fmp4mux: Don't overflow negative composition offset calculation

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1338>

1 files changed, 7 insertions, 1 deletions

diff --git a/mux/fmp4/src/fmp4mux/imp.rs b/mux/fmp4/src/fmp4mux/imp.rs
index 3718ac400..4b9262eb5 100644
--- a/mux/fmp4/src/fmp4mux/imp.rs
+++ b/mux/fmp4/src/fmp4mux/imp.rs
@@ -1741,7 +1741,13 @@ impl FMP4Mux {
                 let pts = buffer.pts;
                 let dts = buffer.dts.unwrap();
 
-                Some(i64::try_from((pts - dts).nseconds()).map_err(|_| {
+                let diff = if pts > dts {
+                    i64::try_from(pts.nseconds() - dts.nseconds())
+                } else {
+                    i64::try_from(dts.nseconds() - pts.nseconds()).map(|x| -x)
+                };
+
+                Some(diff.map_err(|_| {
                     gst::error!(CAT, obj: stream.sinkpad, "Too big PTS/DTS difference");
                     gst::FlowError::Error
                 })?)