Hello all, I am a long time ffmpeg user and recently I've noticed a strange behavior when running multiple ffmpeg instances. I'm streaming video from a server into ffmpeg (in this case using wget for testing) via stdin, and extracting png frames into a pipe at 1 a rate of 1fps using the image2pipe output format. For testing, the pipe's output then goes to /dev/null.
When running just one instance of ffmpeg, it uses about 20-25% CPU. I then continue to run a few more simultaneous instances doing the exact same thing. When I have 4 instances, I see that each instance is now using 30-35% CPU. When I get to 7 instances, each one is using 40-45% CPU. Finally, when I get to 9 instances, each instance uses 55-60% CPU! As you will see below, my ffmpeg is compiled with vaapi support, but I've already tried running with "-hwaccel none" and with "-threads 1" and I still get the same results. One would expect the CPU usage per instance to remain the same, right? am I missing anything here? Just to make things clear, there's no network bandwidth issue here what so ever, I have more than enough bandwidth to download the same live stream multiple times. My machine is a Dell Precision M6800 laptop with a quad-core Core i7-4930MX at 3.00GHz with hyper-threading so it looks like 8 cores. I have 32GB of RAM and running an Ubuntu 12.04 OS with a standard 3.13.0-34-generic kernel. I have an AMD FirePro M6100 Mobility Pro with 2GB GDDR5 dedicated RAM. The tests are running on a custom compiled ffmpeg 2.3.1 with the following configure command: ../ffmpeg-2.3.1/configure --enable-gpl --enable-nonfree --enable-demuxer=concat --enable-libfreetype --enable-fontconfig --enable-bzlib --enable-gnutls --enable-libfaac --enable-librtmp --enable-libx264 --enable-decoder=png --enable-encoder=png --enable-hwaccel=h264_vaapi --prefix=/home/magogo/ffmpeg/dist Any ideas why this behavior should happen and if there is any way to fix this? Thanks, Magogo _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
