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• Concat multiple (self-generated) videos using ffmpeg on raspbian linux

  25 février 2016, par Thomas Kekeisen

  I am a very talented sleep talker, so I decided to write a solution that records the things I talk at night to make funny videos with subtitles of it. The project is nearly done, but I got a big problem with concating videos I generated before.

  The video parts are generated from single png frames using this command :

  ffmpeg -y -framerate 15 -i "${images_file_path}" -c:v libx264 -r 30 -pix_fmt yuv420p "${video_file_path}"

  Then the sound is added using this command (got this from #9049970 and #11779490) :

  ffmpeg -y -i "${video_file_path}" -i "${mp3_file_path}" -map 0:v -map 1:a -vcodec copy -acodec copy -shortest "${final_video_file_path}"

  All this is causing no problems so far, but I think it may be relevant to know how the videos are generated. I can watch all this and get valid video and sound - the full source code of this first part can be found here.

  Now I added a feature that is able to generate "full videos" containing a title and a various number of previously generated "video parts" using this command :

  ffmpeg -f concat -i "${video_list_path}" -filter_complex "${filter_string} concat=n=${input_file_counter}:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" "${full_video_path}"

  But something is wrong with it and I get this error :

  Invalid file index 1 in filtergraph description [0:v:0] [1:v:0] [2:v:0] [2:a:0] [3:v:0] [4:v:0] [4:a:0] [5:v:0] [6:v:0] [6:a:0] [7:v:0] concat=n=8:v=1:a=1 [v] [a].

  The full output is :

  ffmpeg version N-77213-g7c1c453 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.2 (Raspbian 4.9.2-10)
  
    configuration: --enable-shared --enable-gpl --prefix=/usr --enable-nonfree --enable-libmp3lame --enable-libfaac --enable-libx264 --enable-version3 --disable-mmx
  
    libavutil      55. 10.100 / 55. 10.100
  
    libavcodec     57. 17.100 / 57. 17.100
  
    libavformat    57. 20.100 / 57. 20.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 20.100 /  6. 20.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0xc2e900] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from '/usr/sleeptalk/records-rendered/3enguzpuu2gw0ogk8wkko/videos.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 61 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 58 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 2 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Invalid file index 1 in filtergraph description [0:v:0] [1:v:0] [2:v:0] [2:a:0] [3:v:0] [4:v:0] [4:a:0] [5:v:0] [6:v:0] [6:a:0] [7:v:0] concat=n=8:v=1:a=1 [v] [a].

  I also wrote a test case so you can reproduce this on your local machine. Download the files from my dropbox. Also, the full script that renders the "final move" can be found here.

  Would be great to get an Idea, got struggle to fix this the last two days.

• C++ FFMPEG decoder gives -22

  15 mars 2016, par KillerZefi

  I have implemented a video streaming server (video : MPEG1, network : UDP), which seem to be working (I can watch the videos using VLC).

  I want to implement a client for decoding and I’m using this code : FFmpeg decode raw buffer with avcodec_decode_video2

  The problem is, that I always get -22 for nres and 0 for framefinished. I also had a client, that I implemented earlier, and it had the very same problem. The code for calling my method :

  uint8_t inbuf[65500];
  
  memset(inbuf, 0, size + FF_INPUT_BUFFER_PADDING_SIZE);
  
  memcpy(inbuf, recv_buffer->data(), size);
  
  decoder2.decodeStreamData(inbuf, size + FF_INPUT_BUFFER_PADDING_SIZE);

  Any hints for the cause of the problem ? Or can I find the description of this magical -22 ?

• FFmpeg zoom not smooth-centered (but zigzag)

  10 juin 2016, par SebSob

  I try to perform a basic zoompan with FFmpeg. I have an input image (.png 1280x720) and i create an 8 seconds video (.mp4 320x180) from it, with a zoom. This is my command :

  ffmpeg -loop 1 -i in_img.png -c:v libx264 -pix_fmt yuv420p -strict experimental -framerate 25 -vf zoompan=z=’min(zoom+0.011835363,2.1835363)’:d=375:x=400:y=247 -s 320x180 -t 00:00:08.882 out_vid.mp4

  Everything works...but the zoom is not looking okay. It is going zig-zag.

  Does anyone know how to make it zoom smooth, like centered ? (And not first left then right)

  Thanks

  EDIT

  ---

  I’ve come a small step closer to a solution by slightly modifying the ’x’ and ’y’ in the -vf filter (rest of the command is the same as above) :

  -vf
  zoompan=z=’min(zoom+0.022,3.25)’:d=375:x=’if(gte(zoom,3.25),x,x+8.24)’:y=’if(gte(zoom,3.25),y,y+4.72)’:s=1280x720

  I incement x and y every frame (for x +8.24, for y +4.72, i know those values because i know how many frames it takes get to the end-zoom state) so that it will move to its end zoom state coordinate (1011,582), see image :

  
  This is the video of the result, as you can see it does not do the zig-zag effect, but now it looks like its going first to the center and then to the zoomed result. Or is that only an illusion ??
  Any idea’s ?