diff --git a/src/mp4box/mp4a.rs b/src/mp4box/mp4a.rs
index fc8ec69..d654cbc 100644
--- a/src/mp4box/mp4a.rs
+++ b/src/mp4box/mp4a.rs
@@ -53,11 +53,11 @@ impl Mp4aBox {
 
 impl Mp4Box for Mp4aBox {
     fn box_type(&self) -> BoxType {
-        return self.get_type();
+        self.get_type()
     }
 
     fn box_size(&self) -> u64 {
-        return self.get_size();
+        self.get_size()
     }
 
     fn to_json(&self) -> Result<String> {
@@ -159,8 +159,7 @@ impl Mp4Box for EsdsBox {
     }
 
     fn summary(&self) -> Result<String> {
-        let s = format!("");
-        Ok(s)
+        Ok(String::new())
     }
 }
 
@@ -471,13 +470,45 @@ impl Descriptor for DecoderSpecificDescriptor {
     }
 }
 
+fn get_audio_object_type(byte_a: u8, byte_b: u8) -> u8 {
+    let mut profile = byte_a >> 3;
+    if profile == 31 {
+        profile = 32 + ((byte_a & 7) | (byte_b >> 5));
+    }
+
+    profile
+}
+
+fn get_chan_conf<R: Read + Seek>(reader: &mut R, byte_b: u8, freq_index: u8, extended_profile: bool) -> Result<u8> {
+    let chan_conf;
+    if freq_index == 15 {
+        // Skip the 24 bit sample rate
+        let sample_rate = reader.read_u24::<BigEndian>()?;
+        chan_conf = ((sample_rate >> 4) & 0x0F) as u8;
+    } else if extended_profile {
+        let byte_c = reader.read_u8()?;
+        chan_conf = (byte_b & 1) | (byte_c & 0xE0);
+    } else {
+        chan_conf = (byte_b >> 3) & 0x0F;
+    }
+
+    Ok(chan_conf)
+}
+
 impl<R: Read + Seek> ReadDesc<&mut R> for DecoderSpecificDescriptor {
     fn read_desc(reader: &mut R, _size: u32) -> Result<Self> {
         let byte_a = reader.read_u8()?;
         let byte_b = reader.read_u8()?;
-        let profile = byte_a >> 3;
-        let freq_index = ((byte_a & 0x07) << 1) + (byte_b >> 7);
-        let chan_conf = (byte_b >> 3) & 0x0F;
+        let profile = get_audio_object_type(byte_a, byte_b);
+        let freq_index;
+        let chan_conf;
+        if profile > 31 {
+            freq_index = (byte_b >> 1) & 0x0F;
+            chan_conf = get_chan_conf(reader, byte_b, freq_index, true)?;
+        } else {
+            freq_index = ((byte_a & 0x07) << 1) + (byte_b >> 7);
+            chan_conf = get_chan_conf(reader, byte_b, freq_index, false)?;
+        }
 
         Ok(DecoderSpecificDescriptor {
             profile,
diff --git a/tests/lib.rs b/tests/lib.rs
index 0fa0b25..e40fe2b 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,16 +1,11 @@
-use mp4::{AudioObjectType, AvcProfile, ChannelConfig, MediaType, SampleFreqIndex, TrackType};
+use mp4::{AudioObjectType, AvcProfile, ChannelConfig, MediaType, Mp4Reader, SampleFreqIndex, TrackType};
 use std::fs::File;
 use std::io::BufReader;
 use std::time::Duration;
 
 #[test]
 fn test_read_mp4() {
-    let filename = "tests/samples/minimal.mp4";
-    let f = File::open(filename).unwrap();
-    let size = f.metadata().unwrap().len();
-    let reader = BufReader::new(f);
-
-    let mut mp4 = mp4::Mp4Reader::read_header(reader, size).unwrap();
+    let mut mp4 = get_reader("tests/samples/minimal.mp4");
 
     assert_eq!(2591, mp4.size());
 
@@ -119,3 +114,31 @@ fn test_read_mp4() {
     assert_eq!(track2.channel_config().unwrap(), ChannelConfig::Mono);
     assert_eq!(track2.bitrate(), 67695);
 }
+
+#[test]
+fn test_read_extended_audio_object_type() {
+    // Extended audio object type and sample rate index of 15
+    let mp4 = get_reader("tests/samples/extended_audio_object_type.mp4");
+
+    let track = mp4.tracks().get(&1).unwrap();
+    assert_eq!(track.track_type().unwrap(), TrackType::Audio);
+    assert_eq!(track.media_type().unwrap(), MediaType::AAC);
+    assert_eq!(
+        track.audio_profile().unwrap(),
+        AudioObjectType::AudioLosslessCoding
+    );
+    assert_eq!(
+        track.trak.mdia.minf.stbl.stsd.mp4a.as_ref().unwrap().esds.as_ref().unwrap().es_desc.dec_config.dec_specific.freq_index,
+        15
+    );
+    assert_eq!(track.channel_config().unwrap(), ChannelConfig::Stereo);
+    assert_eq!(track.bitrate(), 839250);
+}
+
+fn get_reader(path: &str) -> Mp4Reader<BufReader<File>> {
+    let f = File::open(path).unwrap();
+    let f_size = f.metadata().unwrap().len();
+    let reader = BufReader::new(f);
+
+    mp4::Mp4Reader::read_header(reader, f_size).unwrap()
+}
\ No newline at end of file
diff --git a/tests/samples/extended_audio_object_type.mp4 b/tests/samples/extended_audio_object_type.mp4
new file mode 100644
index 0000000..3d1a711
Binary files /dev/null and b/tests/samples/extended_audio_object_type.mp4 differ