feat(opus): add opus to StsdBox and implement read/write

src/mp4box/opus.rs

@@ -38,6 +38,38 @@ impl Mp4Box for OpusBox {
     }
 }
 
+impl<R: Read + Seek> ReadBox<&mut R> for OpusBox {
+    fn read_box(reader: &mut R, size: u64) -> Result<Self> {
+        box_start(reader)?;
+        reader.read_u32::<BigEndian>()?; // reserved
+        reader.read_u16::<BigEndian>()?; // reserved
+        let data_reference_index = reader.read_u16::<BigEndian>()?;
+        reader.read_u64::<BigEndian>()?; // reserved
+        let channelcount = reader.read_u16::<BigEndian>()?;
+        let samplesize = reader.read_u16::<BigEndian>()?;
+        reader.read_u32::<BigEndian>()?; // reserved
+        let samplerate = reader.read_u32::<BigEndian>()?;
+
+        let num_read = 36;
+        if num_read > size {
+            return Err(Error::InvalidData("opus box is too small"));
+        }
+        let remaining = num_read.saturating_sub(size);
+
+        // todo: if the size of DopsBox becomes variable, then the size of
+        // OpusBox will be needed to determine what size to pass to DopsBox::read_box()
+        let dops = DopsBox::read_box(reader, remaining)?;
+
+        Ok(Self {
+            data_reference_index,
+            channelcount,
+            samplesize,
+            samplerate: FixedPointU16::new_raw(samplerate),
+            dops,
+        })
+    }
+}
+
 impl<W: Write> WriteBox<&mut W> for OpusBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let mut written = 0;
@@ -50,12 +82,8 @@ impl<W: Write> WriteBox<&mut W> for OpusBox {
         writer.write_u16::<BigEndian>(self.data_reference_index)?;
         written += 2;
 
-        writer.write_u16::<BigEndian>(0)?; // reserved
-        written += 2;
-        writer.write_u16::<BigEndian>(0)?; // reserved
-        written += 2;
-        writer.write_u32::<BigEndian>(0)?; // reserved
-        written += 4;
+        writer.write_u64::<BigEndian>(0)?; // reserved
+        written += 8;
         writer.write_u16::<BigEndian>(self.channelcount)?;
         written += 2;
         writer.write_u16::<BigEndian>(self.samplesize)?;
@@ -102,6 +130,33 @@ impl Mp4Box for DopsBox {
     }
 }
 
+impl<R: Read + Seek> ReadBox<&mut R> for DopsBox {
+    fn read_box(reader: &mut R, size: u64) -> Result<Self> {
+        if size < 19 {
+            return Err(Error::InvalidData("Dops box size too small"));
+        }
+        box_start(reader)?;
+        let version = reader.read_u8()?;
+        let num_channels = reader.read_u8()?;
+        let pre_skip = reader.read_u16::<BigEndian>()?;
+        let input_sample_rate = reader.read_u32::<BigEndian>()?;
+        let output_gain = reader.read_i16::<BigEndian>()?;
+
+        // todo: should this be used?
+        let _channel_mapping_family = reader.read_u8()?;
+
+        Ok(DopsBox {
+            version,
+            pre_skip,
+            input_sample_rate,
+            output_gain,
+            channel_mapping_family: ChannelMappingFamily::Family0 {
+                stereo: num_channels == 2,
+            },
+        })
+    }
+}
+
 // https://github.com/Wicpar/async-mp4/blob/master/src/mp4box/dops.rs
 impl<W: Write> WriteBox<&mut W> for DopsBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {

src/mp4box/stsd.rs

@@ -25,8 +25,21 @@ pub struct StsdBox {
 
     #[serde(skip_serializing_if = "Option::is_none")]
     pub tx3g: Option<Tx3gBox>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub opus: Option<OpusBox>,
 }
 
+// todo: all the Options in StsdBox may be better as an enumeration
+// pub enum StsdChildBox {
+//     Avc1(Avc1Box),
+//     Hev1(Hev1Box),
+//     Vp09(Vp09Box),
+//     Mp4a(Mp4aBox),
+//     Tx3g(Tx3gBox),
+//     Opus(OpusBox),
+// }
+
 impl StsdBox {
     pub fn get_type(&self) -> BoxType {
         BoxType::StsdBox
@@ -44,6 +57,8 @@ impl StsdBox {
             size += mp4a.box_size();
         } else if let Some(ref tx3g) = self.tx3g {
             size += tx3g.box_size();
+        } else if let Some(ref opus) = self.opus {
+            size += opus.box_size();
         }
         size
     }
@@ -81,6 +96,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
         let mut vp09 = None;
         let mut mp4a = None;
         let mut tx3g = None;
+        let mut opus = None;
 
         // Get box header.
         let header = BoxHeader::read(reader)?;
@@ -107,6 +123,9 @@ impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
             BoxType::Tx3gBox => {
                 tx3g = Some(Tx3gBox::read_box(reader, s)?);
             }
+            BoxType::OpusBox => {
+                opus = Some(OpusBox::read_box(reader, s)?);
+            }
             _ => {}
         }
 
@@ -120,6 +139,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
             vp09,
             mp4a,
             tx3g,
+            opus,
         })
     }
 }
@@ -143,6 +163,8 @@ impl<W: Write> WriteBox<&mut W> for StsdBox {
             mp4a.write_box(writer)?;
         } else if let Some(ref tx3g) = self.tx3g {
             tx3g.write_box(writer)?;
+        } else if let Some(ref opus) = self.opus {
+            opus.write_box(writer)?;
         }
 
         Ok(size)