EBML: Start parsing segment.Info

Signed-off-by: Serial <69764315+Serial-ATA@users.noreply.github.com>

Author: Serial-ATA

src/ebml/element_reader.rs

@@ -224,6 +224,11 @@ where
 		self.ctx.max_size_length = len
 	}
 
+	fn store_previous_master(&mut self) {
+		self.ctx.previous_master = self.ctx.current_master;
+		self.ctx.previous_master_length = self.ctx.master_length;
+	}
+
 	fn next_master(&mut self) -> Result<ElementReaderYield> {
 		let header = ElementHeader::read(
 			&mut self.reader,
@@ -235,8 +240,7 @@ where
 			return Ok(ElementReaderYield::Unknown(header));
 		};
 
-		self.ctx.previous_master = self.ctx.current_master;
-		self.ctx.previous_master_length = self.ctx.master_length;
+		self.store_previous_master();
 		self.ctx.current_master = Some(*master);
 		self.ctx.master_length = header.size.value();
 		Ok(ElementReaderYield::Master((
@@ -288,6 +292,7 @@ where
 		};
 
 		if child.data_type == ElementDataType::Master {
+			self.store_previous_master();
 			self.ctx.current_master = Some(
 				*MASTER_ELEMENTS
 					.get(&header.id)

src/ebml/properties.rs

@@ -17,11 +17,19 @@ pub struct EbmlExtension {
 	pub(crate) version: u64,
 }
 
+#[derive(Debug, Clone, PartialEq, Default)]
+pub struct SegmentInfo {
+	pub(crate) timecode_scale: u64,
+	pub(crate) muxing_app: String,
+	pub(crate) writing_app: String,
+}
+
 /// EBML audio properties
 #[derive(Debug, Clone, PartialEq, Default)]
 pub struct EbmlProperties {
 	pub(crate) header: EbmlHeaderProperties,
 	pub(crate) extensions: Vec<EbmlExtension>,
+	pub(crate) segment_info: SegmentInfo,
 }
 
 impl From<EbmlProperties> for FileProperties {

src/ebml/read.rs

@@ -1,4 +1,5 @@
 mod segment;
+mod segment_info;
 
 use super::EbmlFile;
 use crate::ebml::element_reader::{ElementHeader, ElementIdent, ElementReader, ElementReaderYield};

src/ebml/read/segment.rs

@@ -1,3 +1,4 @@
+use super::segment_info;
 use crate::ebml::element_reader::{ElementIdent, ElementReader, ElementReaderYield};
 use crate::ebml::properties::EbmlProperties;
 use crate::ebml::tag::EbmlTag;
@@ -9,8 +10,8 @@ use std::io::{Read, Seek};
 
 pub(super) fn read_from<R>(
 	element_reader: &mut ElementReader<R>,
-	_parse_options: ParseOptions,
-	_properties: &mut EbmlProperties,
+	parse_options: ParseOptions,
+	properties: &mut EbmlProperties,
 ) -> Result<Option<EbmlTag>>
 where
 	R: Read + Seek,
@@ -23,7 +24,9 @@ where
 		let res = element_reader.next()?;
 		match res {
 			ElementReaderYield::Master((id, size)) => match id {
-				ElementIdent::Info => todo!("Support segment.Info"),
+				ElementIdent::Info => {
+					segment_info::read_from(element_reader, parse_options, properties)?
+				},
 				ElementIdent::Cluster => todo!("Support segment.Cluster"),
 				ElementIdent::Tracks => todo!("Support segment.Tracks"),
 				ElementIdent::Tags => todo!("Support segment.Tags"),

src/ebml/read/segment_info.rs

@@ -0,0 +1,59 @@
+use crate::ebml::element_reader::{ElementIdent, ElementReader, ElementReaderYield};
+use crate::ebml::properties::EbmlProperties;
+use crate::error::Result;
+use crate::probe::ParseOptions;
+
+use std::io::{Read, Seek};
+
+pub(super) fn read_from<R>(
+	element_reader: &mut ElementReader<R>,
+	_parse_options: ParseOptions,
+	_properties: &mut EbmlProperties,
+) -> Result<()>
+where
+	R: Read + Seek,
+{
+	element_reader.lock();
+
+	loop {
+		let res = element_reader.next()?;
+		match res {
+			ElementReaderYield::Master((id, size)) => {
+				// We do not end up using information from any of the nested master
+				// elements, so we can just skip them.
+
+				log::debug!("Skipping EBML master element: {:?}", id);
+				element_reader.skip(size)?;
+				element_reader.goto_previous_master()?;
+				continue;
+			},
+			ElementReaderYield::Child((child, size)) => {
+				match child.ident {
+					ElementIdent::TimecodeScale => todo!("Support segment.Info.TimecodeScale"),
+					ElementIdent::MuxingApp => todo!("Support segment.Info.MuxingApp"),
+					ElementIdent::WritingApp => todo!("Support segment.Info.WritingApp"),
+					_ => {
+						// We do not end up using information from all of the segment
+						// elements, so we can just skip any useless ones.
+
+						log::debug!("Skipping EBML child element: {:?}", child);
+						element_reader.skip(size)?;
+						continue;
+					},
+				}
+			},
+			ElementReaderYield::Unknown(element) => {
+				log::debug!("Skipping unknown EBML element: {:X}", element.id.0);
+				element_reader.skip(element.size.value())?;
+				continue;
+			},
+			ElementReaderYield::Eof => {
+				element_reader.unlock();
+				break;
+			},
+		}
+	}
+
+	element_reader.goto_previous_master()?;
+	Ok(())
+}