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• How to check if a .mp4 file is not corrupt and not missing movie frames or audio segments programmatically

  2 novembre 2019, par forgodsakehold

  With youtube-dl I was able to download quite a couple of .mp4 files. However, I have just discovered, after manually playing some of them, that they are missing movie frames in some parts while still playing audio (so a blank screen is shown), or missing audio while still playing movie frames.

  Hence,
  (1) Why doesn’t youtube-dl detect or warn against such a scenario ? It looks like the movie segments and audio track were merged and .mp4 produced without any warning. Is there a way to configure youtube-dl to detect such cases and redownload the movie ?
  (2) Otherwise, are there other ways to detect such cases programmatically ? (considering that one might have thousands of such .mp4 files and may not be able to manually go thru all of them ?) A solution with FFmpeg or php will be appreciated.

• Create movie programatically with ffmpeg

  16 janvier 2019, par Martin Delille

  I would like to create a movie programatically with ffmpeg.

  Here is my code :

  QString fileName = "test.mov";
  
  static char errorString[AV_ERROR_MAX_STRING_SIZE];
  
  
  
  printf("Video encoding\n");
  
  
  
  AVOutputFormat *outputFormat = av_guess_format(nullptr, fileName.toStdString().c_str(), nullptr);
  
  
  
  if (outputFormat == nullptr) {
  
      qDebug() << "Could not find suitable format for" << fileName;
  
      return false;
  
  }
  
  
  
  enum AVCodecID codec_id = AV_CODEC_ID_MJPEG;
  
  
  
  qDebug() << "Format Name:" << outputFormat->name;
  
  qDebug() << "Format Video Codec:" << outputFormat->video_codec;
  
  outputFormat->video_codec = codec_id;
  
  
  
  /// allocate the output media context, formatContext
  
  AVFormatContext *formatContext = avformat_alloc_context();
  
  formatContext->oformat = outputFormat;
  
  
  
  // find the mpeg1 video encoder
  
  AVCodec *codec = avcodec_find_encoder(codec_id);
  
  
  
  if (!codec) {
  
      qDebug() << "codec not found";
  
      return false;
  
  }
  
  
  
  qDebug() << "Codec name:" << codec->name;
  
  
  
  AVStream *videoStream = avformat_new_stream(formatContext, codec);
  
  // put sample parameters
  
  videoStream->codecpar->bit_rate = 400000;
  
  videoStream->codecpar->width = width;
  
  videoStream->codecpar->height = height;
  
  videoStream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
  
  videoStream->codecpar->format = AV_PIX_FMT_YUVJ422P;
  
  videoStream->time_base.num = 1;
  
  videoStream->time_base.den = 25;
  
  
  
  AVCodecContext *codecContext = avcodec_alloc_context3(nullptr);
  
  codecContext->codec_id = codec_id;
  
  codecContext->codec_type = AVMEDIA_TYPE_VIDEO;
  
  codecContext->width = width;
  
  codecContext->height = height;
  
  codecContext->time_base.num = 1;
  
  codecContext->time_base.den = 25;
  
  codecContext->pix_fmt = AV_PIX_FMT_YUVJ422P;
  
  
  
  if (int error = avcodec_parameters_to_context(codecContext, videoStream->codecpar)) {
  
      qDebug() << "Error parameting the context:" << av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // open it
  
  if (int error = avcodec_open2(codecContext, codec, nullptr)) {
  
      qDebug() << "Could not open codec:" << av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // alloc image and output buffer
  
  AVFrame *frame = av_frame_alloc();
  
  frame->format = codecContext->pix_fmt;
  
  frame->width = codecContext->width;
  
  frame->height = codecContext->height;
  
  
  
  if (int error = av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, static_cast<enum avpixelformat="avpixelformat">(frame->format), 0)) {
  
      qDebug() &lt;&lt; "Error allocating image data:" &lt;&lt; av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  
  
  // Open the output file, if needed
  
  if (!(outputFormat->flags &amp; AVFMT_NOFILE)) {
  
      if (avio_open(&amp;formatContext->pb, fileName.toStdString().c_str(), AVIO_FLAG_WRITE) &lt; 0) {
  
          qDebug() &lt;&lt; "Could not open" &lt;&lt; fileName;
  
          return false;
  
      }
  
  }
  
  
  
  // some formats want stream headers to be separate
  
  if (formatContext->oformat->flags &amp; AVFMT_GLOBALHEADER) {
  
      codecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  }
  
  
  
  if (int error = avformat_write_header(formatContext, nullptr)) {
  
      qDebug() &lt;&lt; "error writing header:" &lt;&lt; av_make_error_string(errorString, AV_ERROR_MAX_STRING_SIZE, error);
  
      return false;
  
  }
  
  </enum>

  Unfortunately, when I execute it I have the following output :

  Format Name: mov
  
  Format Video Codec: 27
  
  Codec name: mjpeg
  
  [mov @ 0x1048c7000] Could not find tag for codec none in stream #0, codec not currently supported in container
  
  error writing header: Invalid argument

  What am I doing wrong ?

• Encoding a readable movie by QuickTime using FFMPEG

  29 juillet 2018, par itamarb

  I’m trying to encode an image sequence using the following command :

  ffmpeg.exe -i %d.png -f mp4 -vcodec h264 test.mp4

  However, QuickTime failed to open this file or sometimes play a black movie, while this movie plays great in VLC player. Any suggestions how to make it play well in QuickTime ?

  Here is the output :

  ffmpeg.exe -i %d.png -f mp4 -vcodec libx264 13.mp4
  
  ffmpeg version N-49044-g89afa63 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jan 19 2013 20:36:06 with gcc 4.7.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libg
  
  sm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --e
  
  nable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --e
  
  nable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --en
  
  able-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable
  
  -libxavs --enable-libxvid --enable-zlib --enable-filter=frei0r
  
    libavutil      52. 15.100 / 52. 15.100
  
    libavcodec     54. 89.100 / 54. 89.100
  
    libavformat    54. 61.101 / 54. 61.101
  
    libavdevice    54.  3.102 / 54.  3.102
  
    libavfilter     3. 32.101 /  3. 32.101
  
    libswscale      2.  2.100 /  2.  2.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  [image2 @ 0221b940] max_analyze_duration 5000000 reached at 5000000 microseconds
  
  
  
  Input #0, image2, from '%d.png':
  
    Duration: 00:01:19.36, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: png, rgb24, 639x480, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [libx264 @ 0221edc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE
  
  4.2 AVX
  
  [libx264 @ 0221edc0] profile High 4:4:4 Predictive, level 3.0, 4:4:4 8-bit
  
  [libx264 @ 0221edc0] 264 - core 129 r2230 1cffe9f - H.264/MPEG-4 AVC codec - Cop
  
  yleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deb
  
  lock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 m
  
  e_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chro
  
  ma_qp_offset=4 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 in
  
  terlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b
  
  _bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecu
  
  t=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0
  
   qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to '13.mp4':
  
    Metadata:
  
      encoder         : Lavf54.61.101
  
      Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv444p, 639x480, q=-1--1
  
  , 12800 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (png -> libx264)
  
  Press [q] to stop, [?] for help
  
  frame=   76 fps=0.0 q=28.0 size=       3kB time=00:00:00.96 bitrate=  22.3kbits/
  
  frame=  156 fps=155 q=28.0 size=       7kB time=00:00:04.16 bitrate=  14.7kbits/
  
  frame=  219 fps=145 q=28.0 size=      12kB time=00:00:06.68 bitrate=  14.1kbits/
  
  frame=  283 fps=141 q=28.0 size=      16kB time=00:00:09.24 bitrate=  14.2kbits/
  
  frame=  352 fps=140 q=28.0 size=      25kB time=00:00:12.00 bitrate=  17.4kbits/