Channel descriptor implementation

src/wavereader.rs

@@ -5,7 +5,7 @@ use super::parser::Parser;
 use super::fourcc::{FourCC, FMT__SIG,DATA_SIG, BEXT_SIG, JUNK_SIG, FLLR_SIG};
 use super::errors::Error as ParserError;
 use super::raw_chunk_reader::RawChunkReader;
-use super::fmt::WaveFmt;
+use super::fmt::{WaveFmt, ChannelDescriptor, ChannelMask};
 use super::bext::Bext;
 use super::audio_frame_reader::AudioFrameReader;
 use super::chunks::ReadBWaveChunks;
@@ -132,6 +132,37 @@ impl<R: Read + Seek> WaveReader<R> {
         self.chunk_reader(BEXT_SIG, 0)?.read_bext()
     }
 
+    /// Describe the channels in this file
+    /// 
+    /// Returns a vector of channel descriptors, one for each channel
+    /// 
+    /// ```rust
+    /// # use bwavfile::WaveReader;
+    /// # use bwavfile::ChannelMask;
+    /// let mut f = WaveReader::open("tests/media/pt_24bit_51.wav").unwrap();
+    /// 
+    /// let chans = f.channels().unwrap();
+    /// assert_eq!(chans[0].index, 0);
+    /// assert_eq!(chans[0].speaker, ChannelMask::FrontLeft);
+    /// assert_eq!(chans[3].index, 3);
+    /// assert_eq!(chans[3].speaker, ChannelMask::LowFrequency);
+    /// assert_eq!(chans[4].speaker, ChannelMask::BackLeft);
+    /// ```
+    pub fn channels(&mut self) -> Result<Vec<ChannelDescriptor>, ParserError> {
+        
+        let format = self.format()?;
+        let channel_masks : Vec<ChannelMask> = match (format.channel_count, format.extended_format) {
+            (1,_) => vec![ChannelMask::FrontCenter],
+            (2,_) => vec![ChannelMask::FrontLeft, ChannelMask::FrontRight],
+            (n,Some(x)) => ChannelMask::channels(x.channel_mask, n),
+            (n,_) => vec![ChannelMask::DirectOut; n as usize]
+        };
+
+        Ok( (0..format.channel_count).zip(channel_masks)
+            .map(|(i,m)| ChannelDescriptor { index: i, speaker:m, adm_track_audio_ids: vec![] } )
+            .collect() )
+    }
+
     /**
     * Validate file is readable.
     *