movies with 5.1 surround : is it possible

Hi Jask,

I have burned nearly 20 DVDs using HandBrake and/or Mac The Ripper since buying both of my ATVs. In HandBrake I select the 5.1 surround audio track. A typical 1.5/2 hour feature is about 2GB in size.

After syncing with my ATV, I ran a TosLink cable from the optical audio out on the ATV to my Sony surround sound amplifier. When I play the movie, the surround sound amplifier detects 5.1 sound. I have only gotten 5.1 sound when using the optical out on the ATV.

Just to make sure I wasn't crazy I burned the same test movie and used the 'other' audio track on the DVD. When played the surround sound amplifier did not detect 5.1 surround.

PS - My test movie was Star Wars IV - the sound is great!!

Hope this helps.

Gary


MacBook Pro Mac OS X (10.4.9) I love my Apple TV

Digital audio is merely passed through the tv, it all depends on whether the receiving device can play 5.1 AC3 or not. Quicktime itself does not support AC3 but it does support 6 channel AAC, however being a more modern audio codec not all receivers will play AAC.

The fact that it is coming out of five speakers does not make it surround sound!

My AV processor will convert ANY signal and make it into 5.1 most any AV processor will do this.

In my experience AppleTV is not giving a genuine surround sound signal, my AV processor has never picked up a 5.1 surround signal, its simply extrapolating data from stereo and making sudo surround sound.

If Apple TV was genuine 5.1 Apple would be advertising it from here to next Sunday, find your facts first! Dolby Pro Logic People! Its nuffin!

Excellent point Gary (nice name, btw). I just looked through the ATV specs, and you're right - I don't see a mention of it anywhere. Interesting!

Nice to know there are audiophiles out there in mac land keeping us honest. 🙂

oops slipped an extra AC3 in there.

Are you using an AC3 source, have you tried with with DTS or AAC, do you still get the same results.

FWIW, I'm unable to duplicate this. I tried converting a chapter of SW III using handbrake. I selected AC3 5.1 as the source track and Discrete 6 channel as the mix. As I expected, my reciever did not recognize what was coming across the TOSLINK as a 5.1 audio stream. I was a bit surpised that it played at all, but it did give me a stereo signal.

What bitrate did you use ?

What bitrate did you use ?

I just left it at the default for the appleTV preset.

I think one of the previous posters (Gary?) nailed this. It depends on your receiver. I plugged my ATV into my upstairs surround amp via toslink and no "5.1 signal" was detected, just stereo sound.

I wonder what the next Apple TV software will have in store for us besides YouTube?

The apple preset sets audio to DPR, if you adjust the preset for 6 channel audio I think the bitrate alters to 384 which is outside apples specs for the tv.

Hi Gary, which HandBrake setting have you used? Actually I have ripped almost 10 of my DVDs all with AppleTV preset and 6ch audio settings. Only with a Disney movie I had to select Dolby Surround otherwise the result was a mute movie but, anyway, once I reproduce my movies via ATV+Home theatre amp (a not so new Pioneer HTZ-7) connected with TOS link there is only stereo sound... Forcing 5.1 audio will results into a 5+1 speakers working but without surround...
Have you any suggestions?
Many thanks and best regards,
Fabio

I think Winston has pointed out the key...

You can convert 5.1 AC3 or Dolby Digital surround sound to 6 channel AAC via Handbrake. The analog audio bitstream will of course be a stereo downmix, allowing ProLogic at best. The digital output will output bitstream if enabled in the settings - but it will not be AC3 Dolby Digital, it will be 6 channel AAC. Not all surround receivers can decode the AAC codec, even if they can decode AC3. The receivers that use the more modern Cirrus Logic CS49xxx decoder chips in their processing are capable of decoding AAC, but older surround receivers, even if they were high end models, will not be able to.

One might wonder why the Apple TV does not output AC3... I believe that it has to do with the processing power that would be required to recompile a 6 channel AAC source back to AC3 and even if technically feasible, would require licensing from Dolby Labs in order to allow it to do it, potentially making the box very expensive.

The TV, and iPhone, and FrontRow all use QuickTime to play videos. QuickTime has poor to no support for both surround sound and subtitles, hence TV etc. equally have poor to no support for this. A third area that QuickTime is also useless at is supporting multiple alternate audio streams (e.g. different languages or a commentary track). DivX and Xvid for example can cope with all of this (but are not supported by the TV and iPhone), and in any case, the QuickTime player even with DivX files does not give access to these facilities (VLC does).

Yes, an MPEG4 H.264 video with 6 channels of AAC sound in theory will give you a 5.1 surround sound output (via the optical out), but as previously mentioned very, very few AV receivers support 5.1 AAC (and this is unlikely to change).

Because QuickTime is frankly currently useless at this, there is no point Apple providing surround sound movies on the iTunes Store (indeed other than using 5.1 AAC it would be impossible for them to do). Also as I indicated, subtitles support is equally dismal in QuickTime.

Note: According to the Apple website Mac OS X 10.5 will still only come with QuickTime 7.2 (the current version) so it will be no better.

For FrontRow there is a new avenue that could be explored. It has been confirmed that FrontRow 2 as will be included in Mac OS X 10.5 does support playing VIDEO_TS folders. As these are full copies of the DVD and are not being played using QuickTime (they are played using the DVD Framework used by the DVD Player) they will play proper AC3 or DTS 5.1 sound tracks which when output via the optical port on a Mac will be recognised by your AV receiver.

Therefore a ludicrous but possible option would be to convert 5.1 channel video files back to VIDEO_TS (DVD) format.

Note: This will only work for FrontRow 2 on Mac OS X 10.5. We will have to wait and see if Apple (ever) add the option to the TV to play VIDEO_TS folders (or wait even longer and see if Apple ever fix these major inadequacies in QuickTime).

PS. Even Windows Media Player is better at surround sound support and subtitles support than QuickTime!

PPS. Of course all the above could also be construed as suggesting that a Mac mini will be a far better choice than an TV (even if it costs twice as much). Here's hoping that Apple do not discontinue the Mac mini or better still replace it with something better.

I'm pretty certain AppleTV does one of the following with audio:

- converts a known supported codec (WAV/AIFF/AAC/MP3 etc), to PCM to output via the optical digital link

- in some circumstances outputs a 'raw bitstream' which an AV amp will recognise as either Dolby Digital (2 or 5.1 channel) or DTS

I'm also pretty certain that it does not output the 'raw bistream' for the other formats above as most AV amps will not know how to decode them - hence it converts to a generic PCM 2 channel bitstream which most amps recognise.

My Yamaha processor only handles PCM/Dobly digital/DTS. It has no support for raw mp3/AAC bitstreams but plays back via optical as these formats are decoded by AppleTV and output to optical as standard PCM bitstreams.

If AppleTV recognises a format it will do the conversion to PCM - if not it may in certain circumstance just passthrough the raw bitstream, so getting it to do that is the trick to AC3/DTS playback.

See:

http://web.mac.com/ragboy/iWeb/TheGarcias/Dad's%20Blog/9E500240-D005-499D-9E44-74B50E96FE4E.html

AC

Gary I wrote:

"My AV processor will convert ANY signal and make it into 5.1 most any AV processor will do this.

In my experience AppleTV is not giving a genuine surround sound signal, my AV processor has never picked up a 5.1 surround signal, its simply extrapolating data from stereo and making sudo surround sound."

Gary - you are quite correct that most AV amps/processors can simulate 5.1 surround from a stereo analogue or digital input, generally using Dolby Pro Logic or a variant thereof.

Officially AppleTV does not support 5.1 surround, but there are example audio files out there with a 'raw' AC3 or DTS bitstream that AppleTV does not decode to a 2 channel digital PCM bistream, but rather passes through without any alteration - in this manner you can play 5.1 surround.

My processor will identify the incoming bitstream - if I get no DTS/Dolby Digital logo coming up it is receiving a 2 channel PCM bitstream and will offer various Pro Logic type surround modes or basic stereo. It will correctly flag up Dolby digital/DTS 5.1 bitstreams and gives additional surround processing options for the 5.1 signal input. It is not in these cases simply doing a 'Pro Logic' pseudo-surround job.

AC