From 9e6e4962f2346a3fbd96ab3e6c331858ef6ec0d1 Mon Sep 17 00:00:00 2001
From: Felix Kaaman <tmtu@tmtu.ee>
Date: Thu, 7 Jan 2021 20:32:49 +0100
Subject: Initial commit

---
 src/lib.rs | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 src/lib.rs

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..0630a15
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,129 @@
+#![allow(dead_code)]
+
+use std::io;
+
+use byteorder::{BigEndian, ByteOrder};
+use bytes::{BufMut, BytesMut};
+pub use four_cc::FourCC;
+
+mod boxes;
+
+pub use boxes::*;
+
+fn get_total_box_size<B: Mp4Box + ?Sized>(boks: &B) -> u64 {
+    let size = boks.content_size();
+
+    if boks.get_full_box_header().is_some() {
+        size + FullBoxHeader::SIZE + 8
+    } else {
+        size + 8
+    }
+}
+
+fn write_box_header<B: Mp4Box + ?Sized>(header: &mut [u8], size: u64) -> usize {
+    if size > u32::MAX as _ {
+        BigEndian::write_u32(&mut header[..], 1);
+        header[4..8].copy_from_slice(&B::NAME.0);
+        BigEndian::write_u64(&mut header[8..], size);
+
+        16
+    } else {
+        BigEndian::write_u32(&mut header[..], size as u32);
+        header[4..8].copy_from_slice(&B::NAME.0);
+
+        8
+    }
+}
+
+fn write_full_box_header(header: &mut [u8], box_header: FullBoxHeader) -> usize {
+    header[0] = box_header.version;
+    BigEndian::write_u24(&mut header[1..], box_header.flags);
+
+    4
+}
+
+#[derive(Copy, Clone)]
+pub struct FullBoxHeader {
+    version: u8,
+    flags: u32,
+}
+
+impl FullBoxHeader {
+    pub const SIZE: u64 = 4;
+
+    pub fn new(version: u8, flags: u32) -> Self {
+        FullBoxHeader { version, flags }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Mp4BoxError {
+    #[error("Failed to write box: {0}")]
+    IoError(#[from] io::Error),
+}
+
+/// A trait interface for a MP4 box.
+pub trait Mp4Box {
+    const NAME: FourCC;
+
+    fn get_full_box_header(&self) -> Option<FullBoxHeader> {
+        None
+    }
+
+    fn flags(&self) -> Option<u32> {
+        self.get_full_box_header().map(|h| h.flags)
+    }
+
+    /// The size of the contents of the box.
+    fn content_size(&self) -> u64;
+
+    fn size(&self) -> u64 {
+        get_total_box_size::<Self>(&self)
+    }
+
+    fn write_box_contents(&self, writer: &mut BytesMut) -> Result<(), Mp4BoxError>;
+
+    fn write(&self, writer: &mut BytesMut) -> Result<(), Mp4BoxError> {
+        let mut header = [0u8; 20];
+
+        /* println!(
+            "{}: {}/{}",
+            std::any::type_name::<Self>(),
+            self.size(),
+            self.content_size()
+        ); */
+
+        let mut size = write_box_header::<Self>(&mut header, self.size());
+        if let Some(box_header) = self.get_full_box_header() {
+            size += write_full_box_header(&mut header[size..], box_header);
+        }
+
+        writer.put_slice(&header[..size]);
+
+        self.write_box_contents(writer)?;
+
+        Ok(())
+    }
+}
+
+pub struct MediaDataBox<'a> {
+    pub data: &'a [u8],
+}
+
+impl<'a> Mp4Box for MediaDataBox<'a> {
+    const NAME: FourCC = FourCC(*b"mdat");
+
+    fn get_full_box_header(&self) -> Option<FullBoxHeader> {
+        Some(FullBoxHeader::new(0, 0))
+    }
+
+    fn content_size(&self) -> u64 {
+        self.data.len() as _
+    }
+
+    fn write_box_contents(&self, writer: &mut BytesMut) -> Result<(), Mp4BoxError> {
+        writer.put_slice(&self.data);
+
+        Ok(())
+    }
+}
-- 
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