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• png_parser : Fix parsing on big endian

  18 décembre 2013, par Martin Storsjö

  png_parser : Fix parsing on big endian
  Since pc.state is populated by shifting in from the end of the
  
  32 bit word, the content within pc.state is already in native endian
  
  and should not be read with the AV_RL,B functions.
  This was already done correctly for state64 above.
  This fixes the fate-corepng test on big endian.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/png_parser.c

• How to save ffmpeg segmets to disk immediately with sub-second intervals ?

  20 octobre 2023, par amfast

  I'm trying to record video on a raspberry and have it save as much as possible (sub-second resolution) in case of a power cutoff.

  


  I use -f segment to save the encoded stream in 100ms segments with the hope that all but the interrupted (by power cutoff) segment will be saved in memory. Unfortunately, when cutting off power, all the destination files (output_0001.mp4, output_0002.mp4, ...) are created, but empty.

  


  To save the files to disk immediately, I added the -strftime 1 option that allows formatting the output filename as time. It seems weird that this is the (only ?) way to trigger immediate saving of files, but it works - untill I try to have segments smaller than 1 second. The problem seems to be that the format string %d, that previously added a sequence number in my output filenames, now represents "day" (i.e. date) and the smallest resolution time format string is %S for second. I saw %f suggested somewhere for smaller resolutions, but it only prints "%f".

  


  The result is that the segmentation part of ffmpeg does create 100ms segments and save them to disk immediately, but the strftime feature gives the output files names that only change every second, so all the interim files are overwritten.

  


  Example of the failing command below. Without the -strftime option this creates nice segments, but does not save them to disk immediately.

  


  libcamera-vid --flush \
    --framerate ${FRAMERATE} \
    --width ${WIDTH} \
    --height ${HEIGHT} \
    -n \
    -t ${TIMEOUT} \
    --codec yuv420 \
    -o - | 
ffmpeg \
    -fflags nobuffer \
    -strict experimental \
    -loglevel debug \
    -flags low_delay \
    -f rawvideo \
    -pix_fmt yuv420p \
    -s:v ${WIDTH}x${HEIGHT} \
    -r ${FRAMERATE} \
    -i - \
    -c:v h264_v4l2m2m \
    -f segment \
    -segment_time 0.1 \
    -segment_format mp4 \
    -reset_timestamps 1 \
    -strftime 1 \
    -b:v ${ENCODING_BITRATE} \
    -g 1 \
    "output_%04d.mp4"


  


  Question :
  
Is there another way besides -strftime to trigger immediate saving ? Or is there a mechanism to feed finer resolution format strings to the output filename ?

  


• ffmpeg install on my machine but not display in phpinfo()

  17 février 2017, par Pratik Bachchhe

  ffmpeg extension not loaded in phpinfo() when I follow the steps below :

  Install FFMPEG on XAMPP

  • Download ffmpeg from here : https://ffmpeg.org/download.html
  • Copy php_ffmpeg.dll from the php5 folder to the C:\wamp\bin\php\php5.2.9-2\ext
  • Copy files from common to the windows/system32 folder
  • Add extension=php_ffmpeg.dll to php.ini file (\apache...php.ini)
  • Restart all services (Apache, PHP...)
  • Enable extension=php_ffmpeg.dll directive in your php.ini.