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AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 2:15 am
by realeyz
I've been using Playback (DLNA server) to convert MKV files with 5.1 AC3 to MP4 and every time I do it the audio downsamples to 2 channel AAC. The good folks at Yazsoft said that Perian is responsible for the conversion process, they just provide the interface. I can't figure out why this is happening as they claim to be successfully converting these files with AC3 5.1. Is there a way to troubleshoot this? A fix perhaps?

Using OSX 10.6.8
Perian 1.2.3
Playback 1.8.2

Regards :grin:

Re: AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 1:04 pm
by gbooker
Ask them about it; they are responsible. It is their code that's requesting the conversion. If they were doing a stream copy, Perian wouldn't enter into the picture at all.

Re: AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 3:32 pm
by realeyz
gbooker wrote:Ask them about it; they are responsible. It is their code that's requesting the conversion. If they were doing a stream copy, Perian wouldn't enter into the picture at all.


Already did - here's there response:

"Note that the actual conversion is performed by Perian and not Playback directly. We don't control the details of the process."

:\

Re: AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 5:29 pm
by gbooker
realeyz wrote:We don't control the details of the process.

They do control what conversion is done. It sounds like you are wanting a stream passthrough for audio (5.1 AC3 -> 5.1 AC3). If their software is capable of doing this, it will not use Perian for anything in that process. If they insist that Perian is used in that passthrough, then they don't know what they are talking about.

Again:
gbooker wrote:If they were doing a stream copy, Perian wouldn't enter into the picture at all.


Regardless of what they say, Perian is not at issue here; so you need to talk with them. They are using Perian to convert from 5.1 AC3 -> PCM, and then from PCM -> AAC (this step is not in Perian). Perian is doing exactly what it is told here, so you if your complaint is that it is downsampled to 2 channel AAC, Perian is only enabling this because Playback told it to do so. So again:
gbooker wrote:Ask them about it; they are responsible.

Re: AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 7:43 pm
by realeyz
So you're saying Perian converts the audio, but not the container?

Since their software is (at least currently) incapable of converting MKV to MP4 containers without passing through the AC3 audio, do you know of software that does this?

Thanx

Re: AC3 5.1 downsampled to AAC 2CH

Posted: Thu Sep 15, 2011 8:44 pm
by gbooker
realeyz wrote:So you're saying Perian converts the audio, but not the container?

It decodes audio and reads containers. They are using the rest of the QT architecture to do the conversion (or possibly doing it themselves using Perian to read/decode)

realeyz wrote:Since their software is (at least currently) incapable of converting MKV to MP4 containers without passing through the AC3 audio, do you know of software that does this?

I didn't say that it's incapable, just that if it were to do so it shouldn't be using Perian for any audio conversion.

Try Handbrake. It's not streaming on demand, but it'll create MP4s with AAC audio, AC3 audio, or my favorite, both.