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• Flutter FFMPEG : The BackgroundIsolateBinaryMessenger.instance value is invalid until BackgroundIsolateBinaryMessenger.ensureInitialized is executed

  25 juin 2023, par Danny

  Hey guys I have a function that uses ffmpeg to convert images to gifs. I am using the simple compute function provided by flutter, but I am getting this error.

  


  


  I/flutter (12889) : Loading ffmpeg-kit-flutter. E/flutter (12889) :
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled
Exception : Bad state : The BackgroundIsolateBinaryMessenger.instance
value is invalid until
BackgroundIsolateBinaryMessenger.ensureInitialized is executed.
E/flutter (12889) : #0 BackgroundIsolateBinaryMessenger.instance

  


  


  Logs :

  


  


  I/flutter (12889) : Loading ffmpeg-kit-flutter. E/flutter (12889) :
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled
Exception : Bad state : The BackgroundIsolateBinaryMessenger.instance
value is invalid until
BackgroundIsolateBinaryMessenger.ensureInitialized is executed.
E/flutter (12889) : #0 BackgroundIsolateBinaryMessenger.instance
(package:flutter/src/services/_background_isolate_binary_messenger_io.dart:27:7)
E/flutter (12889) : #1 _findBinaryMessenger
(package:flutter/src/services/platform_channel.dart:135:42) E/flutter
(12889) : #2 EventChannel.binaryMessenger
(package:flutter/src/services/platform_channel.dart:619:27) E/flutter
(12889) : #3 EventChannel.receiveBroadcastStream. (package:flutter/src/services/platform_channel.dart:639:7)
E/flutter (12889) : #4 _runGuarded
(dart:async/stream_controller.dart:815:24) E/flutter (12889) : #5
  
_BroadcastStreamController._subscribe (dart:async/broadcast_stream_controller.dart:207:7) E/flutter (12889) :
#6 _ControllerStream._createSubscription (dart:async/stream_controller.dart:828:19) E/flutter (12889) : #7
  
_StreamImpl.listen (dart:async/stream_impl.dart:471:9) E/flutter (12889) : #8 FFmpegKitInitializer._initialize
(package:ffmpeg_kit_flutter_min_gpl/src/ffmpeg_kit_flutter_initializer.dart:311:44)
E/flutter (12889) : #9 FFmpegKitInitializer.initialize
(package:ffmpeg_kit_flutter_min_gpl/src/ffmpeg_kit_flutter_initializer.dart:54:23)
E/flutter (12889) : #10 FFmpegKitConfig.init
(package:ffmpeg_kit_flutter_min_gpl/ffmpeg_kit_config.dart:50:32)
E/flutter (12889) : #11 AbstractSession.createFFmpegSession
(package:ffmpeg_kit_flutter_min_gpl/abstract_session.dart:69:29)
E/flutter (12889) : #12 FFmpegSession.create
(package:ffmpeg_kit_flutter_min_gpl/ffmpeg_session.dart:40:43)
E/flutter (12889) : #13 FFmpegKit.executeWithArguments
(package:ffmpeg_kit_flutter_min_gpl/ffmpeg_kit.dart:44:29) E/flutter
(12889) : #14 FFmpegKit.execute
(package:ffmpeg_kit_flutter_min_gpl/ffmpeg_kit.dart:38:17) E/flutter
(12889) : #15 _shareMoments
(package:carefour/presentation/maker/create_function.dart:217:19)
E/flutter (12889) : #16 compute.
(package:flutter/src/foundation/_isolates_io.dart:19:20) E/flutter
(12889) : #17 _RemoteRunner._run (dart:isolate:1021:47) E/flutter
(12889) : #18 _RemoteRunner._remoteExecute (dart:isolate:1015:12)
E/flutter (12889) : #19 _delayEntrypointInvocation. (dart:isolate-patch/isolate_patch.dart:299:17) E/flutter
(12889) : #20 _RawReceivePort._handleMessage
(dart:isolate-patch/isolate_patch.dart:189:12)

  


  


  This is the code :

  


  Future<bool> shareMoments(ComputeMomentModel data) async {&#xA;  File? imgFile;&#xA;  File? paletteFile;&#xA;  var uuid = const Uuid();&#xA;  String newUuid = uuid.v4();&#xA;  String finalImagePath = "momentGif-$newUuid.gif";&#xA;  String paletteFileName= "momentPalette-$newUuid.png";&#xA;  File? finalImage;&#xA;  finalImage = null;&#xA;&#xA;  await FFmpegKit.execute(&#x27;-i ${data.directoryPath}/image%d.png -vf palettegen ${data.directoryPath}/$paletteFileName&#x27;).then((session) async {&#xA;    final returnCode = await session.getReturnCode();&#xA;&#xA;    if (ReturnCode.isSuccess(returnCode)) {&#xA;      paletteFile = File("${data.directoryPath}/$paletteFileName");&#xA;&#xA;      await FFmpegKit.execute(&#x27;-f image2 -y -r 8 -i ${data.directoryPath}/image%d.png -i ${paletteFile?.path} -filter_complex fps=8,scale=720:-1:flags=lanczos,split[s0][s1];[s0]palettegen=max_colors=32[p];[s1][p]paletteuse=dither=bayer ${data.directoryPath}/$finalImagePath&#x27;).then((session) async {&#xA;        final returnCode = await session.getReturnCode();&#xA;        if (ReturnCode.isSuccess(returnCode)) {&#xA;          finalImage = File("${data.directoryPath}/$finalImagePath");&#xA;        }&#xA;      });&#xA;&#xA;    } else {&#xA;      debugPrint("Failed");&#xA;    }&#xA;  });&#xA;&#xA;  // Below block to clear the cache - else ffmpeg keeps on creating the first one&#xA;  int i = 0;&#xA;  for (i = 0; i&lt;24; i&#x2B;&#x2B;) {&#xA;    imgFile = File(&#x27;${data.directoryPath}/image$i.png&#x27;);&#xA;    imgFile.delete(recursive: true);&#xA;  }&#xA;&#xA;  // —> Calling Backend API&#xA;&#xA;  return true;&#xA;&#xA;}&#xA;</bool>

  


  compute function

  


  Future<bool> computeShareMoments({required String directoryPath}) async {&#xA;  ComputeCreateMomentModel data = ComputeMomentModel(null, directoryPath);&#xA;  return await compute(shareMoments, data);&#xA;&#xA;}&#xA;</bool>

  


  Can anyone help with a solution ? I am stuck for a while now. Thanks in advance.

  


• VP8 for Real-time Video Applications

  15 février 2011, par noreply@blogger.com (John Luther)

  With the growing interest in videoconferencing on the web platform, it’s a good time to explore the features of VP8 that make it an exceptionally good codec for real-time applications like videoconferencing.

  VP8 Design History & Features

  Real-time applications were a primary use case when VP8 was designed. The VP8 encoder has features specifically engineered to overcome the challenges inherent in compressing and transmitting real-time video data.
  

  • Processor-adaptive encoding. 16 encoder complexity levels automatically (or manually) adjust encoder features such as motion search strategy, quantizer optimizations, and loop filtering strength.
  • Encoder can be configured to use a target percentage of the host CPU.
    Ability to measure the time taken to encode each frame and adjust encoder complexity dynamically to keep the encoding time per frame constant
  • Robust error recovery (packet retransmission, forward error correction, recovery frame/new keyframe requests)
  • Temporal scalability (i.e., a single video bitstream that can degrade as needed depending on a participant’s available bandwidth)
  • Highly efficient decoding performance on low-power devices. Conventional video technology has grown to a state of complexity where dedicated hardware chips are needed to make it work well. With VP8, software-based solutions have proven to meet customer needs without requiring specialized hardware.

  For a more information about real-time video features in VP8, see the slide presentation by WebM Project engineer Paul Wilkins (PDF file).

  Commercially Available Products

  Millions of people around the world have been using VP7/8 for video chat for years. VP8 is deployed in some of today’s most popular consumer videoconferencing applications, including Skype (group video calling), Sightspeed, ooVoo and Logitech Vid. All of these vendors are active WebM project supporters. VP8’s predecessor, VP7, has been used in Skype video calling since 2005 and is supported in the new Skype app for iPhone. Other real-time VP8 implementations are coming soon, including ooVoo, and VP8 will play a leading role in Google’s plans for real-time applications on the web platform.

  Real-time applications will be extremely important as the web platform matures. The WebM community has made significant improvements in VP8 for real-time use cases since our launch and will continue to do so in the future.

  John Luther is Product Manager of the WebM Project.

  

• Cutting and rejoining videos causes audio de-synchronization using ffmpeg [closed]

  10 décembre 2023, par Donotalo

  This is the original post. I'm not getting any answer there so I thought may be the programming community knows the answer.

  


  Main Post

  


  I'm trying to cut a video into pieces and rejoin them using ffmpeg on Windows 11 x64. Here's the details of ffmpeg :

  


  ffmpeg version 2023-11-22-git-0008e1c5d5-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads
--disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp
--enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt
--enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2
--enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d
--enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx
--enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi
--enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg
--enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc
--enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo
--enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt
--enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame
--enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb
--enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite
--enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58. 32.100 / 58. 32.100
  libavcodec     60. 34.100 / 60. 34.100
  libavformat    60. 17.100 / 60. 17.100
  libavdevice    60.  4.100 / 60.  4.100
  libavfilter     9. 13.100 /  9. 13.100
  libswscale      7.  6.100 /  7.  6.100
  libswresample   4. 13.100 /  4. 13.100
  libpostproc    57.  4.100 / 57.  4.100


  


  I've a video file in MKV format. I've cut it into 3 pieces using the following command :

  


  ffmpeg.exe -ss 0:0:0 -i input.mkv -t 0:54:15 -c:v hevc_amf -b:v 3M -c:s mov_text seg-01.mp4
ffmpeg.exe -ss 0:54:29 -i input.mkv -t 0:35:35 -c:v hevc_amf -b:v 3M -c:s mov_text seg-02.mp4
ffmpeg.exe -ss 1:30:12 -i input.mkv -t 0:4:10 -c:v hevc_amf -b:v 3M -c:s mov_text seg-03.mp4


  


  The audio is copied in all 3 pieces like original. Now I'm joining them using the following command :

  


  ffmpeg.exe -y -f concat -safe 0 -i .\join.txt -c:v hevc_amf -c:a copy -c:s copy -fflags +genpts out.mp4


  


  where, join.txt is :

  


  file seg-01.mp4
file seg-02.mp4
file seg-03.mp4


  


  ffmpeg throws the following warning :

  


  [mp4 @ 000002a5cf9cc040] Non-monotonic DTS in output stream 0:1; previous: 156240896, current: 156240084; changing to 156240897.
This may result in incorrect timestamps in the output file.
[mp4 @ 000002a5cf9cc040] Non-monotonic DTS in output stream 0:1; previous: 258720980, current: 258720462; changing to 258720981.
This may result in incorrect timestamps in the output file.


  


  I've observed that audio is de-synchronized after the places where I cut.

  


  How to keep audio, video and subtitle synchronized after cutting and rejoining the video using ffmpeg ?