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--- chumbyhackerboard:audio [2010/08/30 17:45]
ladyada created
+++ chumbyhackerboard:audio [2010/08/30 19:37]
ladyada
@@ Line 8: / Line 8: @@
 MP3's will play in the background. To kill **btplay** run **killall btplay**
-Audio will play through the headphone jack at max volume, just plug in your favorite headphones!
+Audio will play through the headphone jack at max volume, just plug in your favorite headphones! (Warning: it may be really loud!)
 ====== Playing remote MP3s! ======
-You can also stream music with **btplay**, just stick a URL in there!
+You can also stream music with **btplay**, just stick a URL in there! Of course, you will have to have network capability up and running first
 {{:chumbyhackerboard:soma.gif|}}
-Just as before, just plug into the headphone jack for stereo listening enjoyment
+Just as before, just plug into the headphone jack to verify its working. (Warning: it may be really loud!)
+====== Splitting out the A/V ======
+The headphone jack is not actually just audio - its actually Audio and Video. That means that you if you just plug headphones you'll notice some buzzing - thats you listening to the video! Now if you're in a Cronenberg film this is probably OK but for most of us its very annoying! There are two solutions. One is to split out the 3 signals into RCA jacks (with a camcorder cable)
+{{http://www.adafruit.com/images/medium/avcable_MED.jpg}}
+and then recombining with an RCA Y cable (such as [[http://www.sweetwater.com/store/detail/YRA154/|a Y female-RCA to male 3.5mm]] or [[http://www.sweetwater.com/store/detail/CMR206/|this]]
+**Note** our A/V cables split out the signals as such - **Red** is Video, **White** and **Yellow** are stereo line-level audio which is not what you would expect!
+**Note Note** apparently like every A/V cable is slightly different. If you get one, try different colors to figure out which ones have audio coming out of them and which have video.
+====== Using the Mixer ======
+If you want to change the volume of the headphones, you'll need to run the audio mixer software **amixer**
+{{:chumbyhackerboard:amixer.gif|}}
+You can get and change the HeadPhone volume (**HP**) by running **amixer sget HP** and **amixer sset HP**
+{{:chumbyhackerboard:sgethp.gif|}}
+To set the volume to 1/2 for example, do this **amixer sset HP 64**
+{{:chumbyhackerboard:ssethp.gif|}}
+====== Speaker ======
+The iMX.233 has a built-in mono speaker amplifier that can push up to 2W into a 4 ohm speaker! To use, connect the two speaker inputs into the **Spkr** 0.1" JST connection near the power jack. You can use either pin, they are not polarized as it is a mono output. Don't ground either of the speaker pins, they are "bridge tied" to improve output volume
+The chumby is 'switched' by default - if you connect headphones into the jack, the speaker will turn off and vice versa.
+If you want the speaker on even with the headphone plugged in, you can use **amixer cset**
+{{:chumbyhackerboard:amixercset.gif|}}
+For example, the Speaker Playback Switch is off, so we turn it on with **amixer cset numid=4 on** to reactivate

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