Playing a wav file using pulseaudio APIs?

问题:

For example, this is how to use pulseaudio: http://freedesktop.org/software/pulseaudio/doxygen/pacat-simple_8c-example.html

but I'm not clear on how I can simply play a wav file or an ogg file for that matter.

回答1:

The example code will play raw PCM data from a file. The trick is getting the data from a wav file into this format. The Microsoft wav files look like this:

https://ccrma.stanford.edu/courses/422/projects/WaveFormat/

Wav files just store raw PCM data. You just have to strip the header off the wav file and dump the rest into a file (extension is irrelevant, but I like to use .raw). That is, you can write a program that either: copies everything past byte 44 into a new file, or just read everything after that directly into a buffer. Pass either format to the pulseaudio example and you should be good to go.

Things to look out for: the endianness of the file and your system; bitdepth; number of channels. These are in the wav header and you may have to read them and tell pa_simple before you play the data. Although, I'm not sure if pa_simple detects this information for you. I like to work with the asynchronous implementation and there I just input the format directly.

-E

回答2:

linux-commands-examples - pacat

pacat --list-file-formats

aiff    AIFF (Apple/SGI)
au  AU (Sun/NeXT)
avr AVR (Audio Visual Research)
caf CAF (Apple Core Audio File)
flac    FLAC (Free Lossless Audio Codec)
htk HTK (HMM Tool Kit)
iff IFF (Amiga IFF/SVX8/SV16)
mat MAT4 (GNU Octave 2.0 / Matlab 4.2)
mat MAT5 (GNU Octave 2.1 / Matlab 5.0)
mpc MPC (Akai MPC 2k)
oga OGG (OGG Container format)
paf PAF (Ensoniq PARIS)
pvf PVF (Portable Voice Format)
raw RAW (header-less)
rf64    RF64 (RIFF 64)
sd2 SD2 (Sound Designer II)
sds SDS (Midi Sample Dump Standard)
sf  SF (Berkeley/IRCAM/CARL)
voc VOC (Creative Labs)
w64 W64 (SoundFoundry WAVE 64)
wav WAV (Microsoft)
wav WAV (NIST Sphere)
wav WAVEX (Microsoft)
wve WVE (Psion Series 3)
xi  XI (FastTracker 2)