Unable to Run

[austinphilp]

gettting an error
error opening stream: Operation not permitted
cava: pcm_params.c:2288: snd_pcm_hw_refine: Assertion `pcm && params' failed.
Aborted (core dumped)
upon trying to start the program.

[ghost]

Try using mpd's FIFO: cava -i fifo -p /tmp/mpd.fifo (/tmp/mpd.fifo is path to your mpd's fifo)

[karlstav]

Are you using a loopback interface?

If so are you using the correct alsa device with cava?

Cava uses hw:1,1 by default. can you give me the output of your 'aplay -l'?

[austinphilp]

**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC1150 Analog [ALC1150 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 1: ALC1150 Digital [ALC1150 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 9: HDMI 3 [HDMI 3]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

[austinphilp]

using celestrial walrus' suggestion(except replacing mpd's fifo with piano bar's) works to start the application but the bars stay at minimal height and don't move. the connection to the fifo is comfirmed by pianobar

[karlstav]

If you want to capture audio straight fom the output (not just mic or line-in), you must create an ALSA loopback interface, then output the audio simultaneously to both the loopback and your normal interface (either with asounc.conf settings or pulseaudio's "combined-sink"). Look in the readme for more info.

Reading about pianopar's fifo here http://linux.die.net/man/1/pianobar, it doesn't look like pianobar's fifo is an audio output, but a control input. So I guess your stuck with the options above.

[livibetter]

I think I just discovered an interesting way to test and run with FIFO for very rough testing. I don't have MPD and have no idea what data MPD feed into FIFO, never ran cava with FIFO input before.

I was thinking about send in some PCM audio, though not sure if that would work, better to check the code first before wasting time. So I opened up the cava.c and skimmed through the fifomusic function.

Immediately, I typed in this:

./cava -i fifo -p /dev/urandom

@austinphilp I believe that you could test with this, if you see bars bouncing that means cava does work with FIFO. As @karlstav stated, either you get some input or switch to MPD. (Does MPD have plugin for Pandora?)

Off-topic: since urandom is uniform, I was expecting to see most of bars are somewhat leveled, but they ain't. More or less like an uphill slope. Hmm, what are those frequency ranges of the bands/bars?

(2015-04-29T11:43:24Z edited: I might be presuming the RNG's property over to the audio wrong)

[karlstav]

@livibetter that's indeed an interesting way to check the fifo input.

The reason for it not being level is because cava equalizes the Fourier-transformed audio signal quite heavily. If it didn't the higher frequencies would be almost invisible. I'm still not 100% sure why this is. But i have three theories:

1. the FFT does something with the audio signal
2. I'm using the fftw library wrong
3. In most audio treble is generally lower then base in amplitude value.

[ghost]

@livibetter see #8

[ghost]

@livibetter @karlstav cava -i fifo -p /dev/null -b 60 gives somewhat weird output. /dev/zero is OK.

[livibetter]

@CelestialWalrus the read reads zero bytes, so every iteration, whatever in buf[] is used, which is never initialized, if:

memset(buf, (signed char) 0, 1024);

It would look like using /dev/zero.

I think that else clause in the loop should be like:

else if (bytes > 0) {
  // ...
} else {
  // read zero bytes, sleep some time, or hogging CPU
}

---

Apologizing to @austinphilp, guess we are hijacking with /dev/*.

After @CelestialWalrus mentioned, /dev/null, I tried this:

cava -i fifo -p /dev/stdin

Press some keys, then [Enter] as a few times. Just for fun.

[karlstav]

closing this as it sort of drifted of topic. I hope @austinphilp made it work eventually, if you need more help just reopen or send me an email.