Dolby AC3 @ 640K Too Much for Blu-ray?

[BassPig]

I burned a Blu-ray disc last night from Adobe Encore CS3.
The video was encoded in Adobe Media Encoder from Premiere.
The AC3 5-channel surround was encoded by Scenarist's AC3 encoder.
I wanted to maximize quality of the encode, so I chose the highest (640K) bitrate.
However, when the disc plays, only the front channels play. The rear left channel is way down in levels and the right rear channel is silent.
I checked my Sony BDP-S301 by playing a DVD that I encoded with 5-ch surround last month and all surround channels work with that disc (448Kbps).

In the past, I've tried higher bitrates for DVD and wound up with unplayable discs, but I thought Blu-ray would have surpassed those limits, and after all, why would the encoder offer 640K as an option?

What does the Blu-ray spec say about AC3 audio? Does it not support rates above 640K?

I'm certain that all tracks fed to the encoder had audio at proper levels. So, I'm puzzled as to why it changed the levels on the rear channels to some 10dB below normal and some infinite dB below normal for the right.

Did Encore fudge it all, or was it the bitrate causing this weirdness?

[ACrowley]

Dolby Digital AC3 maximum Bitrate is 640Kbps..not higher

And BluRay support it as you can see on a lot of Blurays

[BassPig]

Hmmm.. then if the AC3 stream is legal bitrate, why are the rear channels partially missing? All source channels had audio when they were encoded. The resulting BD had front channels normal, a weak Left surround, and no Right surround. Very strange. That's never happened on DVD surround projects, and I've authored many of those.

[SeeMoreDigital]

Here you go: -

http://i29.tinypic.com/iyhrox.png

[BassPig]

Thanks for the chart with supported bitrates.

So 640K is fine. Then it must be something wrong with either the player, or Encore. Adobe tells me that Encore just passes through any pre-encoded AC3 and doesn't alter it in any way.

That leaves one other possibility: Scenarist's AC3 encoder possibly producing a garbage file when any higher bitrate than 448 is chosen. Either that, or my Sony DBP-S301 player doesn't like either the bitrate, or the fact that there's no LFE channel in the stream.

Very odd that the Left Surround is very low in loudness, and the Right Surround is silent. It's almost as if the missing LFE caused the other channels to 'slide over one place', leaving the right surround with inaudible audio.

It's puzzling.

I'm re encoding at 448kbps because it's the only bitrate that seems to produce playable BD-R at the moment.

Is there a utility that can look inside my AC3 files to see if they contain valid audio on ALL tracks? Maybe I've tripped on a bug in the AC3 encoder here...

[setarip_old]

@BassPig

Hi!

Have you tried playing the .AC3 file BEFORE muxing it?

[BassPig]

The editing workstation isn't set up to play more than two front channels. A utility that can display waveform data in each channel would be a good way to see if Scenarist's encoder is simply blanking out at 640kbps, or if something downstream is not playing the right surround.

In the meantime, after a 7-hour burn with Encore DVD CS3, I made a new BD-R with 448kbps AC3 and it plays all tracks happily and at the proper level. So the problem only exists for higher data rates of AC3 files. Not sure if it's my Sony BDP-S301 player, or if Scenarist has a bug in their AC3 encoder.

[setarip_old]

Try installing the "AC3 Filter" - Bar graphs instead of waveforms of both input and output...