diff --git a/internal/playback/remux.go b/internal/playback/remux.go
index 4fdd10b499..b2dd5ea712 100644
--- a/internal/playback/remux.go
+++ b/internal/playback/remux.go
@@ -153,7 +153,7 @@ const (
 
 // buildRemuxArgs constructs the ffmpeg argument list for a remux operation.
 // The args perform codec copy (-c copy) into the target container format,
-// using fragmented output for streaming (frag_keyframe+delay_moov+default_base_moof) and
+// using fragmented output for streaming (frag_keyframe+delay_moov) and
 // pipe:1 for stdout output.
 // When transcodeAudio is true, video is copied but audio is transcoded to
 // stereo AAC (handles cases like DTS/TrueHD that browsers cannot decode).
@@ -266,7 +266,14 @@ func buildRemuxArgsWithAudioV3(filePath, outputFormat string, seekSeconds float6
 		// delay_moov lets the MP4 muxer inspect the first audio packet before
 		// writing codec configuration. empty_moov fails immediately for copied
 		// E-AC-3/Atmos tracks because their frame size is not known at header time.
-		"-movflags", "frag_keyframe+delay_moov+default_base_moof",
+		//
+		// No default_base_moof: this is one progressive byte stream, not MSE/CMAF
+		// segments, so explicit tfhd base data offsets are correct and every
+		// progressive demuxer reads them. Samsung Tizen's native player does not
+		// follow moof-relative offsets: it plays the first fragment, then stalls
+		// with no audio (verified on a QN700B, Tizen 6.5, with the same copied
+		// HEVC + AAC 5.1 stream with and without the flag).
+		"-movflags", "frag_keyframe+delay_moov",
 		"pipe:1",
 	)
 
@@ -276,7 +283,7 @@ func buildRemuxArgsWithAudioV3(filePath, outputFormat string, seekSeconds float6
 // StartRemux starts an ffmpeg process that copies codecs to a new container.
 // When transcodeAudio is false the command is:
 //
-//	ffmpeg -i {input} -c copy -f {format} -movflags frag_keyframe+delay_moov+default_base_moof pipe:1
+//	ffmpeg -i {input} -c copy -f {format} -movflags frag_keyframe+delay_moov pipe:1
 //
 // When transcodeAudio is true video is copied but audio is transcoded to AAC.
 // The caller must call Close() when done to clean up resources.
diff --git a/internal/playback/remux_dv_test.go b/internal/playback/remux_dv_test.go
index 9c9537b958..635f347037 100644
--- a/internal/playback/remux_dv_test.go
+++ b/internal/playback/remux_dv_test.go
@@ -208,11 +208,20 @@ func TestStartRemuxRejectsUnknownModeForAllProfiles(t *testing.T) {
 
 func TestBuildRemuxArgsDelaysMoovForCopiedAtmosConfiguration(t *testing.T) {
 	args := buildRemuxArgs("/x.mkv", "mp4", 0, false, -1, 8, false, false)
-	if !argsContainPair(args, "-movflags", "frag_keyframe+delay_moov+default_base_moof") {
+	if !argsContainPair(args, "-movflags", "frag_keyframe+delay_moov") {
 		t.Fatalf("remux must delay moov until copied audio is parsed, args=%v", strings.Join(args, " "))
 	}
 }
 
+// Tizen's native player stalls after the first fragment when tfhd offsets are
+// moof-relative, so the progressive stream must not set default_base_moof.
+func TestBuildRemuxArgsOmitsDefaultBaseMoof(t *testing.T) {
+	args := buildRemuxArgs("/x.mkv", "mp4", 0, true, -1, 8, false, false)
+	if strings.Contains(strings.Join(args, " "), "default_base_moof") {
+		t.Fatalf("progressive remux must not use default_base_moof, args=%v", strings.Join(args, " "))
+	}
+}
+
 // writeProbeAwareFFmpeg stands in for an ffmpeg that carries the dovi_rpu
 // filter but cannot parse this source's RPU: it advertises the filter, fails
 // the probe the way the real one does (rejecting packets while exiting 0), and
diff --git a/scripts/prairie-invariants.txt b/scripts/prairie-invariants.txt
index 73aba7a74e..ebaccd8e16 100644
--- a/scripts/prairie-invariants.txt
+++ b/scripts/prairie-invariants.txt
@@ -42,3 +42,6 @@ web/src/api/client.ts	1	X-Prairie-	client identity headers
 web/src/player/components/PlaybackInfoOverlay.tsx	1	Recent events	web stats overlay shows the player event log
 web/src/player/components/VideoPlayer.tsx	1	new PlaybackEventLog\(	web player records events for the stats overlay
 internal/api/handlers/stream.go	1	userID == 0 && !apimw\.IsStreamTokenAuthorized\(	v2 progressive/direct delivery honors st (Tizen direct play)
+
+# --- Progressive remux that Samsung Tizen native players can follow.
+internal/playback/remux.go	1	"-movflags", "frag_keyframe\+delay_moov",	no default_base_moof: Tizen stalls after the first fragment (Iron Man, QN700B)