GStreamer: Fix reverse playback

Each gstreamer plugin is responsible for supporting reverse playback
and also might require different start/stop types
(GST_SEEK_TYPE_SET, GST_SEEK_TYPE_NONE, GST_SEEK_TYPE_END).

Some plugins do not support it at all, e.g. wavparse.

if rate > 0:
  change rate from current position to duration.
else:
  change rate from current position to 0.

Fixed also seeking with a negative rate.

This should work for mp3 or some video formats too.

Fixes: QTBUG-83945
Change-Id: I10a98186b9bc63d908667944aa4459da9e63e343
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 10 insertions, 10 deletions

diff --git a/src/gsttools/qgstreamerplayersession.cpp b/src/gsttools/qgstreamerplayersession.cpp
index c6d2df810..f7f3b7ca1 100644
--- a/src/gsttools/qgstreamerplayersession.cpp
+++ b/src/gsttools/qgstreamerplayersession.cpp
@@ -494,10 +494,12 @@ void QGstreamerPlayerSession::setPlaybackRate(qreal rate)
     if (!qFuzzyCompare(m_playbackRate, rate)) {
         m_playbackRate = rate;
         if (m_pipeline && m_seekable) {
+            qint64 from = rate > 0 ? position() : 0;
+            qint64 to = rate > 0 ? duration() : position();
             gst_element_seek(m_pipeline, rate, GST_FORMAT_TIME,
                              GstSeekFlags(GST_SEEK_FLAG_FLUSH),
-                             GST_SEEK_TYPE_NONE,0,
-                             GST_SEEK_TYPE_END, 0);
+                             GST_SEEK_TYPE_SET, from * 1000000,
+                             GST_SEEK_TYPE_SET, to * 1000000);
         }
         emit playbackRateChanged(m_playbackRate);
     }
@@ -1078,15 +1080,13 @@ bool QGstreamerPlayerSession::seek(qint64 ms)
     //seek locks when the video output sink is changing and pad is blocked
     if (m_pipeline && !m_pendingVideoSink && m_state != QMediaPlayer::StoppedState && m_seekable) {
         ms = qMax(ms,qint64(0));
-        gint64  position = ms * 1000000;
-        bool isSeeking = gst_element_seek(m_pipeline,
-                                          m_playbackRate,
-                                          GST_FORMAT_TIME,
+        qint64 from = m_playbackRate > 0 ? ms : 0;
+        qint64 to = m_playbackRate > 0 ? duration() : ms;
+
+        bool isSeeking = gst_element_seek(m_pipeline, m_playbackRate, GST_FORMAT_TIME,
                                           GstSeekFlags(GST_SEEK_FLAG_FLUSH),
-                                          GST_SEEK_TYPE_SET,
-                                          position,
-                                          GST_SEEK_TYPE_NONE,
-                                          0);
+                                          GST_SEEK_TYPE_SET, from * 1000000,
+                                          GST_SEEK_TYPE_SET, to * 1000000);
         if (isSeeking)
             m_lastPosition = ms;