AC3 sound and 5.1 surround problem

Hello everybody, I am an happy user of AppleTv and aTV Flash too and I am new to this forum :wink:

I have some questions/problems with AC3 sound on my AppleTV, I’ll try to explain better:
My AppleTv is connected to a surround system with an optical cable and to a Plasma TV with HDMI cable.
When AppleTV starts there is a video presentation (original from Apple) in AC3 that play in 5.1 mode.
After applying the aTv Flash on my AppleTV the AC3 sound disappear? the presentation video play without audio sound at all??? is it normal?
When i try to play a DivX or Xvid with AC3 sound… it play only in stereo mode???

I have checked all the option (in Mplayer and in AppleTv setting…) and all options are with AC3 enabled?

If I restore AppleTv (removing aTV Flash software) the AC3 sound come back… but I’m not able to play Divx :wink:

Could you please give me any suggestion?

Thanks in advance

The intro sound missing on 4.1 is a known issue, and has to do with an update of Perian in 4.1.

OK, the intro missing sound is known… but the missing AC3 sound with the other file (es. .avi .mkw ecc…)

All the files that have AC3 (5.1 surround) sound play only in stereo mode!
I tried with Boxee and XBMC too but the problem persists :frowning:

Is there any solution???

Which menu are you using to play the files? You may try toggling the ‘AC3 Passthrough’ option through the menu you are using to play the files.

I tried ALL the menu… NitoTV, ATV File, Sapphire, XBMC and Boxee

With NitoTV, ATV File and Sapphire the sound output is in stereo… with XBMC and Boxee the decoder “see” the source in Dolby surround 5.1 but no sound is reproduced by the speaker :frowning:

I have setup in ALL the menu “AC3 Passtrought and Dolby Digital ON” Mplayer, DVD, Manteinance and Apple original setting from Audio-Video menu.

Nothing appened…

What type of audio connection are you using on the AppleTV (HDMI, RCA, optical)? Is the AppleTV connected directly to your AV receiver?

The Apple TV is connected with HDMI to my plasmaTV Sony, and with optical cable to my AV Surround Amplifier Sony
When a file is played with NitoTv (Mplayer with AC3 ON) my AV Decoder say that audio is " PCM 44.1Khz"…

If i try to play the file with Boxee or XBMC (with AC3 option ON)… the AV Amplifier say that audio is Dolby Digital 5.1… but no sound came out from the speaker :frowning:

OK, please tell me if all the option are setup in the right way:

  • Apple TV (Firmware 3.02… aTVFlash 4.1) connected with Optical Cable to AV reciver (5.1 discrete speaker)

  • Plasma TV connected with HDMI to AppleTV

  • AC3 passtrough ENABLED

  • Mplayer Dolby Digital ON

  • File .avi with AC3 audio [file tested on a DVD recorder and the audio is for sure 5.1 ;-)]

  • Wich player do you suggest? NitoTV, Sapphire… or what


Where you able to resolve this issue? I am having th same issue when playing MKV files. Can see the video but no audio plays through my receiver connected with an optical cable to my ATV. If I use my TVs sound connected with HDMI the sound is fine. what can be the problem that through my receiver the sound is not working?

Hi - I think this may be a problem with your cabling set up not ATVFlash (I could be wrong as I am not an expert). If you are running the HDMI cable directly from your ATV to your TV then I believe all your video and sound will be carried directly to your TV. I think this is why you are getting sound from the TV but not the speakers attached to the receiver (even though you have connected an optical cable from ATV to your AVR).

You could try the following to diagnose if it is a cabling problem.

  1. Connect your HDMI cable directly from ATV to an HDMI input on your AV receiver. Then run another HDMI cable out from your receiver directly to your TV. This will at least test if the HDMI is carrying all the sound to your receivers. If you dont have an HDMI recevier or your HDMI cable is not long enough to connect yout AVR to your TV then try option 2
  2. Play your movie in your current set up but once it is playing disconnect your HDMI cable. You will loose picture and sound through the TV but it may force the sound through the optical cable instead and you may start hearing the sound through the AVR connected speakers. Alternatively remove the HDMI at the start and use an RGB component cable to connect just the video component to your TV. Leave the optical to your AVR to carry the sound to your receiver and speakers.

I hope once of these options at least helps diagnose if you have a cabling problem or not. I use the configuration in option 1 - works a treat.

Good Luck

Hi I tried your suggestions and I still have the problem. To give more details is not that I can hear the sound, the problem is that I hear a rattling sound coming form the receiver speakers.

This is one of the files I am trying to play.

Complete name : El secreto de sus ojos.mkv
Format : Matroska
File size : 4.37 GiB
Duration : 2h 9mn
Overall bit rate : 4 842 Kbps
Encoded date : UTC 2010-03-23 23:30:31
Writing application : mkvmerge v3.1.0 (‘Happy up here’) built on Jan 19 2010 12:09:24
Writing library : libebml v0.7.9 + libmatroska v0.8.1

ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Muxing mode : Container profile=Unknown@4.1
Duration : 2h 9mn
Bit rate : 4 105 Kbps
Nominal bit rate : 4 201 Kbps
Width : 1 280 pixels
Height : 544 pixels
Display aspect ratio : 2.35:1
Frame rate : 24.000 fps
Resolution : 8 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.246
Stream size : 3.71 GiB (85%)
Writing library : x264 core 88 r1471 1144615
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-2 / threads=12 / sliced_threads=0 / nr=0 / decimate=1 / mbaff=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / wpredb=1 / wpredp=2 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=4201 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00

ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Codec ID : A_AC3
Duration : 2h 9mn
Bit rate mode : Constant
Bit rate : 640 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Stream size : 592 MiB (13%)
Language : Spanish

ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Language : English

You may try toggling the ‘AC3 Passthrough’ option located in Maintenance --> Settings.

Max, I got it to work with AC3 passthrough but I don’t get Dobly Digital or DTS. Is there a way to get any of them?

The audio will be passed to the receiver unchanged…the file in the specs above contains only AC3 audio not DTS.


The audio will be passed to the receiver unchanged…the file in the specs above contains only AC3 audio not DTS.[/quote]

You are correct, it was my mistake. When I do he passthrough am only getting stereo in my reciver. What do you think could be the problem?

hello everybody…

I solved this way.

I restored ATV to original setup/firmware.
I did all the update and then applied the new ATVFlash 4.1.5…

Now I use NitoTV to play .avi files with MP3 sound and Boxee for files with 5.1 surround or DTS sound

Never turn ON pastrought AC3 on maintenance->setting menu… otherwise all the problems come back (starting video without sound… files without audio or heavy noise etc.)

p.s. now my ATV is linked to AV reciver only with HDMI Cable (no optical sound cable) and then HDMI cable from AV reciver to Plasma TV.

I hope this can help you :wink:


I know I'm coming into this as a relative newbie but I was able to get this to work using the latest version of boxee without having to make any changes to my set up.  I still have optical sound going from my atv to my receiver.  Has anyone else experienced this?


hi people, i have an issue playing any audio files. i can see them but then it says there is no content.


and i cant get 5.1 to play anywhere


any ideas