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Old 29th March 2012, 13:19   #1  |  Link
Compass
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Bd Rebuilder- 1 Hd + 1 AC3 Audio track For BD25 Rip, Is It Possible?

Hi, As the title asks, is it possible to do a BD25 movie only with 1 Hd Audio track(whatever it happens to be) + 1 AC3(5.1)? Is there a setting I can tweak?

At present, after re-encoding to BD25, I demux(using tsMuxer) the HD audio track, covert it to an AC3(5.1) then remux it all back together again so I end up with both a HD and AC3 track.

Have done a search but couldn't find an answer.

Thanks
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Old 29th March 2012, 13:49   #2  |  Link
RobertM
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If the original stream already contains both HD and AC3 tracks then it should simply be a matter of selecting which tracks you want to keep on the "stream" tab. But, if there is only an HD track then I don't think BDRB can both keep the original and simultaneously re-encode it to AC3.

It probably wouldn't be difficult to add that feature, if JDobbs felt like doing it. But, having heard his opinion before regarding HD audio (an opinion that I agree with), it is unlikely that he would encourage such a waste of bits - creating 2 sonically identical tracks while robbing valuable space from the video encode. Just my opinion.
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Old 29th March 2012, 15:12   #3  |  Link
Compass
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Thank Robert, I thought as much, but dont ask, dont get. Most DTS/AC3 tracks are imbedded in the HD track in my experience. The tracks that are seperate are usually commentary etc which I dont care for.



Edit, out of interest, what are your and Mr Dobbs thoughts on HD audio?
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Old 29th March 2012, 18:34   #4  |  Link
RobertM
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Originally Posted by Compass View Post
Edit, out of interest, what are your and Mr Dobbs thoughts on HD audio?
Basically that HD Audio sounds good in theory, but it sounds the same in practice. There have been tests to evaluate whether people could hear the difference, and the results are generally negative. Maybe the most golden-eared of the audiophile set can hear a difference, but I KNOW that I can't. The difference, if it exists, is really subtle.

All else being equal, I would pick HD myself, even though I can't hear the difference, simply because there is no compression so the sound should be technically the best. On a BD-50, where there is a lot of room this might make sense. But on a BD-25 there usually isn't enough room for HD-Audio and the original video, without compressing the video further. I won't trade video quality reduction for an audio "improvement" that I can't hear. Just my opinion.

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Bob
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Old 31st March 2012, 18:08   #5  |  Link
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Basically that HD Audio sounds good in theory, but it sounds the same in practice. There have been tests to evaluate whether people could hear the difference, and the results are generally negative. Maybe the most golden-eared of the audiophile set can hear a difference, but I KNOW that I can't. The difference, if it exists, is really subtle.

All else being equal, I would pick HD myself, even though I can't hear the difference, simply because there is no compression so the sound should be technically the best. On a BD-50, where there is a lot of room this might make sense. But on a BD-25 there usually isn't enough room for HD-Audio and the original video, without compressing the video further. I won't trade video quality reduction for an audio "improvement" that I can't hear. Just my opinion.

Regards,
Bob
In the double-blind tests (which is the only reliable method) no one could distinguish HD from DD 640Kbs when using identical sources. That's according to Dolby's (the developers of True-HD) own testing (google should find it). Interestingly, though, in other tests if the amplitude is "finagled" as sometimes seems to happen in HD, people are fooled into selecting the source with the higher amplitude -- even if it is the non-HD (compressed) source. The term "smoke and mirrors" comes to mind.
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Old 31st March 2012, 22:48   #6  |  Link
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The improvement in sound reproduction (or lack of) related to using lossless audio codecs has been debated numerous times in numerous places. The best description I have to offer based on personal experience (including some testing between lossy tracks vs. lossless tracks on identical titles - although NOT double-blind) goes something like this:

Lossless audio codecs have the ability to provide improved audio quality. However, it is more a subtle improvement in detail and surely not an earth shattering or amazing improvement and greatly depends on the quality of the source material and mastering process. And the differences probably are not very noticeable at all unless being played and compared using high end audio reproduction equipment.

Personally, I opt for dropping menus & extras in favor of keeping the best possible video and audio quality possible when making a backup of one of my titles. I find that I can keep the main movie + the lossless audio on a BD25 just fine, thanks to BD-RB's highest quality settings.
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Old 1st April 2012, 01:22   #7  |  Link
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Interestingly, though, in other tests if the amplitude is "finagled" as sometimes seems to happen in HD, people are fooled into selecting the source with the higher amplitude -- even if it is the non-HD (compressed) source. The term "smoke and mirrors" comes to mind.
I have been noticing that recently, making me wonder if the HD tracks are actually a poorer representation of the original audio. Similar to issues with video DNR & EE
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Old 1st April 2012, 17:31   #8  |  Link
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I agree for the most part. Any audio improvement is slight. I like the HD audio on BD25 encodes. I for one believe I can hear some improvement on a few sound tracks but not most. I bet many and nearly all old movies were just up converted to 24bit uncompressed.

As far as the video goes this program does a spectacular job. I am unable to see any degrading from compressing a BD50 disc down to BD25 while keeping HD audio. I’ll even state it’s very hard to spot a defect in a 90 min, movie only, 448 audio to BD 5 disc. Anything close to 2 hours I use BD 9 and 640 audio.
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Old 3rd April 2012, 00:58   #9  |  Link
Compass
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Thanks for the replies, the reason I asked is because of a few limitations to my set-up. I rip to BD25 then stream from my unRaid server to a PS3 using PS3MediaServer. The PS3 wont do HD audio from a streamed source. My reciever/amp hasn't got HDMI, it's a Pioneer VSX-2011(http://www.pioneer.eu/uk/products/ar...1-S/index.html) an old one yes, but still very good.


Like most of you have mentioned, most titles there is very little if any difference in the sound I can hear, Avatar would be the title I can hear the biggest difference, maybe a few others. I just want/like to have options, I'm sure I wont have a PS3 and the amp forever.


Thanks again
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Old 3rd April 2012, 01:33   #10  |  Link
RobertM
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Avatar would be the title I can hear the biggest difference
Just remember that you may not be hearing what you think you are hearing. If the HD audio tracks are just a touch louder than the AC3 tracks then they will, indeed, sound better -- more detail, clarity, etc., -- but only because it is louder. You can hear more in a louder track, but if you turned up the AC3 tracks a bit they would sound better too.

It was a standard trick when selling hi-fi stereo equipment that you would set the volume slightly louder on the equipment that you wanted to push. Not so loud that the customer would notice an obvious amplitude difference, but enough so that some extra detail was noticeable. All else being equal, the customer would prefer the louder demonstration, because it had more detail that could be perceived, even if the overall sound was actually worse.

That is why proper tests are more difficult to set up. The amplitudes of the compared tracks must be matched exactly, so that this phenomenon can be eliminated as a variable.

So, while you may believe that the HD tracks sound better on a few discs, they may be, in actuality, just a little louder. Or maybe you just have fantastic ears, or are 9 years old,...

But, in the end, whatever floats your boat! If you believe that keeping the HD audio yields a better disc then, by all means, keep doing it. You're only making these backups for yourself, so you are the only one that has to be happy.
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