simplemad is a simple interface for libmad, the MPEG audio decoding library.
simplemad::decode
takes a byte-oriented source and returns a channel that
yields Result<Frame, MadError>
. If you only need to decode part of a file,
you can also use simplemad::decode_interval
.
Frame
and MadError
correspond to libmad's struct types mad_pcm
and
mad_error
, respectively. Samples are signed 32 bit integers and are organized
into channels. For stereo, the left channel is channel 0.
MP3 files often begin with metadata, which will cause libmad to produce errors. It is safe to ignore these errors until libmad reaches audio data and starts producing frames.
```Rust use simplemad::decode; use std::fs::File; use std::path::Path;
let path = Path::new("samplemp3s/constantstereo_128.mp3"); let file = File::open(&path).unwrap(); let mut decoder = decode(file);
for decodingresult in decoder.iter() { match decodingresult { Err(e) => println!("Error: {:?}", e), Ok(frame) => { println!("Frame sample rate: {}", frame.sample_rate); println!("First audio sample (left channel): {}", frame.samples[0][0]); println!("First audio sample (right channel): {}", frame.samples[1][0]); } } } ```
To decode from 30 seconds to 60 seconds, use decode_interval
and provide the start and end time in milliseconds.
Rust
let mut partial_decoder = decode_interval(file, 30_000_f64, 60_000_f64);
First, install libmad. Links to the source can be found below. It might be
necessary to apply the patch found in this guide. Then add simplemad =
"0.4.0"
to the list of dependencies in your Cargo.toml.
http://bendykst.github.io/doc/simplemad/index.html
libmad (FTP: ftp://ftp.mars.org/pub/mpeg/ or SourceForge)
libc
MIT