Re:Smart TVs sending sensitive user data to Netflix and Face...
by tzs on Wednesday September 18, 2019 @10:36PM
(#21012717)
One problem I have with that approach is I'm very confused about how sound works.
Consider three ways to play a movie:
1. From a source device (AppleTV, Blu-ray player, etc) connected to an A/V receiver.
2. From an app on your Smart TV, with the TV passing sound over ARC or optical to the A/V receiver.
3. From a source device, as in #1, but with the device connected to one of the TV's HDMI inputs instead of to the receiver. Sound going from the TV to the A/V receiver via ARC or optical.
Everything I've found seems to agree that #1 can handle anything, with the only limit being formats that are newer than your A/V receiver understands. Mine doesn't know about Dolby Atmos, for example, so wouldn't be able to do that.
For #2, the limit seems to be the bandwidth of ARC or optical. Optical can't do 5.1 or higher PCM, Dolby TrueHD, Dolby Atmos, DTS:X, or a view others. It can only do stereo PCM, or matrix surround formats.
ARC, if your TV and A/V receiver implement a new enough version of the HDMI spec, has the bandwidth for all those formats.
For #3, some sources say that there are licensing limits, enforced by HDCP, that disallow the TV from passing a high bandwidth audio signal directly from an HDMI input to an HDMI output. Instead, the TV has to do the Dolby or DTS decoding itself, and then re-encode to a lower bandwidth Dolby or DTS format, and send that on.
I think that the very latest version of HDCP will remove that restriction, if both the TV and the the A/V receiver support it (not sure if it also needs to be on the source). But I don't think that is expected to start showing up on consumer equipment until next year.
Unfortunately, my receiver is not 4K, and I really don't want to get a new receiver until that latest HDCP is out, to maximize future proofing. So for now I have to choose between #2 and #3 when I want to watch something in 4K. I think the ARC supported by my TV and/or my receiver probably only has enough bandwidth to support matrix formats for surround sound, but with #2 I think it will be using a matrix encoded bitstream from the source, just passing it through. With #3, it's going to be going through decoding and re-encoding on the TV, to then be decoded again on the receiver. #2 seems better, then.
Consider three ways to play a movie:
1. From a source device (AppleTV, Blu-ray player, etc) connected to an A/V receiver.
2. From an app on your Smart TV, with the TV passing sound over ARC or optical to the A/V receiver.
3. From a source device, as in #1, but with the device connected to one of the TV's HDMI inputs instead of to the receiver. Sound going from the TV to the A/V receiver via ARC or optical.
Everything I've found seems to agree that #1 can handle anything, with the only limit being formats that are newer than your A/V receiver understands. Mine doesn't know about Dolby Atmos, for example, so wouldn't be able to do that.
For #2, the limit seems to be the bandwidth of ARC or optical. Optical can't do 5.1 or higher PCM, Dolby TrueHD, Dolby Atmos, DTS:X, or a view others. It can only do stereo PCM, or matrix surround formats.
ARC, if your TV and A/V receiver implement a new enough version of the HDMI spec, has the bandwidth for all those formats.
For #3, some sources say that there are licensing limits, enforced by HDCP, that disallow the TV from passing a high bandwidth audio signal directly from an HDMI input to an HDMI output. Instead, the TV has to do the Dolby or DTS decoding itself, and then re-encode to a lower bandwidth Dolby or DTS format, and send that on.
I think that the very latest version of HDCP will remove that restriction, if both the TV and the the A/V receiver support it (not sure if it also needs to be on the source). But I don't think that is expected to start showing up on consumer equipment until next year.
Unfortunately, my receiver is not 4K, and I really don't want to get a new receiver until that latest HDCP is out, to maximize future proofing. So for now I have to choose between #2 and #3 when I want to watch something in 4K. I think the ARC supported by my TV and/or my receiver probably only has enough bandwidth to support matrix formats for surround sound, but with #2 I think it will be using a matrix encoded bitstream from the source, just passing it through. With #3, it's going to be going through decoding and re-encoding on the TV, to then be decoded again on the receiver. #2 seems better, then.
This is all WAY too freaking complicated.