AppleTV 4 surround sound issue

AAfter much messing I left the ATV4 in auto, so it outputs uncompressed PCM in multiple channels, since this is uncompressed and the DD setting was outputing fake DD 5.1 when I knew the source only had stereo 2.0, DD or not DD.

I Left my Pioneer 9140TXH receiver in auto surround mode, now it plays stuff in stereo or 5.1 automatically using the PCM uncompressed signals in the ripped files

I Have been reading through the tread. And this has nothing to do with streaming movies but it has to do with Apple Music and YouTube. My ATV4 when first purchased showed my Apple Music and some of my YouTube videos in Dolby Surround. After I did the first update that went away. Can anyone verify this ?

Thanks

moochman wrote:

My ATV4 when first purchased showed my Apple Music and some of my YouTube videos in Dolby Surround

Surround output depends in the input, the app and the Surround Sound setting. This did change in the tvOS 9.1 update. Auto and Dolby Surround work much better given straightforward inputs like 2/0/.0, 3/2/.1 and 3/4/.1 (if you don't need an E-AC-3 bitstream) but there are still issues. Some have been described at length by Jon Walker. Others are completely puzzling. E.g. a 3/2/.1 input played by Plex in Auto does the right thing but in Dolby Surround the output is 2/0/.0.

If you don't have mono inputs and you don't need a bitstream then Surround Sound:Auto is currently the best mode. tvOS is still beta. Expect changes.

I Have been reading through the tread. And this has nothing to do with streaming movies but it has to do with Apple Music and YouTube. My ATV4 when first purchased showed my Apple Music and some of my YouTube videos in Dolby Surround. After I did the first update that went away. Can anyone verify this ?

Consider it verified. The explanation (or problem, depending on your point of view) is simple. The original TV4 tvOS v9.0 used a Dolby output connection with downstream devices to transfer non-Dolby audio in the "Dolby Surround" mode. This meant that your Apple Music and YouTube video 1.0 and/or 2.0 audio was actually sent as the active left and right channels on a "pseudo" 5.1 Dolby surround connection which, of course, triggered the receiving device Dolby decoder indicators. Active channels played correctly as long as the receiving device was capably of decoding a Dolby bitstream but many found this workflow to be very confusing. Switching to the TV4 "Stereo" mode would play these files in their normal "Stereo" PCM manner but most users found doing so to be inconvenient.

As a result, the TV4 "logic" was modified. Under tvOS v9.0.1 and v9.1, the source audio tracks are first evaluated to determine whether or not the audio is "multichannel" in nature. (I.e., for the purpose of this evaluation, it seems that any Dolby audio having an LFE channel is considered multichannel and any audio without an LFE channel is considered non-multichannel.) Once the "multichannel" status is known, the audio is then processed according to the "logic" of the particular Surround preference setting and tvOS release in use. Currently, under TV4 tvOS v9.1, non-multichannel audio is sent to the downstream device as "Stereo" PCM in both the "Auto" and "Dolby Surround" modes. Multichannel audio in the "Auto" mode is sent via a multichannel PCM connection with "active" channels carried on corresponding channels of the multichannel connection. (E.g., a 2.1 source Dolby audio track would only carry "active" audio on the left, right, and LFE channels of the multichannel PCM connection.) In the "Dolby Surround" mode, the same 2.1 Dolby source track would be sent to the downstream device as left, right, and LFE channels on a DD 5.1 connection.

Thus, your problem is solved but, as bodosom indicated, different problems can crop up for other users. For instance, under the current v9.1 logic, there is no such thing as Dolby "passthrough" of non-multichannel audio as under TV IOS v6.2.1 (TV2), TV IOS v7.2 (TV3), or tvOS v9.0/v9.0.1 (TV4) systems. Thus, under tvOS v9.1 DD 1.0 audio is sent as "Stereo" PCM which requires manual post-processing to restore playback through the center channel speaker. On the other hand, a DD 2.1 Dolby ProLogic II audio track is sent as a "pseudo" DD 5.1 connection which automatically disables decoding of the active matrix center and surround channels since the Dolby decoder is already operating in the multichannel mode. Am, therefore, requesting Apple engineers restore the previous "Dolby (Auto)" passthrough over HDMI option as a fourth TV4 mode option in addition to the current "Auto", "Dolby Surround", and "Stereo" options. (I.e., this option would unconditionally passthrough any Dolby bitstream for downstream decoding and send non-Dolby audio as "Stereo" PCM). Request anyone interested in restoring this workflow send feedback to Apple regarding the current lack of support for certain Dolby audio compression formats.

I turned off the control loud noises (or whatever it is called) and get a better result. Someone mentioned this earlier in this dialog.

Very late to this discussion which is excellent, although as an Apple share holder, this is a disappointing product as it dumbs down the audiophile experience I have grown to love about Apple. With that slight rant out of my system, here is what I found very helpful about this discussion:

1. Set Audio to Dolby Digital - great relief although would prefer AUTO smarts of ATV3; I suspect that the removal of Toslink(SPDIF) Out impacted the software/firmware to a point where ATV4 lost the smarts to recognize source and seamlessly encode/decode both audio and video.
2. Set Audio Loud Noises to On (Loud) - Now I can hear the Cannonball bounce across the prairie in Patriot and U2 belt out In the Name of Love.
3. Very informative all the different formats and encodings that need to be supported and surprised to hear the number of issues going directly HDMI into very powerful AV Equipment

I did go out and buy an Audio De-Embedder with 3D support (KanexPro) and split the HDMI out into HDMI Out and SPDIF out; this made it more of an ATV3 "like" configuration into my Marantz AV Surround and Pioneer Plasma. Worked very well although, even with this device, I needed to set Dolby Digital on which does impact the overall listening experience.

Thank you all for the great discussion; I learned a lot - LET'S HOPE APPLE (APPL) DID THE SAME.

Happy New Year 2016

Had the same issue with a Marantz - purchased and KanexPro Audio De-Embedder mimicking the ATV3 setup (HDMI --> Pioneer (TV) and SPDIF Optical --> Marantz (AV Surround). This coupled with setting ATV4 to Dolby Digital solved most of my issues. Very frustrating experience. Thank you PWNELL for all your insight. BTW - You will need an additional HDMI Cable to connect ATV4 --> De-Embedder (splitter).

Happy New Year 2016

This helped me. Thank you. Not sure why I can't highlight this as an answer.

Set Audio to Dolby Digital - great relief although would prefer AUTO smarts of ATV3; I suspect that the removal of Toslink(SPDIF) Out impacted the software/firmware to a point where ATV4 lost the smarts to recognize source and seamlessly encode/decode both audio and video.

It is my understanding that the HDMI connection has a greater capacity specification. Others have speculated that the dropping of the optical audio output was to ensure adequate compatibility with the newly added DD+ 7.1 connection requirements. AV output worked fine under TV4 tvOS v9.0 and v9.0.1 until the engineers removed the ability to pass generic DD and DD+ bitstreams through to the downstream device. This is my only major complaint at this time as far as TV4 reduced capabilities are concerned.

Set Audio Loud Noises to On (Loud) - Now I can hear the Cannonball bounce across the prairie in Patriot and U2 belt out In the Name of Love.

The dynamic range issue is actually a separate problem. I always encode my AC-3 content with a full dynamic range (-31 db) setting for my listening and switch to ALC when my wife decides to join me in viewing something. I.e., she prefers a -27 db (common home theater) setting which I pre-programm into my AVR for those occasions when she complains about my "listening habits." The ability to disable the encoded Dial Normalization setting locally or globally is new to the TV4 device whereas older TV units appear to have simply passed the DialNorm setting through to the user's downstream device for handling. (So, for me, this is less of an issue than the inability of my receiver to automatically decode active matrix encoded AC-3 bitstream content that is no longer being passed to my AVR as an AC-3 bitstream.)

Very informative all the different formats and encodings that need to be supported and surprised to hear the number of issues going directly HDMI into very powerful AV Equipment

As previously indicated, I'm hoping the current absence of passthrough support in tvOS v9.1 "Auto" and "Dolby Surround" modes is merely a prelude to future support of other possible compression formats. However, until full Dolby bitstream passthrough support is restored, I will continue to lament its loss. I see no reason why the previously proven bitstream mode option cannot be restored as a fully supported but separate output option allowing the TV4 to function in the same manner as TV2 and TV3 devices and how the TV4 might have worked under tvOS v9.0 or v9.0.1 if bitstreams were passed to downstream devices directly—without any preprocessing—and thus, not forcing users to find processing workarounds for content normally played properly by downstream devices alone and on their own without being modified by the TV4.

Totally agree with your comments Jon. Previous movies which played fine in 5.1 on the ATV3 now only give stereo or mock surround sound whatever I choose, whether it be Auto or DS setting. Others seem to pump through PCM automatically which is fine by me. I was suprised yesterday , testing some new Polk speakers I receiv3ed, that the previously fine versions of Lord Of The Rings merely gave me Stereo and I know for sure they are 5.1

***4CT wrote:

Had the same issue with a Marantz - purchased and KanexPro Audio De-Embedder mimicking the ATV3 setup (HDMI --> Pioneer (TV) and SPDIF Optical --> Marantz (AV Surround). This coupled with setting ATV4 to Dolby Digital solved most of my issues. Very frustrating experience. Thank you PWNELL for all your insight. BTW - You will need an additional HDMI Cable to connect ATV4 --> De-Embedder (splitter).

Happy New Year 2016

first - (and I just learned this) hit the "quote" button at the top of the reply box before you start typing your reply. 😉

I am not sure how your down stream cable configuration would change anything here. At the end of the day, the same digital audio signal (however processed) is passing along either ATV>HDMI>AVR or, in your case ATV>HDMI>(split audio to)Optical>AVR. In both cases, the same signal (assuming it is of lower resolution that can be handled by the optical - see below) is hitting your AVR, and the ATV only "sees" an HDMI output.

HDMI and Optical are both capable of DD multi channel audio. HDMI is capable of higher resolution digital audio (i.e. uncompressed 5.1 or 7.1 - Dolby TrueHD, DTS-MA etc). But, if you are limiting your source material to compressed 7.1 or standard DD5.1, you should be indifferent and the actions of the ATV or your AVR should in no way be impacted by the two different digital pathways described here.

Speakers are not 5.1, only their amplification is multi channel. There is no such thing as a 5 channel speaker.

meegwell wrote:

if you are limiting your source material to compressed 7.1 or standard DD5.1, you should be indifferent and the actions of the ATV or your AVR should in no way be impacted by the two different digital pathways described here.

Consumer optical (S/PDIF) is limited to AC-3 (5.1). E-AC-3 (7.1) has to be down-sampled.

bodosom wrote:

meegwell wrote:

if you are limiting your source material to compressed 7.1 or standard DD5.1, you should be indifferent and the actions of the ATV or your AVR should in no way be impacted by the two different digital pathways described here.

Consumer optical (S/PDIF) is limited to AC-3 (5.1). E-AC-3 (7.1) has to be down-sampled.

thanks bodosom - I was writing 'off the cuff'...I think I swapped "compressed" for "down-sampled". To be clear, standard DD5.1 = AC-3 (5.1)...correct?

And while I'm writing about this issue for the God-knows-how-many-times between threads here and threads at AV forums....

PLEASE anyone with a surround issue on ATV4 make a formal communication with Apple (email, chat, call). Tell them you want the option to just pass through the bit-stream and let your AV equipment handle surround decoding! At a minimum, tell them its not working correctly.