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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>In a video previewer that I am writing, I am trying to synchronize the audio to the video as in ffplay.c with av_sync_type = AV_SYNC_VIDEO_MASTER. The resulting audio seems to be in sync with the video; however, it is warbly, like it’s playing through water or something. Obviously, I am missing something in mimicking the technique from ffplay.c <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>In synchronize_audio() of ffplay.c, there is this line:<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>diff = get_audio_clock(is) - get_master_clock(is);<o:p></o:p></p><p class=MsoNormal>I am using the get_audio_clock() as in ffplay, but for the get_master_clock(), I am using a custom get_video_clock() directly, as I will always be syncing to the video. However, I am not using the same function as in ffplay.c, because I am not handling the video stream through a PacketQueue. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My app performs video analysis on the video frames as they are decoded and then passes them to a Windows C# UI for display and optional saving to disk. The throughput of the video analysis drives the video playback. That is, when it is done processing a frame, then it requests the next one. If the processing takes less time than a frame interval, then I insert a delay to ensure that the playback is close to real time for the user. (Maybe this is not the best design?)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Therefore, I would like the audio to follow the video. The problem seems to be in getting the proper value for the video “clock”. To this end, I have been using a function as in Dranger’s tutorial06.c:<o:p></o:p></p><p class=MsoNormal>double get_video_clock(VideoState *is) {<o:p></o:p></p><p class=MsoNormal> double delta;<o:p></o:p></p><p class=MsoNormal> delta = (av_gettime() - video_current_pts_time) / 1000000.0;<o:p></o:p></p><p class=MsoNormal> return video_current_pts + delta;<o:p></o:p></p><p class=MsoNormal>}<o:p></o:p></p><p class=MsoNormal>where delta is amount of time since the video_current_pts was obtained. Seems to me that this should work in my context, yet the result is not yet acceptable. If I change the function to simply <o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>return video_current_pts; <o:p></o:p></p><p class=MsoNormal>Then the warble is more pronounced.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>How do I get the audio to properly synchronize with the video?<o:p></o:p></p></div></body></html>