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Lossless Playback via Receiver from PC, How to get the best quality audio through a connected receiver.
heyo_speaker
post Jan 17 2013, 11:48
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I have a few questions regarding the best way to play audio from my PC through my surround-sound receiver.

I recently purchased a nice receiver that supposedly has good audio quality and can decode a wide variety of digital formats. I plan to use my PC as the main audio source when listening to music or gaming. I am aware of the benefits of digitally transmitting audio to the receiver to avoid loss of audio quality in the transmission, but I am unfamiliar with what goes on inside the computer to produce this digital stream. I plan to use the HDMI output from a graphics card (once I get around to installing it).

I am guessing that for the purest sound I should leave all the audio processing to the receiver, rather than allow the PC to apply any processing, but I don't really know. The computer could be allowed do the decoding of files (and so could the receiver), but my guess is that for the purest sound I should not allow the computer to do any modification to the audio itself before streaming it through HDMI. This PC doesn't even have a sound card as far as I know (but does somehow produce audio through the pre-installed HDMI and 3.5mm stereo connections), so perhaps it wouldn't do a good job of processing the audio.

I am running Windows 7. I would like to use Windows Media Player 12 for normal music playback (if doing so won't affect audio quality). I also have foobar2000 but my mom is familiar with Windows Media Player. I have installed some DirectShow filters on this PC, which I believe allow me to play certain audio file formats in Windows Media Player, as well as burn CDs from them using ImgBurn, but I don't know what exactly these filters are or how they work, or whether they alter the audio output at all after decoding a file.


Here are all the questions I can think of thus far:

-- Do you agree that I should probably leave all audio processing (EQ, surround effects, mixing, etc.) for the receiver rather than the PC?

-- Do I need to reserve surround-sound format decoding for the receiver, or would the PC transmit all audio channels through HDMI after decoding? (Will it automatically down-mix to 2 channels or anything like that before sending it to the receiver?)

-- Is it possible to send un-modified (but decoded) audio digitally through HDMI? Does this happen by default in Windows Media Player and/or foobar2000?

-- When playing music, how can I send un-modified (but possibly decoded) audio through HDMI? Do I need to install anything more / change any settings to get Windows Media Player or foobar2000 to do this? (I did a quick search and saw mention of something called "ASIO" that I should probably read about when I have time.)

-- When playing games, how can I send un-modified (but possibly decoded) audio through HDMI? Do I need to install anything more / change any settings to achieve this?

-- When transmitting audio to the receiver through WMP or foobar, if it is possible to bypass audio processing within the PC.... and if I have it set up properly.... Will anything happen if I start messing with the EQ settings in WMP or foobar, or will the sound / digital stream remain the same?

-- Is there a way to transmit audio files directly to the receiver to be decoded entirely by the receiver? (I understand this question might require me to look in the receiver manual.)

-- Does the use of DirectShow filters on a PC have any effect on the output, other than decoding certain file types?


It would help a lot if I understood what happens to the audio within the PC once an audio file is decoded.


I really appreciate any insights you can provide!!!! Thank you.

This post has been edited by heyo_speaker: Jan 17 2013, 11:54
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heyo_speaker
post Jan 21 2013, 10:38
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Maybe I should try to be more specific. I had to refresh my memory on a few things.


...Sorry if any of these questions are, like, so dumb that it makes them hard to answer. I'm formulating these questions based on what I've learned so far about digital audio, and it might seem like I'm making some incorrect assumptions or random guesses (if they are in fact incorrect). But that is why I'm hoping someone can point me in the right direction regarding these notions. Bear with me....


In a PC, does each application that produces sound output PCM audio to some software or hardware within the PC that mixes it all together channel-by-channel and then sends it out?

If so, then to avoid any audio processing on the PC, should I just make sure my media player isn't applying any EQ or other effects? Is that the only thing I need to do; is that the proper way to ensure that only the receiver is applying audio effects? Or is something more required?

Do I need to use any special software and/or settings to make sure the PCM coming out through HDMI is unadulterated? Like, is there any digital manipulation going on in Windows to produce that digital output that I might want to work around / improve?

Will all surround-sound channels be preserved when the audio is passed to the receiver via HDMI? (It seems like that must be a "yes", but I'm wondering if I have to do anything special on the PC to achieve that.)

Lastly: is there any reason to buy a sound card if my computer has an HDMI output?


I am a novice about digital audio; I understand some basic concepts but lack a technical understanding of how much of it works. I feel like it should be simple to set things up properly for the best audio and I'm really hoping I don't have to read a textbook to figure out how!

As time permits, I will try to research some of this on my own and refine my questions. (Admittedly, I probably haven't Googled around yet for enough information.)

Thanks!
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icstm
post Jan 21 2013, 17:21
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ok some quick answers:

1) Rx can either be sent audio "bitstreamed" where the Rx decodes or already decoded, but still digitally (PCM/Linear PCM)
2) Most common bitstream formats played by Rx are surround sound by Dolby or DTS, though some might support mp3 via USB
3) Most computers send non movie surround sound via multi-channel PCM, though some computers (MoBos or sound cards) over the last 12 years have supported Dolby encoding
4) By default when a computer sends a bitstream this is the only sound going to the Rx, when it is going PCM, then it is mixed - unless an app asks for "exclusive mode"
sending an mp3 or flac in its pure (but uncompressed) form is often called Bitperfect
5) Even exclusive mode might not provide you bitperfect if the sound goes through Windows mixer, so you need WSAPI or ASIO or the like to ensure the sound correctly gets to the Rx - add-ins for Winamp, foobar or the settings in JRiver help with this
6) Most games for the PC are NOT sending dolby sound, so HDMI is needed for surround sound listening
7) But many HDMI links require a video path before the audio works, so SPDIF cable might be needed for audio only in the digital domain.
6)
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Dynamic
post Jan 21 2013, 17:44
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Don't fret too much about purity of sound these days. Windows 7's default sound handling & resamplers are high enough quality to be transparent and aside from some very low power devices for battery use, most sound chips provide clean linear audio on analogue stereo line output (they may differ in ability to drive low impedance loads like some headphones)

Unless you bypass it, using exlusive mode/ASIO etc, Windows 7's Mixer will convert all sources to 48000 Hz at high bit depth and mix them together. Unlike the default settings in some earlier version of Windows that used kmixer, this uses high quality resampling by default and I believe this does a great job and is audibly transparent.

Support for sound on HDMI seems to vary:
My brother has recently acquired a MiniDP to HDMI adaptor for a MacBook, and hasn't so far discovered audio support.

I've got a DisplayPort to HDMI adapter on my HP laptop and it supports HDMI audio as a separate device. I'm not sure whether the mode supported is a function of the TV or just the laptop's ATI Display Adapter, but in my case supports 44.1 and 48kHz, 16 bit, 2 channels & Dolby Digital, which again is enough for transparent stereo audio (I don't know about the surround conversion in Dolby Digital). (Conversely, my IDT soundcard supports a wider range of sampling rates and bit depths, as does a BOSE L1 Tonematch over USB that I sometimes plug into)

I suspect that if it has a stereo 3.5mm jack, it has as on-board sound chip (integrated into the motherboard), which is likely in this day and age to be very good for the output of stereo audio and at least pretty good for audio input.

Your biggest issue might be if you have sources with more than 2 channels (e.g. 5.1) to ensure they reach the receiver OK. Dolby Digital includes discrete channel AC3, which could come direct from a DVD, for example. It might be possible to hook up certain software (e.g. Windows Media Player) in exclusive mode, to give them sole control of the sound card. I believe DirectSound and ASIO can both achieve this.

Don't hesitate to repeat questions that have been missed. You had a lot of questions, probably too many to get them answered at once.
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heyo_speaker
post Jan 21 2013, 21:19
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Thank you!

Just to clarify, my computer has an HDMI output and my receiver has an HDMI input, so I plan to connect them via HDMI. I think my receiver has built-in decoding for any audio format I would ever use, so I might be able to bitstream. I still need to read the receiver manual.


Here are my conclusions based on your posts. (Please correct me if I'm wrong -- I'm actually kind of in a hurry and may not have read/interpreted things correctly):

-- To ensure no audio channels or quality are lost, I should try to bitstream audio files. (Question: is this a setting I would find in the media player software?)

-- "Exclusive mode" in a media player is just a mode that disables audio output from other programs (but is not necessarily bitstreaming).

-- Sound from games will be output perfectly as long as I'm using HDMI between the computer and receiver.


Questions:

-- icstm: What did you mean by "non-movie surround sound"?

-- Would you recommend WASAPI or ASIO over Windows 7's audio mixer? Is it possible to use those with Windows Media Player?


Thanks again.
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LithosZA
post Jan 21 2013, 22:07
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You don't have to bitstream; HDMI supports 8 channels uncompressed lpcm audio natively. Let the PC do the decoding in my opinion. The number of channels and output formats that your receiver will accept is determined by the EDID sent to your PC. All that I would do is disable all the windows enhancements, set the volume to 100%(0dbFS) and set the output channels to the number of speakers you have, set the speaker types to full range speakers, 16bit or higher, 48Khz or higher. When listening to music you could use foobar2000 in WASAPI exclusive mode to skip the mixer.

This post has been edited by LithosZA: Jan 21 2013, 22:11
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heyo_speaker
post Jan 28 2013, 02:29
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Thanks for the advice.

QUOTE
All that I would do is [...] set the output channels to the number of speakers you have, set the speaker types to full range speakers, 16bit or higher, 48Khz or higher.


Were you referring to settings on the PC or the receiver?

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heyo_speaker
post Jan 28 2013, 10:15
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Never mind! I seem to be finding all of the settings that have been mentioned in the Windows 7 sound settings.
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