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aplay is a simple native ALSA wav player.



   Usage: aplay [OPTION]... [FILE]...
   --help                  help
   --version               print current version
   -l, --list-devices      list all soundcards and digital audio devices
   -L, --list-pcms         list all PCMs defined
   -D, --device=NAME       select PCM by name
   -q, --quiet             quiet mode
   -t, --file-type TYPE    file type (voc, wav, raw or au)
   -c, --channels=#        channels
   -f, --format=FORMAT     sample format (case insensitive)
   -r, --rate=#            sample rate
   -d, --duration=#        interrupt after # seconds
   -s, --sleep-min=#       min ticks to sleep
   -M, --mmap              mmap stream
   -N, --nonblock          nonblocking mode
   -F, --period-time=#     distance between interrupts is # microseconds
   -B, --buffer-time=#     buffer duration is # microseconds
   -A, --avail-min=#       min available space for wakeup is # microseconds
   -R, --start-delay=#     delay for automatic PCM start is # microseconds
                           (relative to buffer size if <= 0)
   -T, --stop-delay=#      delay for automatic PCM stop is # microseconds from xrun
   -v, --verbose           show PCM structure and setup (accumulative)
   -I, --separate-channels one file for each channel
   Recognized sample formats are: S8 U8 S16_LE S16_BE U16_LE U16_BE S24_LE S24_BE U24_LE U24_BE S32_LE S32_BE U32_LE U32_BE FLOAT_LE FLOAT_BE FLOAT64_LE FLOAT64_BE IEC958_SUBFRAME_LE IEC958_SUBFRAME_BE MU_LAW A_LAW IMA_ADPCM MPEG GSM SPECIAL S24_3LE S24_3BE U24_3LE U24_3BE S20_3LE S20_3BE U20_3LE U20_3BE S18_3LE S18_3BE U18_3LE
   Some of these may not be available on selected hardware
   The availabled format shortcuts are:
   -f cd (16 bit little endian, 44100, stereo)
   -f cdr (16 bit big endian, 44100, stereo)
   -f dat (16 bit little endian, 48000, stereo)

Aplay can be used to test, if your pcm outputs are working. Be sure to unmute and set volume for master and pcm channels with ((amixer)) first. It might be a good idea to set a moderate volume level for not damaging your boxes. Then call

   aplay -Dhw:0,0 /boot/vmlinuz!

If you hear a terrible noise, your hardware works. If you have pcm coded files such as .wav files at hand you might want to use these instead.

Note that by using the -d switch you choose card number and pcm output of the card. If you already configured your .asoundrc you may use name aliases defined there.


Device name

It would be nice to have "device name" explained (i.e. hw:0,0)

It's ALSA-geek-speak for the initial hardware device that will convert digitzed sample to a smooth analog voltage or vice-versa. See below.

aplay -D will accept the output of aplay -L as device names. So, for example, my output has the lines

    HDMI Audio Output

The top line of that (hdmi:CARD=HDMI,DEV=0) will be directly accepted by aplay -D like so:

aplay -Dhdmi:CARD=HDMI,DEV=0

It would be even nicer if the --help and man output of aplay would define what NAME of "--device=NAME" should be set to. Then people would not have to search the Internet to find out.

It would be even nicer still if the device name appeared in the output of aplay -l. Surely that's pretty fundamental - when a user lists available devices give them the names that you expect to see back. Probably some UI design principle of least surprise applies!

What's a PCM output?

PCM stands for Pulse Code Modulation where analog volume is sampled at so many kilohertz (1000s times per second) and a snapshot of the voltage at that point becomes a digitzed sample. PCM output would refer to the hardware part of a soundcard that takes a digital waveform (that may have been a wav or mp3 file on a hard drive) and converts it back into a smooth analog oscillating voltage that can produce sound from speakers or headphone, once amplified to a suitable level.