TrueHD vs. TrueHD - Is All TrueHD Created Equal?

[Ascended_Saiyan]

I've been observing this for quite some time, but just decided to write about it now. Sony and Warner Bros. have been putting tracks in Dolby TrueHD for a good amount of time. But, I noticed something of an audio difference awhile ago (Warner titles being a little muffled at times). And, quess what? Sony's bitrates are a lot higher than Warner Bros. for ALL 48kHz 16bit tracks. That begs the following question. Is all TrueHD created equal?

Of course, we know that heavy action scenes would naturally require higher bitrates. Let's take two movies (I Am Legend and Dogma) for example. They are both 48kHz 16-bit titles. I Am Legend PEAKS at around 3Mbps. Dogma PEAKS at around 5.2Mbps! I Am Legend usually hangs around 1.2Mbps for the most part. Dogma usually hangs around 3.7Mbps. It doesn't stop there. ALL audio matched TrueHD tracks will have much higher bitrates on Sony's titles.

Now, some people say that the machine that encodes audio as TrueHD uses what is needed to be lossless. This would suggest that the machine can be changed/adjusted. If that is true, the following question needs to be answered. Is Sony needlessly boosting the audio bitrates for no reason? OR, is Warner Bros. lowering the bitrates (or altering the audio before the TrueHD machine encodes it) to the point of being lossy to add TrueHD to HD DVD titles?

[Driver_King]

Sounds like Sony knows what they're doing and not so much Warner Bros.

[MOONPHASE]

its weird sometimes Warner will bring out a good Dolby TrueHD once in awhile

[Hunter]

First off, TrueHD is a mathematically lossless codec, once decoded it's bit for bit identical to the original PCM master so bit-rate means nothing.

Second you can't compare 2 different soundtracks and say since one sounds better or has a higher bit-rate then the other that the "TrueHD compression" was done better, it all depends on the original PCM master.

There is nothing to tweak when encoding to TrueHD.

[Ascended_Saiyan]

Originally Posted by Hunter

First off, TrueHD is a mathematically lossless codec, once decoded it's bit for bit identical to the original PCM master so bit-rate means nothing.

Second you can't compare 2 different soundtracks and say since one sounds better or has a higher bit-rate then the other that the "TrueHD compression" was done better, it all depends on the original PCM master.

There is nothing to tweak when encoding to TrueHD.

From your reply, I can only assume you didn't read through to the end before posting.

[MarekM]

Originally Posted by Ascended_Saiyan

I've been observing this for quite some time, but just decided to write about it now. Sony and Warner Bros. have been putting tracks in Dolby TrueHD for a good amount of time. But, I noticed something of an audio difference awhile ago (Warner titles being a little muffled at times). And, quess what? Sony's bitrates are a lot higher than Warner Bros. for ALL 48kHz 16bit tracks. That begs the following question. Is all TrueHD created equal?

Of course, we know that heavy action scenes would naturally require higher bitrates. Let's take two movies (I Am Legend and Dogma) for example. They are both 48kHz 16-bit titles. I Am Legend PEAKS at around 3Mbps. Dogma PEAKS at around 5.2Mbps! I Am Legend usually hangs around 1.2Mbps for the most part. Dogma usually hangs around 3.7Mbps. It doesn't stop there. ALL audio matched TrueHD tracks will have much higher bitrates on Sony's titles.

Now, some people say that the machine that encodes audio as TrueHD uses what is needed to be lossless. This would suggest that the machine can be changed/adjusted. If that is true, the following question needs to be answered. Is Sony needlessly boosting the audio bitrates for no reason? OR, is Warner Bros. lowering the bitrates (or altering the audio before the TrueHD machine encodes it) to the point of being lossy to add TrueHD to HD DVD titles?

with those parts bolded, I am sure Dogma is 24bit !!

Marek

[Ascended_Saiyan]

Originally Posted by MarekM

with those parts bolded, I am sure Dogma is 24bit !!

Marek

I hear you, but the review sites say 16-bit. Plus, that was ONE example. There is more than one instance of a large bitrate difference (following the guidelines of my post).

[Hunter]

Originally Posted by Ascended_Saiyan

From your reply, I can only assume you didn't read through to the end before posting.

Is Sony needlessly boosting the audio bitrates for no reason? OR, is Warner Bros. lowering the bitrates (or altering the audio before the TrueHD machine encodes it) to the point of being lossy to add TrueHD to HD DVD titles?

The answer is no, I said before, there is nothing to tweak, ie bit-rates, the TrueHD encoder handles the encoding automatically.

It could be that Sony is encoding their media at a higher sound level, but this should have nothing to do with bit-rates.

[Ascended_Saiyan]

Originally Posted by Hunter

The answer is no, I said before, there is nothing to tweak, ie bit-rates, the TrueHD encoder handles the encoding automatically.

I was hoping that you hadn't read through to the end and would still post what you posted. It seems that's not the case, though.

Pay CLOSE attention to the part in parenthesis.

[Hunter]

Most Warner TrueHD soundtracks are downrezed before encoding from 48/24 to 48/16 this would cause the TrueHD bit-rate to be lower; most Sony TrueHD soundtracks are 48/24 or 48/20.

Also Sony does not use "Dialnorm" whereas Warner does, this would effect the overall loudness being that the Sony soundtracks would sound louder at the same volume, but this doesn't effect the bit-rate.

[WickyWoo]

I've been observing this for quite some time, but just decided to write about it now. Sony and Warner Bros. have been putting tracks in Dolby TrueHD for a good amount of time. But, I noticed something of an audio difference awhile ago (Warner titles being a little muffled at times). And, quess what? Sony's bitrates are a lot higher than Warner Bros. for ALL 48kHz 16bit tracks. That begs the following question. Is all TrueHD created equal?

They all feed it into the same box. The bitrate of THD is wildly dependant on the material, as it's a VBR codec

I Am Legend is quiet for virtually all the movie for example.

Most Warner TrueHD soundtracks are downrezed before encoding from 48/24 to 48/16 this would cause the TrueHD bit-rate to be lower; most Sony TrueHD soundtracks are 48/24 or 48/20.

Remember also that 24bit mastering is a relatively new thing as well

[Slec]

Originally Posted by WickyWoo

They all feed it into the same box. The bitrate of THD is wildly dependant on the material, as it's a VBR codec

I Am Legend is quiet for virtually all the movie for example.

I was just about to type that!!!!! I think something like Unbreakable (for movie type) would be a better comparison to Dogma. Lots of dialog, and some sound fx....

[Ascended_Saiyan]

Originally Posted by WickyWoo

They all feed it into the same box. The bitrate of THD is wildly dependant on the material, as it's a VBR codec

I Am Legend is quiet for virtually all the movie for example.



Remember also that 24bit mastering is a relatively new thing as well

Justice League
The Brave One
The Invasion

Are all of those quiet films vs. Dogma? There's more than one example people.

[Slec]

Originally Posted by Ascended_Saiyan

Justice League
The Brave One
The Invasion

Are all of those quiet films vs. Dogma? There's more than one example people.

so make the comparison and provide the bitrates. We can only surmise based on the example you gave...

[Ascended_Saiyan]

Originally Posted by Slec

so make the comparison and provide the bitrates. We can only surmise based on the example you gave...

It's not about the one example I gave. Clearly, I said "all" or any titles from Sony that match with Warner titles audio wise (16bit vs. 16bit).

Using PSP... otherwise I would spell everything out.

Gattaca is Sony 16bit.

[Clark Kent]

Warner uses dialnorm on all of their Dolby TrueHD tracks, Sony does not. Warner also has the habit of giving us lower resolution tracks that are 16 bit as opposed to the other Blu-ray studios who regularly give us 24 bit soundtracks.

Up until now Warner had been creating their Blu-rays to what could fit on HD DVD and that had been effecting what their BDs contained. Warner always seemed very sensitive when they were neutral to not let the Blu-ray appear superior to the HD DVD version, hence we got a lot of 640 kbps lossy Dolby Digital tracks on BD from them.

[Slec]

Ascended... I've dug through some of the stuff Sir Terrence has posted on in his Insider thread (may be a good place for your question as well). here's my bastardization of some possibilities

Not all sound effects are recorded in 48/24. So if some is 48/24 and others are 48/16, it may be part of the issue and they will vary from movie to movie.

This one backs up what Wicky was saying and why its a bit difficult to compare tracks and peaks: Link

Since the bitrate would be variable from moment to moment, this is an impossible question to answer. With variable bitrate codecs the bitrate is determined squarely on how many bits it takes to represent the signal tranparently from second to second. The more demanding a soundtrack is, the more bits required. In the absence of sound effects and music, and with just dialog the bitrate drops substantially. This is unlike the lossy DD and Dts which use a constant bitrate and code and allocate what bits are available in that steady pool.

my emphasis is bolded.

Put those two together and it could be a reason. I'm not discounted the HD DVD theory... that's why it may be a better question for an insider.

[cajmoyper]

Originally Posted by Driver_King

Sounds like Sony knows what they're doing and not so much Warner Bros.

Are you kidding me? I've heard both I Am Legend and Dogma. Dogma doesn't hold a candle to the IAL track. Bitrates aren't the endall factor in being able to tell what's best. If it weren't for that bitrate counter at the top of your screen, you wouldn't even be able to tell TrueHD from DD.

[Marcusarilius]

Originally Posted by Hunter

First off, TrueHD is a mathematically lossless codec, once decoded it's bit for bit identical to the original PCM master so bit-rate means nothing.

Question: Does the decoding process in any way or to any degree, lessen the quality of the sound?

[RBFilms]

I do not know the specs on the soundtracks...but it could be a 24 bit verses 16 bit quality difference you are hearing. Don't tell the MS Boys this if it is the case....they will send a team of deprogrammers in the middle of the night to convince you that there is no difference between 16 bit and 24 bit...

Perhaps ... albeit I am not sure ... it could just be a filtering and engineering issue. Not all mixes are created equal and decimation / brick wall filters are used in many electronic instruments. Sound libraries are also of limited quality.

All of this can create a sense of reduced fidelity by comparison. Just listen to how lousy many CD Recordings sound these days. There are a multitude of reasons why they do not sound great. It is simply not possible to compare two different soundtracks and identify any one thing that makes one worse than the other. Some producers and engineers are more concerned about quality than others.

In the end, you can see / hear the difference when someone is paying attention throughout the process.

Originally Posted by MarekM

with those parts bolded, I am sure Dogma is 24bit !!

Marek