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• Superimposing two videos onto a static image ?

  15 décembre 2014, par Archagon

  I have two videos that I’d like to combine into a single video, in which both videos would sit on top of a static background image. (Think something like this.) My requirements are that the software I use is free, that it runs on OSX, and that I don’t have to re-encode my videos an excessive number of times. I’d also like to be able to perform this operation from the command line or via script, since I’ll be doing it a lot. (But this isn’t strictly necessary.)

  I tried fiddling with ffmpeg for a couple of hours, but it just doesn’t seem very well suited for post-processing. I could potentially hack something together via the overlay feature, but so far I haven’t figured out how to do it, aside from pain-stakingly converting the image to a video (which takes 2x as long as the length of my videos !) and then superimposing the two videos onto it in another rendering step.

  Any tips ? Thank you !

  ---

  Update :

  Thanks to LordNeckbeard’s help, I was able to achieve my desired result with a single ffmpeg call ! Unfortunately, encoding is quite slow, taking 6 seconds to encode 1 second of video. I believe this is caused by the background image. Any tips on speeding up encoding ? Here’s the ffmpeg log :

  MacBook-Pro:Video archagon$ ffmpeg -loop 1 -i underlay.png -i test-slide-video-short.flv -i test-speaker-video-short.flv -filter_complex "[1:0]scale=400:-1[a];[2:0]scale=320:-1[b];[0:0][a]overlay=0:0[c];[c][b]overlay=0:0" -shortest -t 5 -an output.mp4
  
  ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Nov 14 2012 16:18:58 with Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn)
  
    configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-libtheora --enable-libschroedinger --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libspeex --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --arch=x86_64 --enable-yasm --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid
  
    libavutil      51. 73.101 / 51. 73.101
  
    libavcodec     54. 59.100 / 54. 59.100
  
    libavformat    54. 29.104 / 54. 29.104
  
    libavdevice    54.  2.101 / 54.  2.101
  
    libavfilter     3. 17.100 /  3. 17.100
  
    libswscale      2.  1.101 /  2.  1.101
  
    libswresample   0. 15.100 /  0. 15.100
  
    libpostproc    52.  0.100 / 52.  0.100
  
  Input #0, image2, from 'underlay.png':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: png, rgb24, 1024x768, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  Input #1, flv, from 'test-slide-video-short.flv':
  
    Metadata:
  
      author          : 
  
      copyright       : 
  
      description     : 
  
      keywords        : 
  
      rating          : 
  
      title           : 
  
      presetname      : Custom
  
      videodevice     : VGA2USB Pro V3U30343
  
      videokeyframe_frequency: 5
  
      canSeekToEnd    : false
  
      createdby       : FMS 3.5
  
      creationdate    : Mon Aug 16 16:35:34 2010
  
      encoder         : Lavf54.29.104
  
    Duration: 00:50:32.75, start: 0.000000, bitrate: 90 kb/s
  
      Stream #1:0: Video: vp6f, yuv420p, 640x480, 153 kb/s, 8 tbr, 1k tbn, 1k tbc
  
  Input #2, flv, from 'test-speaker-video-short.flv':
  
    Metadata:
  
      author          : 
  
      copyright       : 
  
      description     : 
  
      keywords        : 
  
      rating          : 
  
      title           : 
  
      presetname      : Custom
  
      videodevice     : Microsoft DV Camera and VCR
  
      videokeyframe_frequency: 5
  
      audiodevice     : Microsoft DV Camera and VCR
  
      audiochannels   : 1
  
      audioinputvolume: 75
  
      canSeekToEnd    : false
  
      createdby       : FMS 3.5
  
      creationdate    : Mon Aug 16 16:35:34 2010
  
      encoder         : Lavf54.29.104
  
    Duration: 00:50:38.05, start: 0.000000, bitrate: 238 kb/s
  
      Stream #2:0: Video: vp6f, yuv420p, 320x240, 204 kb/s, 25 tbr, 1k tbn, 1k tbc
  
      Stream #2:1: Audio: mp3, 22050 Hz, mono, s16, 32 kb/s
  
  File 'output.mp4' already exists. Overwrite ? [y/N] y
  
  using cpu capabilities: none!
  
  [libx264 @ 0x7fa84c02f200] profile High, level 3.1
  
  [libx264 @ 0x7fa84c02f200] 264 - core 119 - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      encoder         : Lavf54.29.104
  
      Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1024x768, q=-1--1, 25 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 (png) -> overlay:main
  
    Stream #1:0 (vp6f) -> scale
  
    Stream #2:0 (vp6f) -> scale
  
    overlay -> Stream #0:0 (libx264)
  
  Press [q] to stop, [?] for help

  ---

  Update 2 :

  It works ! One important tweak was to move the underlay.png input to the end of the input list. This increased performance substantially. Here’s my final ffmpeg call. (The maps at the end aren’t required for this particular arrangement, but I sometimes have a few extra audio inputs that I want to map to my output.)

  ffmpeg
  
      -i VideoOne.flv
  
      -i VideoTwo.flv
  
      -loop 1 -i Underlay.png
  
      -filter_complex "[2:0] [0:0] overlay=20:main_h/2-overlay_h/2 [overlay];[overlay] [1:0] overlay=main_w-overlay_w-20:main_h/2-overlay_h/2 [output]"
  
      -map [output]:v
  
      -map 0:a
  
      OutputVideo.m4v

• FFMPEG compilation without compiler optimization

  11 juin 2014, par Kamil_H

  I’m compiling ffmpeg for win32 using Microsoft cl compiler. I need to compile it without any optimization, so added configure —extra-cflags= -Od".

  Compilation goes fine, but there are a few places like this :

  Last 3 ifs.

  The code compiles, but doesn’t link because calls like ff_sbrdsp_init_arm(s) ; are not removed by compiler. Of course everything is fine when compiling with optimization. Then compiler removes all if(0)s.

  There are several similar places in ffmpeg. Why if(0) is used instead of preprocessor’s #if 0 ?

  Is there any hidden trick behind this ?

• Raspberry Pi HLS streaming [on hold]

  5 mars 2015, par Razvan-Catalin Olaru

  I have a rev. B Raspberry Pi and want to stream from my Microsoft Lifecam VX-800 to a web server using HLS protocol and avconv/ffmpeg, preferably without using raspivid because it’s not working (couldn’t figure out why). The stream needs to be fed to jwplayer. I went through a lot of guides but none seem to be fitting my needs. Could you give me detailed instructions on how to do the live streaming or give me links to detailed tutorials that you tried and worked ?

  Thanks.