On Wed, Oct 30, 2013 at 5:51 AM, YIRAN LI <[email protected]> wrote: > > Hi friends, > > Here I have a question about AVFrame pts needs your help. > > My application uses av_read_frame to get packets and then calls > avcodec_decode_video2 to get video frames. But recently I found one specific > video file generates strange pts/dts. > > Below is a part of the log: > > 00:00:17.301 MAIN timestamp_debug: pkt.pts = -9223372036854775808, dts = 0 > 00:00:17.301 MAIN timestamp_debug: frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = -9223372036854775808, frame.pts = > -9223372036854775808 > 00:00:17.301 1108 FFMPEG: looks like this file was encoded with > (divx4/(old)xvid/opendivx) -> forcing low_delay flag > > 00:00:17.301 MAIN timestamp_debug: pkt.pts = -9223372036854775808, dts = 1 > 00:00:17.301 MAIN timestamp_debug: frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = -9223372036854775808, frame.pts = > -9223372036854775808 > 00:00:17.301 MAIN timestamp_debug: pkt.pts = -9223372036854775808, dts = 2 > 00:00:17.301 MAIN timestamp_debug: frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = -9223372036854775808, frame.pts = > -9223372036854775808 > 00:00:17.301 MAIN timestamp_debug: pkt.pts = -9223372036854775808, dts = 3 > 00:00:17.301 MAIN timestamp_debug: frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = -9223372036854775808, frame.pts = > -9223372036854775808 > 00:00:17.301 MAIN timestamp_debug: pkt.pts = -9223372036854775808, dts = 4 > 00:00:17.301 MAIN timestamp_debug: [a full frame : frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = 0], frame.pts = 0 > 00:00:18.393 LVid236 timestamp_debug: pkt.pts = -9223372036854775808, dts > = 5 > 00:00:18.408 LVid236 timestamp_debug: [a full frame : frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = 1], frame.pts = 0 > 00:00:18.439 LVid236 timestamp_debug: pkt.pts = -9223372036854775808, dts > = 6 > 00:00:18.439 LVid236 timestamp_debug: [a full frame : frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = 2], frame.pts = 0 > 00:00:18.439 LSou259 FFMPEG: first_dts 0 not matching first dts 113424 in > the queue > 00:00:18.486 LVid236 timestamp_debug: pkt.pts = -9223372036854775808, dts > = 7 > 00:00:18.486 LVid236 timestamp_debug: [a full frame : frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = 3], frame.pts = 0 > 00:00:18.517 LVid236 timestamp_debug: pkt.pts = -9223372036854775808, dts > = 8 > 00:00:18.517 LVid236 timestamp_debug: [a full frame : frame.pkt_pts = > -9223372036854775808, frame.pkt_dts = 4], frame.pts = 0 > 00:00:18.549 LSou259 FFMPEG: first_dts 0 not matching first dts 114675 in > the queue > > We can see that, it was until 4th packet is sent to decode function that we > got the first full frame. and all frames had pts = 0 > > So here I want to know, frame.pts, frame.pkt_dts, packet,dts. which is best > to represent the time stamp of a video frame (I mean pts, but in this case, > no pts is valid). > > For example, in this case, for the 1st frame, should I use frame.pkt_dts > (that's 0), or pkt.pts (the last packet that generates this frame, in this > case 4) as the time position > of the frame? > > The file I used to test is here > https://dl.dropboxusercontent.com/u/89678527/av_divx_24_yuv420p_mp3_44100_2_1.avi > > Thanks
That's what best_effort_timestamp is for. See http://dranger.com/ffmpeg/tutorial05.html about different values of pts/dts. BR, Alex Cohn _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
