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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

• Is there a set of working P/Invoke declarations for FFMpeg, libavutil, libavformat and libavcodec in .NET ?

  11 février 2014, par casperOne

  I'm currently looking to access libavutil, libavformat and libavcodec (all part of FFMpeg) from .NET.

  Currently, I'm getting the libraries from the automated builds of the shared FFMpeg package performed every night for Windows 32-bit.

  I am also using the code from the ffmpeg-sharp project. In that project, I have removed a number of classes that were not compiling (they are wrapper classes not the P/Invoke declarations).

  The code compiles fine, but I am running into a few issues.

  First, it appears that the build of av*.dll uses the cdecl calling convention, as I was receiving a number of PInvokeStackImbalanceException when trying to call av_open_input_file. This was easy enough to change to get it to work right. The AVFormatContext structure is populated.

  After that, I want to call av_find_stream_info to get information about the streams in the file. However, when calling that with the AVFormatContext retrieved from the call to av_open_input_file, an AccessViolationException is thrown indicating that I am trying to read or write from protected memory.

  Has anyone used P/Invoke to access the libavutil, libavformat and libavcodec dll libraries through P/Invoke and have gotten it to work ?

  I should mention that working with the command-line version of FFMpeg, while a solution, is not a viable solution in this case, access needs to occur through the libraries. The reason for this is that I'd have to thrash the disk way too much to do what I need to do (I have to do a frame-by-frame analysis of some very high definition video) and I want to avoid the disk as much as possible.

• Is there a set of working P/Invoke declarations for FFMpeg, libavutil, libavformat and libavcodec in .NET ?

  30 août 2011, par casperOne

  I'm currently looking to access libavutil, libavformat and libavcodec (all part of FFMpeg) from .NET.

  Currently, I'm getting the libraries from the automated builds of the shared FFMpeg package performed every night for Windows 32-bit.

  I am also using the code from the ffmpeg-sharp project. In that project, I have removed a number of classes that were not compiling (they are wrapper classes not the P/Invoke declarations).

  The code compiles fine, but I am running into a few issues.

  First, it appears that the build of av*.dll uses the cdecl calling convention, as I was receiving a number of PInvokeStackImbalanceException when trying to call av_open_input_file. This was easy enough to change to get it to work right. The AVFormatContext structure is populated.

  After that, I want to call av_find_stream_info to get information about the streams in the file. However, when calling that with the AVFormatContext retrieved from the call to av_open_input_file, an AccessViolationException is thrown indicating that I am trying to read or write from protected memory.

  Has anyone used P/Invoke to access the libavutil, libavformat and libavcodec dll libraries through P/Invoke and have gotten it to work ?

  I should mention that working with the command-line version of FFMpeg, while a solution, is not a viable solution in this case, access needs to occur through the libraries. The reason for this is that I'd have to thrash the disk way too much to do what I need to do (I have to do a frame-by-frame analysis of some very high definition video) and I want to avoid the disk as much as possible.