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• Android NDK : How to replace AAsset to work with files from external Storage for FFmpeg decoding

  13 janvier 2020, par michpohl

  I am using Oboe’s RhytmGame example as a guideline to implement oboe and mp3 decoding using FFmpeg into my app. Since I am fairly new to the NDK and a C++ beginner I still struggle with some of the basic concepts I encounter.
  My problem : The example mentioned above only handles files from the asset folder, using the native implementation of Android’s AssetManager.
  Since I am looking to access files on external storage, I have to change this, but it is unclear to me how to do that.

  This is where I am stuck :
  I have a FFmpegExtractor class that calls this method in FFmpeg's avio.h :

   * Allocate and initialize an AVIOContext for buffered I/O. It must be later
  
   * freed with avio_context_free().
  
   *
  
   * @param buffer Memory block for input/output operations via AVIOContext.
  
   *        The buffer must be allocated with av_malloc() and friends.
  
   *        It may be freed and replaced with a new buffer by libavformat.
  
   *        AVIOContext.buffer holds the buffer currently in use,
  
   *        which must be later freed with av_free().
  
   * @param buffer_size The buffer size is very important for performance.
  
   *        For protocols with fixed blocksize it should be set to this blocksize.
  
   *        For others a typical size is a cache page, e.g. 4kb.
  
   * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
  
   * @param opaque An opaque pointer to user-specific data.
  
   * @param read_packet  A function for refilling the buffer, may be NULL.
  
   *                     For stream protocols, must never return 0 but rather
  
   *                     a proper AVERROR code.
  
   * @param write_packet A function for writing the buffer contents, may be NULL.
  
   *        The function may not change the input buffers content.
  
   * @param seek A function for seeking to specified byte position, may be NULL.
  
   *
  
   * @return Allocated AVIOContext or NULL on failure.
  
   */
  
  AVIOContext *avio_alloc_context(
  
                    unsigned char *buffer,
  
                    int buffer_size,
  
                    int write_flag,
  
                    void *opaque,
  
                    int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  
                    int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  
                    int64_t (*seek)(void *opaque, int64_t offset, int whence));

  The call is made here :

  bool FFMpegExtractor::createAVIOContext(AAsset *asset, uint8_t *buffer, uint32_t bufferSize,
  
                                          AVIOContext **avioContext) {
  
  
  
      constexpr int isBufferWriteable = 0;
  
  
  
      *avioContext = avio_alloc_context(
  
              buffer, // internal buffer for FFmpeg to use
  
              bufferSize, // For optimal decoding speed this should be the protocol block size
  
              isBufferWriteable,
  
              asset, // Will be passed to our callback functions as a (void *)
  
              read, // Read callback function
  
              nullptr, // Write callback function (not used)
  
              seek); // Seek callback function
  
  
  
      if (*avioContext == nullptr){
  
          LOGE("Failed to create AVIO context");
  
          return false;
  
      } else {
  
          return true;
  
      }
  
  }

  I am looking to replace the asset, read and seek arguments so that I can use files from storage instead of AAsset objects.

  This is the read callback passed above :

  int read(void *opaque, uint8_t *buf, int buf_size) {
  
  
  
      auto asset = (AAsset *) opaque;
  
      int bytesRead = AAsset_read(asset, buf, (size_t)buf_size);
  
      return bytesRead;
  
  }

  And this is the seekcallback :

  int64_t seek(void *opaque, int64_t offset, int whence){
  
  
  
      auto asset = (AAsset*)opaque;
  
  
  
      // See https://www.ffmpeg.org/doxygen/3.0/avio_8h.html#a427ff2a881637b47ee7d7f9e368be63f
  
      if (whence == AVSEEK_SIZE) return AAsset_getLength(asset);
  
      if (AAsset_seek(asset, offset, whence) == -1){
  
          return -1;
  
      } else {
  
          return 0;
  
      }
  
  }

  I have tried just replacing AAsset with FILE, but of course that doesn’t do it. I know how to open and read files, but it is unclear to me if that is what’s expected here, and how I can translate the methods in AAsset to operations that return the desired values for files in storage.
  Can anyone point me in the right direction ?

  Edit : As it couldn’t fit down there here is the code block mentioned in my reply to @BrianChen’s helpful comments :

  bool FFMpegExtractor::openAVFormatContext(AVFormatContext *avFormatContext) {
  
  
  
      int result = avformat_open_input(&avFormatContext,
  
                                       "", /* URL is left empty because we're providing our own I/O */
  
                                       nullptr /* AVInputFormat *fmt */,
  
                                       nullptr /* AVDictionary **options */
  
      );

  Unfortunately avformat_open_input() produces a
  Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x20 in tid 23767, pid 23513

• FFmpeg os.system commands not working but work in Terminal

  28 janvier 2020, par Oscar Dolloway

  I’ve downloaded ffmpeg through the website and ran some commands through the terminal to confirm its install.

  when running the command ’ffmpeg’ in the Terminal it returns

   ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg 
  
   developers
  
   built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)

  if i type into Python

  import os
  
  os.system ('ffmpeg')

  it returns

   os.system ('ffmpeg')
  
   sh: ffmpeg: command not found
  
   Out[25]: 32512

  any ideas ?

  Solution :

   ffmpeg = '/bin/ffmpeg' #path to the binary file
  
  
  
   os.system(ffmpeg)

  Output :

  os.system (ffmpeg)
  
  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)

• FFMPEG JAVA ffmpeg doesn't work in .jar application

  3 février 2020, par xkenzzo

  FFMPEG works only in developer mode. When I compile my jar program it returns the following error
  the log of the program launched with eclipse in this case everything works

    ffmpeg version git-2019-12-29-e20c6d9 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 9.2.1 (GCC) 20191125
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  
    libavutil      56. 38.100 / 56. 38.100
  
    libavcodec     58. 65.100 / 58. 65.100
  
    libavformat    58. 35.101 / 58. 35.101
  
    libavdevice    58.  9.101 / 58.  9.101
  
    libavfilter     7. 70.100 /  7. 70.100
  
    libswscale      5.  6.100 /  5.  6.100
  
    libswresample   3.  6.100 /  3.  6.100
  
    libpostproc    55.  6.100 / 55.  6.100
  
  Input #0, h264, from '.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: h264 (Main), yuv420p(progressive), 3840x2160 [SAR 1:1 DAR 16:9], 60 fps, 60 tbr, 1200k tbn, 120 tbc
  
  Output #0, mp4, to '.mp4':
  
    Metadata:
  
      encoder         : Lavf58.35.101
  
      Stream #0:0: Video: h264 (Main) (avc1 / 0x31637661), yuv420p(progressive), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 60 tbr, 15360 tbn, 120 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp4 @ 000001cedad59440] Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
  
  frame= 9273 fps=0.0 q=-1.0 Lsize=  121326kB time=00:01:17.26 bitrate=12863.3kbits/s speed= 207x    
  
  video:121287kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.032451%

  This is where it gets complicated. You can observe the messages that FFMPEG returns to me when I launch my program compile in jar :

  > [h264 @ 0000017c43e5b700] error while decoding MB 58 6, bytestream -14
  
  > [h264 @ 0000017c43e5b700] concealing 30951 DC, 30951 AC, 30951 MV
  
  > errors in I frame [h264 @ 0000017c43e49d80] Stream #0: not enough
  
  > frames to estimate rate; consider increasing probesize [h264 @
  
  > 0000017c43e49d80] decoding for stream 0 failed

  This is the java code which thanks to the ProcessBuilder will launch FFMPEG :

  String urlVideoMp4 = movie.getPath().replace(".h264", ".mp4");
  
  
  
  File videoFinal = new File(urlVideoMp4);
  
  //checking if new video exists : if not, creating it with FFMPEG
  
  
  
  LOG.info("moviePath : " + movie);
  
  ProcessBuilder processBuilder = new ProcessBuilder(FFMPEG, "-framerate", "60", "-r", "120", "-i", movie.getPath(),"-c:v", "copy", urlVideoMp4);
  
  LOG.debug(processBuilder.command());
  
  
  
  processBuilder.inheritIO().start().waitFor();
  
  
  
  return videoFinal;