it will feed your AVR with DD 5.1.
I use Beamer to stream movies from my MBP to my AppleTV via LAN.
Beamer always send the surround sound data, yet the AppleTV does not pass it to the receiver over HDMI like the previous AppleTV did.
Not sure if it's a Beamer issue or an AppleTV issue.
Beamer always send the surround sound data, yet the AppleTV does not pass it to the receiver over HDMI like the previous AppleTV did.
Not sure if it's a Beamer issue or an AppleTV issue.
Like others above, I've not noticed any positive changes in respect to surround sound with the new update. I've seem other issues resolved (e.g. Apple music stuttering), but that appears to be it.
I have a 5.1 receiver and 5.1 speaker setup. Will my receiver still output 5.1 if it is fed PCM 7.1? Is there any downside to setting it to Auto or Dolby Surround?
I think I will use my AppleTV 3 untill this sound issue is fixed. I am really disappointed from Apple!
My problem is 2.0 stereo source is up mixed to 5.1 DD. I have to set The AppleTV 4 manually to stereo to get Dolby pro logic II for a 2.0 source video.
Only in menus I get stereo output with auto or Dolby setting.
My problem is 2.0 stereo source is up mixed to 5.1 DD. I have to set The AppleTV 4 manually to stereo to get Dolby pro logic II for a 2.0 source video.
Only in menus I get stereo output with auto or Dolby setting.
And thats exactly my problem aswell. For example, everytime im using Apple Music i have to switch from the dolby surround setting to stereo to get dolby prologic. Annoying.
If you use a receiver that's only capable of a 5.1 output I guess it would downmix the PCM 7.1 signal it gets when you use "Auto" in the ATV4 settings. If you had a receiver that were capable of handling 7.1 but you only had a 5.1 speaker setup you would lose the audio sent to the two channels you don't have speakers for.
Downsides? Of course. You don't get the correct audio output from your receiver since the ATV4 is handling the audio incorrectly. One should be able to use "Auto" and get 2.0 from the receiver when fed 2.0. One should get DD 5.1 from the receiver when it's fed DD 5.1. One should get DD 7.1 from the receiver when fed DD 7.1.
Preferably one should have the option on the ATV4 to use pass through, so the receiver could do all the audio decoding.
This is what most of us in this thread actually want - our ATV4s to have an option to pass through to allow all decoding to be handled by our amps.
Exactly.
I don't see why Apple doesn't give us this option, it would relieve Apple of many hours of work.
Annoyingly, this is also the case for stereo music played by the Music or Computers apps. Only music sent to the ATV4 via Airplay is output as PCM 2.0.
I guess, for now the best solution is using the Auto setting. After all, what does it matter where Dolby Digital movie sound gets decoded? It's a deterministic process. With music, on the other hand, I like it to reach the speakers with as little processing as possible. Up-mixing to 5.1 is clearly unacceptable there.
I'm still wondering whether the ATV4 in Auto would still send 7.1 PCM if the connected AVR was only 5.1 capable. I've already given away my old 5.1 AVR, so I can't test.
Did you have any luck with your experiments? I'm in the same boat with ripped movies, having to go into the options and select the 2nd English language track to get DD 5.1 is a pain.
Funny how the aTV3 did this automatically.
I don't know if will work for everyone, but I think I've found a work-around solution to make the ATV4 default to 2nd (5.1) audio track instead of the 1st one. However, it'll require re-post-proceesing (using Subler) all your media files.
When you have your file in Subler, check the box that is to the left of the the corresponding audio track you want to be the default (probably audio track 2). Then un-select the normally checked track 1. Save and optimize.
'So far' this seems to be working for me.
I know I don't want to do this to all my files, but at least I can fix other problems at the same time... Like getting my chapters back (and little pictures for them, thanks to Subler) and renaming my audio tracks (so I can tell which one is which.
HTH
When you have your file in Subler, check the box that is to the left of the the corresponding audio track you want to be the default (probably audio track 2). Then un-select the normally checked track 1. Save and optimize.
'So far' this seems to be working for me.
I know I don't want to do this to all my files, but at least I can fix other problems at the same time... Like getting my chapters back (and little pictures for them, thanks to Subler) and renaming my audio tracks (so I can tell which one is which.
HTH
Thanks for the tip. Need to get my head round Subler as I've not used it before.
My workflow was MakeMKV - Handbrake - identify
I'll have a look though, thanks.
Actually I was able to switch which english channel is first during ripping and since I've done that with DVDFab it finds that one first and I don't have to change any setting to get it to play in full DD 5.1. You are right ATV2 and 3 both did this automatically.