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• Mix audio from various sources, regardless if an input video has sound or not

  17 février 2021, par Basj

  The following code :

  


  ffmpeg -i test.png            
       -t 2 -i a.mp3          
       -t 4 -i video.mp4      
       -t 1 -i b.mp3          
       -filter_complex [1]adelay=2000|2000[s1];[3]adelay=5000|5000[s3];[s1][2][s3]amix=inputs=3[outa];[0][2]overlay[outv]^
       -map [outa] -map [outv]^
       out.mp4 -y


  


  works, and mixes the audio from the MP3s (time-shifted, as desired) and from the MP4 video.

  


  But it fails if the MP4 has no audio channel (= a no-sound video) :

  


  


  Stream specifier '' in filtergraph description ... matches no stream

  


  


  I'd like my script to work in both cases, if the video has audio or not.

  


  How to include [2] in the amix if and only if this video has sound ?

  


  ---

  


  Note : A good way would be to be able to load a MP4 with always a sound stream : the original sound stream if the video has sound, and a silence audio track if the MP4 has no sound in it. Is this possible with a single command in ffmpeg ?

  


• Compiling FFmpeg lib and add it to NDK sources on Windows8

  2 février 2021, par Nativ

  I've seen some articles about how to compile and uses FFmpeg for Android.

  


  These are 2 good examples - example1 and example2

  


  Unfortunately, non off them, or others I found helped me. In those two examples a build_android.sh is created and configure the FFmpeg's configuraion file and call to make. Every time when I'm running the script I'm getting the following error :

  


  c:\android\development\android-ndk-r9\sources\ffmpeg>sh build_android.sh
c:/android/development/android-ndk-r9/toolchains/arm-linux-androideabi-4.8/prebu
ilt/windows-x86_64/arm-linux-androideabi/bin/bin/arm-linux-androideabi-gcc is un

able to create an executable file.
C compiler test failed.

If you think configure made a mistake, make sure you are using the latest
version from Git.  If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
Include the log file "config.log" produced by configure as this will help
solving the problem.
Makefile:2: config.mak: No such file or directory
Makefile:49: /common.mak: No such file or directory
Makefile:92: /libavutil/Makefile: No such file or directory
Makefile:92: /library.mak: No such file or directory
Makefile:169: /doc/Makefile: No such file or directory
Makefile:170: /tests/Makefile: No such file or directory
make: *** No rule to make target `/tests/Makefile'.  Stop.
Makefile:2: config.mak: No such file or directory


  


  If someone encountered and solved this issue it'll be much appreciated !

  


  After trying the suggested script I ran into a new problem that I couldn't solved, this is the output of the script :

  


  .... Enabled components list....

  


  In the end of the list I got the following :

  


  Enabled indevs :
dv1394 v4l2i
fbdev

  


  Enabled outdevs :
fbdev v4l2

  


  License : LGPL version 2.1 or later
Creating config.mak, config.h, and doc/config.texi...

  


  WARNING : C :/android/development/android-ndk-r9/toolchains/arm-linux-androideabi-
4.8/prebuilt/windows-x86_64/bin/arm-linux-androideabi-pkg-config not found, libr
ary detection may fail.
make : *** No rule to make target libavfilter/libavfilter.so', needed by all-ye
s'. Stop.
make : *** No rule to make target install-libavfilter-shared', needed by instal
l-libs-yes'. Stop.

  


• I trying to stream screen to multiple sources with ffmpeg and got error

  13 janvier 2021, par vova

  My command

  


  ffmpeg -thread_queue_size 1024 -f x11grab -draw_mouse 0 -video_size 1920x1080 -i :99.0+0,0 -f alsa -i pulse -channels 2 -c:a aac -b:a 160k -ar 44100 -threads 8 -c:v libx264 -x264-params nal-hrd=cbr -profile:v baseline -framerate 30 -level:v 4.2 -vf format=yuv420p -b:v 1000k -maxrate 1500k -minrate 1000k -bufsize 8000k -g 60 -preset ultrafast -tune zerolatency -f tee -flags +global_header -map 0:v -map 1:a "[f=flv:onfail=ignore]rtmp://stream1|[f=flv:onfail=ignore]rtmp://stream2"


  


  Error in console :

  


  [NULL @ 0x55aaf9a54bc0] Unable to find a suitable output format for '"[f=flv:onfail=ignore]rtmp://strea1
[tee @ 0x55aaf96f3200] Slave muxer #0 failed, aborting.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:1 --