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Topic: Proper setting for output: Stereo->Dolby Pro Logic (Read 4419 times) previous topic - next topic
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Proper setting for output: Stereo->Dolby Pro Logic

Hello.  I have a dedicated htpc connected to an old Dolby Pro Logic system via analog stereo output.  I want to get the best sound out of the stereo so I have a couple of questions for video and audio playback based on the software i use.

Btw, my motherboard is an nForce with soundstorm APU.

1)  I know that the soundstorm APU converts audio to signals to Dolby Digital 5.1 on the hardware.  I would like to know since I am doing analog stereo output, is there any setting in NVMixer/registry I need to change?  Under NVMixer, I currently have output speaker setup as "2 Speaker Stereo (Cinesurround)".  Since I dont have 5.1, encoding the signal to DD5.1 seems unnecessary so is there a setting that will bypass this or is the apu smart enough to know that since my output type is stereo analog, it wont reencode the sound?

2) For ffdshow audio output, are there any special settings I need for dolby pro logic?  For example, I know in the ffdShow settings audio panel, there is a "Mixer" tab that allows you to encode the audio to "Dolby Pro Logic" format.  Should I enable this?  If so, will having the soundstorm APU also effect sound as well.  If i do enable it, the output path of the sound would look like this

Code: [Select]
audio format (mp3) -> ffdshow processor/decoder -> soundstorm apu -> dolby pro logic system


I would like to remove unnecessary processing so I was wondering whether or not to enable the Mixer/DDPL option.

3) For DVD (AC3) audio, I have intervideo codecs setup to output as "Stereo"  There is another option for output in intervideo codec for "Dolby Surround Compatible".  Does that apply to the Pro Logic Systems?  Are there any additional registry settings I could try

4) Under winamp, I have setup MP3 input using otachan's mpg123 and output set up to kernel streaming.  Should I get any additional DSP plugins? For example i read this this forum as a guide and it refers to a Realtime Dolby Pro-Logic Encoder. DSP plugin for winamp.  Should I use that dsp to encode the output to DPL before I pass it out.


To sum it all up, what I am really interested in knowing is that if I take a any audio file on my system (lets say an MP3 file) should I reencode the sound to a Dolby Pro-Logic format before sending it out to the soundstorm apu, which will send the output to my Pro logic sound system via analog stereo??

Thanx.

iTCHY

Proper setting for output: Stereo->Dolby Pro Logic

Reply #1 –
1) I know that the soundstorm APU converts audio to signals to Dolby Digital 5.1 on the hardware.

This is probably done for the SPDIF output. There would be an incredible waste of processing power and quality to convert everything that is played to AC3 on the fly for output unless there is an external decoder that needs to be feed with an digital AC3 signal.

2) For ffdshow audio output, are there any special settings I need for dolby pro logic?
If the stereo is already DPL encoded, then u do not need to and MUST NOT alter the stereo signal (by adding DSPs or anything else), cause the decoder is gonna be fed with this signal that must remain as original as possible to be properly decoded.
If the file is a multichannel WAV or AC3, then u should used a DPL encoding matrix, that will output the multicchannel to a stereo signal to be decoded by the Prologic system.
Dolby Pro Logic        Left  Right  Center Rear Left Rear Right
Left Total        1.000 0.000  0.707  -0.707    0.707
Right Total      0.000 1.000  0.707  0.707    -0.707
"Screw u guys, I´m going home."

Proper setting for output: Stereo->Dolby Pro Logic

Reply #2 –
Quote
1) I know that the soundstorm APU converts audio to signals to Dolby Digital 5.1 on the hardware.

This is probably done for the SPDIF output. There would be an incredible waste of processing power and quality to convert everything that is played to AC3 on the fly for output unless there is an external decoder that needs to be feed with an digital AC3 signal.

Quote
2) For ffdshow audio output, are there any special settings I need for dolby pro logic?

If the stereo is already DPL encoded, then u do not need to and MUST NOT alter the stereo signal (by adding DSPs or anything else), cause the decoder is gonna be fed with this signal that must remain as original as possible to be properly decoded.
If the file is a multichannel WAV or AC3, then u should used a DPL encoding matrix, that will output the multicchannel to a stereo signal to be decoded by the Prologic system. DO enable the DPL matrix.
Dolby Pro Logic        Left      Right    Center    Rear Left    Rear Right
Left Total                1.000    0.000    0.707        -0.707          0.707
Right Total              0.000    1.000    0.707        0.707        -0.707

Quote
3) For DVD (AC3) audio, I have intervideo codecs setup to output as "Stereo" There is another option for output in intervideo codec for "Dolby Surround Compatible". Does that apply to the Pro Logic Systems? Are there any additional registry settings I could try?

Yes to the first, No to the second. Dolby Surround Compatible will create a DPL matrix-encoded stereo. No need for aditional settings.

Quote
4) Under winamp, I have setup MP3 input using otachan's mpg123 and output set up to kernel streaming. Should I get any additional DSP plugins? For example i read this this forum as a guide and it refers to a Realtime Dolby Pro-Logic Encoder. DSP plugin for winamp. Should I use that dsp to encode the output to DPL before I pass it out.

Only if your using multichannel input. If the source is stereo non-matrix encoded, it CAM NOT be DPL matrix-encoded thru Winamp. If the source is DPL matrix-encoded, then try to render as clean as possible (no modifications, no DSP, no nothing).
"Screw u guys, I´m going home."

Proper setting for output: Stereo->Dolby Pro Logic

Reply #3 –
I know its been a while a since I posted.  Just wanted to say thanks Skelsgard for your input.  Very much overdue.  Quality rocks thanks to your suggestions.
 

Proper setting for output: Stereo->Dolby Pro Logic

Reply #4 –
Your welcome, dude. Good to hear u got it working.
"Screw u guys, I´m going home."