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• Prevent FFmpeg from closing when a named pipe has been read completely

  21 octobre 2019, par Werther Berselli

  I’m doing a C++ application for a university project that takes a video file (e.g. matroska) and using FFmpeg (embedding commands inside std::system() instructions) apply these steps :

  • Extract chunks of frames (e.g. 10 seconds per chunk) and chunks of .aac audio

  • Apply some filters to frames

  • Encode video chunk and audio chunk with x264 and send it to a listening client using RTSP. This step is achieved using two named pipes, one for video and one for audio.

  • Receive the stream into another process and play it using ffplay (on localhost or lan).

  I need to divide my stream in chunks because I need eventually to satisfy real-time constraints, so I can’t apply filters before to my entire input video file and only then start streaming to client.
  My primary problem here is that once FFmpeg has emptied the two pipes, it close ; but other chunks of video and audio have still to be piped and streamed. I need FFmpeg to listen to the pipes waiting for new data.

  In bash I achieved this with the following commands.

  Start to listen in a prompt for a RTSP stream :

  ffplay -rtsp_flags listen rtsp://127.0.0.1@127.0.0.1:8090

  Create a video named pipe and an audio named pipe :

  mkfifo video_pipe
  
  mkfifo audio_pipe

  Use this command to prevent FFmpeg to close when video pipe is emptied :

  exec 7<>video_pipe

  (it is sufficient to apply it to the pipe video and neither will the audio pipe give problems)

  Activate FFmpeg command

  ffmpeg -probesize 2147483647 -re -s 1280x720 -pix_fmt rgb24 -i pipe:0 -vsync 0 -i audio_pipe -r 25 -vcodec libx264 -crf 23 -preset ultrafast -f rtsp -rtsp_transport tcp rtsp://127.0.0.1@127.0.0.1:8090 < video_pipe

  And then feed the pipes in another prompt :

  cat audiochunk.aac > audio_pipe & cat frame*.bmp > video_pipe

  These commands work well using 3 prompts, then I tried them in C++ embedding commands in std::system() instructions (using different threads) ; everything works, but once ffmpeg command empty the video pipe (finishing first chunk), it closes.
  exec command seems to be uneffective here.
  How could I prevent FFmpeg from closing ?

  Two days struggling on that problem, viewing all possible internet solution. I hope I was clear despite a great headache, thanks for your suggestions in advance.

  UPDATE :
  My C++ code is something like this ; I putted it in a single function on a single thread, but it doesn’t change it’s behaviour.
  I’m on Ubuntu 18.04.2

  void CameraThread::ffmpegJob()
  
  {
  
      std::string strvideo_length, command, timing;
  
      long video_length, begin_chunk, end_chunk;
  
      int begin_h, begin_m, begin_s, end_h, end_m, end_s;
  
  
  
      command = "ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 " + Configurations::file_name;
  
      strvideo_length = execCmd(command.c_str());
  
      strvideo_length.pop_back(); // remove \n character
  
      video_length = strToPositiveDigit(strvideo_length);
  
  
  
      if(video_length == -1)
  
      {
  
          std::cout << "Invalid input file";
  
          return;
  
      }
  
  
  
      std::system("bash -c \"rm mst-temp/mst_video_pipe\"");
  
      std::system("bash -c \"rm mst-temp/mst_audio_pipe\"");
  
      std::system("bash -c \"mkfifo mst-temp/mst_video_pipe\"");
  
      std::system("bash -c \"mkfifo mst-temp/mst_audio_pipe\"");
  
      // Keep video pipe opened
  
      std::system("bash -c \"exec 7<>mst-temp/mst_video_pipe\"");
  
  
  
      std::string rtsp_url = "rtsp://" + Configurations::my_own_used_ip + "@" + Configurations::client_ip +
  
              ":" + std::to_string(Configurations::port + 1);
  
  
  
      command = "ffmpeg -probesize 2147483647 -re -s 1280x720 -pix_fmt rgb24 -i pipe:0 "
  
                "-i mst-temp/mst_audio_pipe -r 25 -vcodec libx264 -crf 23 -preset ultrafast -f rtsp "
  
                "-rtsp_transport tcp " + rtsp_url + " < mst-temp/mst_video_pipe &"; // Using & to continue without block on command
  
      std::system(command.c_str());
  
  
  
      begin_chunk = -1 * VIDEO_CHUNK;
  
      end_chunk = 0;
  
  
  
      // Extract the complete audio track
  
      command = "bash -c \"ffmpeg -i " + Configurations::file_name + " -vn mst-temp/audio/complete.aac -y\"";
  
      std::system(command.c_str());
  
  
  
      while(true)
  
      {
  
          // Define the actual video chunk (in seconds) to use, if EOF is reached, exit
  
          begin_chunk += (end_chunk - begin_chunk);
  
          if(begin_chunk == video_length)
  
              break;
  
          if(end_chunk + VIDEO_CHUNK <= video_length)
  
              end_chunk += VIDEO_CHUNK;
  
          else
  
              end_chunk += (video_length - end_chunk);
  
  
  
          // Set begin and end H, M, S variables
  
          begin_h = static_cast<int>(begin_chunk / 3600);
  
          begin_chunk -= (begin_h * 3600);
  
          begin_m = static_cast<int>(begin_chunk / 60);
  
          begin_chunk -= (begin_m * 60);
  
          begin_s = static_cast<int>(begin_chunk);
  
          end_h = static_cast<int>(end_chunk / 3600);
  
          end_chunk -= (end_h * 3600);
  
          end_m = static_cast<int>(end_chunk / 60);
  
          end_chunk -= (end_m * 60);
  
          end_s = static_cast<int>(end_chunk);
  
  
  
          // Extract bmp frames and audio from video chunk
  
          // Extract frames
  
          timing = " -ss " + std::to_string(begin_h) + ":" + std::to_string(begin_m) +
  
                  ":" + std::to_string(begin_s) + " -to " + std::to_string(end_h) +
  
                  ":" + std::to_string(end_m) + ":" + std::to_string(end_s);
  
          command = "bash -c \"ffmpeg -i " + Configurations::file_name + timing +
  
                  " -compression_algo raw -pix_fmt rgb24 mst-temp/frames/output%03d.bmp\"";
  
          std::system(command.c_str());
  
          // Extract audio
  
          command = "bash -c \"ffmpeg -i mst-temp/audio/complete.aac" + timing +
  
                  " -vn mst-temp/audio/audiochunk.aac -y\"";
  
          std::system(command.c_str());
  
  
  
          // Apply elaborations on audio and frames.........................
  
  
  
          // Write modified audio and frames to streaming pipes
  
          command = "bash -c \"cat mst-temp/audio/audiochunk.aac > mst-temp/mst_audio_pipe &amp; "
  
                    "cat mst-temp/frames/output*.bmp > mst-temp/mst_video_pipe\"";
  
          std::system(command.c_str());
  
      }
  
  }
  
  </int></int></int></int></int></int>

• Applying fades between images ffmpeg command

  29 octobre 2015, par Jon Stevens

  I am trying to create a video slideshow that fade out/in between each image solely from an ffmpeg cli command. After researching this for hours, the only way I discovered that this was possible was to use the -filter_complex argument and pass in all images and specify a complex filter that defines multiple fades out and back in that I could time to happen between frames. The command I have so far :

  ffmpeg -y -framerate 1/5 \
  
  -loop 1 -i img-1.jpg \
  
  -loop 1 -i img-2.jpg \
  
  -loop 1 -i img-3.jpg \
  
  -filter_complex \
  
  "[1:v]fade=out:4:d=1,fade=in:5:d=1[fad1]; \
  
  [2:v]fade=out:9:d=1,fade=in:10:d=1[fad2]; \
  
  [3:v]fade=out:14:d=1,fade=in:15:d=1[fad3];" \
  
  -c:v libx264 -r 25 -pix_fmt yuv420p test.mp4

  Here’s the output from executing this command :

   ffmpeg version 2.6.4 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 5.1.1 (GCC) 20150618 (Red Hat 5.1.1-4)
  
    configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  
    libavutil      54. 20.100 / 54. 20.100
  
    libavcodec     56. 26.100 / 56. 26.100
  
    libavformat    56. 25.101 / 56. 25.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 11.102 /  5. 11.102
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, image2, from img-1.jpg':
  
    Duration: 00:00:05.00, start: 0.000000, bitrate: 141 kb/s
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 72:72 DAR 16:9], 0.20 fps, 0.20 tbr, 0.20 tbn, 0.20 tbc
  
  Input #1, image2, from img-2.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 17789 kb/s
  
      Stream #1:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 67:67 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  Input #2, image2, from 'img-3.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 17764 kb/s
  
      Stream #2:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 62:62 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [AVFilterGraph @ 0xbc2a00] No such filter: ''
  
  Error configuring filters.

  All I am trying to do is create a video slideshow with fades/transitions between images. Any help is greatly appreciated !

• Cant link against ffmpeg static build

  24 mars 2017, par David Barishev

  I have build ffmpeg libraries statically for x86 android using a custom configuration.Now i wanted to add them in my android project.

  Im using ffmpeg 3.2.git, android studio 2.3.

  I created a folder named distribution which had my binaries, and the minimum headers i needed for it to not tell me about missing header (Except for the avutil- i just included them all), located the root of my project.
  Here is a file tree :

  distribution
  
  ├── libavcodec
  
  │   ├── lib
  
  │   │   └── x86
  
  │   │       └── libavcodec.a
  
  │   ├── avcodec.h
  
  │   └── version.h
  
  ├── libavfilter
  
  │   ├── lib
  
  │   │   └── x86
  
  │   │       └── libavfilter.a
  
  │   ├── avfiltergraph.h
  
  │   └── avfilter.h
  
  ├── libavformat
  
  │   ├── lib
  
  │   │   └── x86
  
  │   │       └── libavformat.a
  
  │   ├── avformat.h
  
  │   ├── avio.h
  
  │   └── version.h
  
  ├── libavutil
  
  │   ├── lib
  
  │   │   └── x86
  
  │   │       └── libavutil.a
  
  │   ├── attributes.h
  
  │   ├── avconfig.h
  
  │   ├── avutil.h
  
  │   ├── buffer.h
  
  │   ├── buffer_internal.h
  
  │   ├── camellia.h
  
  │   ├── cast5.h
  
  │   ├── channel_layout.h
  
  │   ├── colorspace.h
  
  │   ├── color_utils.h
  
  │   ├── common.h
  
  │   ├── cpu.h
  
  │   ├── cpu_internal.h
  
  │   ├── crc.h
  
  │   ├── des.h
  
  │   ├── dict.h
  
  │   ├── display.h
  
  │   ├── downmix_info.h
  
  │   ├── dynarray.h
  
  │   ├── error.h
  
  │   ├── eval.h
  
  │   ├── ffmath.h
  
  │   ├── ffversion.h
  
  │   ├── fifo.h
  
  │   ├── file.h
  
  │   ├── fixed_dsp.h
  
  │   ├── float_dsp.h
  
  │   ├── frame.h
  
  │   ├── hash.h
  
  │   ├── hmac.h
  
  │   ├── hwcontext_cuda.h
  
  │   ├── hwcontext_cuda_internal.h
  
  │   ├── hwcontext_dxva2.h
  
  │   ├── hwcontext.h
  
  │   ├── hwcontext_internal.h
  
  │   ├── hwcontext_qsv.h
  
  │   ├── hwcontext_vaapi.h
  
  │   ├── hwcontext_vdpau.h
  
  │   ├── imgutils.h
  
  │   ├── integer.h
  
  │   ├── internal.h
  
  │   ├── intfloat.h
  
  │   ├── intmath.h
  
  │   ├── intreadwrite.h
  
  │   ├── lfg.h
  
  │   ├── libm.h
  
  │   ├── lls.h
  
  │   ├── log.h
  
  │   ├── lzo.h
  
  │   ├── macros.h
  
  │   ├── mastering_display_metadata.h
  
  │   ├── mathematics.h
  
  │   ├── md5.h
  
  │   ├── mem.h
  
  │   ├── mem_internal.h
  
  │   ├── motion_vector.h
  
  │   ├── murmur3.h
  
  │   ├── opencl.h
  
  │   ├── opencl_internal.h
  
  │   ├── opt.h
  
  │   ├── parseutils.h
  
  │   ├── pca.h
  
  │   ├── pixdesc.h
  
  │   ├── pixelutils.h
  
  │   ├── pixfmt.h
  
  │   ├── qsort.h
  
  │   ├── random_seed.h
  
  │   ├── rational.h
  
  │   ├── rc4.h
  
  │   ├── replaygain.h
  
  │   ├── reverse.h
  
  │   ├── ripemd.h
  
  │   ├── samplefmt.h
  
  │   ├── sha512.h
  
  │   ├── sha.h
  
  │   ├── softfloat.h
  
  │   ├── softfloat_ieee754.h
  
  │   ├── softfloat_tables.h
  
  │   ├── spherical.h
  
  │   ├── stereo3d.h
  
  │   ├── tablegen.h
  
  │   ├── tea.h
  
  │   ├── thread.h
  
  │   ├── threadmessage.h
  
  │   ├── timecode.h
  
  │   ├── time.h
  
  │   ├── time_internal.h
  
  │   ├── timer.h
  
  │   ├── timestamp.h
  
  │   ├── tree.h
  
  │   ├── twofish.h
  
  │   └── version.h
  
  └── libswresample
  
      ├── lib
  
      │   └── x86
  
      │       └── libswresample.a
  
      ├── swresample.h
  
      └── swresample_internal.h 

  I edited my cmake to include the libraries :

  add_library(
  
           native-lib
  
           SHARED
  
           src/main/cpp/native-lib.cpp )
  
  
  
  set(distribution_DIR ${CMAKE_SOURCE_DIR}/../distribution)
  
  
  
  add_library(lib_avcodec STATIC IMPORTED)
  
  set_target_properties(lib_avcodec PROPERTIES IMPORTED_LOCATION
  
      ${distribution_DIR}/libavcodec/lib/${ANDROID_ABI}/libavcodec.a)
  
  
  
  add_library(lib_avfilter STATIC IMPORTED)
  
  set_target_properties(lib_avfilter PROPERTIES IMPORTED_LOCATION
  
      ${distribution_DIR}/libavfilter/lib/${ANDROID_ABI}/libavfilter.a)
  
  
  
  add_library(lib_avformat STATIC IMPORTED)
  
  set_target_properties(lib_avformat PROPERTIES IMPORTED_LOCATION
  
      ${distribution_DIR}/libavformat/lib/${ANDROID_ABI}/libavformat.a)
  
  
  
  add_library(lib_avutil STATIC IMPORTED)
  
  set_target_properties(lib_avutil PROPERTIES IMPORTED_LOCATION
  
      ${distribution_DIR}/libavutil/lib/${ANDROID_ABI}/libavutil.a)
  
  
  
  add_library(lib_swresample STATIC IMPORTED)
  
  set_target_properties(lib_swresample PROPERTIES IMPORTED_LOCATION
  
      ${distribution_DIR}/libswresample/lib/${ANDROID_ABI}/libswresample.a)
  
  
  
  
  
  include_directories(
  
                            ${distribution_DIR}
  
                            )
  
  
  
  
  
  target_link_libraries( 
  
                         native-lib
  
  
  
                         lib_avcodec
  
                         lib_avfilter
  
                         lib_avformat
  
                         lib_avutil
  
                         lib_swresample
  
                          )

  I also restricted the build to only x86, in my app build.gradle :

  ndk {
  
              // Specifies the ABI configurations of your native
  
              // libraries Gradle should build and package with your APK.
  
              abiFilters 'x86'
  
      }

  The project gradle sync worked successfully.
  I wrote the following code in my cpp file :

  #include 
  
  
  
  
  
  extern "C"{
  
      #include "libavformat/avformat.h"
  
  }
  
  JNIEXPORT void JNICALL
  
  Java_com_example_david_testffmpegcpp_MainActivity_stringFromJNI(
  
          JNIEnv *env,
  
          jobject /* this */) {
  
  
  
      av_register_all ();
  
      avformat_network_init ();
  
  
  
  
  
  }

  Just to check if the library works, but i cant seem to link against the libraries correctly. It complains about undefined symbols.
  What did i do wrong ?

  Error :

  [2/2] Linking CXX shared library 
  
  
  
  ..\..\..\..\build\intermediates\cmake\debug\obj\x86\libnative-lib.so
  
  FAILED: cmd.exe /C "cd . && D:\AndroidSDK\ndk-bundle\toolchains\llvm\prebuilt\windows-x86_64\bin\clang++.exe  --target=i686-none-linux-android --gcc-toolchain=D:/AndroidSDK/ndk-bundle/toolchains/x86-4.9/prebuilt/windows-x86_64 --sysroot=D:/AndroidSDK/ndk-bundle/platforms/android-16/arch-x86 -fPIC -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security  -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security   -O0 -fno-limit-debug-info -O0 -fno-limit-debug-info  -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,libnative-lib.so -o ..\..\..\..\build\intermediates\cmake\debug\obj\x86\libnative-lib.so CMakeFiles/native-lib.dir/src/main/cpp/native-lib.cpp.o  -llog ../../../../../distribution/libavcodec/lib/x86/libavcodec.a ../../../../../distribution/libavfilter/lib/x86/libavfilter.a ../../../../../distribution/libavformat/lib/x86/libavformat.a ../../../../../distribution/libavutil/lib/x86/libavutil.a ../../../../../distribution/libswresample/lib/x86/libswresample.a -lm "D:/AndroidSDK/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/libs/x86/libgnustl_static.a" && cd ."
  
  src/libavformat/allformats.c:51: error: undefined reference to 'avcodec_register_all'
  
    src/libavformat/id3v2.c:1009: error: undefined reference to 'uncompress'
  
    src/libavformat/id3v2.c:1153: error: undefined reference to 'av_init_packet'
  
    src/libavformat/matroskadec.c:1393: error: undefined reference to 'inflateInit_'
  
    src/libavformat/matroskadec.c:1408: error: undefined reference to 'inflate'
  
    src/libavformat/matroskadec.c:1401: error: undefined reference to 'inflateEnd'
  
    src/libavformat/matroskadec.c:1411: error: undefined reference to 'inflateEnd'
  
    src/libavformat/matroskadec.c:3113: error: undefined reference to 'av_new_packet'
  
    src/libavformat/matroskadec.c:3134: error: undefined reference to 'av_packet_new_side_data'
  
    src/libavformat/matroskadec.c:2855: error: undefined reference to 'av_new_packet'
  
    src/libavformat/matroskadec.c:3147: error: undefined reference to 'av_packet_new_side_data'
  
    src/libavformat/matroskadec.c:3022: error: undefined reference to 'av_new_packet'
  
    src/libavformat/matroskadec.c:3031: error: undefined reference to 'av_packet_new_side_data'
  
    src/libavformat/matroskadec.c:3042: error: undefined reference to 'av_packet_new_side_data'
  
    src/libavformat/matroskadec.c:3151: error: undefined reference to 'av_packet_unref'
  
    src/libavformat/matroskadec.c:2680: error: undefined reference to 'av_packet_unref'
  
    src/libavformat/matroskadec.c:963: error: undefined reference to 'av_fast_padded_malloc'
  
    src/libavformat/matroskadec.c:2163: error: undefined reference to 'av_get_codec_tag_string'
  
    src/libavformat/matroskadec.c:2680: error: undefined reference to 'av_packet_unref'
  
    src/libavformat/matroskadec.c:2579: error: undefined reference to 'av_init_packet'
  
    src/libavformat/matroskadec.c:2580: error: undefined reference to 'av_new_packet'
  
    src/libavformat/matroskadec.c:1715: error: undefined reference to 'avpriv_mpeg4audio_sample_rates'
  
    src/libavformat/matroskadec.c:1715: error: undefined reference to 'avpriv_mpeg4audio_sample_rates'
  
    src/libavformat/matroskadec.c:1715: error: undefined reference to 'avpriv_mpeg4audio_sample_rates'
  
    src/libavformat/matroskadec.c:1866: error: undefined reference to 'avcodec_chroma_pos_to_enum'
  
    src/libavformat/matroskadec.c:2680: error: undefined reference to 'av_packet_unref'
  
    src/libavformat/matroskaenc.c:2482: error: undefined reference to 'avcodec_get_type'
  
    src/libavformat/matroskaenc.c:646: error: undefined reference to 'avpriv_split_xiph_headers'
  
    src/libavformat/matroskaenc.c:1066: error: undefined reference to 'av_get_bits_per_sample'
  
    src/libavformat/matroskaenc.c:723: error: undefined reference to 'avpriv_mpeg4audio_get_config'
  
    src/libavformat/matroskaenc.c:875: error: undefined reference to 'avcodec_enum_to_chroma_pos'
  
    src/libavformat/matroskaenc.c:813: error: undefined reference to 'avcodec_get_name'
  
    src/libavformat/matroskaenc.c:806: error: undefined reference to 'avcodec_get_name'
  
    src/libavformat/matroskaenc.c:824: error: undefined reference to 'avcodec_get_name'
  
    .....