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• How to put H264 encoded data, inside a container like .mp4 using libAV libraries (ffmpeg) ?

  27 mai 2022, par Vivekanand V

  I have been playing around with the libAV* family of libraries, that comes along with FFMPEG and I am learning how to implement things like encoding, decoding, muxing etc.

  


  I came across this code : https://libav.org/documentation/doxygen/master/encode_video_8c-example.html , that encodes, YUV frames, to a file, using an encoder. In my implementation, I will change the encoder to H264 using avcodec_find_encoder(AV_CODEC_ID_H264) But I do not know, how to put this encoded data, into a proper container (.mp4) using libav libraries, so that the output file, can be played by any media player like VLC, QuickTime, etc...

  


  Can anyone please help me on that ? Every help will be greatly appreciated !

  


• avformat/mxfdec : fix frame wrapping detection for J2K essence container

  18 juillet 2021, par Pierre-Anthony Lemieux

  avformat/mxfdec : fix frame wrapping detection for J2K essence container
  For JPEG 2000 essence, the MXF input format module currently uses the value of
  
  byte 14 of the essence container UL to determine whether the J2K essence is
  
  clip- (byte 14 is 0x02) or frame-wrapped (byte 14 is 0x01). Otherwise it
  
  assumes an unknown wrapping.
  Additional wrappings are documented in SMPTE ST422:2019 :
  0x03 : Interlaced Frame, 1 field/KLV
  
  0x04 : Interlaced Frame, 2 fields/KLV
  
  0x05 : Field-wrapped Picture Element
  
  0x06 : Frame-wrapped Picture Element
  And these should also be handled as frame wrapped content.
  Signed-off-by : Pierre-Anthony Lemieux <pal@sandflow.com>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mxf.h
  • [DH] libavformat/mxfdec.c

• .mp4 cant play on WMplayer. Tried to change container and work. How to create a ffmpeg batch fix to apply to entire directory ?

  3 octobre 2019, par luiza

  I have some .mp4 files which are not playing in Windows Media Player, (Error : Windows Media Player cannot play the file. The Player might not support the file type or might not support the codec that was used to compress the file)_, but does play in VLC. I tried to change the container from .mp4 to .flv using a .bat and after I changed it back to .mp4 and the file started playing normally without the error message. Does anyone have an idea of what it might be or how I can write a a command for batch conversion which changes the containers in all folders, and then change it back to .mp4 and save in another folder, (or will I have to do folder by folder ?)

  I used ffmpeg, and the command I put in the batch file was :

  The first .bat to change the container from .mp4 to another container, (I chose .flv) :

  for %%a in ("*.mp4") do ffmpeg -i "%%a" -vcodec copy -acodec copy "%%~na.flv" pause

  The second .bat to change back to .mp4 :

  for %%a in ("*.flv") do ffmpeg -i "%%a" -vcodec copy -acodec copy "%%~na.mp4" pause

  I wrote this on notepad and then saved .bat. After changing all files I wrote the way back.

  I dont know exactly what it does, but I know it fixes any issues.

  Can someone help me to write it better and make it work with the whole directory and then save it to another directory to not overwrite the older files ?

  Thanks !

  for %%a in ("*.mp4") do ffmpeg -i "%%a" -vcodec copy -acodec copy "%%~na.flv" pause