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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2026 metamuffin <metamuffin.org>
*/
use crate::muxers::FragmentMuxer;
use anyhow::Result;
use log::debug;
use std::sync::Mutex;
use winter_matroska::{Segment, TrackType};
use winter_mp4::*;
pub struct MP4FragmentMuxer;
impl FragmentMuxer for MP4FragmentMuxer {
fn write_init(out: &mut Vec<u8>, segment: Segment) -> Result<()> {
let mut out = BoxW::new(out);
out.write(FileType {
major_brand: *b"iso5",
minor_version: 512,
compatible_brands: &[*b"iso5", *b"iso6", *b"mp41"],
});
out.write(Movie(|moov| {
moov.write(MovieHeader {
timescale: 1_000_000_000,
..Default::default()
});
for track in &segment.tracks.as_ref().unwrap().entries {
moov.write(Track(|trak| {
trak.write(TrackHeader {
width: track.video.as_ref().map_or(0, |v| v.pixel_width as u32),
height: track.video.as_ref().map_or(0, |v| v.pixel_height as u32),
volume: track.audio.as_ref().map_or(0, |_| 0x0100),
track_id: track.track_number as u32,
..Default::default()
});
// trak.write(Edit(|edts| {
// edts.write(EditList(&[]));
// }));
trak.write(Media(|mdia| {
mdia.write(MediaHeader {
duration: 0,
timescale: 1_000_000_000,
..Default::default()
});
mdia.write(Handler {
handler_type: match track.track_type {
TrackType::Video => *b"vide",
TrackType::Audio => *b"soun",
_ => todo!(),
},
name: &format!("ISO Media file produced by {}", env!("CARGO_PKG_NAME")),
});
mdia.write(MediaInformation(|minf| {
match track.track_type {
TrackType::Video => minf.write(VideoMediaHeader::default()),
TrackType::Audio => minf.write(SoundMediaHeader::default()),
_ => todo!(),
};
minf.write(DataInformation(|dinf| {
dinf.write(DataReference(&[DataReferenceEntry::URL(
String::default(),
)]));
}));
minf.write(SampleTable(|stbl| {
stbl.write(SampleDescription(|stsd| {
if let Some(video) = &track.video
&& track.codec_id == "V_MPEG4/ISO/AVC"
{
stsd.write(AVCSampleEntry {
visual: VisualSampleEntry {
sample: SampleEntry {
data_reference_index: 1,
},
width: video.pixel_width as u16,
height: video.pixel_height as u16,
pasp: Some(PixelAspectRatio {
h_spacing: 1,
v_spacing: 1,
}),
colr: Some(ColourInformation::OnScreenColours {
colour_primaries: 1,
transfer_charateristics: 1,
matrix_coefficients: 1,
full_range: false,
}),
..Default::default()
},
config: AVCConfiguration(
track.codec_private.as_ref().unwrap(),
),
});
} else {
todo!("{:?}", track.codec_id)
}
}));
stbl.write(TimeToSample(&[]));
stbl.write(TimeToChunk(&[]));
stbl.write(ChunkOffset(&[]));
stbl.write(SyncSample(&[]));
stbl.write(SampleSize {
sample_size: 0,
entries: &[],
});
}));
}));
}));
}));
moov.write(MovieExtends(|mvex| {
mvex.write(MovieExtendsHeader {
fragment_duration: (segment.info.duration.unwrap_or_default()
* segment.info.timestamp_scale as f64)
as u64,
});
for track in &segment.tracks.as_ref().unwrap().entries {
mvex.write(TrackExtends {
track_id: track.track_number as u32,
default_sample_description_index: 1,
..Default::default()
});
}
}));
}
}));
Ok(())
}
fn write_frag(out: &mut Vec<u8>, segment: Segment, index: usize, end_pts: u64) -> Result<()> {
let mut out = BoxW::new(out);
let start_pts =
(segment.clusters[0].timestamp as i64) * segment.info.timestamp_scale as i64;
let num_samples = segment
.clusters
.iter()
.map(|c| c.simple_blocks.len())
.sum::<usize>();
let dts_delta = ((end_pts - start_pts as u64) / num_samples as u64) as u32;
let mut mdat = Vec::new();
let mut samples = Vec::new();
let mut dts = 0;
let mut max_cts_offset = 0;
for cluster in segment.clusters {
for block in cluster.simple_blocks {
let ts = (cluster.timestamp as i64 + block.timestamp_off as i64)
* segment.info.timestamp_scale as i64;
let pts_off = (ts - start_pts) - dts;
max_cts_offset = max_cts_offset.max(pts_off.abs());
samples.push(TrackRunSample {
composition_time_offset: pts_off.try_into().expect("cts_offset overflow"),
duration: dts_delta,
flags: 0,
size: block.data.len() as u32,
});
mdat.extend(block.data);
dts += dts_delta as i64;
}
}
debug!(
"max composition_time_offset = {:.03}ms",
max_cts_offset as f32 / 1000_000.
);
out.write(SegmentType {
major_brand: *b"msdh",
minor_version: 0,
compatible_brands: &[*b"msdh", *b"msix"],
});
let data_offset_offset = Mutex::new(0);
let base_data_offset = out.buffer_mut().len();
out.write(MovieFragment(|moof| {
moof.write(MovieFragmentHeader {
sequence_number: index as u32,
});
moof.write(TrackFragment(|traf| {
traf.write(TrackFragmentHeader { track_id: 1 });
traf.write(TrackFragmentBaseMediaDecodeTime {
base_media_decode_time: 0,
});
*data_offset_offset.lock().unwrap() = traf.buffer_mut().len() + 16; // full box header (size+tag+ver+flags+sample_count)
traf.write(TrackRun {
data_offset: -1,
samples: &samples,
});
}));
}));
let data_offset_offset = data_offset_offset.into_inner().unwrap();
let data_offset = out.buffer_mut().len() + 8 - base_data_offset; // box header (size+tag)
out.buffer_mut()[data_offset_offset..data_offset_offset + 4]
.copy_from_slice(&(data_offset as u32).to_be_bytes());
out.write(MediaData(&mdat));
Ok(())
}
}
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