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• How can I encode a video in a MP4 container using OpenCV 2.4.10 ? (Win 8.1)

  24 juin 2015, par Angie Quijano

  I have been trying to encode a vector that contains images, in a MP4 video. I have tried to use a lot of FOURCC codecs for this purpose, but I have not been successful.
  I have achieved to encode my vector in a AVI video using as CV_FOURCC code this : CV_FOURCC(’X’,’V’,’I’,’D’), but I really need to obtain a MP4 video. I have tried the following FOURCC codes : MP4S, MP4V, XVID, DVIX, X264, H264, FMP4, and others than I can’t remember.

  My line of code is :

  VideoWriter(videoName, CV_FOURCC('X','2','6','4'), fps, outputSize)
  
  where videoName = "OutputVideo.mp4", fps = 47, outputSize = [4225x2030].

  I checked if I built my OpenCV with Ffmpeg support and I got this :

   Video I/O:
  
     Video for Windows:           YES
  
     DC1394 1.x:                  NO
  
     DC1394 2.x:                  NO
  
     FFMPEG:                      YES (prebuilt binaries)
  
       codec:                     YES (ver 55.18.102)
  
       format:                    YES (ver 55.12.100)
  
       util:                      YES (ver 52.38.100)
  
       swscale:                   YES (ver 2.3.100)
  
       gentoo-style:              YES
  
     OpenNI:                      NO
  
     OpenNI PrimeSensor Modules:  NO
  
     PvAPI:                       NO
  
     GigEVisionSDK:               NO
  
     DirectShow:                  YES
  
     Media Foundation:            NO
  
     XIMEA:                       NO
  
     Intel PerC:                  NO

  I don’t know what I’m doing wrong. Can anyone help me, please ?

  Sorry for my english.

• Request for ffmpeg raw data to mp4 container example

  3 octobre 2018, par Chi Fai Wong

  I have a binary file with raw h264 data which is arranged like that
  NAL(SPS), NAL(PPS), NAL(Frame), NAL(SPS), NAL(PPS)....
  and i want to mux it (without encode) into a mp4 container.
  The muxing.c in the ffmpeg example do the encoding of yuv data, but it is different from my case, and i have no ideas how to change the example to do what i want to do...

  I knew the commaned ffmpeg -i h264file -c copy h264.mp4 can do what i want to do, but i have to do it in my program, so i need to know how to use the ffmpeg api to do the same thing, but so far, i cannot find any simple example to do it. Is there anyone has hint on how to do it ?? Thanks

  Updated, i have write the code as below from the reference, it seems can create the mp4 but the time is not correct, it lost the frame rate information and the time information, it play very fast.

  av_register_all();
  
  
  
  int ret;
  
  AVDictionary *opt = NULL;
  
  //bool is264 = true;
  
  const char * inputFileName = "input.264";
  
  const char * outputFileName = "output.mp4";
  
  
  
  AVFormatContext *ic = avformat_alloc_context(); 
  
  if((ret = avformat_open_input(&ic, inputFileName, NULL, NULL)) < 0)
  
      return -1;//
  
  
  
  // Get format info (retrieve stream information)
  
  if ((ret = avformat_find_stream_info(ic, NULL)) < 0)
  
      return ret; // Couldn't find stream information
  
  
  
  for (int i = 0; i < ic->nb_streams; i++) 
  
  {
  
      AVStream *stream;
  
      AVCodecContext *codec_ctx;
  
      stream = ic->streams[i];
  
      codec_ctx = stream->codec;
  
      /* Reencode video & audio and remux subtitles etc. */
  
      if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO
  
          || codec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          /* Open decoder */
  
          ret = avcodec_open2(codec_ctx, avcodec_find_decoder(codec_ctx->codec_id), NULL);
  
          if (ret < 0) {
  
              //av_log(NULL, AV_LOG_ERROR, "Failed to open decoder for stream #%u\n", i);
  
              return ret;
  
          }
  
      }
  
  }
  
  
  
  // Dump information about file onto standard error
  
  av_dump_format(ic, 0, inputFileName, 0);
  
  
  
  AVFormatContext *oc;
  
  
  
  avformat_alloc_output_context2(&oc, NULL, NULL, outputFileName);
  
  if (!oc) {
  
      //printf("Could not deduce output format from file extension: using MPEG.\n");
  
      //avformat_alloc_output_context2(&oc, NULL, "mpeg", outputFileName);
  
      return -1;
  
  }
  
  
  
  AVStream *ist = ic->streams[0];
  
  
  
  AVCodec *out_vid_codec = avcodec_find_encoder(oc->oformat->video_codec);
  
  if (NULL == out_vid_codec)
  
      return -1;  // Couldn't find video encoder
  
  
  
  AVStream *out_vid_strm = avformat_new_stream(oc, out_vid_codec);
  
  if (NULL == out_vid_strm)
  
      return -1;  // Couldn't output video stream
  
  
  
  ret = avcodec_copy_context(out_vid_strm->codec, ist->codec);
  
  if (ret < 0)
  
      return ret;  // Failed to copy context
  
  
  
  ret = avio_open(&oc->pb, outputFileName, AVIO_FLAG_WRITE);
  
  ret = avformat_write_header(oc, NULL);
  
  
  
  AVPacket pkt;   
  
  
  
  while(1)
  
  {           
  
      AVStream *in_stream, *out_stream;
  
      ret = av_read_frame(ic, &pkt);
  
      if (ret < 0)
  
          break;
  
  
  
      pkt.stream_index = 0;
  
      in_stream = ic->streams[pkt.stream_index];
  
      out_stream = oc->streams[pkt.stream_index];
  
  
  
  
  
      pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
  
      pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
  
      pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
  
      pkt.pos = -1;
  
      //log_packet(ofmt_ctx, &pkt, "out");
  
  
  
      ret = av_interleaved_write_frame(oc, &pkt);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error muxing packet\n");
  
          break;
  
      }
  
      av_packet_unref(&pkt);
  
  }
  
  
  
  av_write_trailer(oc);

• x264 encoded frames into a mp4 container with ffmpeg API

  10 septembre 2019, par PJD

  I’m struggling with understanding what is and what is not needed in getting my already encoded x264 frames into a video container file using ffmpeg’s libavformat API.

  My current program will get the x264 frames like this -

  while( x264_encoder_delayed_frames( h ) )
  
  {
  
      printf("Writing delayed frame %u\n", delayed_frame_counter++);
  
      i_frame_size = x264_encoder_encode( h, &nal, &i_nal, NULL, &pic_out );
  
      if( i_frame_size < 0 ) {
  
              printf("Failed to encode a delayed x264 frame.\n");
  
              return ERROR;
  
          }
  
      else if( i_frame_size )
  
      {
  
          if( !fwrite(nal->p_payload, i_frame_size, 1, video_file_ptr) ) {
  
              printf("Failed to write a delayed x264 frame.\n");
  
              return ERROR;
  
          }
  
      }
  
  }

  If I use the CLI to the ffmpeg binary, I can put these frames into a container using :

  ffmpeg -i "raw_frames.h264" -c:v copy -f mp4 "video.mp4"

  I would like to code this function into my program using the libavformat API though. I’m a little stuck in the concepts and the order on which each ffmpeg function is needed to be called.

  So far I have written :

          mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
  
          printf("Guessed format\n");
  
  
  
          int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
  
          printf("Created context = %d\n", ret);
  
          printf("Format = %s\n", mAVFormatContext->oformat->name);
  
  
  
          mAVStream = avformat_new_stream(mAVFormatContext, 0);
  
          if (!mAVStream) {
  
              printf("Failed allocating output stream\n");
  
          } else {
  
              printf("Allocated stream.\n");
  
          }
  
  
  
          mAVCodecParameters = mAVStream->codecpar;
  
          if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
  
              mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
  
              mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
  
              printf("Invalid codec?\n");
  
          }
  
  
  
          if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
  
              ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
  
              if (ret < 0) {
  
                printf("Could not open output file '%s'", "gen_vid.mp4");
  
              }
  
            }
  
  
  
          ret = avformat_write_header(mAVFormatContext, NULL);
  
          if (ret < 0) {
  
            printf("Error occurred when opening output file\n");
  
          }

  This will print out :

  Guessed format
  
  Created context = 0
  
  Format = mp4
  
  Allocated stream.
  
  Invalid codec?
  
  [mp4 @ 0x55ffcea2a2c0] Could not find tag for codec none in stream #0, codec not currently supported in container
  
  Error occurred when opening output file

  How can I make sure the codec type is set correctly for my video ?
  Next I need to somehow point my mAVStream to use my x264 frames - advice would be great.

  Update 1 :
  So I’ve tried to set the H264 codec, so the codec’s meta-data is available. I seem to hit 2 newer issues now.
  1) It cannot find the device and therefore cannot configure the encoder.
  2) I get the "dimensions not set".

  mAVOutputFormat = av_guess_format("gen_vid.mp4", NULL, NULL);
  
  printf("Guessed format\n");
  
  
  
  // MUST allocate the media file format context. 
  
  int ret = avformat_alloc_output_context2(&mAVFormatContext, NULL, NULL, "gen_vid.mp4");
  
  printf("Created context = %d\n", ret);
  
  printf("Format = %s\n", mAVFormatContext->oformat->name);
  
  
  
  // Even though we already have encoded the H264 frames using x264,
  
  // we still need the codec's meta-data.
  
  const AVCodec *mAVCodec;
  
  mAVCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  if (!mAVCodec) {
  
      fprintf(stderr, "Codec '%s' not found\n", "H264");
  
      exit(1);
  
  }
  
  mAVCodecContext = avcodec_alloc_context3(mAVCodec);
  
  if (!mAVCodecContext) {
  
      fprintf(stderr, "Could not allocate video codec context\n");
  
      exit(1);
  
  }
  
  printf("Codec context allocated with defaults.\n");
  
  /* put sample parameters */
  
  mAVCodecContext->bit_rate = 400000;
  
  mAVCodecContext->width = width;
  
  mAVCodecContext->height = height;
  
  mAVCodecContext->time_base = (AVRational){1, 30};
  
  mAVCodecContext->framerate = (AVRational){30, 1};
  
  mAVCodecContext->gop_size = 10;
  
  mAVCodecContext->level = 31;
  
  mAVCodecContext->max_b_frames = 1;
  
  mAVCodecContext->pix_fmt = AV_PIX_FMT_NV12;
  
  
  
  av_opt_set(mAVCodecContext->priv_data, "preset", "slow", 0);
  
  printf("Set codec parameters.\n");
  
  
  
  // Initialize the AVCodecContext to use the given AVCodec.
  
  avcodec_open2(mAVCodecContext, mAVCodec, NULL);            
  
  
  
  // Add a new stream to a media file. Must be called before
  
  // calling avformat_write_header().
  
  mAVStream = avformat_new_stream(mAVFormatContext, mAVCodec);
  
  if (!mAVStream) {
  
      printf("Failed allocating output stream\n");
  
  } else {
  
      printf("Allocated stream.\n");
  
  }
  
  
  
  // TODO How should codecpar be set?
  
  mAVCodecParameters = mAVStream->codecpar;
  
  if (mAVCodecParameters->codec_type != AVMEDIA_TYPE_AUDIO &&
  
      mAVCodecParameters->codec_type != AVMEDIA_TYPE_VIDEO &&
  
      mAVCodecParameters->codec_type != AVMEDIA_TYPE_SUBTITLE) {
  
      printf("Invalid codec?\n");
  
  }
  
  
  
  if (!(mAVFormatContext->oformat->flags & AVFMT_NOFILE)) {
  
      ret = avio_open(&mAVFormatContext->pb, "gen_vid.mp4", AVIO_FLAG_WRITE);
  
      if (ret < 0) {
  
        printf("Could not open output file '%s'", "gen_vid.mp4");
  
      }
  
    }
  
  printf("Called avio_open()\n");
  
  
  
  // MUST write a header.
  
  ret = avformat_write_header(mAVFormatContext, NULL);
  
  if (ret < 0) {
  
    printf("Error occurred when opening output file (writing header).\n");
  
  }

  Now I am getting this output -

  Guessed format
  
  Created context = 0
  
  Format = mp4
  
  Codec context allocated with defaults.
  
  Set codec parameters.
  
  [h264_v4l2m2m @ 0x556460344b40] Could not find a valid device
  
  [h264_v4l2m2m @ 0x556460344b40] can't configure encoder
  
  Allocated stream.
  
  Invalid codec?
  
  Called avio_open()
  
  [mp4 @ 0x5564603442c0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
  
  [mp4 @ 0x5564603442c0] dimensions not set
  
  Error occurred when opening output file (writing header).