Uploaded image for project: 'Qt'
  1. Qt
  2. QTBUG-131465

[ffmpeg] race condition in looped playback (discovered through tst_QMediaPlayerBackend being flaky)

XMLWordPrintable

    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: P2: Important P2: Important
    • None
    • 6.8.1
    • Multimedia
    • None

      tst_QMediaPlayerBackend::play_playbackLastsForTheExpectedTime seems to be flaky:

          3556: ********* Start testing of tst_QMediaPlayerBackend *********
    FAIL!  : tst_QMediaPlayerBackend::play_playbackLastsForTheExpectedTime(file qrc:/testdata/busMpeg4.mp4, loops 2, rate 1, pause before 1) 'abs(duration - expectedDuration) < 600ms' returned FALSE. (expected duration: 2000ms, actual duration: 1014ms)
       Loc: [/home/qt/work/qt/qtmultimedia/tests/auto/integration/qmediaplayerbackend/tst_qmediaplayerbackend.cpp(1720)]
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/tst_qmediaplayerbackend.VTvzBS.mp4':
      Metadata:
    FAIL!  : tst_QMediaPlayerBackend::play_playbackLastsForTheExpectedTime(file qrc:/testdata/busMpeg4.mp4, loops 2, rate 0.5, pause before 1) 'abs(duration - expectedDuration) < 600ms' returned FALSE. (expected duration: 4000ms, actual duration: 2032ms)
       Loc: [/home/qt/work/qt/qtmultimedia/tests/auto/integration/qmediaplayerbackend/tst_qmediaplayerbackend.cpp(1720)]
    Input #0, wav, from '/tmp/tst_qmediaplayerbackend.uebPqK.wav':
      Duration: 00:00:01.00, bitrate: 705 kb/s
    Totals: 198 passed, 2 failed, 9 skipped, 0 blacklisted, 331294ms
    
    
    13313: ********* Start testing of tst_QMediaPlayerBackend *********
    FAIL!  : tst_QMediaPlayerBackend::play_playbackLastsForTheExpectedTime(file qrc:/testdata/busMpeg4.mp4, loops 2, rate 0.5, pause before 1) 'abs(duration - expectedDuration) < 600ms' returned FALSE. (expected duration: 4000ms, actual duration: 2037ms)
       Loc: [/home/qt/work/qt/qtmultimedia/tests/auto/integration/qmediaplayerbackend/tst_qmediaplayerbackend.cpp(1720)]
    PASS   : tst_QMediaPlayerBackend::cleanupTestCase()
    Totals: 2 passed, 1 failed, 0 skipped, 0 blacklisted, 2547ms
    
    
    14194: ********* Start testing of tst_QMediaPlayerBackend *********
    FAIL!  : tst_QMediaPlayerBackend::play_playbackLastsForTheExpectedTime(file qrc:/testdata/busMpeg4.mp4, loops 2, rate 0.5, pause before 1) 'abs(duration - expectedDuration) < 600ms' returned FALSE. (expected duration: 4000ms, actual duration: 2036ms)
       Loc: [/home/qt/work/qt/qtmultimedia/tests/auto/integration/qmediaplayerbackend/tst_qmediaplayerbackend.cpp(1720)]
    PASS   : tst_QMediaPlayerBackend::cleanupTestCase()
    Totals: 2 passed, 1 failed, 0 skipped, 0 blacklisted, 2545ms

      compare:
      https://testresults.qt.io/logs/qt/qtmultimedia/c18c436124a37838ee8090bc5f6e64df5dfd5a9f/LinuxUbuntu_22_04x86_64LinuxUbuntu_22_04x86_64GCCqtci-linux-Ubuntu-22.04-x86_64-51-e8468bSccache_TestDocs_TestOnly/c88cb678bc24d1640e7642a55aa7c01c0e08e406/test_1732209990/log.txt.gz

      observations:

      • test fails with the ffmpeg backend
      • test failures are spurious
      • test fail when the loop count is 2, because the actual playback duration is roughly half of the actual playback duration.

      this smells like a race condition in the looping machinery of the ffmpeg backend, where the playback stops instead of seeking to the beginning

        No reviews matched the request. Check your Options in the drop-down menu of this sections header.

            qtmultimediateam Qt Multimedia Team
            timblechmann tim blechmann
            Votes:
            0 Vote for this issue
            Watchers:
            1 Start watching this issue

              Created:
              Updated:

                There are no open Gerrit changes