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• ffmpeg : missing frames with mp4 encoding

  6 juillet 2016, par Sierra

  I’m currently developing a desktop app that generates videos from pictures (QImage to be more specific). I’m working with Qt 5.6 and the last build of ffmpeg (build git-0a9e781 (2016-06-10)).

  I encode severals QImage to create an .mp4 video. I already have an output but it seems that some frames are missing.

  Here is my code. I tried to be as clear as possible, removing comments and errors catching.

  ## INITIALIZATION
  
  #####################################################################
  
  
  
  AVOutputFormat  * outputFormat  = Q_NULLPTR;
  
  AVFormatContext * formatContext = Q_NULLPTR;
  
  
  
  // filePath: "C:/Users/.../qt_temp.Jv7868.mp4" 
  
  avformat_alloc_output_context2(&formatContext, NULL, NULL, filePath.data());
  
  
  
  outputFormat = formatContext->oformat;
  
  if (outputFormat->video_codec != AV_CODEC_ID_NONE) {
  
      // Finding a registered encoder with a matching codec ID...
  
      *codec = avcodec_find_encoder(outputFormat->video_codec);
  
  
  
      // Adding a new stream to a media file...
  
      stream = avformat_new_stream(formatContext, *codec);
  
      stream->id = formatContext->nb_streams - 1;
  
  
  
  
  
      AVCodecContext * codecContext = avcodec_alloc_context3(*codec);
  
  
  
      switch ((*codec)->type) {
  
      case AVMEDIA_TYPE_VIDEO:
  
          codecContext->codec_id  = outputFormat->video_codec;
  
          codecContext->bit_rate  = 400000;
  
  
  
          codecContext->width     = 1240;
  
          codecContext->height    = 874;
  
  
  
          // Timebase: this is the fundamental unit of time (in seconds) in terms of which frame
  
          // timestamps are represented. For fixed-fps content, timebase should be 1/framerate
  
          // and timestamp increments should be identical to 1.
  
          stream->time_base       = (AVRational){1, 24};
  
          codecContext->time_base = stream->time_base;
  
  
  
          // Emit 1 intra frame every 12 frames at most
  
          codecContext->gop_size  = 12;
  
          codecContext->pix_fmt   = AV_PIX_FMT_YUV420P;
  
  
  
          if (codecContext->codec_id == AV_CODEC_ID_H264) {
  
              av_opt_set(codecContext->priv_data, "preset", "slow", 0);
  
          }
  
          break;
  
      }
  
  
  
      if (formatContext->oformat->flags & AVFMT_GLOBALHEADER) {
  
          codecContext->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      }
  
  }
  
  
  
  avcodec_open2(codecContext, codec, NULL);
  
  
  
  // Allocating and initializing a re-usable frames...
  
  frame = allocPicture(codecContext->width, codecContext->height, codecContext->pix_fmt);
  
  tmpFrame = allocPicture(codecContext->width, codecContext->height, AV_PIX_FMT_BGRA);
  
  
  
  avcodec_parameters_from_context(stream->codecpar, codecContext);
  
  
  
  av_dump_format(formatContext, 0, filePath.data(), 1);
  
  
  
  if (!(outputFormat->flags & AVFMT_NOFILE)) {
  
      avio_open(&formatContext->pb, filePath.data(), AVIO_FLAG_WRITE);
  
  }
  
  
  
  // Writing the stream header, if any...
  
  avformat_write_header(formatContext, NULL);
  
  
  
  ## RECEIVING A NEW FRAME
  
  #####################################################################
  
  
  
  // New QImage received: QImage image
  
  const qint32 width  = image.width();
  
  const qint32 height = image.height();
  
  
  
  // When we pass a frame to the encoder, it may keep a reference to it internally;
  
  // make sure we do not overwrite it here!
  
  av_frame_make_writable(tmpFrame);
  
  
  
  for (qint32 y = 0; y < height(); y++) {
  
      const uint8_t * scanline = image.scanLine(y);
  
  
  
      for (qint32 x = 0; x < width() * 4; x++) {
  
          tmpFrame->data[0][y * tmpFrame->linesize[0] + x] = scanline[x];
  
      }
  
  }
  
  
  
  // As we only generate a BGRA picture, we must convert it to the
  
  // codec pixel format if needed.
  
  if (!swsCtx) {
  
      swsCtx = sws_getContext(width, height,
  
                              AV_PIX_FMT_BGRA,
  
                              codecContext->width, codecContext->height,
  
                              codecContext->pix_fmt,
  
                              swsFlags, NULL, NULL, NULL);
  
  }
  
  
  
  sws_scale(swsCtx,
  
            (const uint8_t * const *)tmpFrame->data,
  
            tmpFrame->linesize,
  
            0,
  
            codecContext->height,
  
            frame->data,
  
            frame->linesize);
  
  
  
  ...
  
  
  
  AVFrame * frame = Q_NULLPTR;
  
  int gotPacket = 0;
  
  
  
  av_init_packet(&packet);
  
  
  
  // Packet data will be allocated by the encoder
  
  this->packet.data = NULL;
  
  this->packet.size = 0;
  
  
  
  frame->pts = nextPts++; // nextPts starts to 0
  
  avcodec_encode_video2(codecContext, &packet, frame, &gotPacket);
  
  
  
  if (gotPacket) {
  
      if (codecContext->coded_frame->key_frame) {
  
         packet.flags |= AV_PKT_FLAG_KEY;
  
      }
  
  
  
      // Rescale output packet timestamp values from codec to stream timebase
  
      av_packet_rescale_ts(packet, *codecContext->time_base, stream->time_base);
  
      packet->stream_index = stream->index;
  
  
  
      // Write the compressed frame to the media file.
  
      av_interleaved_write_frame(formatContext, packet);
  
  
  
      av_packet_unref(&this->packet);
  
  }
  
  
  
  ## FINISHING ENCODING
  
  #####################################################################
  
  
  
  // Retrieving delayed frames if any...
  
  for (int gotOutput = 1; gotOutput;) {
  
      avcodec_encode_video2(codecContext, &packet, NULL, &gotOutput);
  
  
  
      if (gotOutput) {
  
          // Rescale output packet timestamp values from codec to stream timebase
  
          av_packet_rescale_ts(packet, *codecContext->time_base, stream->time_base);
  
          packet->stream_index = stream->index;
  
  
  
          // Write the compressed frame to the media file.
  
          av_interleaved_write_frame(formatContext, packet);
  
          av_packet_unref(&packet);
  
      }
  
  }
  
  
  
  av_write_trailer(formatContext);
  
  
  
  avcodec_free_context(&codecContext);
  
  av_frame_free(&frame);
  
  av_frame_free(&tmpFrame);
  
  sws_freeContext(swsCtx);
  
  
  
  if (!(outputFormat->flags & AVFMT_NOFILE)) {
  
      // Closing the output file...
  
      avio_closep(&formatContext->pb);
  
  }
  
  
  
  avformat_free_context(formatContext);

  A part of the last second is always cut (e.g. when I send 48 frames, 24 fps, media players show 1,9 seconds of the video). I analyzed the video (48 frames, 24fps) with ffmpeg in command line, and I found something weird :
  
  When I re encode the video with ffmpeg (in command line) to the same format, I get a more logical output :
  

  From what I rode on different topics, I think it is closely connected to the h264 codec but I have no idea how to fix it. I’m not familiar with ffmpeg so any kind of help would be highly appreciated. Thank you.

  EDIT 06/07/2016
  Digging a little bit more in ffmpeg examples, I noticed these lines when closing the media file :

  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  ...
  
  /* add sequence end code to have a real mpeg file */
  
  fwrite(endcode, 1, sizeof(endcode), f);

  Is that sequence could be linked to my problem ? I’m trying to implement this to my code but, for now, it corrupts the media file. Any idea on how can I implement that line for my case ?

• No such filter in ffmpeg

  13 avril 2017, par sneha desai

  I am trying to create the slideshow with below command.

  Here is the command I have executed :

   ffmpeg
  
  -loop 1 -t 1 -i /sdcard/input0.png 
  
  -loop 1 -t 1 -i /sdcard/input1.png 
  
  -loop 1 -t 1 -i /sdcard/input2.png 
  
  -loop 1 -t 1 -i /sdcard/input3.png 
  
  -loop 1 -t 1 -i /sdcard/input4.png 
  
  -filter_complex 
  
  "[0:v]trim=duration=15,fade=t=out:st=14.5:d=0.5[v0]; 
  
   [1:v]trim=duration=15,fade=t=in:st=0:d=0.5,fade=t=out:st=14.5:d=0.5[v1]; 
  
   [2:v]trim=duration=15,fade=t=in:st=0:d=0.5,fade=t=out:st=14.5:d=0.5[v2]; 
  
   [3:v]trim=duration=15,fade=t=in:st=0:d=0.5,fade=t=out:st=14.5:d=0.5[v3]; 
  
   [4:v]trim=duration=15,fade=t=in:st=0:d=0.5,fade=t=out:st=14.5:d=0.5[v4]; 
  
   [v0][v1][v2][v3][v4]concat=n=5:v=1:a=0,format=yuv420p[v]" -map "[v]" /sdcard/out.mp4

  on execution of this command it gives error something like :

   onFailure: ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 4.8 (GCC)
  
    configuration: --target-os=linux --cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- --arch=arm --cpu=cortex-a8 --enable-runtime-cpudetect --sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot --enable-pic --enable-libx264 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-fontconfig --enable-pthreads --disable-debug --disable-ffserver --enable-version3 --enable-hardcoded-tables --disable-ffplay --disable-ffprobe --enable-gpl --enable-yasm --disable-doc --disable-shared --enable-static --pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config --prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a --extra-cflags='-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all' --extra-ldflags='-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie' --extra-libs='-lpng -lexpat -lm' --extra-cxxflags=
  
    libavutil      55. 17.103 / 55. 17.103
  
    libavcodec     57. 24.102 / 57. 24.102
  
    libavformat    57. 25.100 / 57. 25.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 31.100 /  6. 31.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [mjpeg @ 0x4362af10] Changing bps to 8
  
  Input #0, image2, from '/sdcard/img0001.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 2410 kb/s
  
      Stream #0:0: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 259x194 [SAR 1:1 DAR 259:194], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [mjpeg @ 0x436300a0] Changing bps to 8
  
  Input #1, image2, from '/sdcard/img0002.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 2053 kb/s
  
      Stream #1:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 290x174 [SAR 1:1 DAR 5:3], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [mjpeg @ 0x436383a0] Changing bps to 8
  
  Input #2, image2, from '/sdcard/img0003.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 3791 kb/s
  
      Stream #2:0: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 300x168 [SAR 1:1 DAR 25:14], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [mjpeg @ 0x43648f50] Changing bps to 8
  
  Input #3, image2, from '/sdcard/img0004.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 1796 kb/s
  
      Stream #3:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 259x194 [SAR 1:1 DAR 259:194], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [mjpeg @ 0x437b4070] Changing bps to 8
  
  Input #4, image2, from '/sdcard/img0005.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 1083 kb/s
  
      Stream #4:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 212x160 [SAR 1:1 DAR 53:40], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [AVFilterGraph @ 0x4393c960] No such filter: '"'
  
  Error initializing complex filters.
  
  Invalid argument

  and i used this demo https://github.com/WritingMinds/ffmpeg-android-java

• gst-ffmpeg building from source failure

  30 juin 2016, par Bharath Vemula

  I’am a non-root user on a cluster and i’am using centos-6.2 , i had to install gst-ffmpeg. i was installing it from source as i was a non-root user in 3 steps as known

  1. ./configure —prefix="my homedirectory"
     2.make
     3.make install

  when i configure it shows all the dependecies have been resolved when i run the make command i get the following error

  > gcc -g -O2 -Wall -Wno-switch -o ffplay ffplay-cmdutils.o
  
  > ffplay-ffplay.o  -lSDL -lpthread libavutil/.libs/libavutil.a
  
  > libavformat/.libs/libavformat.a -ldl libavcodec/.libs/libavcodec.a -lz
  
  > -lm ffplay-ffplay.o: In function `main': /home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg/ffplay.c:2451:
  
  > undefined reference to `XOpenDisplay'
  
  > /home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg/ffplay.c:2455:
  
  > undefined reference to `XCloseDisplay' collect2: ld returned 1 exit
  
  > status make[7]: *** [ffplay] Error 1 make[7]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg'
  
  > make[6]: *** [all-recursive] Error 1 make[6]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg'
  
  > make[5]: *** [all] Error 2 make[5]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg'
  
  > make[4]: *** [all-local] Error 2 make[4]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext'
  
  > make[3]: *** [all-recursive] Error 1 make[3]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs/ext'
  
  > make[2]: *** [all-recursive] Error 1 make[2]: Leaving directory
  
  > `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1/gst-libs' make[1]:
  
  > *** [all-recursive] Error 1 make[1]: Leaving directory `/home/internal/evol/sskadam/test/gst-ffmpeg-0.10.1' make: *** [all]
  
  > Error 2 [sskadam@ycn1 gst-ffmpeg-0.10.1]$ cd gst-libs/ext/ffmpeg/
  
  > [sskadam@ycn1 ffmpeg]$ vi ffplay.c

  Please help me resolve this