mirror of
https://github.com/alfg/mp4-rust.git
synced 2024-05-20 01:08:06 +00:00
162 lines
4.7 KiB
Rust
162 lines
4.7 KiB
Rust
use byteorder::{BigEndian, WriteBytesExt};
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use serde::Serialize;
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use std::io::Write;
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use std::mem::size_of;
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use crate::mp4box::*;
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#[derive(Debug, Clone, PartialEq, Eq, Default, Serialize)]
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pub struct StscBox {
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pub version: u8,
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pub flags: u32,
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#[serde(skip_serializing)]
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pub entries: Vec<StscEntry>,
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}
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impl StscBox {
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pub fn get_type(&self) -> BoxType {
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BoxType::StscBox
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}
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pub fn get_size(&self) -> u64 {
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HEADER_SIZE + HEADER_EXT_SIZE + 4 + (12 * self.entries.len() as u64)
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}
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}
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#[derive(Debug, Clone, PartialEq, Eq, Default, Serialize)]
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pub struct StscEntry {
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pub first_chunk: u32,
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pub samples_per_chunk: u32,
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pub sample_description_index: u32,
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pub first_sample: u32,
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}
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impl Mp4Box for StscBox {
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const TYPE: BoxType = BoxType::StscBox;
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fn box_size(&self) -> u64 {
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self.get_size()
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}
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fn to_json(&self) -> Result<String> {
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Ok(serde_json::to_string(&self).unwrap())
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}
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fn summary(&self) -> Result<String> {
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let s = format!("entries={}", self.entries.len());
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Ok(s)
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}
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}
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impl BlockReader for StscBox {
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fn read_block<'a>(reader: &mut impl Reader<'a>) -> Result<Self> {
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let (version, flags) = read_box_header_ext(reader);
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let entry_size = size_of::<u32>() + size_of::<u32>() + size_of::<u32>(); // first_chunk + samples_per_chunk + sample_description_index
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let entry_count = reader.get_u32();
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if entry_count as usize > reader.remaining() / entry_size {
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return Err(Error::InvalidData(
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"stsc entry_count indicates more entries than could fit in the box",
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));
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}
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let mut entries = Vec::with_capacity(entry_count as usize);
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for _ in 0..entry_count {
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let entry = StscEntry {
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first_chunk: reader.get_u32(),
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samples_per_chunk: reader.get_u32(),
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sample_description_index: reader.get_u32(),
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first_sample: 0,
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};
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entries.push(entry);
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}
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let mut sample_id = 1;
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for i in 0..entry_count {
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let (first_chunk, samples_per_chunk) = {
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let entry = entries.get_mut(i as usize).unwrap();
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entry.first_sample = sample_id;
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(entry.first_chunk, entry.samples_per_chunk)
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};
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if i < entry_count - 1 {
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let next_entry = entries.get(i as usize + 1).unwrap();
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sample_id = next_entry
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.first_chunk
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.checked_sub(first_chunk)
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.and_then(|n| n.checked_mul(samples_per_chunk))
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.and_then(|n| n.checked_add(sample_id))
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.ok_or(Error::InvalidData(
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"attempt to calculate stsc sample_id with overflow",
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))?;
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}
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}
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Ok(StscBox {
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version,
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flags,
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entries,
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})
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}
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fn size_hint() -> usize {
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8
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}
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}
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impl<W: Write> WriteBox<&mut W> for StscBox {
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fn write_box(&self, writer: &mut W) -> Result<u64> {
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let size = self.box_size();
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BoxHeader::new(Self::TYPE, size).write(writer)?;
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write_box_header_ext(writer, self.version, self.flags)?;
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writer.write_u32::<BigEndian>(self.entries.len() as u32)?;
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for entry in self.entries.iter() {
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writer.write_u32::<BigEndian>(entry.first_chunk)?;
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writer.write_u32::<BigEndian>(entry.samples_per_chunk)?;
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writer.write_u32::<BigEndian>(entry.sample_description_index)?;
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}
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Ok(size)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::mp4box::BoxHeader;
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#[test]
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fn test_stsc() {
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let src_box = StscBox {
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version: 0,
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flags: 0,
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entries: vec![
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StscEntry {
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first_chunk: 1,
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samples_per_chunk: 1,
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sample_description_index: 1,
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first_sample: 1,
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},
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StscEntry {
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first_chunk: 19026,
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samples_per_chunk: 14,
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sample_description_index: 1,
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first_sample: 19026,
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},
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],
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};
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let mut buf = Vec::new();
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src_box.write_box(&mut buf).unwrap();
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assert_eq!(buf.len(), src_box.box_size() as usize);
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let mut reader = buf.as_slice();
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let header = BoxHeader::read_sync(&mut reader).unwrap().unwrap();
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assert_eq!(header.kind, BoxType::StscBox);
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assert_eq!(src_box.box_size(), header.size);
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let dst_box = StscBox::read_block(&mut reader).unwrap();
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assert_eq!(src_box, dst_box);
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}
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}
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