Question PCM v Bitstream quandary

Discussion in 'AV Receivers & Amplifiers' started by nickymarshall, Jan 7, 2017.

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  1. nickymarshall

    nickymarshall
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    Hi - I have an old Yammy A763, so I don't pass through much stuff, as my BD & TV are 4k.

    A brief description -
    Sky to Amp via Optical
    Sky to TV via HDMI
    BD to Amp via HDMI
    BD to TV via HDMI
    XB360 to Amp via HDMI
    Amp to TV via HDMI

    I'd like to send the signal from my BD to the Amp in Bitstream, so that the Amp decodes HD Codecs. It doesn't seem that the HDMI out's are individually selectable PCM/BS, so that means sending Bitstream to the TV too (the mrs may want to watch a disc without the amp on, so have to be able to send sound to TV. Selecting BS on the TV inputs means that I can't hear Sky - going into the Sky menu, there are no options, so I presume this is PCM

    So, is there a workaround, or should I just keep all sources happy and send PCM to my Amp?

    Thanks to anyone that understands my rather dodgy explanation
     
  2. andym81

    andym81
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    Bitstream everything. Especially on bluray
     
  3. nickymarshall

    nickymarshall
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    If I set every input/output in my system to bitstream, then I get no sound to the tv from Sky (no option to set Sky HD to BS)
     
  4. andym81

    andym81
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    What receiver have you got
     
  5. nickymarshall

    nickymarshall
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    Yamaha AX763
     
  6. andym81

    andym81
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    I've got onkyo 646 and when in pcm audio from my ps4 it sound awfully compressed compared to bit streamed.
     
  7. dante01

    dante01
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    Even though it the exact same audio? Nothing has been compressed and the only difference is which device is decoding the audio. If you bitstream the audio then the AV receiver decodes it and inputs the resulting PCM data into its DAC. If outputting the digital data as PCM from the source then the source is decoding the audio to the receiver as PCM. PCM is lossless uncompressed digital data.

    Whether you bitstream the audio formats or have the source decode them and output the data as PCM, both result in exactly the same audio.
     
  8. andym81

    andym81
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    If you pcm the device is decoding. If you bitstream the av is doing it basically. The average does a far better job from what I've herd
     
  9. dante01

    dante01
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    SKY boxes have two digital audio output options. One option is to output Dolby Digital if and when present while the other is to only output all audio as stereo PCM irrespective of the audio format present. SKY HD boxes usually have such a setting for both their HDMI and their optical audio outputs.
     
  10. dante01

    dante01
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    You've heard wrong. Both result in exactly the same PCM digital signal. As I said, the only difference is which device decodes the compressed audio format to digital PCM data.

    Blu-ray Disc Audio - Bitstream vs PCM Output - Which Is Best?
     
  11. andym81

    andym81
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    I've tried films in both an by my ears letting the receiver do it makes a lot of difference. This is in my opinion
     
  12. dante01

    dante01
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    You can effectively send both audio and video via HDMI to your TV from the SKY box and the additional optical connection isn't required. Connect the TV's optical output to the AV receiver and passthrough the audio associated with your SKY box to the receiver. Ensure you set the TV's speaker setting to OPTICAL. You should be able to set the SKY box's HDMI audio output to Dolby Digital and the TV should be able to pass this through to your AV receiver via the optical output.

    Your UHD BD player does allow you to configure it so that only video is output via the video HDMI output while only audio is output via its audio HDMI output. Connect the video output to the TV and the audio output to the receiver. Configure the player so that only video is output via the video connection and so that audio is bitstreamed via the audio HDMI connection to the AV receiver. Your TV doesn't have the audio abilities that your AV receivers has so the player takes the least capable device as guidance for the audio it can output. If you were to use the connection from the player to the TV to convey audio to the TV in tandem with the connection to the receiver then both outputs would only output audio the TV can handle. I'd advise only using the AV receiver to handle the audio from the player and not to output audio from the player to your TV. If you do then you'd be restricted to Dolby Digital or stereo PCM.

    Still make an HDMI connection between the TV and the AV receiver for any other legacy devices you may want to pass video from through the receiver to the TV.
     
    Last edited: Jan 8, 2017
  13. dante01

    dante01
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    Get your hearing checked. Sorry if I'm coming across as being rude, but the fact is that the audio is exactly the same audio irrespective of which device does the decoding. Both result in the exact same PCM data and it is just a matter of the receiver not indicating the fact the formats are decompressed by it resulting in the same PCM data.
     
    Last edited: Jan 8, 2017
  14. andym81

    andym81
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    Yea i must need them checking
     
  15. Captain Ron

    Captain Ron
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    I have a similar setup and the solution is indeed to make tha av receiver do all sound duties and only send video to the display. The ergonomic difficulties with this are that you need to be comfortable with juggling lots of remotes or have the time to setup an intuitive activity based solution on a universal remote. It is worth spending the time to do this.
     
  16. dante01

    dante01
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    I'd maybe suggest investing in a Logitech Harnony remote. One Harmony remote will control multiple devices.
     
  17. nickymarshall

    nickymarshall
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    Thanks for your lengthy reply.

    Yep, I could send audio from Sky to the amp via ARC on the TV - I suppose that would be advantageous to allow use of the amp when watching Netflix etc via the tv app, rather than the BD player app

    Sending video only from the BD player to the tv would frustrate the mrs, as she may put a disc in and not want to turn the amp on. I'm aware of the tv's limited passthrough capabilities.

    I've read that sending the decoded HD sound codecs to the amp from the BD player via PCM over HDMI will give exactly the same audio quality as letting the amp decode, so will probably stick with that
     
  18. dante01

    dante01
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    This isn't the issue, the issue is that if the HDMI connection between the player and the TV is set to convey audio then the player will not output any audio the TV cannot handle via either of its HDMI outputs. Your TV cannot handle multichannel PCM or the HD audio formats associated with Blu-ray titles. THe same issue would be apparent irrespective of whther you bitstream the audio or not and would still restrict the types of audio you can access even if not listening via the TV and using the AV receiver. You'd have to configure the player not to convey audio via the TV connection in order to circumvent this issue.
     

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