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• ffmpeg watermark without background [closed]

  22 décembre 2022, par Edwin Pitters

  I have a problem, I am trying to add a watermark to my videos with ffmpeg using a gtx 1060 graphics card, the process works well and very fast, the problem is that the watermark appears with a black background , the image has no background, it is transparent, the problem happens only when I use the nvidia graphics card, because if I do the process with my processor the watermark is placed correctly as expected, so I am sure it is a problem in my configuration when running ffmpeg

  


  Here I leave the command that I am using :

  


  .\ffmpeg.exe -y -hide_banner -init_hw_device cuda=cuda -filter_hw_device cuda -hwaccel cuda -hwaccel_output_format cuda -i test.mp4 -i watermark.png -filter_complex "[1:v]colorchannelmixer=aa=0.3,scale=iw*0.6:-1,format=nv12,hwupload[img];[0:v][img]overlay_cuda=x='if(lt(mod(t\,16)\,8)\,W-w-W*10/100\,W*10/100)':y='if(lt(mod(t+4\,16)\,8)\,H-h-H*5/100\,H*5/100)'[out]" -map [out] -c:v h264_nvenc -b:v 6M -an -preset fast out_overlay.mp4


  


  If I use my processor with the following command, the guide mark without background is added, that is, as expected

  


  for %%a in ("*.m*") do ffmpeg -y -hide_banner -threads 4 -i "%%a" -preset ultrafast -vcodec libx264 -b:v 4000k -minrate 4000k -maxrate 4000k -bufsize 4000k -c:a aac -b:a 64k -pass 1 -f mp4 NUL && ffmpeg -y -hide_banner -threads 8 -i "%%a" -i watermark.png -preset ultrafast -vcodec libx264 -b:v 4000k -minrate 4000k -maxrate 4000k -bufsize 4000k -filter_complex "[1]colorchannelmixer=aa=0.3,scale=iw*0.8:-1[a];[0][a]overlay=x='if(lt(mod(t\,8)\,4)\,W-w-W*10/100\,W*10/100)':y='if(lt(mod(t+2\,8)\,4)\,H-h-H*10/100\,H*10/100)'" -c:a copy -tune film -movflags +faststart -pass 2 "watermark/%%a"
pause


  


  I also tried changing colorchannelmixer=aa=0.3 for lut=a=val*0.3 but it seems that this command is not having any effect

  


  I find that the image is well reviewed to discard, in fact I tried with other images also with a transparent background and I have the same result, a watermark but with a black background

  


• Revision 3606b78108 : Modified test for auto key frame detection. The existing test was triggering a

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  Modified test for auto key frame detection.

  The existing test was triggering a lot of false positives on some types
  of animated material with very plain backgrounds. These were triggering
  code designed to catch key frames in letter box format clips.

  This patch tightens up the criteria and imposes a minimum requirement
  on the % blocks coded intra in the first pass and the ratio between the
  % coded intra and the modified inter % after discounting neutral (flat)
  blocks that are coded equally well either way.

  On a particular problem animation clip this change eliminated a large
  number of false positives including some cases where the old code
  selected kf several times in a row. Marginal false negatives are less
  damaging typically to compression and in the problem clip there are now
  a couple of cases where "visual" scene cuts are ignored because of well
  correlated content across the scene cut.

  Replaced some magic numbers related to this with #defines and added
  explanatory comments.

  Change-Id : Ia3d304ac60eb7e4323e3817eaf83b4752cd63ecf

• How to convert to QString from const char* result from ffmpeg C function

  18 octobre 2022, par Lucas

  I use the ffmpeg library in c++ / qt project

  


  extern "C" {&#xA;    #include <libavformat></libavformat>avformat.h>&#xA;    #include <libavutil></libavutil>dict.h>&#xA;}&#xA;

  


  With this I read the media metadata from a local music file. This works quite fine :

  


  avformat_open_input(&format_song, path, NULL, NULL);

while((tag = av_dict_get(format_song->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))){
                std::cout << tag.key << tag.value << std::endl;
                // tag.value is a const char* (but in C!?)
}


  


  Altough the encoding of the tag.value seems to be different for files (maybe saved different in the id3tags). Here are some examples of different title values for different files :

  


  "Töhne" [ö]
"Die Ärzte" [Ä]
"Für Immer"


  


  How to convert this to a readable QString ?

  


  There are some problems with the encoding of special characters. For most cases the following works :

  


  QString result = QString(tag->value).normalized(QString::NormalizationForm_C);
//or:
QString result = QString::fromUtf8(tag->value);


  


  But sometimes this results in a U+FFFD � REPLACEMENT CHARACTER for some "Ü" "Ä" "ß" etc. chars.
But in in that cases fromLocal8Bit works. So I end up testing for replacement characters and choose a different conversion :

  


  if(result.contains(QChar::ReplacementCharacter)){
      result = QString::fromLocal8Bit(tag->value);
}


  


  I expect there is a better way to do this ?