Dolby Digital v PCM question

[robfosters]

I have a Q85R connected to a HW80R soundbar. In my TV settings I can select either Dolby digital or PCM audio output.

What’s the difference between the two? Is one better than the other and which should I be using?

 

[mmj_uk]

As I understand it PCM is uncompressed so should be a higher quality but it'll be limited to 2 channels and even though Dolby Digital is compressed it might sound better due to enhancements in the sound.

 

[lucid]

In the case of your TV, PCM means digital stereo (2 channels - L & R). Dolby Digital means that the TV will output up to DD 5.1 surround, and anything below that.

With your sound bar, you want to select the Dolby Digital output option on the TV.



PCM from a TV is almost always plain stereo or stereo with Dolby Surround (not to be confused with Dolby Digital). Most of the non-HD core TV channels us Dolby Surround because the signal carries a hidden centre and rear surround field that is ignored by basic stereo-only capable gear. Your soundbar would detect the hidden Dolby Surround and activate its Dolby ProLogic decoder (DPL or DPLII) and you might have the option of setting it to DPL II Movie/Music/Game.

Most of the HD TV channels carry audio that can be formatted in the TV to be Dolby Digital in up to 5.1 channels. This is exactly what happens when you select Dolby Digital. So long as the program being viewed has full 5.1 audio, then that's what you'll get. When a channels program changes such as when the adverts play, you'll find that the audio changes to Dolby Surround. That's perfectly normal. The adverts don't have full surround generally.

For those with Sky Q and the UHD subscription, the UHD sports channel and some of UHD Movie downloads carry the additional Dolby ATMOS channels as a hidden signal extra to DD5.1. This is called Dolby Digital Plus. With a Sky Q box connected directly to your sound bar, and when playing content that has the additional ATMOS channels (5.1.2 format), then the sound bar would detect DD+ and direct the extra sound to the upfiring speakers.

 

[hornetstinger]

To add on the above ideally the TV should be set to native in and out so if you playback stereo files or from a cd, your TV will output this as pcm. Not Dolby digital or if it converts pcm to Dolby digital

 

[robfosters]

In the case of your TV, PCM means digital stereo (2 channels - L & R). Dolby Digital means that the TV will output up to DD 5.1 surround, and anything below that.

With your sound bar, you want to select the Dolby Digital output option on the TV.



PCM from a TV is almost always plain stereo or stereo with Dolby Surround (not to be confused with Dolby Digital). Most of the non-HD core TV channels us Dolby Surround because the signal carries a hidden centre and rear surround field that is ignored by basic stereo-only capable gear. Your soundbar would detect the hidden Dolby Surround and activate its Dolby ProLogic decoder (DPL or DPLII) and you might have the option of setting it to DPL II Movie/Music/Game.

Most of the HD TV channels carry audio that can be formatted in the TV to be Dolby Digital in up to 5.1 channels. This is exactly what happens when you select Dolby Digital. So long as the program being viewed has full 5.1 audio, then that's what you'll get. When a channels program changes such as when the adverts play, you'll find that the audio changes to Dolby Surround. That's perfectly normal. The adverts don't have full surround generally.

For those with Sky Q and the UHD subscription, the UHD sports channel and some of UHD Movie downloads carry the additional Dolby ATMOS channels as a hidden signal extra to DD5.1. This is called Dolby Digital Plus. With a Sky Q box connected directly to your sound bar, and when playing content that has the additional ATMOS channels (5.1.2 format), then the sound bar would detect DD+ and direct the extra sound to the upfiring speakers.

Thanks a lot.

Bit confused about my TV and Atmos. People were telling me that I would have to plug my Blu-ray player directly into the soundbar to get atmos, as the Samsung can’t pass atmos through ARC, which I did, but when I select Atmos stuff in Netflix on the telly, Dolby atmos shows up on my soundbar screen, so the TV is clearly passing atmos through ARC.

 

[lucid]

Thanks a lot.

Bit confused about my TV and Atmos. People were telling me that I would have to plug my Blu-ray player directly into the soundbar to get atmos, as the Samsung can’t pass atmos through ARC, which I did, but when I select Atmos stuff in Netflix on the telly, Dolby atmos shows up on my soundbar screen, so the TV is clearly passing atmos through ARC.

The thing is, you're both right. You see, if you have you BD player set to give the best sound (Dolby True-HD and DTS-MA) then those formats aren't supported by ARC, so the TV won't pass that audio from its HDMI in to the HDMI ARC socket. The signal takes up too much bandwidth for ARC to handle.

DD+ is a compressed (lossy) format, so it takes up little more space than DD which the TV already handles. This is why SkyQ's ATMOS gets through.

DD+ is the standard for broadcast and streaming sources of ATMOS.

 

[robfosters]

The thing is, you're both right. You see, if you have you BD player set to give the best sound (Dolby True-HD and DTS-MA) then those formats aren't supported by ARC, so the TV won't pass that audio from its HDMI in to the HDMI ARC socket. The signal takes up too much bandwidth for ARC to handle.

DD+ is a compressed (lossy) format, so it takes up little more space than DD which the TV already handles. This is why SkyQ's ATMOS gets through.

DD+ is the standard for broadcast and streaming sources of ATMOS.

Gotcha. I’m very surprised Samsung didn’t use eARC in such an expensive high end TV.

 

[200sols]

Gotcha. I’m very surprised Samsung didn’t use eARC in such an expensive high end TV.

Most manufacturers seem to be a year behind LG with these features.

 

[Broken Hope]

LG just needs to fix it so PCM passed through eARC is multi channel which they state will be fixed in Q2.

 

[ShiWarrior]

In the case of your TV, PCM means digital stereo (2 channels - L & R). Dolby Digital means that the TV will output up to DD 5.1 surround, and anything below that.

With your sound bar, you want to select the Dolby Digital output option on the TV.



PCM from a TV is almost always plain stereo or stereo with Dolby Surround (not to be confused with Dolby Digital). Most of the non-HD core TV channels us Dolby Surround because the signal carries a hidden centre and rear surround field that is ignored by basic stereo-only capable gear. Your soundbar would detect the hidden Dolby Surround and activate its Dolby ProLogic decoder (DPL or DPLII) and you might have the option of setting it to DPL II Movie/Music/Game.

Most of the HD TV channels carry audio that can be formatted in the TV to be Dolby Digital in up to 5.1 channels. This is exactly what happens when you select Dolby Digital. So long as the program being viewed has full 5.1 audio, then that's what you'll get. When a channels program changes such as when the adverts play, you'll find that the audio changes to Dolby Surround. That's perfectly normal. The adverts don't have full surround generally.

For those with Sky Q and the UHD subscription, the UHD sports channel and some of UHD Movie downloads carry the additional Dolby ATMOS channels as a hidden signal extra to DD5.1. This is called Dolby Digital Plus. With a Sky Q box connected directly to your sound bar, and when playing content that has the additional ATMOS channels (5.1.2 format), then the sound bar would detect DD+ and direct the extra sound to the upfiring speakers.

That is the best explanation ive read ever!

ive looked up all this before, and still got confused which to set my TV, soundbar etc etc on

now i know, thank you !

 

[NickK]

Yup PCM can be any number of channels but there is a Phillips SII and a Sony interpretation (lsb/msb orientation etc)

Linear PCM is the most raw form - a stream of numbers, for stereo it basically has alternate left then right.

Mac’s OSX usb audio 2.0 converts any audio format to LPCM or DSD and simply sends it over usb for the dac. It’s the codec that transcodes the formats to the required LPCM/DSD. Windows has caught up but may need drivers.

DSD is the other format.

Designed by own usb dac/headphone amp from scratch. Spdif & toslink is the same mechanism.