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• Android ICS FFMPEG scale video not working

  20 avril 2015, par Android-Developer

  I am using Guardian Project Android Java FFMPEG library to resize videos. Current code which is working on android 5.0.1 / 5.1.0 / 4.4.4 :

      File fileTmp = getCacheDir();
  
      FfmpegController fc = null;
  
      try {
  
          fc = new FfmpegController(this, fileTmp);
  
      } catch (IOException e) {
  
          e.printStackTrace();
  
      }
  
      String path = Environment.getExternalStorageDirectory().getPath() + "/Movies/nexus.mp4";
  
      final String outPath = Environment.getExternalStorageDirectory().getPath() + "/Movies/test.mp4";
  
      final Clip out = new Clip(path);
  
      try {
  
          if (fc != null) {
  
              fc.convert(out, outPath, new ShellUtils.ShellCallback() {
  
                  @Override
  
                  public void shellOut(String shellLine) {
  
                      Log.e("", "SHELL OUT: " + shellLine);
  
                  }
  
  
  
                  @Override
  
                  public void processComplete(int exitValue) {
  
                      Log.e("", "PROCESS COMPLETE: " + exitValue);
  
                  }
  
              });
  
          }
  
      } catch (Exception e) {
  
          e.printStackTrace();
  
      }

  Using this code on Android 4.0.4 (Ice Cream Sandwich) doesn’t do anything. While testing on other devices exitValue in processComplete is always equal to 0, but on ICS it’s 11. Here is the output in LogCat :

  SHELL OUT: /data/data/org.hardartcore.ffmpeg/app_bin/ffmpeg -y -i /mnt/sdcard/Movies/NEXUS.mp4 -ab 160k -r ntsc-film -vf scale=568:320 -strict -2 /mnt/sdcard/Movies/Test.mp4
  
  PROCESS COMPLETE: 11

  I don’t think it’s something from ffmpeg, more like a problem when the library is trying to execute ffmpeg executable from raw folder in internal memory, but I can’t see any logs or errors which indicate that too.

  So my question is, if there is any mistake which I am doing using / running this code or something which can prevent ffmpeg executable from running on old devices with Android ICS ?

  Thanks in advance !

• ffmpeg quality conversion options (video compression)

  25 septembre 2020, par Jason Hunter

  Can you provide a link, or an explanation, to the -q:v 1 argument that deals with video/image quality, and compression, in ffmpeg.

  


  Let me explain...

  


  for f in *
   do 
     extension="${f##*.}"
     filename="${f%.*}"
     ffmpeg -i "$f" -q:v 1 "$filename"_lq."$extension"
     rm -f "$f"
   done


  


  The ffmpeg for loop above compresses all images and videos in your working directory, it basically lowers the quality which results in smaller file sizes (the desired outcome).

  


  I'm most interested in the -q:v 1 argument of this for loop. The 1 in the -q:v 1 argument is what controls the amount of compression. But I can't find any documentation describing how to change this value of 1, and describing what it does. Is it a percentage ? Multiplier ? How do I adjust this knob ? Can/should I use negative values ? Integers only ? Min/max values ? etc.

  


  I started with the official documentation but the best I could find was a section on video quality, and the -q flag description is sparse.

  


  


  -frames[:stream_specifier] framecount (output,per-stream)
  
Stop writing to the stream after framecount frames.
  
.
  
-q[:stream_specifier] q (output,per-stream)
  

  
-qscale[:stream_specifier] q (output,per-stream)
  
Use fixed quality scale (VBR). The meaning of q/qscale is codec-dependent. If qscale is used without a stream_specifier then it applies only to the video stream, this is to maintain compatibility with previous behavior and as specifying the same codec specific value to 2 different codecs that is audio and video generally is not what is intended when no stream_specifier is used.

  


  


• checkasm : Remove unnecessary const on scalar parameters

  15 décembre 2023, par Martin Storsjö

  checkasm : Remove unnecessary const on scalar parameters
  The ffmpeg coding style doesn't usually use const on scalar
  
  parameters (or on the pointer values - as opposed to the type
  
  that is pointed to, where it has a semantic meaning), contrary
  
  to the dav1d coding style (where this was imported from).
  This avoids warnings about differences in the type signatures
  
  between declaration and definition of this function, with older
  
  versions of MSVC.
  The issue was observed with one version of MSVC 2017,
  
  19.16.27024.1, with warnings like these :
      src/tests/checkasm/checkasm.c(969) : warning C4028 : formal parameter 3 different from declaration
  The warning itself is bogus as the const here is harmless, and
  
  newer versions of MSVC no longer warn about this.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tests/checkasm/checkasm.c
  • [DH] tests/checkasm/checkasm.h