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• ffmpeg : Extract every nth frame and save only that frame with frame index as name [duplicate]

  2 février 2021, par CatTheGrimReaper

  I want to create a bash script (Windows 10) that lets me extract every 5th frame from every video in the current folder. The frames should be saved as "videoname-framenumber.jpg". So the output should be

  


  


  "videoname-frame_1.jpg", "videoname-frame_5.jpg",
"videoname-frame_10.jpg", etc.

  


  


  for %%F in (*.mp4) do (
ffmpeg -i %%F -vf "select=not(mod(n\,5))" %%~nF-%%4d.jpg
)


  


  This is what I have so far, but it doesn't do what I want. This extracts the first frame and saves it four times (as "videoname-0001.jpg", "videoname-0002.jpg", "videoname-0003.jpg", "videoname-0004.jpg"), then extracts the fifth frame and saves it four times (as "videoname-0005.jpg", "videoname-0006.jpg".....) and so on.

  


  My two problems are :

  


  

  1. I don't know why it saves every 5th frame four times, it should only save it one time each.

  


  2. How do I insert the current frame index as a suffix to my output image file's name ?

  


  


  Any help would be appreciated, thanks !

  


• Raspivid & Avconv add watermark and save .mp4 from Youtube output stream

  25 octobre 2017, par walolinux

  I have this ffmpeg command working with a USB webcam in my raspberry pi :

  ffmpeg -thread_queue_size 512 -f v4l2 -video_size 1280x720 -i /dev/video0 -f lavfi -i anullsrc=cl=stereo:r=44100 -map 0:v -map 1:a -r 30 -aspect 16:9 -c:v h264 -preset veryfast -crf 25 -pix_fmt yuv420p -g 60 -maxrate:v 820k -bufsize:v 820k -profile:v baseline -c:a aac -b:a 128k -strict experimental -flags +global_header -vf "movie=logo.png [watermark]; [in][watermark] overlay=main_w-overlay_w-5:main_h-overlay_h-5 [out]" -f tee "[f=flv]rtmp://a.rtmp.youtube.com/live2/XXX|video.flv"

  This command adds a watermark (logo), saves mp4 to disk and broadcast to youtube the stream. It is working, but my raspberry pi hangs because it gets out of memory (CPU and RAM).

  This is why i have changed my USB webcam to raspicam 2.1.

  Now i am trying to do the same but using raspivid and avconv. But this is the only command i have already managed to use :

  raspivid -o - -t 0 -vf -hf -fps 30 -b 6000000 | avconv -re -ar 44100 -ac 2 -acodec pcm_s16le -f s16le -ac 2 -i /dev/zero -f h264 -i - -vcodec copy -acodec aac -ab 128k -g 50 -strict experimental -f flv rtmp://a.rtmp.youtube.com/live2/XXX

  I am looking to replicate functionality but with raspicam 2.1.

  Thanks.

• FFMPEG to both save a file and stream to MPLayer on a different computer

  8 octobre 2016, par Laurent Bazinet

  Here’s what i’m trying to do : Have a raspberry pi grab a video with a camera, using raspivid and pipe this directly to my main computer, which would act as a kind of server, by both saving the video, and allowing a live stream using MPlayer to be displayed by another computer on the network.

  My problem is only on the last part : display the stream on another computer.

  For clarity, Main computer is going to be Comp-A, and the computer running MPlayer will be Comp-X (because this can be any computer on my network, or even outside my network)

  If we follow the information, here’s how i’ve done it so far : Grab the video and pipe it to the network (this is done on the raspberry pi)

  raspivid -t 0 -w 1280 -h 720 -a 12 -ih -v -fps 30 -n -o - | sudo nc -k -w 1 -l 80

  This works great for my purpose.

  Next, on Comp-A, I’m grabbing this stream with FFMPEG, and tee-ing to both a file and a UDP stream using this command :

  ffmpeg -i tcp://raspberryIP:80 -c:v h264 -f tee -map 0:v "[f=stream_segment:segment_wrap=25:segment_time=3600:reset_timestamps=1]output%%03d.mp4|[f=mpegts]udp://maincomputerIP:80"

  (side note, the [f=stream_segment:segment_wrap=25:segment_time=3600:reset_timestamps=1] is to have 25 videos of 1 hour long, and looping)

  Then I run into issues.

  If I run this on Comp-A :
  mplayer -fps 200 -demuxer mpegts "udp://Comp-A-IP:80"
  It works great.

  If I run the same command on Comp-X, it doesn’t work.

  If I change the [f=mpegts]udp://Comp-A-IP:80" to [f=mpegts]udp://Comp-X-IP:80", then the Comp-X works, but the Comp-A doesn’t anymore.

  This leads me to believe my issue is that the UDP url from FFMPEG is asking for the computer it’s going to connect to, not the host computer.

  My problem is that Comp-X’s IP is unknown.

  Is there a way ? Maybe I’m over-complicating things. I don’t know.