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• compile the examples of ffmpeg in C99 get wrong info

  29 janvier 2016, par Daniel

  I can run "make examples" using the ffmpeg build environment to get the .o files.
  But I cannot compile using C99. The operating system I use is Ubuntu 14.04 and I configure ffmpeg following Installation of FFmpeg-2.8.5 in linux, installing it without error.

  Here is the detail(demuxing_decoding demuxing_decoding.c is in the ffmpeg_souce_folder/doc/examples) :

   c99 -o demuxing_decoding demuxing_decoding.c -lavdevice -lavformat -lavcodec -lavfilter 
  
  -lavutil -lswresample -lswscale -lz -lbz2

  demuxing_decoding.c: In function ‘main’:
  
  demuxing_decoding.c:326:9: warning: ‘avcodec_alloc_frame’ is deprecated (declared at /usr/include/libavcodec/avcodec.h:3927) [-Wdeprecated-declarations]
  
           frame = avcodec_alloc_frame();
  
           ^
  
  demuxing_decoding.c:406:9: warning: ‘avcodec_free_frame’ is deprecated (declared at /usr/include/libavcodec/avcodec.h:3952) [-Wdeprecated-declarations]
  
           avcodec_free_frame(&frame);
  
           ^
  
  /tmp/ccgEq0Zc.o: In function `decode_packet':
  
  demuxing_decoding.c:(.text+0x561): undefined reference to `av_frame_unref'
  
  /tmp/ccgEq0Zc.o: In function `open_codec_context':
  
  demuxing_decoding.c:(.text+0x5f4): undefined reference to `av_get_media_type_string'
  
  demuxing_decoding.c:(.text+0x66c): undefined reference to `av_get_media_type_string'
  
  demuxing_decoding.c:(.text+0x6df): undefined reference to `av_get_media_type_string'
  
  /tmp/ccgEq0Zc.o: In function `main':
  
  demuxing_decoding.c:(.text+0xcc1): undefined reference to `av_frame_alloc'
  
  demuxing_decoding.c:(.text+0x1082): undefined reference to `av_frame_free'
  
  collect2: error: ld returned 1 exit status

  I don’t where is wrong...I’ve got stuck for two days...Needing your help. Thanks a lot !

• How to check when ffmpeg completes a video segment ?

  27 mai 2022, par Matthew Czarnek

  I'm using a ffmpeg Process from within my C# program. I start it off and run it in segmented mode.

  


  ffmpeg -i rtsp://127.0.0.1/axis-media/media.amp?resolution=1280x720 -c copy -map 0 -f segment -segment_time 21600 -strftime 1 -reset_timestamps 1 -segment_format flv "C:\REPLACE_ME_WITH_REAL_DIRECTORY\%Y-%m-%d_%H%M%S.flv"


  


  This creates a number of recording segments each in their own folder that are 6 hours long. I now need to be able to detect whether a file has started being written and whether it's completed being written as fast as possible to record it to a database. And this needs to work even in the face of crashes.

  


  I'm polling the folder and can detect that a file has started being written. But detecting whether a file has completed is much trickier. Possibly can be done by polling whether or not a file is being written to. Does ffmpeg have some sort of support for this ? Such as when it finishes a file it can launch another program or run a command ?

  


  I will occasionally scan through all the files and make sure that I record the ones that are there in case one is missed. But the more reliable, the better for this application.

  


• MP3 Audio requiring overlays at specific intervals to ensure I dont break copyright rules

  15 novembre 2012, par user1828008

  I have started a project as a DJ to record my online radio shows to mp3. The station I play on is licenced so I am not breaking any copyright rules there. I have had the idea to upload the recordings onto Youtube.

  Clearly that needed some form of adjustment to make a video over the top of the audio which I have achieved using ffmpeg so I have an mp4 file with a picture overlay for the duration of the audio. I did a quick test run to upload the video to Youtube and it tracked that I was playing copyrighted material. It was exactly right in its statement and yes as my own channel on youtube I am not licenced to do so. Either way I have spoke to the copyright owners and they have agreed it is fine.

  However in order to not have to do this every week if I overlay a 5 second 'jingle' every 4 minutes over the audio (fading down if possible) the main volume slightly to play the jingle and fade up after (once again if possible) then I am 100% in the clear. I could do this manually but would rather something I can script in bash to do it for me.

  I am using Centos 6.3 operating system and FFMPEG solved the merge of video and audio together, but I couldnt find anything to do a predefined audio overlay at specific intervals.

  I have looked at programs like Avisynth and Sox but dont believe from the documentation that they have anything that can do regular interval overlays during a single track. The closest thing I could find is on this post :

  Add multiple audio files to video at specific points using FFMPEG

  But it would be nice to do everything in a single sweep with ffmpeg of the audio file (video and audio overlay) if thats possible somehow or any better options that are out there ?

  If you need any more info from me then please let me know.
  Thanks