definitions of terms such as pcm, mhl, dts, bitstream, lpcm, dsd Dolby hd , true hd etc. - AVS Forum
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Old 06-27-2013, 08:51 AM - Thread Starter
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A while back I recall seeing a detailed explanation of this in some thread. Does anyone know where I might find this?
Thanks Mrfixit58
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Old 06-27-2013, 12:49 PM
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All of those terms require more than a one-sentence explanation. I think you'll do better with Google and Wikipedia etc, or a good technical book. Or maybe use the Forum Search feature here.

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Old 06-27-2013, 07:52 PM - Thread Starter
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Thanks Ethan, I saw it somewhere before I just can't recall if it was on AVS or Audioholics. Somebody took the time and broke it all down.
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Old 06-27-2013, 10:45 PM
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Very quickly:

PCM (Pulse Code Modulation) is the basic digital format used for most home entertainment audio, including movies and CDs. Audio systems are engineered to process PCM to produce sound.

DSD (Direct Stream Digital) is an alternate digital format developed by Sony and used on SACDs. DSD cannot be processed by most players and receivers.

DD 5.1, DTS, TrueHD, and dts-MA are data compression codecs whose sole purpose is saving space on discs. A PCM track is fed into the encoder, which compresses it using one if those codecs. The decoder decompresses the file, turning it back into PCM. DD 5.1 and DTS are "lossy" codecs, meaning some of the data removed during encoding is not restored in the decompression phase. TrueHD and dts-MA are "lossless" codecs, meaning every bit removed by the encoder is restored by the decoder. Lossless codecs work just like zip files.

Bitstream refers to transmitting an encoded file such as DTS or DD 5.1 from a player to a receiver so that the AVR can do the decoding.
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Old 06-27-2013, 10:52 PM
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Mhl is mobile high definition link


Sent from my iPad using Tapatalk HD

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Old 06-28-2013, 06:57 PM
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Old 07-01-2013, 09:10 AM - Thread Starter
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Thanks for the help guys!
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Old 07-10-2013, 09:40 AM
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Quote:
Originally Posted by BIslander View Post

Very quickly:

PCM (Pulse Code Modulation) is the basic digital format used for most home entertainment audio, including movies and CDs. Audio systems are engineered to process PCM to produce sound.

DSD (Direct Stream Digital) is an alternate digital format developed by Sony and used on SACDs. DSD cannot be processed by most players and receivers.

DD 5.1, DTS, TrueHD, and dts-MA are data compression codecs whose sole purpose is saving space on discs. A PCM track is fed into the encoder, which compresses it using one if those codecs. The decoder decompresses the file, turning it back into PCM. DD 5.1 and DTS are "lossy" codecs, meaning some of the data removed during encoding is not restored in the decompression phase. TrueHD and dts-MA are "lossless" codecs, meaning every bit removed by the encoder is restored by the decoder. Lossless codecs work just like zip files.

Bitstream refers to transmitting an encoded file such as DTS or DD 5.1 from a player to a receiver so that the AVR can do the decoding.

Just a noobie add-on question to this topic: when I play my blu-ray content & send the TrueHD or dts-MA signal via HDMI through the AVR - PCM appears on my AVR.

Does that mean I am getting uncompressed lossless sound & equate to "best possible" ?

How about a TV signal through a TiVo to AVR via optical cable - that also shows PCM on the AVR screen - but from what I understand TV programming passes 5.1 or 2 Channel Stereo thus equating to PCM of lossy?

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Old 07-10-2013, 10:41 AM
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Quote:
Originally Posted by tripleM View Post

Just a noobie add-on question to this topic: when I play my blu-ray content & send the TrueHD or dts-MA signal via HDMI through the AVR - PCM appears on my AVR.

Does that mean I am getting uncompressed lossless sound & equate to "best possible" ?

How about a TV signal through a TiVo to AVR via optical cable - that also shows PCM on the AVR screen - but from what I understand TV programming passes 5.1 or 2 Channel Stereo thus equating to PCM of lossy?
If the source decodes those and sends PCM to the AVR, then you don't know the origin and hence fidelity of said samples. Check your sources to make sure they are set to "bit stream" and the AVR to make sure it has the ability to identify compressed bit streams and signal them the way.
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Old 07-10-2013, 01:32 PM
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When the source device decodes the file, you are not sending TrueHD or dts-MA to the receiver. Rather, you are sending the resulting PCM to the receiver. The AVR has no way of reporting whether the source was a lossless codec such as TrueHD or as lossy one such as DD 5.1 because the AVR doesn't have that information when the source device had already done the decoding.

If you play a lossless track and set up the device to decode that track, then you'll get the best quality possible. That is likely the case with your PS3. Your TiVo, on the other hand, is likely sending PCM that comes from a lossy DD 5.1 track since that's the best format used on HD television broadcasts. Again, it's the quality of the source that matters.
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Old 07-10-2013, 01:43 PM
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can anyone help edit this audio so I can hear what is going on? I will provide the clip
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Old 07-10-2013, 02:50 PM
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Quote:
Originally Posted by BIslander View Post

When the source device decodes the file, you are not sending TrueHD or dts-MA to the receiver. Rather, you are sending the resulting PCM to the receiver. The AVR has no way of reporting whether the source was a lossless codec such as TrueHD or as lossy one such as DD 5.1 because the AVR doesn't have that information when the source device had already done the decoding.

If you play a lossless track and set up the device to decode that track, then you'll get the best quality possible. That is likely the case with your PS3. Your TiVo, on the other hand, is likely sending PCM that comes from a lossy DD 5.1 track since that's the best format used on HD television broadcasts. Again, it's the quality of the source that matters.

So in laymen's term I interpret - in regards to most modern day BluRay movies where there is lossless audio - it as a leap of faith on the packaging of the content because everything is processed before it gets to the receiver.

& btw - true on both examples above.

Thanks for the clarification.

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Old 07-10-2013, 02:51 PM
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Quote:
Originally Posted by tripleM View Post


How about a TV signal through a TiVo to AVR via optical cable - that also shows PCM on the AVR screen - but from what I understand TV programming passes 5.1 or 2 Channel Stereo thus equating to PCM of lossy?

Is theTiVo connected to the TV? If so you probably are getting only 2 ch. stereo. Connect the TiVo directly to the AVR via HDMI. The AVR should then report DD5.1 when you are watching DD content.

TripleM, if your AVR was able to decode lossless formats then you would bitstream from the BD source and you would see the source format displayed instead of PCM.
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Old 07-10-2013, 03:11 PM
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Quote:
Originally Posted by Possumgirl View Post

Is theTiVo connected to the TV? If so you probably are getting only 2 ch. stereo. Connect the TiVo directly to the AVR via HDMI. The AVR should then report DD5.1 when you are watching DD content.

I have reasons to use optical from th TiVo to the AVR - primarily able to watch TiVO without the AVR.

That said, I believe HDMI does pass 5.1 on the TiVo to the AVR.

But in the TiVo's 2 audio settings -1) is classified 'Dolby Digital' or 2) classified as 'Dolby Digital to PCM'.

Though - I am unsure what the benefit of the TiVo doing #2 is vs. #1.

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Old 07-10-2013, 04:53 PM
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Optical is limited to two channels of PCM. So, if you set the TiVo output to DD, your receiver will be able to do the decoding and produce a discrete 5.1 output. If you set the TiVo to PCM, the TiVo will do the decoding and then downmix any 5.1 content to stereo for transmission over optical. So, set the output to DD.

As for it being a leap of faith when your PS3 decodes lossless tracks, not really. When you select the lossless track on the disc, that's what the PS3 will decode. It can't decode anything else. These days, the vast majority of BDs only have one English track. So, there's nothing to worry about.
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Old 07-10-2013, 06:51 PM
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Quote:
Originally Posted by tripleM View Post

So in laymen's term I interpret - in regards to most modern day BluRay movies where there is lossless audio - it as a leap of faith on the packaging of the content because everything is processed before it gets to the receiver.
Not quite. There are two options there: the source sends out the compressed stream to the AVR and decoding gets done there. The other option is have the player decode it and send the samples to the AVR. The math for both is the same.

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Old 07-10-2013, 08:32 PM
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One more note: the PS3 is only doing the decoding, which is nothing more than unzipping the compressed file. The receiver still handles all subsequent processing - things like bass management, room correction, and the digital-analog conversion.
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Old 07-11-2013, 04:08 AM
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Originally Posted by amirm View Post

Not quite. There are two options there: the source sends out the compressed stream to the AVR and decoding gets done there. The other option is have the player decode it and send the samples to the AVR. The math for both is the same.

As is the sound quality.The D/A conversion either happens or it doesn't.
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Old 07-11-2013, 04:09 AM
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Quote:
Originally Posted by tripleM View Post

So in laymen's term I interpret - in regards to most modern day BluRay movies where there is lossless audio - it as a leap of faith on the packaging of the content because everything is processed before it gets to the receiver.

& btw - true on both examples above.

Thanks for the clarification.

If the player is doing the decoding,use the display or info button on it to see which track you're playing.
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Old 07-11-2013, 10:06 AM
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Quote:
Originally Posted by BIslander View Post

Optical is limited to two channels of PCM. So, if you set the TiVo output to DD, your receiver will be able to do the decoding and produce a discrete 5.1 output. If you set the TiVo to PCM, the TiVo will do the decoding and then downmix any 5.1 content to stereo for transmission over optical. So, set the output to DD.

So if I am reading this correctly, it's the optical connection piping that is limiting the source track from being delivered in whole right?

What if I set the TiVo to DD only & connect via optical- would optical be able to handle DD 5.1?

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Old 07-11-2013, 10:34 AM
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Yes, set the TiVo to output Dolby Digital. Optical supports DD 5.1 just fine.
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Old 01-13-2015, 12:45 PM
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Here are few other terms as well. Its about 25 or so. Some of these are from the home automation sector but they correspond nicely to this as well.

http://www.control4.com/blog/2014/07...-terms-defined
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