Implement EBML date element

src/ebml/error.rs

@@ -59,6 +59,10 @@ pub enum ErrorKind {
     /// which is not allowed.
     FloatWidthIncorrect,
 
+    /// A date element has declared a length that is not 0 or 8 octets,
+    /// which is not allowed.
+    DateWidthIncorrect,
+
     /// A string element contains non-UTF-8 data, which is not allowed.
     StringNotUtf8,
 

src/ebml/parse.rs

@@ -58,6 +58,25 @@ impl<'a> EbmlParsable<'a> for f64 {
     }
 }
 
+/// Date Element. Contains the number of nanoseconds since
+/// 2001-01-01T00:00:00.000000000 UTC.
+///
+/// This struct can't really do anything by itself. If you want
+/// date/time handling, you should use a crate like [time].
+///
+/// [time]: https://crates.io/crates/time
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Date(pub i64);
+
+impl<'a> EbmlParsable<'a> for Date {
+    fn try_parse(data: &'a [u8]) -> Result<Self, ErrorKind> {
+        match data.len() {
+            0 | 8 => i64::try_parse(data).map(Date),
+            _ => Err(ErrorKind::DateWidthIncorrect),
+        }
+    }
+}
+
 impl<'a> EbmlParsable<'a> for String {
     fn try_parse(data: &'a [u8]) -> Result<Self, ErrorKind> {
         String::from_utf8(data.to_vec()).map_err(|_| ErrorKind::StringNotUtf8)

src/elements.rs

@@ -7,8 +7,8 @@ use nom::{
 
 pub use uuid::Uuid;
 
-use crate::ebml::macros::impl_ebml_master;
 use crate::ebml::{check_id, checksum, crc, elem_size, vid, vint, EbmlParsable, EbmlResult, Error};
+use crate::ebml::{macros::impl_ebml_master, Date};
 use crate::elements;
 
 #[derive(Debug, Clone, PartialEq)]
@@ -108,7 +108,7 @@ impl_ebml_master! {
         // [0x6924] chapter_translate: (Option<ChapterTranslate>),
         [0x2AD7B1] timestamp_scale: (u64) = 1000000,
         [0x4489] duration: (Option<f64>),     // FIXME: should be float
-        [0x4461] date_utc: (Option<Vec<u8>>), // FIXME: should be date
+        [0x4461] date_utc: (Option<Date>),
         [0x7BA9] title: (Option<String>),
         [0x4D80] muxing_app: (String),
         [0x5741] writing_app: (String),

src/serializer/ebml.rs

@@ -3,7 +3,7 @@ use cookie_factory::gen_slice;
 use cookie_factory::GenError;
 use nom::AsBytes;
 
-use crate::ebml::EbmlHeader;
+use crate::ebml::{Date, EbmlHeader};
 use crate::serializer::cookie_utils::{
     gen_at_offset, gen_skip, gen_slice, set_be_f64, set_be_i8, tuple,
 };
@@ -315,6 +315,13 @@ impl EbmlSize for f64 {
     }
 }
 
+impl EbmlSize for Date {
+    fn capacity(&self) -> usize {
+        // FIXME: Handle zero-sized date
+        8
+    }
+}
+
 impl<T: EbmlSize> EbmlSize for Option<T> {
     fn capacity(&self) -> usize {
         match *self {

src/serializer/elements.rs

@@ -87,7 +87,9 @@ pub(crate) fn gen_info<'a, 'b>(
                 gen_opt(i.segment_family.as_ref(), |v| gen_ebml_binary(0x4444, v)),
                 gen_ebml_uint(0x2AD7B1, i.timestamp_scale),
                 gen_opt(i.duration.as_ref(), |v| gen_f64(0x4489, *v)),
-                gen_opt(i.date_utc.as_ref(), |v| gen_ebml_binary(0x4461, v)),
+                gen_opt(i.date_utc.as_ref(), |v| {
+                    gen_ebml_binary(0x4461, v.0.to_be_bytes())
+                }),
                 gen_opt(i.title.as_ref(), |v| gen_ebml_str(0x7BA9, v)),
                 gen_ebml_str(0x4D80, &i.muxing_app),
                 gen_ebml_str(0x5741, &i.writing_app),

tools/Cargo.toml

@@ -17,3 +17,4 @@ matroska = { path = ".." }
 nom = "7.0"
 pretty_env_logger = "0.4"
 err-derive = "0.3.0"
+time = { version = "0.3.20", features = ["formatting"] }

tools/src/matroska_info.rs

@@ -181,6 +181,20 @@ fn run(filename: &str) -> Result<(), InfoError> {
                     }
                     println!("| + Multiplexing application: {}", i.muxing_app);
                     println!("| + Writing application: {}", i.writing_app);
+                    if let Some(ref date) = i.date_utc {
+                        use time::format_description::well_known::Rfc3339;
+                        use time::{Date, Duration};
+
+                        let formatted = Date::from_ordinal_date(2001, 1)
+                            .unwrap()
+                            .midnight()
+                            .assume_utc()
+                            .saturating_add(Duration::nanoseconds(date.0))
+                            .format(&Rfc3339)
+                            .unwrap();
+
+                        println!("| + Date: {formatted}");
+                    }
                     if info.is_some() {
                         return Err(InfoError::InfoElement);
                     } else {