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• FFmpeg - How to scale a video then apply a watermark ?

  28 août 2016, par Olibanum

  Im trying to scale a video so that it is always 512 wide where the height changes in proportion to the original video.
  Once scaled, I then want to apply a watermark/overlay to the video, therefore the video will scale but the watermark wont.

  I am able to achieve each of these separately using the following filters :

  Scale

  -vf "scale=512:-1"

  Watermark

  -vf "movie=watermark.png [watermark]; [in][watermark] overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]"

  They work successfully on their own.

  However when trying to combine the two, Im having a bit of trouble.

  Having both as parameters of course does not work as one will override the other.

  Ive tried :

  -vf "scale=512:-1,movie=watermark.png [watermark]; [in][watermark] overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2 [out]"

  my thinking was that the scale would be applied first then the watermark but all I get is an error

  Too many inputs specified for the "movie" filter.

  Error opening filters !

  Then changing the , to a ; resulted in :

  Simple filtergraph ’scale=512 :-1 ;
  movie=watermark.png
  [watermark] ; [in][watermark]
  overlay=(main_w-overlay_w)/2 :(main_h-overlay_h)/2 [out]’ does not have
  exactly one input and output.

  Error opening filters !

  I presume I need to do something more with filterchains but Im struggling to figure it out.

  Any ideas anyone ?

  Many thanks in advance.

• vp9 : initial attempt at a idct_idct_4x4 12bpp x86 simd (sse2) impl.

  12 octobre 2015, par Ronald S. Bultje

  vp9 : initial attempt at a idct_idct_4x4 12bpp x86 simd (sse2) impl.
  The trouble with this function is that intermediates overflow 31+sign
  
  bits, so I’ve added some helpers (that will also be used in 10/12bpp
  
  8x8, 16x16 and 32x32) to make that easier, basically emulating a half-
  
  assed pmaddqd using 2xpmaddwd. It’s currently sse2-only, if anyone sees
  
  potential in adding ssse3, I’d love to hear it.
  

  • [DH] libavcodec/x86/vp9dsp_init_16bpp_template.c
  • [DH] libavcodec/x86/vp9itxfm_16bpp.asm

• ffmpeg : Duplicate output and stream raw/no compression video/webcam to localhost without latency

  23 juin 2014, par Ralf Anderson

  I want to stream a video locally, webcam which I want to duplicate to be precise, but I’m having trouble doing this without any latency.

  I can directly access the camera with ffplay...

  ffplay.exe -f dshow -i video="ManyCam Virtual Webcam"

  This gives me no (noticeable) latency. When I stream it to the localhost like

  ffmpeg.exe -f dshow -i video="ManyCam Virtual Webcam" -r 25 -vcodec mpeg2video -preset ultrafast -threads 0 -q 5 -f mpegts udp://127.0.0.1:33333

  though, I get a notable latency on ffplay and it’s definitely buffering too. I don’t know if the delay purely comes from buffering or if it’s the encoding. Obviously I want an instant display with no caching/buffering/latency like I get when directly accessing the webcam.

  Is it the parameters (I’ve tried quite a few settings and codecs besides this, but no luck) ? Is it the player ?

  No encoding at all would be fine too. ffmpeg says, that the webcam delivers

  Stream #0:0: Video: rawvideo, bgr24, 640x480, 29.97 tbr, 10000k tbn, 29.97 tbc

  which I can display with ffplay. What would be the best way to duplicate the webcam feed ? Or can I stream the raw video to the localhost (with the tee muxer) and if, how do I correctly set this up and acces it again with e.g. ffplay ? I had no luck yet streaming raw video.

  Just any solution that allows me to locally have two processes access the data from the webcam would work.