Bitstream vs LPCM to AVR - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 01-06-2020, 05:50 PM - Thread Starter
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Bitstream vs LPCM to AVR

Hi,
Searched and couldn’t find any posts related to the sound quality of having a device (such as Apple TV or Blu-ray player) send bitstream vs LPCM.

I have an old Blu-ray player that VUDU no longer seems to support. I have it set up to send bitstream do my Denon AVR and it accurately produces the correct Dolby and DTS signal including True HD which I like.

Apple TV, only enables LPCM which I don’t think sounds as good to me.

So, my question is: Is having the AVR decode bitstream produce better quality audio than having a streaming device do the decoding sending LPCM or is this subjective or device dependent? I’m sure the Denon decoder is better than whatever is in ATV but now sure.
Thanks,


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post #2 of 9 Old 01-07-2020, 12:46 PM
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Apple TV should be able to bitstream, see here.

But to answer your question, there should be no audible difference between bitstream and PCM.
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post #3 of 9 Old 01-08-2020, 03:41 PM
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Not sure about Denon but in my experience if you don't sent a bitstream signal to the avr it cannot decode it, to Dolby or dts. When I use my PS4 I can send Linear PCM, Dolby bitstream or dts bitstream. So for example if I have it set to PCM and play a Blu-ray that's supports Dolby true HD my avr doesn't recognize the signal as dolby, it just pushes it thru as PCM. From what I understand PCM is uncompressed 2 channel audio which is fine unless you're looking for more channels, 5.1, 7.1 etc. Then you need to pick the appropriate bitstream? Not exactly sure about that one though, maybe somebody else can drop in here with some more info...
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post #4 of 9 Old 01-08-2020, 03:56 PM
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Quote:
Originally Posted by Robchap83 View Post
Not sure about Denon but in my experience if you don't sent a bitstream signal to the avr it cannot decode it, to Dolby or dts. When I use my PS4 I can send Linear PCM, Dolby bitstream or dts bitstream. So for example if I have it set to PCM and play a Blu-ray that's supports Dolby true HD my avr doesn't recognize the signal as dolby, it just pushes it thru as PCM. From what I understand PCM is uncompressed 2 channel audio which is fine unless you're looking for more channels, 5.1, 7.1 etc. Then you need to pick the appropriate bitstream? Not exactly sure about that one though, maybe somebody else can drop in here with some more info...
If source device is set to Bitstream = AVR decodes (2.0/5.1/7.1)
If source device is set to PCM = source device decodes (2.0/5.1/7.1)

The resulting signal is identical, unless we are talking Atmos. Atmos must be bitstreamed.
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post #5 of 9 Old 01-08-2020, 04:24 PM
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Ah I see, but wouldn't it be better to send bitstream signal from the apple TV and have the Denon decode it, which (I am assuming) would do a better job than an apple TV?
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post #6 of 9 Old 01-08-2020, 04:38 PM
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Quote:
Originally Posted by Robchap83 View Post
Ah I see, but wouldn't it be better to send bitstream signal from the apple TV and have the Denon decode it, which (I am assuming) would do a better job than an apple TV?
I don't think it works that way. The decoders are virtually identical as I'm sure is required by the licensing with Dolby and DTS.
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post #7 of 9 Old 01-08-2020, 05:27 PM
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Hmmmm, Ok, but when you send bitstream your receiver will show "Dolby true HD" etc. on the display to give you a warm and fuzzy lol
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post #8 of 9 Old 01-09-2020, 08:23 AM
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Quote:
Originally Posted by Robchap83 View Post
Hmmmm, Ok, but when you send bitstream your receiver will show "Dolby true HD" etc. on the display to give you a warm and fuzzy lol
Truth, and why many insist bitstream must be superior to PCM.
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post #9 of 9 Old 01-09-2020, 08:58 PM - Thread Starter
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Thanks for the comments everyone. Unfortunately the ATV HD which I have does’t support bitstream or Atmos but the ATV 4K does. Although Apple’s documentation looks like it’s not a pass through but maybe decodes and creates a new bitsream that adds “system sounds” to support Siri.

I swear my Blu-ray player sounds better with Vudu than ATV but maybe that little blue light on my receiver is making me think that. . Who knows...


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