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• ffmpeg setpts filter not applied to output

  29 avril 2019, par joe5

  Learning to speed up and slow down video using the ffmpeg setpts filter, but I am struggling to get a simple expression to work.

  ffmpeg -i .\F5-ff.mp4 -filter:v "setpts=0.25*PTS" ff-test3.mp4

  I get the output file, but it is not any faster than the original.

  I’m sorry if this has already been addressed. Most related post I’ve found were trouble shooting more complex operations past this step. Im working in a powershell terminal fyi.

• Controlling ffmpeg at runtime with zmq

  3 avril 2023, par Gavin

  I want to dynamically change the rectilinear view (eg its yaw) of a 360 video as it plays.

  


  basic command

  


  To take a 360 video and show a flat/normal view at a yaw perspective of 60 degrees

  


  ffmpeg -i input360.mp4 -vf "v360=input=e:rectilinear:yaw=60,scale=iw/4:-1" out60.mp4
This works fine.

  


  Changing the yaw during playback

  


  I understand ffmpeg has two methods to change filter params at runtime ; sendcmd (file based) and zmq (message based)

  


  I got sendcmd method working, but am struggling to understand zmq syntax and use. ffmpeg's zmq docs are pretty sparse.
I am using a local Windows 10 PC

  


  sendcmd

  


  ffplay -i input360.mp4 -vf "sendcmd=f=cmd.txt,v360=input=e:rectilinear:reset_rot=1,scale=iw/4:-1"

  


  with a cmd.txt file

  


  0-5 [expr] v360 yaw 'lerp(0,90,TI)';
5-10 [expr] v360 yaw 'lerp(90,0,TI)';


  


  result : yaw changes from 0 to 90 degrees from t=0-5s and then 90 to 0 degrees from t=5-10s. Perfect

  


  zmq

  


  ffplay -i input360.mp4 -vf "v360=input=e:rectilinear:reset_rot=1,zmq,scale=iw/4:-1"

  


  I got zmqsend from ffmpeg-tools.zip and added to my ffmpeg bin directory

  


  


  1. execute above ffplay command from terminal window #1 - and see video playing

     


  


  2. Open terminal window #2 and execute : echo v360 yaw 90 > zmqsend

     


  


  


  result : no change to video yaw. No errors either

  


  What am I doing wrong ? Im not sure if my ffmpeg command is wrong, or if my zmq message does not reach ffmpeg (or both). I checked my ffmpeg v2022-10-10 config has —enable-libzmq

  


• Why is ffmpeg taking up so much memory when I try to stop a livestream ?

  4 juillet 2019, par FiskFan1999

  When the ffmpeg function is running, there are no problems with memory and everything runs smoothly. However, when I attempt to stop the stream/ffmpeg by pressing q (or ctrl-c), ffmpeg freezes, doesn’t take any other inputs, and suddenly takes up an obscene amount of memory.

  I am using ffmpeg to livestream on youtube. I am using a MacBook Mid 2015 running macOS Mojave.

  here is the function I am using with ffmpeg.

  ffmpeg -re -f lavfi -i testsrc2=s=1280x720:r=60 -re -i "INPUT FILE.mp3" -vcodec libx264 -pix_fmt yuv420p -preset "ultrafast" -r 60 -g 120 -b:v 6168000 -filter_complex "[0]scale=1280:720;[1]aloop=start=0:size=202*44100:loop=-1" -acodec libmp3lame -ar 44100 -threads 3 -b:a 640000 -qscale:a 5 -bufsize 512k -f flv ${YOUTUBE_URL}/${KEY}

  The command runs perfectly and as expected while it is running. At this point, in Activity Monitor I can see that ffmpeg seems to peak to about 101 MB. When I press q, which is the button to end the encoding, if the stream had been going for about ten minutes ffmpeg freezes and in Activity monitor the ffmpeg command appears to climb to several gigabytes of memory without any sign of stopping. The most I have noticed is about 6 GB before I killed the command. Ffmpeg seems to be writing almost a gigabyte of data into memory a second. In fact, this slows down my computer when it occurs and threatens to completely fill up my memory.

  When this occurs, there are no error messages (except for warnings about running out of memory) and the terminal running ffmpeg seems to not respond to any kill commands, and the only way to alleviate the situation is to force close the terminal window itself.

  I’m wondering if somehow I am creating a memory leak issue or if I wrote something wrong or didn’t include something that would be necessary for live-streaming with ffmpeg.