Le mardi 12 août 2014, 16:34:18 Carl Eugen Hoyos a écrit : > > SF <sylvain <at> lahiette.com> writes: > > > * If i add "maxrate" and "bufsize" options, then > > it varies between 5 ms and 80ms (yes !) for the > > same video sequence. > > > It seems to be related to movement in the scene, > > but i do not see the relationship between the > > maxrate/bufsize parameters and the movement. > > I don't know much about motion compensation and rate > control but I find the relationship unavoidable.
Yes, i understand the relationship, but with such variations, i do not understand. > > Is the performance issue you see reproducible with > "ffmpeg" (the application)? Here is the equivalent FFMPEG command : ./ffmpeg -loglevel debug -f v4l2 -re -i /dev/video0 -vcodec mpeg2video -pix_fmt yuv420p -s 704x576 -r 25 -b:v 2500k -maxrate 3000k -bufsize 2700k -threads 1 -f mpegts -muxrate 2550k udp://192.168.144.56:55000?pkt_size=1316 FFMPEG is consuming approx. 9% of the CPU, which seems OK for me. If i provide the same parameters by calling directly libavcodec/libavformat, it uses 30% of the CPU. After investigation, encoding an intra takes more than 40 ms ( !!!) and approx. 18ms for P pictures. I checked the values in AVCodecContext between what is set by FFMPEG and what i set in my application and i see no differences. Any idea what can cause this CPU over-consumption when encoding I frames ? Thanks, Sylvain. > > Carl Eugen > > _______________________________________________ > ffmpeg-user mailing list > [email protected] > http://ffmpeg.org/mailman/listinfo/ffmpeg-user _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
