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• Symbol from C file is not being added even though the MakeFile includes its object file

  3 février 2021, par Mahfujur Rahman

  I'm trying to build libavformat with this MAKEFILE. Although the makefile includes avio.o file in its build instruction but it doesn't add any symbol for the functions that are declared on the header file url.h. Source folder which includes the avio.c, avio.h and url.h files can be found HERE.

  


  The nm command for avio.o returns

  


  nm: avio.o: File format not recognized

  


  file command on avio.o shows the following output

  


  avio.o: LLVM IR bitcode


  


  I have checked the nm command on the generated libavformat.so and did not find any symbols for the functions declared on the url.h file

  


  I have been stuck on this for two days. Could not figure out how to solve this problem !

  


  Calling the ff_check_interrupt method and results in

  


  


  undefined reference to 'ff_check_interrupt'

  


  


  Configurations and flags.

  


  

  • FFmpeg Configuration File : Config.h

  


  • FFmpeg Root MakeFile : Root MakeFile

  


  • CC, CXX, CFLAGS, LDFLAGS : FLAGS

  


  


• Covert a file from mp4 to a file that HTML video tag can display

  26 juin 2019, par Trying_To_Understand

  I have a mp4 file and I want to display it in HTML. The problem is that it won’t, not only in HTML but also in my player. In VLC I can watch the video but there is no sound. Maybe the file is corrupted ?
  This is the output when I run ffmpeg -i my_file.mp4 :

  [h264 @ 000001b4afc61880] decode_slice_header error
  
  [h264 @ 000001b4afc61880] no frame!
  
  [h264 @ 000001b4afc61880] non-existing PPS 0 referenced
  
      Last message repeated 1 times
  
  [h264 @ 000001b4afc61880] decode_slice_header error
  
  [h264 @ 000001b4afc61880] no frame!
  
  Input #0, mpeg, from '150_2.mp4':
  
    Duration: 00:50:51.75, start: 13182.386222, bitrate: 983 kb/s
  
      Stream #0:0[0x1e0]: Video: h264 (High), yuv420p(progressive), 1280x720, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x1c0]: Audio: pcm_alaw, 8000 Hz, mono, s16, 64 kb/s
  
  At least one output file must be specified.

  Can I convert this with ffmpeg to a good quality of video and audio ?

• How to add delay to only one audio file in an mp4 file containing many language sounds with ffmpeg ?

  10 décembre 2023, par Mesut

  I have an mp4 movie file. It contains audio files of two different languages. Audio #0 and Audio #1. The codec of both sounds is AAC. Now I only want to give 2000ms delay to Audio #1 audio file. I do this with ffmpeg and add the delay successfully, the command I give below adds delay to both sounds. I only want to delay Audio #1. After doing this, I want to get an output containing all sounds and subtitles without re-encoding. I just couldn't achieve this. Does anyone know how I can do this ?

  


  ffmpeg -i "input_movie.mp4" -itsoffset 2000ms -i "input_movie.mp4" -map 1:v -map 0:a -map 0:s -c copy "Output_movie.mp4"
This command adds delay to all streams, I don't want that.

  


  ffmpeg -i "input_movie.mp4" -itsoffset 2000ms -i "input_movie.mp4" -map 1:v -map 0:a:1 -map 0:s -c copy "Output_movie.mp4"
In the command line above, this time it adds delay only to audio file #1, but this time it does not include other audio files in the output mp4 file.