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• Wildcard for sequential images

  16 septembre 2013, par abalter

  I'm trying to animate a series of jpg files using avconv. Based on numerous examples, I'm trying using %d.jpg to specify the files. Or %05d.jpg. However, I'm getting :

  avconv -i %d.jpg a.avi
  
  avconv version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers built on Jun 12 2012 16:37:58 with gcc 4.6.3
  
  %d.jpg: No such file or directory

  Here is a snip of my directory listing :

  10380.jpg
  
  10390.jpg
  
  10400.jpg
  
  1040.jpg
  
  10410.jpg
  
  10420.jpg
  
  10430.jpg
  
  10440.jpg

  There are jpegs from 00000.jpg to 14400.jpg

  I don't really understand that wildcard system, but that is what is in examples.

  (note : I tagged it ffmpeg because a tag for avconv does not exist, and avconv supersedes ffmpeg)

  Update
  I'm updating the question based on the answer below by @av501.

  To begin with, I have a list of png files with sequential ordering by 10. They have text preceding a 5 digit integer. For example :

  SkinMattekNutrient_py_00000.png
  
  SkinMattekNutrient_py_00010.png
  
  SkinMattekNutrient_py_00020.png
  
  ...
  
  SkinMattekNutrient_py_10440.png

  What would be the way to batch convert these to jpg ? I tried

  convert ...
  
  SkinMattekNutrient_py_%05d.png %05d.jpg

  and

  convert ...
  
  SkinMattekNutrient_py_%5d.png %5d.jpg

  But I get :

  convert SkinMattekNutrient_py_%05d.png %05d.jpg
  
  convert: missing an image filename `%05d.jpg' @ error/convert.c/ConvertImageCommand/3011.

• application using ffmpeg segfaults because of for loop ?

  6 décembre 2012, par larvyde

  I am writing my first ffmpeg application using the tutorial linked to from the ffmpeg.org documentation page [tutorial] [sample]. Here is my initial code :

  const char * fnmVideoIn = argv [1];
  
  const char * fnmImageOut = argv [2];
  
  
  
  av_register_all ();
  
  
  
  // [] Open the file
  
  AVFormatContext * pcxFormat;
  
  if (avformat_open_input (&pcxFormat, fnmVideoIn, NULL, NULL)) {
  
      fprintf (stderr, "Could not open file %s for reading\n",
  
              fnmVideoIn);
  
      return -1;
  
  }
  
  
  
  // [] Get stream information
  
  if (avformat_find_stream_info (pcxFormat, NULL) < 0) {
  
      fprintf (stderr, "Could not find stream info\n");
  
      return -1;
  
  }
  
  
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);

  and all is well. The program runs without errors and dumps the video info properly. but then I got to the next step...

  ...
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);
  
  
  
  int ixVideoStream = -1, ixStrm;
  
  for (ixStrm = 0; ixStrm < pcxFormat->nb_streams; ++ixStrm) {
  
      if (pcxFormat->streams [ixStrm]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          ixVideoStream = ixStrm;
  
          break;
  
      }
  
  }

  and it exits with a segfault. gdb says :

  (gdb) r test.mp4 out
  
  ...
  
  Program received signal SIGSEGV, Segmentation fault.
  
  0xb7f572c5 in avformat_open_input () from /usr/lib/libavformat.so.53

  how is it possible that avformat_open_input segfaults because of code added after it is called ? I even tested it with a regular i=0 ; i<100 for-loop and it still segfaults ! is this a bug ? For reference, my system is :

  $ gcc --version
  
  gcc (GCC) 4.7.0 20120414 (prerelease)
  
  
  
  $ uname -srvmpio
  
  Linux 3.3.4-1-ARCH #1 SMP PREEMPT Sat Apr 28 06:04:27 UTC 2012 i686 Intel(R) Core(TM)2 Duo CPU P7450 @ 2.13GHz GenuineIntel GNU/Linux
  
  
  
  $ ffmpeg -version
  
  ffmpeg version 0.10.2
  
  built on Mar 17 2012 08:53:01 with gcc 4.6.3
  
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  
  libavutil      51. 35.100 / 51. 35.100
  
  libavcodec     53. 61.100 / 53. 61.100
  
  libavformat    53. 32.100 / 53. 32.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 61.100 /  2. 61.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100

• Chiptune Database and API

  14 septembre 2012, par Multimedia Mike — General

  So I set out to create a website that allows people to easily listen to video game music directly through their web browser. I succeeded in that goal. However, I must admit that the project has limited appeal since the web player is delivered via Chrome’s Native Client technology, somewhat limiting its audience. I’m not certain if anyone really expects NaCl to take off in any serious way, but I still have a few other projects in mind.

  I recently realized that, as a side effect of this project, I accidentally created something of significant value to fans of old video games and associated music– a searchable database of chiptune music and metadata. To my knowledge, no one else has endeavored to create such a thing. I figured that I might as well make the database easily accessible with an API and see where it leads.

  To that end, I created 2 API entry points. First, there is the search API located at http://gamemusic.multimedia.cx/api/search/. This can be exercised by ending the URL with a URL-encoded search string, e.g. : http://gamemusic.multimedia.cx/api/search/super+mario. This returns JSON data containing an array of results in decreasing order of relevance. Each result has a game title, database ID, media URL, system type, and an SHA-1 hash. This is the same API that the site’s own search page uses.

  The database ID can be plugged into http://gamemusic.multimedia.cx/api/metadata/ to retrieve the song’s metadata in JSON format. E.g., the ID for Super Mario Bros. 3 on the NES is 161 : http://gamemusic.multimedia.cx/api/metadata/161.

  I recently read an article about sins against true RESTful API principles which led me to believe I’m almost certainly doing this web API stuff wrong. I don’t think it’s a huge deal, though, since I don’t think anyone actually listens to chiptunes any more. But if there are offline chiptune music players that are still in service and actively maintained, perhaps the authors would like to implement this API. It would require some type of HTTP networking library, a JSON parser, the embedded XZ decoder, and some new code to parse through my .gamemusic and .psfarchive formats.

  This database could be a significant value-add to chiptune playback software, and could help people experience classic game music much more easily.