How to use Pandora as an amplifier

[TrashyMG]

Or something is wrong with your setup still..

 

[peelie]

anyway to troubleshoot that?

 

[TrashyMG]

Could check your connecting cables first.. plug the audio source with the same cables into another amplifying device..

Double check if your setup properly in the mixer. have AUXL and AUXR enabled and the Mic inputs disabled..

 

[WizardStan]

What you are describing cannot be attributed to hardware. There may ALSO be a problem with the hardware, but "buffer underrun" means that aplay is trying to read data faster than arecord is streaming it. If you do not plug in anything, arecord will still stream silence, just a continuous feed of zeros, which aplay will dutifully (not) play. If you are getting under runs, that means arecord isn't streaming anything.

Not sure how deep your knowledge is so forgive me if anything sounds condescending.

Open a terminal and type this: "arecord -D hw:0,1 > test.raw", and then hit enter. Wait a few seconds and then hit "ctrl-c" (the control button and the C key at the same time). Type "ls -lrt" and hit enter and you should see a list of files with "test.raw" being at the bottom. There should be a number just before the date in that line, that's the file size. What is that file size? If it's zero, or very close, then there's a problem. It should be around 20000 or so if it is working properly, more if you left it running for longer.

Also when you run the "arecord" command, can you copy what it says (something like "Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono") or if there is any error?

When finished, make sure to run "rm test.raw" to delete the file.

 

[TrashyMG]

There is always a few buffer underrun messages when first kicking off that command, but it stabilizes.. if he's seeing nothing but those errors and keeps coming up then I'd say he has an issue.

 

[peelie]

What you are describing cannot be attributed to hardware. There may ALSO be a problem with the hardware, but "buffer underrun" means that aplay is trying to read data faster than arecord is streaming it. If you do not plug in anything, arecord will still stream silence, just a continuous feed of zeros, which aplay will dutifully (not) play. If you are getting under runs, that means arecord isn't streaming anything.


Not sure how deep your knowledge is so forgive me if anything sounds condescending.


Open a terminal and type this: "arecord -D hw:0,1 > test.raw", and then hit enter. Wait a few seconds and then hit "ctrl-c" (the control button and the C key at the same time). Type "ls -lrt" and hit enter and you should see a list of files with "test.raw" being at the bottom. There should be a number just before the date in that line, that's the file size. What is that file size? If it's zero, or very close, then there's a problem. It should be around 20000 or so if it is working properly, more if you left it running for longer.


Also when you run the "arecord" command, can you copy what it says (something like "Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono") or if there is any error?


When finished, make sure to run "rm test.raw" to delete the file.

i get a zero file size for test.raw

after running command i get:


Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
arecord: set_params:979: Sample format non available
thanks

 

[WizardStan]

Strange, but ok. What if we specify a different format?

arecord -f CD -D hw:0,1 test.rawOk, yes, that apparently works, at least on my BeagleBoard. It should output raw audio to the file test.raw which you can then play with "aplay test.raw".If these two steps, recording and then playback, work individually then it's something weird going on when combined.

You can try increasing the buffer size, make it 2000 instead of 100. It will introduce a very very small amount of lag, but 2000 out of 44100 is so small that you shouldn't notice.

 

[peelie]

Strange, but ok. What if we specify a different format?


arecord -f CD -D hw:0,1 test.raw
Ok, yes, that apparently works, at least on my BeagleBoard. It should output raw audio to the file test.raw which you can then play with "aplay test.raw".
If these two steps, recording and then playback, work individually then it's something weird going on when combined.


You can try increasing the buffer size, make it 2000 instead of 100. It will introduce a very very small amount of lag, but 2000 out of 44100 is so small that you shouldn't notice.

raw audio records

tried with increased buffer size and getting stereo but with noticeable delay but then stereo effect switches off, very strange;

 

[TrashyMG]

Odd my command works on all my Pandoras at default speeds..

 

[Askarus]

I can confirm what TrashyMg says.

There are a few buffer underrun messages and then it's stable.

Didn't try with default speed as I always have overclocked.

Sound is stereo. I can clearly hear it.

Will try Sunvox as soon as I find time.

Unfortunately it's not the time for it now.

 

[notaz]

This could also happen on old kernel.

 

[cube48]

After getting the TV-out cable from Dragonbox, I tried to route the signal through SunVox. Strangely I could hear the line-input even without setting anything in the OS mixer. There was just some buzz along with the signal but I knocked it down by turning the volume down on the Master and Mic-In.

I've tried to route the signal with arecord > aplay with TrashyMG's command (also disabling the mic-in in the OS mixer). Then I tried various setting of SunVox audio input devices (hw:0,1; hw:0,0) but none of them took the line-in signal from the cables. When the mic-in is on in the OS mixer, I can take it's signal in SunVox with hw:0,1 address and process it.

TrashyMG's command directs the signal to the speakers/headphone output. Is there a way to route the line-in signal from the cable to the application? Some sort of virtual/soft port that can be set within an app?

 

[Loonie]

Pandora as a headphone amplifier? Brilliant idea. I was looking into making a simple one for PS3 usage at night, since the TV has no audio out, but I might have to try this. I suppose the only disadvantage would be a little latency, but the sound quality would be fantastic.

 

[Askarus]

I didn't notice big latency.

It's great.

 

[cube48]

Did you guys managed to boost the signal? I didn't succeed. It only plays the level comparable to what goes into Pandora (tried the phone output). Pandora volume wheel and OS mixer can't boost it up.

 

[Askarus]

Sorry to bring up this old thread.

Did you guys managed to boost the signal? I didn't succeed. It only plays the level comparable to what goes into Pandora (tried the phone output). Pandora volume wheel and OS mixer can't boost it up.

I have the same now.

It did work before.

I'm 100% sure.

Now it stopped working on the classic and Giga Pandora.

If I set the mixer to max/min it doesn't change anything.

Only the vloume wheel does have an impact.

Seems like it doesn't go through the amplifier any more (or it doesn't work any more).

It's less hear able now through the Pandora.

Also if I press CTRL+C in the Terminal the command quits but the sound still keeps playing through Pandora for quite a while.

If I enter "alsamixer" in terminal I can only set "Master" and "analog".

Can't access the others (they are shown).

(I can only bring themup by pressing F5. Pressing F2-F4 crashes and brings back the Terminal).

I'll try a reflash on my CC Pandora today.

Any idea anyone?

 

[Linux-SWAT]

I can have audio from line-in to headphones, but there's a loss of volume.

Found no way to increase it.