<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi There,<br class=""><div><font color="#5856d6" class=""><br class=""></font>I am trying to MUX H264 video and AAC audio into a TS file. The sources of these streams are separate and provide NTP timestamps for each frame.<br class=""><font color="#5856d6" class=""><br class=""></font>I have decided to go with video master TS mode to use NTP timestamp of first video frame as reference to calculate PTS values before MUXing. I also drop all the audio frames received before first video frame.<br class=""><font color="#5856d6" class=""><br class=""></font>I am not able to achieve proper AV sync and my audio is leading by the difference in NTP timestamps of respective first frames.<br class=""><font color="#5856d6" class=""><br class=""></font>e.g. <br class=""><font color="#5856d6" class=""><br class=""></font>1. First Video Frame - <span class="Apple-tab-span" style="white-space: pre;">      </span>NTP 11:00:00:000 <span class="Apple-tab-span" style="white-space: pre;"> </span>- Duration 30mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS=0 <span class="Apple-tab-span" style="white-space: pre;">  </span><span class="Apple-tab-span" style="white-space: pre;">  </span>timebase{1,90000}<br class="">2. First Audio Frame - <span class="Apple-tab-span" style="white-space: pre;">     </span>NTP 11:00:00:040 <span class="Apple-tab-span" style="white-space: pre;"> </span>- Duration 70 mSec <span class="Apple-tab-span" style="white-space: pre;">       </span>- PTS= 3600 <span class="Apple-tab-span" style="white-space: pre;">      </span>timebase{1,90000}<br class="">3. Second V Frame<span class="Apple-tab-span" style="white-space: pre;">   </span>  -<span class="Apple-tab-span" style="white-space: pre;">  </span>NTP  11:00:00:030 <span class="Apple-tab-span" style="white-space: pre;">   </span>- Duration 30mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS= 2700 <span class="Apple-tab-span" style="white-space: pre;">      </span>timebase{1,90000}<br class="">4. Third V Frame       -<span class="Apple-tab-span" style="white-space: pre;">      </span>NTP  11:00:00:060 <span class="Apple-tab-span" style="white-space: pre;">   </span>- Duration 30mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS= 7200 <span class="Apple-tab-span" style="white-space: pre;">      </span>timebase{1,90000}<br class="">5. Forth V Frame       -<span class="Apple-tab-span" style="white-space: pre;">      </span>NTP  11:00:00:090 <span class="Apple-tab-span" style="white-space: pre;">   </span>- Duration 30mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS= 8100 <span class="Apple-tab-span" style="white-space: pre;">      </span>timebase{1,90000}<br class="">6. Second  A Fram     -<span class="Apple-tab-span" style="white-space: pre;">    </span>NTP  11:00:00:110 <span class="Apple-tab-span" style="white-space: pre;">   </span>- Duration 70mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS= 9900 <span class="Apple-tab-span" style="white-space: pre;">      </span>timebase{1,90000}<br class="">7. Fifth V Frame         -<span class="Apple-tab-span" style="white-space: pre;">  </span>NTP  11:00:00:120 <span class="Apple-tab-span" style="white-space: pre;">   </span>- Duration 30mSec <span class="Apple-tab-span" style="white-space: pre;">        </span><span class="Apple-tab-span" style="white-space: pre;">  </span>- PTS= 10800 <span class="Apple-tab-span" style="white-space: pre;">     </span>timebase{1,90000}<br class=""><font color="#5856d6" class=""><br class=""><br class=""></font>For the above case the drift is 40mSec. If I correct Audio sync by -40mSec VLC plays the video just fine.<br class=""><font color="#5856d6" class=""><br class=""></font>Please let me know if my logic is right and if not suggest a correction. Am I supposed to set an output_ts_offset to correct the drift and if yes how to do that?<br class=""><font color="#5856d6" class=""><br class=""></font>Regards,<br class=""><div class=""><div class="">Ameya Tambekar</div></div></div><br class=""><div class="">_______________________________________________<br class="">Libav-user mailing list<br class=""><a href="mailto:Libav-user@ffmpeg.org" class="">Libav-user@ffmpeg.org</a><br class=""><a href="http://ffmpeg.org/mailman/listinfo/libav-user" class="">http://ffmpeg.org/mailman/listinfo/libav-user</a></div></body></html>