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/*
REFERENCES
----------
1. https://github.com/shaka-project/shaka-player/blob/d465942c4393e6c891d6a230bea90a44d90cc70b/lib/util/mp4_box_parsers.js
*/
use crate::{Error, Reader, Result};
pub(super) struct TFHDBox {
/// As per the spec: an integer that uniquely identifies this
/// track over the entire life‐time of this presentation
pub(super) _track_id: u32,
/// If specified via flags, this overrides the default sample
/// duration in the Track Extends Box for this fragment
pub(super) default_sample_duration: Option<u32>,
/// If specified via flags, this overrides the default sample
/// size in the Track Extends Box for this fragment
pub(super) _default_sample_size: Option<u32>,
/// If specified via flags, this indicate the base data offset
pub(super) _base_data_offset: Option<u64>,
}
impl TFHDBox {
/// Parses a TFHD Box.
pub(super) fn parse(reader: &mut Reader, flags: u32) -> Result<Self> {
let mut default_sample_duration = None;
let mut default_sample_size = None;
let mut base_data_offset = None;
let track_id = reader
.read_u32()
.map_err(|_| Error::new_read("TFHD box track id (u32)."))?;
// Skip "base_data_offset" if present.
if (flags & 0x000001) != 0 {
base_data_offset = Some(
reader
.read_u64()
.map_err(|_| Error::new_read("TFHD box data offset (u64)."))?,
);
}
// Skip "sample_description_index" if present.
if (flags & 0x000002) != 0 {
reader.skip(4).map_err(|_| {
Error::new_read("TFHD box sample description index data (4 bytes).")
})?;
}
// Read "default_sample_duration" if present.
if (flags & 0x000008) != 0 {
default_sample_duration = Some(
reader
.read_u32()
.map_err(|_| Error::new_read("TFHD box default sample duration (u32)."))?,
);
}
// Read "default_sample_size" if present.
if (flags & 0x000010) != 0 {
default_sample_size = Some(
reader
.read_u32()
.map_err(|_| Error::new_read("TFHD box default sample size (u32)."))?,
);
}
Ok(Self {
_track_id: track_id,
default_sample_duration,
_default_sample_size: default_sample_size,
_base_data_offset: base_data_offset,
})
}
}
pub(super) struct TFDTBox {
/// As per the spec: the absolute decode time, measured on the media
/// timeline, of the first sample in decode order in the track fragment
pub(super) base_media_decode_time: u64,
}
impl TFDTBox {
/// Parses a TFDT Box.
pub(super) fn parse(reader: &mut Reader, version: u32) -> Result<Self> {
Ok(Self {
base_media_decode_time: if version == 1 {
reader
.read_u64()
.map_err(|_| Error::new_read("TFDT box base media decode time (u64)."))?
} else {
reader
.read_u32()
.map_err(|_| Error::new_read("TFDT box base media decode time (u32)."))?
as u64
},
})
}
}
pub(super) struct MDHDBox {
/// As per the spec: an integer that specifies the time‐scale for this media;
/// this is the number of time units that pass in one second
pub(super) timescale: u32,
/// Language code for this media
pub(super) _language: String,
}
impl MDHDBox {
/// Parses a MDHD Box.
pub(super) fn parse(reader: &mut Reader, version: u32) -> Result<Self> {
if version == 1 {
reader
.skip(8)
.map_err(|_| Error::new_read("MDHD box creation time data (8 bytes)."))?;
reader
.skip(8)
.map_err(|_| Error::new_read("MDHD box modification time data (8 bytes)."))?;
} else {
reader
.skip(4)
.map_err(|_| Error::new_read("MDHD box creation time data (4 bytes)."))?;
reader
.skip(4)
.map_err(|_| Error::new_read("MDHD box modification time data (4 bytes)."))?;
}
let timescale = reader
.read_u32()
.map_err(|_| Error::new_read("MDHD box timescale (u32)."))?;
reader
.skip(4)
.map_err(|_| Error::new_read("MDHD box duration data (4 bytes)."))?;
let language = reader
.read_u16()
.map_err(|_| Error::new_read("MDHD box language data (u16)."))?;
// language is stored as an ISO-639-2/T code in an array of three
// 5-bit fields each field is the packed difference between its ASCII
// value and 0x60
let language_string = String::from_utf16(&[
(language >> 10) + 0x60,
((language & 0x03c0) >> 5) + 0x60,
(language & 0x1f) + 0x60,
])
.map_err(|_| Error::new_decode("MDHD box language as vaild utf-16 data."))?;
Ok(Self {
timescale,
_language: language_string,
})
}
}
pub(super) struct TRUNBox {
/// As per the spec: the number of samples being added in this run;
pub(super) _sample_count: u32,
/// An array of size sampleCount containing data for each sample
pub(super) sample_data: Vec<TRUNSample>,
/// If specified via flags, this indicate the offset of the sample in bytes.
pub(super) _data_offset: Option<u32>,
}
impl TRUNBox {
/// Parses a TRUN Box.
pub(super) fn parse(reader: &mut Reader, version: u32, flags: u32) -> Result<Self> {
let sample_count = reader
.read_u32()
.map_err(|_| Error::new_read("TRUN box sample count (u32)."))?;
let mut sample_data = vec![];
let mut data_offset = None;
// "data_offset"
if (flags & 0x000001) != 0 {
data_offset = Some(
reader
.read_u32()
.map_err(|_| Error::new_read("TRUN box data offset (u32)."))?,
);
}
// Skip "first_sample_flags" if present.
if (flags & 0x000004) != 0 {
reader
.skip(4)
.map_err(|_| Error::new_read("TRUN box first sample flags (4 bytes)."))?;
}
for _ in 0..sample_count {
let mut sample = TRUNSample {
sample_duration: None,
sample_size: None,
sample_composition_time_offset: None,
};
// Read "sample duration" if present.
if (flags & 0x000100) != 0 {
sample.sample_duration = Some(
reader
.read_u32()
.map_err(|_| Error::new_read("TRUN box sample duration (u32)."))?,
);
}
// Read "sample_size" if present.
if (flags & 0x000200) != 0 {
sample.sample_size = Some(
reader
.read_u32()
.map_err(|_| Error::new_read("TRUN box sample size (u32)."))?,
);
}
// Skip "sample_flags" if present.
if (flags & 0x000400) != 0 {
reader
.skip(4)
.map_err(|_| Error::new_read("TRUN box sample flags (u32)."))?;
}
// Read "sample_time_offset" if present.
if (flags & 0x000800) != 0 {
sample.sample_composition_time_offset = Some(if version == 0 {
reader
.read_u32()
.map_err(|_| Error::new_read("TRUN box sample time offset (u32)."))?
as i32
} else {
reader
.read_i32()
.map_err(|_| Error::new_read("TRUN box sample time offset (i32)."))?
});
}
sample_data.push(sample);
}
Ok(Self {
_sample_count: sample_count,
sample_data,
_data_offset: data_offset,
})
}
}
pub(super) struct TRUNSample {
/// The length of the sample in timescale units.
pub(super) sample_duration: Option<u32>,
/// The size of the sample in bytes.
pub(super) sample_size: Option<u32>,
/// The time since the start of the sample in timescale units. Time
/// offset is based of the start of the sample. If this value is
/// missing, the accumulated durations preceeding this time sample will
/// be used to create the start time.
pub(super) sample_composition_time_offset: Option<i32>,
}