stream.dash: respect the manifest's minBufferTime

Don't allow the manifest's `suggestedPresentationDelay` to be lower than
the `minBufferTime` value.

src/streamlink/stream/dash/manifest.py

@@ -292,6 +292,8 @@ class MPD(MPDNode):
     parent: None  # type: ignore[assignment]
     timelines: Dict[TTimelineIdent, int]
 
+    DEFAULT_MINBUFFERTIME = 3.0
+
     def __init__(self, *args, url: Optional[str] = None, **kwargs) -> None:
         # top level has no parent
         kwargs["root"] = self
@@ -350,9 +352,12 @@ class MPD(MPDNode):
         self.suggestedPresentationDelay = self.attr(
             "suggestedPresentationDelay",
             parser=MPDParsers.duration(self.publishTime),
-            # if there is no delay, use a delay of 3 seconds
+            # if there is no delay, use a delay of 3 seconds, but respect the manifest's minBufferTime
             # TODO: add a customizable parameter for this
-            default=timedelta(seconds=3),
+            default=timedelta(seconds=max(
+                self.DEFAULT_MINBUFFERTIME,
+                self.minBufferTime.total_seconds(),
+            )),
         )
 
         # parse children

tests/resources/dash/test_suggested_presentation_delay.mpd

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<MPD
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xmlns="urn:mpeg:dash:schema:mpd:2011"
+  xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd"
+  profiles="urn:mpeg:dash:profile:isoff-live:2011,http://dashif.org/guidelines/dash-if-simple"
+  type="dynamic"
+  availabilityStartTime="1970-01-01T00:00:00Z"
+  publishTime="2000-01-01T00:00:00Z"
+  maxSegmentDuration="PT5S"
+  minBufferTime="PT5S"
+>
+ <Period id="p0" start="PT0S">
+  <AdaptationSet mimeType="video/mp4" segmentAlignment="true" startWithSAP="1">
+   <SegmentTemplate initialization="$RepresentationID$_init.mp4" media="$RepresentationID$_t$Time$.m4s" timescale="90000">
+    <SegmentTimeline>
+      <S t="152740179303376" d="360000" r="899"/>
+    </SegmentTimeline>
+   </SegmentTemplate>
+   <Representation id="V0" bandwidth="1255000" codecs="avc1.640028" frameRate="25" width="1920" height="1080" sar="1:1"/>
+   <Representation id="V1" bandwidth="535000" codecs="avc1.64001f" frameRate="25" width="1280" height="720" sar="1:1"/>
+   <Representation id="V2" bandwidth="353000" codecs="avc1.4d401f" frameRate="25" width="960" height="540" sar="1:1"/>
+   <Representation id="V3" bandwidth="213000" codecs="avc1.4d401e" frameRate="25" width="768" height="432" sar="1:1"/>
+   <Representation id="V4" bandwidth="157000" codecs="avc1.4d401e" frameRate="25" width="640" height="360" sar="1:1"/>
+  </AdaptationSet>
+ </Period>
+</MPD>

tests/stream/dash/test_manifest.py

@@ -112,6 +112,16 @@ class TestMPDParsers:
 
 
 class TestMPDParser:
+    @pytest.mark.parametrize(("min_buffer_time", "expected"), [
+        pytest.param("PT1S", 3.0, id="minBufferTime lower than suggestedPresentationDelay"),
+        pytest.param("PT5S", 5.0, id="minBufferTime greater than suggestedPresentationDelay"),
+    ])
+    def test_suggested_presentation_delay(self, min_buffer_time: str, expected: float):
+        with xml("dash/test_suggested_presentation_delay.mpd") as mpd_xml:
+            mpd_xml.attrib["minBufferTime"] = min_buffer_time
+            mpd = MPD(mpd_xml, base_url="http://test/", url="http://test/manifest.mpd")
+        assert mpd.suggestedPresentationDelay.total_seconds() == expected
+
     def test_no_segment_list_or_template(self):
         with xml("dash/test_no_segment_list_or_template.mpd") as mpd_xml:
             mpd = MPD(mpd_xml, base_url="http://test/", url="http://test/manifest.mpd")