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PCM vs Dolby 5.1

52K views 20 replies 16 participants last post by  Trista Brown 
#1 ·
It sounds heaps better, but sometimes I just wonder if its the loudness that tricks me into assuming its better... Why is PCM so much louder than Dolby 5.1?
 
#2 ·
Well I take it you're talking about uncompressed PCM. Uncompressed PCM sounds better than DD 5.1 simply because it's uncompressed, it really has nothing to do with the loudness of the soundtrack. Dynamic peaks are clearer and more vibrant, bass has more impact and slam. Your ears are not playing tricks on you, uncompressed PCM is leaps and bounds over DD. Of course everyone's ears are different.


Just my .02
 
#4 ·
I have a friend who bought a DVD-A player and he was telling me how great his DVD-As sounded than his CDs. He said they were clear and clean and had bass and high end that he had never heard before.

Then I went to his house and connected his player so that he could hear something other than Dolby Digital...
 
#5 ·
It's the lack of compression and full on dynamic range you are now hearing that is waking you up out of your DD DVD inducing coma.


Welcome to no compression. It's so 1990
I say that because Laserdisc had uncompressed PCM and people kept telling me but DD is so much better. Yeah right.
 
#7 ·
When listening to the POTC BRs I noticed that the dolby 5.1 track had more bass than the PCM. Now I assume this is because Im using optical for audio out, but my receiver is detecting the PCM signal and when I switch to the Dolby EX track it shows 6.1 dolby.


Is it possible to get uncompressed PCM over optical? I was wondering why the bass was so poor on both of these movies until I put them in Dolby 5.1 mode. Could this be some setting on my receiver?
 
#8 ·

Quote:
Originally Posted by Hayrab /forum/post/0


When listening to the POTC BRs I noticed that the dolby 5.1 track had more bass than the PCM. Now I assume this is because Im using optical for audio out, but my receiver is detecting the PCM signal and when I switch to the Dolby EX track it shows 6.1 dolby.


Is it possible to get uncompressed PCM over optical? I was wondering why the bass was so poor on both of these movies until I put them in Dolby 5.1 mode. Could this be some setting on my receiver?

The only way (to the best of my knowledge) to get any advanced audio; this includes Dolby True HD, PCM uncompressed, etc... is to use HDMI or analog cables. You can NOT get uncompressed sound via optical as there is not enough "room" for the large signal to transmit.


Someone feel free to correct me if I am wrong, but this is what my understanding is.


As for the difference in sound... I just watched Dreamgirls (HD DVD) and then Apocalypto (BD) and Batman Begins (HD DVD) and both Batman and Apocalypto DESTROYED Dreamgirls' DD+ soundtrack.


I hadn't really appreciated the difference uncompressed sound offered, but upon watching these discs, it was apparent that Dreamgirls sounded a bit anemic in comparison.


I was disappointed, too; I was expecting a walloping soundtrack on that film, being a musical and all...
 
#19 ·
Quote: Originally Posted by Hayrab

When listening to the POTC BRs I noticed that the dolby 5.1 track had more bass than the PCM. Now I assume this is because Im using optical for audio out, but my receiver is detecting the PCM signal and when I switch to the Dolby EX track it shows 6.1 dolby.

Is it possible to get uncompressed PCM over optical? I was wondering why the bass was so poor on both of these movies until I put them in Dolby 5.1 mode. Could this be some setting on my receiver?


The only way (to the best of my knowledge) to get any advanced audio; this includes Dolby True HD, PCM uncompressed, etc... is to use HDMI or analog cables. You can NOT get uncompressed sound via optical as there is not enough "room" for the large signal to transmit.

Someone feel free to correct me if I am wrong, but this is what my understanding is.

As for the difference in sound... I just watched Dreamgirls (HD DVD) and then Apocalypto (BD) and Batman Begins (HD DVD) and both Batman and Apocalypto DESTROYED Dreamgirls' DD+ soundtrack.

I hadn't really appreciated the difference uncompressed sound offered, but upon watching these discs, it was apparent that Dreamgirls sounded a bit anemic in comparison.

I was disappointed, too; I was expecting a walloping soundtrack on that film, being a musical and all...


Just in case anyone is still tracking this thread, I should correct the above statement "You can NOT get uncompressed sound via optical as there is not enough "room" for the large signal to transmit."

Wrong

S/PDIF is based on the professional AES3 interconnect standard.[1] S/PDIF can carry two channels of uncompressed PCM audio or compressed 5.1/7.1 surround sound (such as DTS audio codec); it cannot support lossless formats (such as Dolby TrueHD and DTS-HD Master Audio) which require greater bandwidth like that available with HDMI or DisplayPort.

my 2 cents
 
#9 ·

Quote:
Originally Posted by wired1 /forum/post/0


The only way (to the best of my knowledge) to get any advanced audio; this includes Dolby True HD, PCM uncompressed, etc... is to use HDMI or analog cables. You can NOT get uncompressed sound via optical as there is not enough "room" for the large signal to transmit.


Someone feel free to correct me if I am wrong, but this is what my understanding is.


As for the difference in sound... I just watched Dreamgirls (HD DVD) and then Apocalypto (BD) and Batman Begins (HD DVD) and both Batman and Apocalypto DESTROYED Dreamgirls' DD+ soundtrack.


I hadn't really appreciated the difference uncompressed sound offered, but upon watching these discs, it was apparent that Dreamgirls sounded a bit anemic in comparison.


I was disappointed, too; I was expecting a walloping soundtrack on that film, being a musical and all...

Through optical and from my PS3 to my receiver you can get 3.1 uncompressed. The center, fronts and sub are all active. It sounds great and on most movies it is 6.9 Kbps which is more than 10 times DD 5.1, but I like the surround sound so until I upgrade my receiver to one that is HDMI, I wil listen in DD 5.1.
 
#11 ·

Quote:
Originally Posted by Hughmc /forum/post/0


Through optical and from my PS3 to my receiver you can get 3.1 uncompressed. The center, fronts and sub are all active. It sounds great and on most movies it is 6.9 Kbps which is more than 10 times DD 5.1, but I like the surround sound so until I upgrade my receiver to one that is HDMI, I wil listen in DD 5.1.

how do i go about doing this just to see how it sounds in the front channels?
 
#12 ·

Quote:
Originally Posted by Hughmc /forum/post/0


Through optical and from my PS3 to my receiver you can get 3.1 uncompressed. The center, fronts and sub are all active. It sounds great and on most movies it is 6.9 Kbps which is more than 10 times DD 5.1, but I like the surround sound so until I upgrade my receiver to one that is HDMI, I wil listen in DD 5.1.

When selecting a 5.1 or 6.1 PCM soundtrack and you play it back through optical on the PS3, a 2ch downmix of the 5.1 or 6.1 pcm is being sent, not a 3.1. And based on your settings on your receiver, it will apply pro-logic decoding on this 2ch downmix which is why you get audio from your center channel and your subwoofer is receiving a bass signal due to your bass management configuration.
 
#14 ·

Quote:
Originally Posted by Shane Martin /forum/post/0


It's not that. Dialnorm won't affect this amount of difference on the dynamics. there is clear compression being heard on a DD track.

True, there is a difference in dynamics, as well as other sound qualities being better on PCM vs DD because of uncompressed vs compressed lossy.


But the volume level or loudness difference that Luke212 was noticing when trying to compare Dolby Digital and PCM would be attributed to Dial Norm. For example, if the Dolby Digital soundtrack he is trying to compare has a dial norm offset of -27, the dolby digital decoder will automatically attenuate the audio by -4db. Now if the PCM or DTS version of the same soundtrack is played, it will play 4db louder compared to the dolby digital track being attenuated by -4db due to dial norm. From what Luke212 wrote, this is what he was experiencing.
 
#15 ·

Quote:
Originally Posted by Dwellon /forum/post/0


When selecting a 5.1 or 6.1 PCM soundtrack and you play it back through optical on the PS3, a 2ch downmix of the 5.1 or 6.1 pcm is being sent, not a 3.1. And based on your settings on your receiver, it will apply pro-logic decoding on this 2ch downmix which is why you get audio from your center channel and your subwoofer is receiving a bass signal due to your bass management configuration.


My receiver would tell me exactly what it is decoding and or being applied and it is not decoding or applying pro logic. It is DTS Neo 6 PCM without surround sound.
 
#16 ·

Quote:
Originally Posted by Hughmc /forum/post/0


My receiver would tell me exactly what it is decoding and or being applied and it is not decoding or applying pro logic. It is DTS Neo 6 PCM without surround sound.

1. their is no way your getting more then 2 channel pcm from the ps3 or any high def player. through optical

2. what receiver are you using?


you may think its 3.1 uncompressed but it is not. now is it possible that its taking the uncompressed 2 channel track and turning it into 3.1 i would so and same with taking the 5.1 track and compressing it to 3.1...
 
#17 ·

Quote:
Originally Posted by Hughmc /forum/post/0


My receiver would tell me exactly what it is decoding and or being applied and it is not decoding or applying pro logic. It is DTS Neo 6 PCM without surround sound.

DTS Neo is DTS's version of Pro-Logic II. Your receiver is applying DTS Neo processing to the 2 channel downmix which is why it seems you are getting more than 2 channels.
 
#18 ·
its the opposite on my system. Dolby is much louder than PCM? My problrm ids dolby hiccups - looses "connection" or software requires too much memory? So for audio from my computer to my sound system I just use pcm. Dolby works fine from Blue Ray & TV source. Perhaps because the tv & BR are hdmi pass thru & the computer is sound out thru usb to a sound blaster to yamaha amp via digital optical. I originally went directly from the computer to the yamaha via headphone jack but thought "the sb digital box would perform 5.1 conversion better. Perhaps it does but the signal is unacceptable as dolby output!
 
#20 ·
The "normalization," data rates, frequency range, and level of compression that are part of Dolby Digital as used in TV broadcasts are specs set by the industry and were not chosen by Dolby Labs. It sounded better than the version submitted for consideration by DTS using those same limitation set by the industry. Different specs can be used on DVD's to provide a superior sound than that used on TV broadcasts.


The "compression" codex used in Dolby Digital is more efficient than that used by DTS and thus a direct comparison in sample size is like an apples and oranges comparison. The codex used on broadcast HD radio is the most efficient now in use, too bad it is wasted on broadcast radio, imo.
 
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