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• ffmpeg record before and after applying filters

  7 mai 2019, par Mark

  I’m trying to use ffmpeg to do the following things :

  • acquire input streaming [OK]
  • save to disk the video as is [TODO]
  • apply filter, i.e. drawtext [OK]
  • save to disk the overlayed video [OK]
  • preview the overlayed video [OK]

  Here my current command line :

  ffmpeg -rtsp_transport tcp -i  -vf "[in]drawtext=textfile='text.txt': reload=1: font=arial: fontcolor=red: fontsize=80: box=1: boxcolor=yellow@0.5: boxborderw=5: x=(w-text_w)/2: y=(h-text_h)/2[out]" -vcodec libx264 -f tee -map 0:v "[f=mp4]test.mp4|[f=nut]pipe:" | ffplay pipe:

  The only thing I don’t understand how to do is the recording of the video before drawtext. I guess I have to create another tee :

  INPUT ---> TEE ---->RECORD
  
                  |
  
                  |-->FILTERS---> TEE ---->RECORD
  
                                       |
  
                                       |-->PLAY

  So I tried with this cumbersome command :

  ffmpeg -rtsp_transport tcp -i  -vcodec libx264 -f tee -map 0:v "[f=mp4]before.mp4|[f=nut]pipe:" | ffmpeg -f mp4 -i pipe: -vf "[in]drawtext=textfile='text.txt': reload=1: font=arial: fontcolor=red: fontsize=80: box=1: boxcolor=yellow@0.5: boxborderw=5: x=(w-text_w)/2: y=(h-text_h)/2[out]" -vcodec libx264 -f tee -map 0:v "[f=mp4]after.mp4|[f=nut]pipe:" | ffplay pipe:

  It doesn’t throw errors, records "before.mp4" but neither "after.mp4" nor the preview are working. Surely I forgot something in the syntax.

• how to copy mp4 file generated by FFMPEG spawn using another FFMPEG spawn

  2 mai 2021, par Abadi

  I am using the following code that records screen on Linux and the output is an mp4 file.

  


  const transcodeStreamToOutput = spawn('ffmpeg',[
'-hide_banner',
'-loglevel', 'error',
// disable interaction via stdin
'-nostdin',
// screen image size
'-s', `${BROWSER_SCREEN_WIDTH}x${BROWSER_SCREEN_HEIGHT}`,
// video frame rate
'-r', `${VIDEO_FRAMERATE}`,
// hides the mouse cursor from the resulting video
'-draw_mouse', '0',
// grab the x11 display as video input
'-f', 'x11grab',
    '-i', `${DISPLAY}`,
// grab pulse as audio input
'-f', 'pulse',
    '-ac', '2',
    '-i', 'default',
// codec video with libx264
'-c:v', 'libx264',
    '-pix_fmt', 'yuv420p',
    '-profile:v', 'main',
    '-preset', 'veryfast',
    '-x264opts', 'nal-hrd=cbr:no-scenecut',
    '-minrate', `${VIDEO_BITRATE}`,
    '-maxrate', `${VIDEO_BITRATE}`,
    '-g', `${VIDEO_GOP}`,
// apply a fixed delay to the audio stream in order to synchronize it with the video stream
'-filter_complex', 'adelay=delays=1000|1000',
// codec audio with aac
'-c:a', 'aac',
    '-b:a', `${AUDIO_BITRATE}`,
    '-ac', `${AUDIO_CHANNELS}`,
    '-ar', `${AUDIO_SAMPLERATE}`,
// adjust fragmentation to prevent seeking(resolve issue: muxer does not support non seekable output)
'-movflags', 'frag_keyframe+empty_moov',
// set output format to mp4 and output file to stdout
'-f', 'mp4', '-'
]


  


  ) ;

  


  I need to run ffmpeg -i captured.mp4 -c copy new.mp4 using another spawn process on the output.
I tried the following :

  


  const newStdOut =  spawn('ffmpeg',[

    '-i', `${transcodeStreamToOutput.stdout}`, 
    '-codec:v', 'copy', 
    '-codec:a', 'copy', 
    '-f', 'mp4', '-'
    ]
);


  


  But it is not working. I would appreciate any help.

  


• avcodec/tiff_data : Avoid relocations for TiffGeoTagNameType

  9 mars 2024, par Andreas Rheinhardt

  avcodec/tiff_data : Avoid relocations for TiffGeoTagNameType
  Instead store all the strings in one continugous string
  
  (with internal \0) and use offsets to access the actual
  
  substrings. This replaces the pointers to the strings
  
  and therefore avoids relocations (and on x64, it actually
  
  shrinks TiffGeoTagNameType by reusing padding to store
  
  the offset field).
  This saves 720B of .data.rel.ro and 1080B of .rela.dyn
  
  (containing the relocation records) here while increasing
  
  .rodata by 384B.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/tiff.c
  • [DH] libavcodec/tiff.h
  • [DH] libavcodec/tiff_data.h