[Libav-user] PTS values and writing encoded audio and video frames ?

[ashika umanga]

Greetings all,

I am writing a wrapper class for video/audio encoding by following the
"muxing.c".
http://ffmpeg.org/doxygen/trunk/muxing_8c-source.html

I see in the example that before writing frames to the file ,is checks
whether the PTS value of audiostream is
lesser than that of videostream.

code snippet:

 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
            write_audio_frame(oc, audio_st);
        } else {
            write_video_frame(oc, video_st);
            picture->pts++;
        }

Can someone explain why this test is done? Whats the connection between PTS
values ?
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