A Guide to Home Theater Audio CODECs

[bmcelvan]

Hi a question for you all - Copying Blurays to 25GB discs. Given the limited space issue, entire HD audio Blurays won't fit. So...with that said, would you keep a higher fidelity of video and copy a non HD audio (AC-3 or DTS) or keep the HD Audio and have a slightly less bitrate for the video.

Example: Movie with DTS-HD Master Audio: 29.636GB-->23.307GB (video bitrate re-encoded at 22227 kbps) whereas if I remove the HD Audio it's 27.233GB-->23.307GB with a video re-encode bitrate of (25025).

Another way of asking the question is what is the lowest video bitrate that you deem acceptable - is the HD Audio really that worth it or is AC-3 or DTS good enough as compared to the video improvements.

Lastly, sorry if this is the wrong thread to post this - can someone send me to the correct thread if necessary

[ramicio]

It's your project and it's up for you to decide what is acceptable.

[bmcelvan]

If you personally watch (listen) to a bluray in DTS Master Audio then re-listen to the same scene or movie in DTS, can you really notice a HUGE difference. Or is it mainly some or the high highs are missing.

I have an okay A/V receiver and 5.1 channel speaker setup but plan on upgrading in the future...so I'm not sure I can do a proper test at this time since everything that I've read says that if you don't have a top end A/V system and especially speakers, the HD audio is rather meaningless anyway because you won't hear a difference. For movies that I'm backing up now, regular DTS is certainly fine given my system but I just wanted them to be "good" for when I upgrade next month/year or whenever it is.

thx

[Captainhawk1]

Originally Posted by bmcelvan

Hi a question for you all - Copying Blurays to 25GB discs. Given the limited space issue, entire HD audio Blurays won't fit. So...with that said, would you keep a higher fidelity of video and copy a non HD audio (AC-3 or DTS) or keep the HD Audio and have a slightly less bitrate for the video.

Example: Movie with DTS-HD Master Audio: 29.636GB-->23.307GB (video bitrate re-encoded at 22227 kbps) whereas if I remove the HD Audio it's 27.233GB-->23.307GB with a video re-encode bitrate of (25025).

Another way of asking the question is what is the lowest video bitrate that you deem acceptable - is the HD Audio really that worth it or is AC-3 or DTS good enough as compared to the video improvements.

Lastly, sorry if this is the wrong thread to post this - can someone send me to the correct thread if necessary

It's only worth it if you have the equipment to support it. If you do, you can use one of the many pieces of software out there to shrink the content to fit on a SL BD-R. Since I assume you're talking about converting the main movie of a BD only, you won't lose any audio quality of the DTS-HD MA track and any video lost will be completely imperceptible. That's about at 80% so you'd be fine.

If you're talking about doing a straight-up clone of an entire disc, that seems kind of pointless unless the disc has a whole bunch of SF on it which at 29.636 seems unlikely.

[Captainhawk1]

Originally Posted by bmcelvan

If you personally watch (listen) to a bluray in DTS Master Audio then re-listen to the same scene or movie in DTS, can you really notice a HUGE difference. Or is it mainly some or the high highs are missing.

I have an okay A/V receiver and 5.1 channel speaker setup but plan on upgrading in the future...so I'm not sure I can do a proper test at this time since everything that I've read says that if you don't have a top end A/V system and especially speakers, the HD audio is rather meaningless anyway because you won't hear a difference. For movies that I'm backing up now, regular DTS is certainly fine given my system but I just wanted them to be "good" for when I upgrade next month/year or whenever it is.

thx

This isn't accurate. If you have the equipment to support it, you DEFINITELY will notice the difference and that's across the board., regardless of whether it's the same content. I can immediately tell when I have a DTS HD-MA/Dolby TrueHD track on my receiver as opposed to a standard 5.1 track without even looking at the receiver or the BD.

You say you have an "OK 5.1 channel receiver." What exactly does that mean? How old is it? Make/Model? Does it support the HD audio formats?

[bmcelvan]

Thanks for your input - Yes burning a BD-R single layer disc 25GB with main movie only. I just got my setup at costco a few months ago for what I perceived to be pretty cheap but am finding out I think was just a really good deal...Yamaha HTR-4065 (Which is the same thing as RX-V473) for around $279 and jbl cinema 500 5.1 speaker setup for $199.99. It fully supports the HD audio codecs and just about everything else I can think of.

So in your opinion, the lossless higher fidelity sound codecs sound much much better as compared to the lossy compressed versions to the point where they are a must have (when only using up an extra 1.5-3GB of space out of the 23.3GB) whereas the video only losing about 10-20% of bitrate won't be a noticeable factor at all?

One last question...is there a video bitrate you wouldn't go below? Say for example you have a long movie on a single disc, like The Return Of The King Disc 2 which is 139 minutes and 35.5GB (The DTS-HD Master audio is 4.9 GB whereas the AC-3/5.1 is only 470MB and the DTS is 1.56GB). That is a little more significant, the video will only be 60% of what it started with HD audio versus 75% of what it started with dolby digital (AC-3). Or is it still worth it to you anyway to have the best sound possible as the video on these discs are so good to begin with that you can compress them a lot?

(On a side note, even though DTS has a higher bitrate, any preference between AC-3 and DTS). I've been told Dolby's compression algorithm is just that much better so their 640kbps sound just as good as DTS 1.5Mbps).

[bmcelvan]

Originally Posted by Captainhawk1

Just to make a point here: under normal circumstances is it even worth an argument? A BD normally has either a DTS HD-MA or a Dolby TrueHD track, not both. So there's no point of reference. The only way you could make qualitative judgment is if you were comparing the same source material. That's why asked about the Close Encounters BD because it's an oddity and you certainly can't proclaim one codec better than the other based on one BD.

Am I missing something, here?

On a PC can you decode either True-HD or DTMA to PCM and then reencode to the other and then compare any bluray soundtrack. Anyone have time and want to do this? There has to be encoding software out there. I have a 9 month old currently and therefore don't have enough time right now But apparently I have enough time to write these three post of late!

[Captainhawk1]

Originally Posted by bmcelvan

Thanks for your input - Yes burning a BD-R single layer disc 25GB with main movie only. I just got my setup at costco a few months ago for what I perceived to be pretty cheap but am finding out I think was just a really good deal...Yamaha HTR-4065 (Which is the same thing as RX-V473) for around $279 and jbl cinema 500 5.1 speaker setup for $199.99. It fully supports the HD audio codecs and just about everything else I can think of.

Dumb question but you are using HDMI for both your video and audio, right?

So in your opinion, the lossless higher fidelity sound codecs sound much much better as compared to the lossy compressed versions...

To the point where they give me a nerd-boner, they sound so good.

to the point where they are a must have (when only using up an extra 1.5-3GB of space out of the 23.3GB) whereas the video only losing about 10-20% of bitrate won't be a noticeable factor at all?

I'm completely comfortable at 30% and I haven't been able to see a difference, however...

One last question...is there a video bitrate you wouldn't go below? Say for example you have a long movie on a single disc, like The Return Of The King Disc 2 which is 139 minutes and 35.5GB (The DTS-HD Master audio is 4.9 GB whereas the AC-3/5.1 is only 470MB and the DTS is 1.56GB). That is a little more significant, the video will only be 60% of what it started with HD audio versus 75% of what it started with dolby digital (AC-3). Or is it still worth it to you anyway to have the best sound possible as the video on these discs are so good to begin with that you can compress them a lot?

...there, my friend is the million dollar question and why I keep a spool of cheap BD-R's handy so can experiment when it's iffy. It really depends on the source BD is the only honest answer I can give. Fer instance... I compressed the Star Wars Saga (all six films) down to a rate of between 65% and 68% and they looked great... couldn't tell the difference and neither could my cheap-ass cousin who I made them for. However, I banged out a Dr. Who Christmas Special BD at 80% and it was choppy.

(On a side note, even though DTS has a higher bitrate, any preference between AC-3 and DTS). I've been told Dolby's compression algorithm is just that much better so their 640kbps sound just as good as DTS 1.5Mbps).

To me, compressed 5.1 sounds all the same and yes, I have tried to listen to the difference between the two.

Originally Posted by bmcelvan

On a PC can you decode either True-HD or DTMA to PCM and then reencode to the other and then compare any bluray soundtrack. Anyone have time and want to do this? There has to be encoding software out there. I have a 9 month old currently and therefore don't have enough time right now But apparently I have enough time to write these three post of late!

That's a helluva interesting question but I will say that if you notice, a page back I asked a question about the quality difference between DTS-HD MA and Dolby TrueHD because of the fact that Close Encounters of the Third Kind offers both and it was the first time I'd come across a BD that had both. That was last summer and I will tell you that I have since listened to both the Dolby TrueHD and DTS-HD MA and bounced between the two codecs and I can't really tell a difference and when I can I'm not sure if it's just because I'm listening for one or not.

Mind me asking, but what software are you using? Sounds like you're getting yourself into a lot of the technical nitty-gritty that I don't bother with much because mine just does it automatically. Feel free to PM me as we've kinda hijacked this thread talking about the best ways to copy commercial discs and I'm not sure how they feel about that around here if you know what I mean.