I have a source media and used
ffprobe to inspect the audio track for
pts_time and the start time, and it looks fine as below
ffprobe -v 0 -show_packets -select_streams audio [source_media].mp4 | grep 'pts_time' | head
pts_time=0.023220 pts_time=0.046440 pts_time=0.069660 pts_time=0.092880 pts_time=0.116100 pts_time=0.139320 pts_time=0.162540 pts_time=0.185760 pts_time=0.208980
However, after I transcoded it using the following
ffmpeg command, the start time of the audio track became negative and it causes playback issue on Tizen3
ffmepg -c:v libx264 -vf scale=320x180,setdar=16/9 -crf 22 -maxrate 172k -bufsize 236k -pix_fmt yuv420p -profile:v main -level 3.0 -refs 3 -r 25 -force_key_frames expr:gte\(t,n_forced*2\) -c:a libfdk_aac -b:a 128k -ar 44100 -ac 2 -movflags +faststart -threads 0 -y.
ffprobe to inspect it, it has 2 packets at the beginning that have negative pst_time which ended up the negative start time
ffprobe -v 0 -show_packets -select_streams audio [transcoded_video].mp4 | grep pts_time | head
pts_time=-0.046440 pts_time=-0.023220 pts_time=0.000000 pts_time=0.023220 pts_time=0.046440 pts_time=0.069660 pts_time=0.092880 pts_time=0.116100 pts_time=0.139320 pts_time=0.162540
ffmpegchanges the start time of the audio track?
- Is it valid that a track can start with negative timestamp? what does it even mean?
-avoid_negative_ts make_non_negativeto the
ffmpegcommand seems to be able to fix up the playback issue on Tizen3, however, what does it mean and what the implication of them respectively