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• duration change after transcode ts

  1er mai 2017, par Feilong Luo

  i have a problem about transcode with ffmpeg

  i want to cover m3u8 to mp4, so i transcode every ts file first, and then concat them to a mp4, but i found that the duration will be bigger than source file.

  source file is :
  http://oc7iy3eta.bkt.clouddn.com/src_20.ts

  after transcode, test file is :
  http://oc7iy3eta.bkt.clouddn.com/test_20.ts

  i use the command as bellow to change to 5fps, and 400k bitrate :

  sudo ffmpeg -analyzeduration 2147483647 -probesize 2147483647 -nostdin -y -v warning -i ./src_20.ts -threads 3 -movflags faststart -metadata:s:v rotate=0 -chunk_duration 520000 -video_track_timescale 25000 -pix_fmt yuv420p -copytb 1 -vcodec libx264 -b:v 400000 -minrate 400000 -maxrate 400000 -bufsize 500k -force_key_frames "expr:gte(t,n_forced*2)" -vsync 1 -r 5 -s 544*960 -acodec libfaac -async 1 ./test_20.ts

  i use ffprobe command to see video info :

  source file info :

  Duration : 00:00:01.26, start : 28.346989, bitrate : 921 kb/s
  Program 1
  Metadata :
  service_name : Service01
  service_provider : FFmpeg
  Stream #0:0[0x100] : Audio : aac ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 23 kb/s
  Stream #0:1[0x101] : Video : h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 544x960, 10.67 tbr, 90k tbn, 180k tbc

  test file :

  Input #0, mpegts, from ’test_20.ts’ :
  Duration : 00:00:01.62, start : 1.576778, bitrate : 447 kb/s
  Program 1
  Metadata :
  service_name : Service01
  service_provider : FFmpeg
  Stream #0:0[0x100] : Video : h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 544x960, 5 fps, 5 tbr, 90k tbn, 10 tbc
  Stream #0:1[0x101] : Audio : aac ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 5 kb/s

  =======================================================================

  question

  so , we can see that the duration of src file is 1.26s , but after transcode, the test file is 1.62s.

  why ? can anybody help

• Encoding RGB frames using x264 and AVCodec in C

  6 novembre 2016, par deepwork

  I have RGB24 frames streamed from camera and i want to encode them into h264 ,i found that AVCodec and x264 can do so, the problem is x264 as default accepts YUV420 as input so what i wrote was a program which convert RGB frames to YUV420 .that was by sws_scale function .this works well except that it does not satisfy the required FPS because the converting (RGB->YUV420) takes time.

  This is how i setup my encoder context :

  videoStream->id = 0;
  
  vCodecCtx = videoStream->codec;
  
  
  
  vCodecCtx->coder_type       = AVMEDIA_TYPE_VIDEO;
  
  vCodecCtx->codec_id         = AV_CODEC_ID_H264;
  
  vCodecCtx->bit_rate         = 400000;
  
  vCodecCtx->width            = Width;
  
  vCodecCtx->height           = Height;
  
  vCodecCtx->time_base.den    = FPS;
  
  vCodecCtx->time_base.num    = 1;
  
  //vCodecCtx->time_base      = (AVRational){1,};
  
  vCodecCtx->gop_size         = 12;
  
  vCodecCtx->max_b_frames     = 1;
  
  vCodecCtx->pix_fmt          = AV_PIX_FMT_YUV420P;
  
  
  
  if(formatCtx->oformat->flags & AVFMT_GLOBALHEADER)
  
      vCodecCtx->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  av_opt_set(vCodecCtx->priv_data, "preset", "ultrafast", 0);
  
  av_opt_set(vCodecCtx->priv_data, "profile", "baseline", AV_OPT_SEARCH_CHILDREN);
  
  
  
  if (avcodec_open2(vCodecCtx, h264Codec, NULL) < 0){
  
      return 0;
  
  }

  when i changes AV_PIX_FMT_YUV420P to AV_PIX_FMT_RGB24 ,avcodec_open2 will fail.
  i read that there is a version of libx264 for RGB called libx264rgb but i even dont know whether i have to rebuild x264 with enabling this option or to download another source or i have to do it programmatically with the first x264 lib.

  the question is how to enable RGB as input to libx264 to use with libavcodec in C .or how to make the encoding or sws_scale more fast .

  Edit :

  How i built ffmpeg :

  NDK=D:/AndroidDev/android-ndk-r9
  
  PLATFORM=$NDK/platforms/android-18/arch-arm/
  
  PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/windows-x86_64
  
  
  
  GENERAL="\
  
  --enable-small \
  
  --enable-cross-compile \
  
  --extra-libs="-lgcc" \
  
  --arch=arm \
  
  --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
  --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
  
  --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
  
  --extra-cflags="-I../x264/android/arm/include" \
  
  --extra-ldflags="-L../x264/android/arm/lib" "
  
  
  
  
  
  MODULES="\
  
  --enable-gpl \
  
  --enable-libx264"
  
  
  
  function build_ARMv6
  
  {
  
    ./configure \
  
    --target-os=linux \
  
    --prefix=./android/armeabi \
  
    ${GENERAL} \
  
    --sysroot=$PLATFORM \
  
    --enable-shared \
  
    --disable-static \
  
    --extra-cflags=" -O3 -fpic -fasm -Wno-psabi -fno-short-enums -fno-strict-aliasing -finline-limit=300 -mfloat-abi=softfp -mfpu=vfp -marm -march=armv6" \
  
    --extra-ldflags="-lx264 -Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib -lc -lm -ldl -llog" \
  
    --enable-zlib \
  
    ${MODULES} \
  
    --disable-doc \
  
    --enable-neon
  
  
  
    make clean
  
    make
  
    make install
  
  }
  
  
  
  build_ARMv6
  
  
  
  echo Android ARMEABI builds finished

  How i built x264 :

  NDK=D:/AndroidDev/android-ndk-r9
  
  PLATFORM=$NDK/platforms/android-18/arch-arm/
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/windows-x86_64
  
  PREFIX=./android/arm
  
  
  
  function build_one
  
  {
  
    ./configure \
  
    --prefix=$PREFIX \
  
    --enable-static \
  
    --enable-pic \
  
    --host=arm-linux \
  
    --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
    --sysroot=$PLATFORM
  
  
  
    make clean
  
    make
  
    make install
  
  }
  
  
  
  build_one
  
  
  
  echo Android ARM builds finished

• AccessViolationException occurred in AForge.Video.FFMPEG.dll

  11 mai 2017, par Prakash M

  I have a camera class, in this class I used a timer and in its tick event I am saving video using AForge.Net’s VideoFileWriter in C++/Cli (x86, .net framework : v4.6).
  This is not supposed to happen, as this is managed code. But even if I wrap in try catch block, program crashes because of AccessViolationException. I have verified that Image is not null. Something to do with VideoFileWriter. This happens anytime between app start to 30 minutes of running.

  An unhandled exception of type ’System.AccessViolationException’
  occurred in AForge.Video.FFMPEG.dll
  Additional information : Attempted to read or write protected memory.
  This is often an indication that other memory is corrupt.

  In Visual Studio’s output I see

  Exception thrown at 0x0C4D689F (swscale-2.dll) in test.exe : 0xC0000005 : Access violation writing location 0x09F83D80.
  Exception thrown : ’System.AccessViolationException’ in
  AForge.Video.FFMPEG.dll

  code :

   private: System::Void Video_Recorder_Tick(System::Object^  sender, System::Timers::ElapsedEventArgs^  e)
  
    {
  
        Bitmap^ save = ConvertMatToBitmap(image); //function to convert opencv's Mat to .net's Bitmap        
  
        if(writer!= nullptr)
  
         writer->WriteVideoFrame(save);
  
         delete save;
  
     }
  
  
  
    VideoFileWriter ^writer = gcnew VideoFileWriter();
  
  
  
    private: Void load_VideoWriter()
  
    {
  
      writer->Open("C:/video.avi", 640, 480, 10, VideoCodec::Default);        
  
    }

  Visual Studio showed few values for writer

  BitRate 400000
  Codec Default
  FrameRate 10
  Height 480
  IsOpen true
  Width 640
  

  Let me know if anybody needs more info.
  call stack didn’t help much

  

  To my surprise no one on internet is having this issue !
  Code seems straight forward, what could possibly be the issue ?