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• How to build ffmpeg with android-ndk-r10d in windows

  8 février 2019, par hosseinAmini

  In my application user can selects several images and create movie(mp4) with those images, For this reason i want to use ffmpeg library.
  i have searched more than 2 days but did not find a good tutorial for build ffmpeg with ndk in windows.

  can any body describe me, how to do that ?(if you have any link, please share me)

  i used roman10 tutorial and this is what i do :
  1-i have decompressed "ffmpeg-2.6.2" folder into "android-ndk-r10d/sources".

  2-i have created "build_android.sh" file into "ffmpeg-2.6.2" folder and these are my build_android.sh codes :

  #!/bin/bash
  
  NDK=C:/Users/HAKHASIN/Desktop/android-ndk-r10d
  
  
  
  SYSROOT=$NDK/platforms/android-9/arch-arm/
  
  
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/windows-x86_64
  
  
  
  function build_one
  
  
  
  {
  
  
  
  ./configure \
  
  
  
  --prefix=$PREFIX \
  
  
  
  --enable-shared \
  
  
  
  --disable-static \
  
  
  
  --disable-doc \
  
  
  
  --disable-ffmpeg \
  
  
  
  --disable-ffplay \
  
  
  
  --disable-ffprobe \
  
  
  
  --disable-ffserver \
  
  
  
  --disable-avdevice \
  
  
  
  --disable-doc \
  
  
  
  --disable-symver \
  
  
  
  --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
  
  
  --target-os=linux \
  
  
  
  --arch=arm \
  
  
  
  --enable-cross-compile \
  
  
  
  --sysroot=$SYSROOT \
  
  
  
  --extra-cflags="-Os -fpic $ADDI_CFLAGS" \
  
  
  
  --extra-ldflags="$ADDI_LDFLAGS" \
  
  
  
  $ADDITIONAL_CONFIGURE_FLAG
  
  
  
  make clean
  
  
  
  make
  
  
  
  make install
  
  
  
  }
  
  
  
  CPU=arm
  
  
  
  PREFIX=$(pwd)/android/$CPU 
  
  
  
  ADDI_CFLAGS="-marm"
  
  
  
  build_one

  3- when write "sudo chmod +x build_android.sh" and "./build_android.sh" commands in cygwin, it not work correctly

  

• Trying to use decklink output from ffmpeg's libavdevice in a C++ app

  10 février 2021, par Raster

  I'm trying to add support for decklink devices in an video streaming app that my company is developing. We're using C++ and FFMpeg as a processing library. Other types of inputs and outputs are working. Adding support for decklink inputs was really easy, it just worked (at least with the device we tested it on - DeckLink SDI Quad). But for outputs... I'm fighting this for 3 days as of now with no results. I cannot find any docs for this, neither I can find any code example, how should I initialize AVFormatContext and other parts that are needed.

  


  By reading FFMpeg's decklink avdevice code, I managed to get to the point that AVFormatContext doesn't complain about incorrect data format anymore. I'm using wrapped_avframe and pcm_s16le as a codecs, I'm setting (converting) video and audio params to values accepted by device, I'm sending AVPackets with av_interleaved_write_frame, and it doesn't work. Couple of packets are being accepted, couple of libDeckLinkAPI.so threads are spawned, and it just locks - my output thread locks on some 80-ish call to av_interleaved_write_frame. And it is a deadlock, it never goes any further. Debugger shows only that it is waiting for something :

  


  #0  futex_wait_cancelable (private=<optimized out="out">, expected=0, futex_word=0x7fe34c0402c8) at ../sysdeps/nptl/futex-internal.h:183&#xA;#1  __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7fe34c040178, cond=0x7fe34c0402a0) at pthread_cond_wait.c:508&#xA;#2  __pthread_cond_wait (cond=0x7fe34c0402a0, mutex=0x7fe34c040178) at pthread_cond_wait.c:638&#xA;#3  0x00007fe35c69bd04 in ?? () from /lib/libDeckLinkAPI.so&#xA;#4  0x00007fe371394ac7 in ?? () from /lib/libavdevice.so.58&#xA;#5  0x00007fe370f249ad in ?? () from /lib/libavformat.so.58&#xA;#6  0x00007fe370f26615 in av_interleaved_write_frame () from /lib/libavformat.so.58&#xA;</optimized>

  


  I'm obviously doing something wrong, but I can't find what...
Can anyone point me to some documentation or (working) code example how it should be done ?

  


  Thanks in advance :)

  


• How do you make a modern bleep censor ?

  2 août 2023, par nick carraway

  I have always been a fan of live caller radio shows. These (sports) shows allow callers to call a hotline and talk to the radio host directly.

  


  One of the oldest problems with this show format is what if the caller curses, or says something highly inappropriate ? To keep the show clean (and legal), the radio shows broadcast with a 7 second delay. They also use a "bleep" censor, which historically allowed them to wipe the incriminating phrase with a "Beeeeeep" sound. These days, however, they completely cut out the caller's sentence before it even begins. ("Ah, we had to let you go there pal. Can't say that on the radio"). In the modern method, the transition is seamless, almost like they shorten the 7 second delay to a 4 second delay as they remove the start of the caller's reply entirely, and overwrite it with the host's explanations. The caller does not appear to be "interrupted" at all, the start of their sentence leading to the bad phrase is never even broadcasted.

  


  I've been thinking about how to do this in software. I found a project that looked promising. It adds a 7 second delay to your streams, and allows you to convert X amount of those seconds into silence assuming a caller says something inappropriate. While not ideal (since it's a few seconds of dead silence and would interrupt the caller mid-sentence), how can you do something like this in ffmpeg ? It is a good starting point before implementing the more modern features.

  


  

  1. How do you use ffmpeg to livestream a video/audio stream with a delay ?

  


  2. How do you overwrite the last 3 seconds of that stream with silence or a "bleep", when you need to ?

  


  3. Are you able to easily switch your stream to overwrite those 3 seconds with new audio (e.g. the host's explanation for why the caller was hung-up on) ? And how can you go back from a 4 second delay to a 7 second delay ?

  


  


  OR, is there a ready-made software to get flawless "radio-like" hang-ups on bad callers ?