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• swscale/output : Altivec-optimize yuv2plane1_8

  17 novembre 2018, par Lauri Kasanen

  swscale/output : Altivec-optimize yuv2plane1_8
  ./ffmpeg_g -f rawvideo -pix_fmt rgb24 -s hd1080 -i /dev/zero -pix_fmt yuv420p \
  
   f null -vframes 100 -v error -nostats -
  1158 UNITS in planar1,   65528 runs,      8 skips
   cpuflags 0
  19082 UNITS in planar1,   65533 runs,      3 skips
  16.48 speedup ratio. On x86, SSE2 is 7. Curiously, the Power C version
  
  takes as many cycles as the x86 SSE2 version, yikes it's fast.
  Note that this function uses VSX instructions, but is not marked so.
  
  This is because several existing functions also make that mistake.
  
  I'll submit a patch moving them once this is reviewed.
  Signed-off-by : Lauri Kasanen <cand@gmx.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libswscale/ppc/swscale_altivec.c

• ffmpeg record timelapse camera v4l2

  21 mars 2019, par Paul G.

  How can I instruct ffmpeg (v. : 3.4.5) to record only one frame per minute from my video camera at /dev/video0 and copy it to a new file with 30 frames per second ? Goal is timelapse video of some months and record only one frame per minute into the out video to save space and processing power instead of just capturing the camera at 30fps and then preprocess the huge video file for speed up...

  The camera delivers a 1920x1080 30fps stream with "mjpeg" selected in commandline. I would like to keep the raw frames and just copy them into the out file. I tried this command to get 1fps input to 30fps output but this seems not to work :

  ffmpeg -framerate 1 -input_format mjpeg -i /dev/video0 -r 30 -c:v copy -an out.mp4
  
  
  
  [video4linux2,v4l2 @ 0x55ece63ac360] The driver changed the time per frame from 1/1 to 1/30
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 37064.594605, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1920x1080, 30 fps, 30 tbr, 1000k tbn, 1000k tbc

  But this doesnt work.

• avconv/ffmpeg simultaneously stream from usb webcam and save video onto disk

  27 novembre 2017, par BojowyZajaczek

  I need to simultaneously stream/broadcast (over rtmp) and save video (with audio) from my USB webcam. The webcam is Logitech c920 which have hardware h.264 encoder.

  I don’t want to reencode the media, so I’m using the -c:v copy option.

  The whole script looks like below :

  #! /bin/bash
  
  
  
  SOURCEV="/dev/video0"
  
  SOURCEA="hw:1"
  
  
  
  FILE_TO_SAVE="Archive/file_to_save.mp4"
  
  YOUTUBE_URL="rtmp://x.rtmp.youtube.com/live2"
  
  KEY="my-secret-key"        
  
  
  
  avconv -f alsa -ac 2 -r 44100 -i $SOURCEA \
  
  -s 1920x1080 -r 24 -c:v h264 -i "$SOURCEV" \
  
  -ar "44100" -r:v 24 -c:a aac -c:v copy -s 1920x1080 -f mp4 "$FILE_TO_SAVE" \
  
  -g $FPS*4 -ar "44100" -b:a "128k" -ac 2 -r 24 -c:a aac -c:v copy -s 1920x1080 -f flv "$YOUTUBE_URL/$KEY"

  This method "works" - it means’ it can stream content and save it to disk, but the problem with this method is that file video relies on the stream. For example if the Internet connection is too slow, the saved file will have low FPS. If the Internet connection is interrupted the "recording" of video file is stopped.

  Can anyone help me with making this two streams independent ?

  The whole things is happening on raspberrypi 3 so computing power is highly limited.