Sur d’autres sites (13059)

• Parsing custom track data from ARCore mp4 recordings

  11 juillet 2022, par George Ellickson

  I'm using the Android ARCore Recording API to record custom data per frame and replay those values in tests to instrument test our ARCore functionality on devices and in CI. However, separately I'd also like to parse the generated mp4 recordings myself, outside of ARCore, and use my per frame recorded data for analysis. In my ARCore app, I'd like to simply be able to add custom text data like following, encoded as utf-8 strings (or really any other simple encoding) for the given ARCore frame :

  


  val data = "Hello world!"
val buffer = ByteBuffer.wrap(data.encodeToByteArray())
frame.recordTrackData(TRACK_UUID_MY_DATA, buffer


  


  I can't find any docs or good examples though of parsing the mp4 from ARCore and no luck in their arcore-android-sdk repo either. I've tried ffmpeg / ffprobe to figure out how the data is bundled into the MP4, but I'm stumped on which track to use and how best to deserialize as I'm unsure how the bytes are actually encoded under the hood.

  


  Using ffmpeg, I just get information like this about the tracks :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'HoverCapture/ar-recording-tests/src/androidTest/res/raw/ar_recording_2_photos.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2022-01-20T22:03:13.000000Z
  Duration: 00:00:17.12, start: 0.000000, bitrate: 26865 kb/s
  Stream #0:0[0x1](und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, unknown/bt470bg/unknown, progressive), 1920x1080, 25615 kb/s, 28.08 fps, 29.58 tbr, 90k tbn (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Data: none (mett / 0x7474656D), 18 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
  Stream #0:2[0x3](und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, unknown/bt470bg/unknown, progressive), 640x480, 1929 kb/s, 28.12 fps, 29.42 tbr, 90k tbn (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
      vendor_id       : [0][0][0][0]
  Stream #0:3[0x4](und): Data: none (mett / 0x7474656D), 18 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
  Stream #0:4[0x5](und): Data: none (mett / 0x7474656D), 54 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
  Stream #0:5[0x6](und): Data: none (mett / 0x7474656D), 54 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
  Stream #0:6[0x7](und): Data: none (mett / 0x7474656D), 0 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.
  Stream #0:7[0x8](und): Data: none (mett / 0x7474656D), 6 kb/s (default)
    Metadata:
      creation_time   : 2022-01-20T22:03:13.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 01/20/2022.


  


• Compiling FFmpeg staticly using NDK

  27 février 2017, par David Barishev

  I have been trying to compile ffmpeg into a static library in order to use it in my android application, but i couldn’t get it to work.

  Im working with FFmpeg 3.2.4, and ndk r13b, using bash on windows 10(Ubuntu 14.04).

  Here is what i did :

  • I made a stand alone toolchain for x86_64 and api 21 using :
    python make_standalone_toolchain.py --api 21 --arch x86_64 --install-dir {}

  • Made a configuration script :

    ./configure                                                           \
    
    --target-os=linux                                                    \
    
    --arch=x86                                             \
    
    --prefix=<output path="path">                                                  \
    
    --cross-prefix=<stand alone="alone" toolchain="toolchain" path="path">/bin/x86_64-linux-android-           \
    
    --sysroot=<stand alone="alone" toolchain="toolchain" path="path">/sysroot                                  \
    
    --enable-cross-compile                                               \
    
    --pkg-config-flags="--static"                                        \
    
    --enable-yasm       \
    
    --enable-ffmpeg     \
    
    --disable-ffplay    \
    
    --disable-ffprobe   \
    
    --disable-ffserver  \
    
    --disable-doc                                                          \
    
    --disable-htmlpages                                                    \
    
    --disable-manpages                                                     \
    
    --disable-podpages                                                     \
    
    --disable-txtpages                                                     \
    
    
    
    make install
    
    </stand></stand></output>

  It produced an FFmpeg executable, however when i ran it on my API 23 emulator, i got an error message :error: only position independent executables (PIE) are supported.

  How can i fix it ? Also i’m not sure about my configuration, there wasn’t up to date sources on how to compile it correctly for every ABI (arm,arm64,x86,x86_64,mips,mips64) that i need for my application.
  I have seen many script, and im not too familiar with compiling native code, so i wasn’t sure what settings i need, for example like C flags and etc.

  To be precise on how i tried to configure FFmpeg :

  • I need a static library
  • I Only need the ffmpeg command line utility
  • I want to compile the library for every ABI i listed above.This configuration tried to compile for x86_64.
  • Running on android of course

  I would greatly appreciate some help on how to configure and compile this correctly.

  EDIT

  I tried compiling for x86, on an Ubuntu 16.04 (x86_64) VM, using roughly the same config , and i got a different error.

  I made a standalone toolchain for x86 :
  python make_standalone_toolchain.py --arch x86 --api 19 --install-dir ~/x86_toolchain

  And made this configuration file :

  ./configure \
  
  --target-os=linux                                       \
  
  --arch=x86                                              \
  
  --prefix=~/ffmpeg_x86_build                             \
  
  --cross-prefix=~/x86_toolchain/bin/i686-linux-android-  \
  
  --sysroot=~/x86_toolchain/sysroot                       \
  
  --enable-cross-compile                                  \
  
  --pkg-config-flags="--static"                           \
  
  --enable-yasm                                           \
  
  --enable-ffmpeg                                         \
  
  --disable-ffplay                                        \
  
  --disable-ffprobe                                       \
  
  --disable-ffserver                                      \
  
  --disable-doc                                           \
  
  --disable-htmlpages                                     \
  
  --disable-manpages                                      \
  
  --disable-podpages                                      \
  
  --disable-txtpages                                      \
  
  
  
  make clean
  
  make install

  The error im getting now is :

  ~/x86_toolchain/bin/i686-linux-android-gcc is unable to create an executable file.
  
  C compiler test failed.

  In the log file, it seems like it cant access the compiler, even though he is OK (i tested it with a simple hello world).Also its not a permission problem(Everybody has read write access)

  ~/x86_toolchain/bin/i686-linux-android-gcc -fPIC -c -o /tmp/ffconf.yYKPHtht.o /tmp/ffconf.Nxskyxyb.c
  
  ./configure: 874: ./configure: ~/x86_toolchain/bin/i686-linux-android-gcc: not found
  
  C compiler test failed.

  So i’m clearly doing something wrong.Does anyone know why ? And how should i do it instead ?

• installing yasm / nasm on heroku with vulcan

  21 novembre 2013, par scientiffic

  I'm trying to do a build of ffmpeg on Heroku, and I need to use libvpx. In order to install libvpx, I need to have nasm or yasm. I tried installing both using vulcan, but I keep getting the error Neither yasm not nasm has been found

  Here is what I did

  Installing Nasm

  • get nasm source from http://www.linuxfromscratch.org/blfs/view/svn/general/NASM.html
  • tar file using : tar -xJf nasm-2.10.09.tar.xz
  • build using : vulcan build -v -s . -c "./configure -prefix=/app/vendor/nasm && make && make install"
  • add the output of the tar file from vulcan to vendor/nasm
  • push to heroku

  Installing Yasm

  • get yasm source from http://www.linuxfromscratch.org/blfs/view/svn/general/yasm.html
  • extra tar file and build using : vulcan build -v -s . -c "./configure -prefix=/app/vendor/yasm && make && make install"
  • add the output of the tar file from vulcan to vendor/yasm
  • push to heroku

  Installing Libvpx

  • get libvpx source from http://www.linuxfromscratch.org/blfs/view/svn/multimedia/libvpx.html
  • build libvpx using : vulcan build -v -s . -c "./configure —enable-shared —disable-static —prefix=/app/vendor/llibvpx && make && make install"

  Attemping to build libvpx yields this error :

  Packaging local directory... /.rvm/gems/ruby-1.9.2-p320/gems/vulcan-0.8.2/lib/vulcan/cli.rb:49: warning: Insecure world writable dir /usr/local in PATH, mode 040777
  
  done
  
  Uploading source package... done
  
  Building with: ./configure --enable-shared --disable-static --prefix=/app/vendor/llibvpx && make && make install
  
  Configuring selected codecs
  
    enabling vp8_encoder
  
    enabling vp8_decoder
  
  Configuring for target 'x86_64-linux-gcc'
  
    enabling x86_64
  
    enabling pic
  
    enabling runtime_cpu_detect
  
    enabling mmx
  
    enabling sse
  
    enabling sse2
  
    enabling sse3
  
    enabling ssse3
  
    enabling sse4_1
  
  **Neither yasm nor nasm have been found**
  
  
  
  Configuration failed. This could reflect a misconfiguration of your
  
  toolchains, improper options selected, or another problem. If you
  
  don't see any useful error messages above, the next step is to look
  
  at the configure error log file (config.err) to determine what
  
  configure was trying to do when it died.

  How can I successfully build libvpx on heroku using vulcan ?

  The instructions I've been (loosely) following are from here :

  https://gist.github.com/czivko/4392472

  And the reason I need to use libvpx is that I'm using the carrierwave-video gem in my Rails app to convert videos, and it needs libvpx to convert to webm to support video playback in Firefox.