fix mp4 trun bug; set correct cts_offset

1 files changed, 9 insertions, 9 deletions

diff --git a/remuxer/src/muxers/mp4.rs b/remuxer/src/muxers/mp4.rs
index 85bb244..dd8a066 100644
--- a/remuxer/src/muxers/mp4.rs
+++ b/remuxer/src/muxers/mp4.rs
@@ -4,9 +4,9 @@
     Copyright (C) 2026 metamuffin <metamuffin.org>
 */
 
-use std::sync::Mutex;
 use crate::muxers::FragmentMuxer;
 use anyhow::Result;
+use std::sync::Mutex;
 use winter_matroska::{Segment, TrackType};
 use winter_mp4::*;
 
@@ -138,23 +138,23 @@ impl FragmentMuxer for MP4FragmentMuxer {
             .map(|c| c.simple_blocks.len())
             .sum::<usize>();
         let dts_delta = ((end_pts - start_pts as u64) / num_samples as u64) as u32;
-        eprintln!("dts_delta {dts_delta}");
 
         let mut mdat = Vec::new();
         let mut samples = Vec::new();
+        let mut dts = 0;
         for cluster in segment.clusters {
             for block in cluster.simple_blocks {
-                let ts = cluster.timestamp as i64 + block.timestamp_off as i64;
-
+                let ts = (cluster.timestamp as i64 + block.timestamp_off as i64)
+                    * segment.info.timestamp_scale as i64;
+                let pts_off = (ts - start_pts) - dts;
                 samples.push(TrackRunSample {
-                    composition_time_offset: 0,
+                    composition_time_offset: pts_off.try_into().expect("cts_offset overflow"),
                     duration: dts_delta as u32,
                     flags: 0,
                     size: block.data.len() as u32,
                 });
-
-                // samples.push((ts, block.data.len()));
                 mdat.extend(block.data);
+                dts += dts_delta as i64;
             }
         }
 
@@ -174,9 +174,9 @@ impl FragmentMuxer for MP4FragmentMuxer {
                 traf.write(TrackFragmentBaseMediaDecodeTime {
                     base_media_decode_time: 0,
                 });
-                *data_offset_offset.lock().unwrap() = traf.buffer_mut().len() + 12; // full box header (size+tag+ver+flags)
+                *data_offset_offset.lock().unwrap() = traf.buffer_mut().len() + 16; // full box header (size+tag+ver+flags+sample_count)
                 traf.write(TrackRun {
-                    data_offset: 0,
+                    data_offset: -1,
                     samples: &samples,
                 });
             }));