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• ffmpeg concat of two files results in malformed video

  18 avril 2021, par Stas Ezersky

  I processing two videos as follows :

  


  ffmpeg -i video-raw/455848793538790988_duration18.051.mp4 -b:v 993k -b:a 128k -vf "scale=720x1280:force_original_aspect_ratio=decrease,pad=720:1280:(ow-iw)/2:(oh-ih)/2,setsar=1:1" video-proc/455848793538790988_duration18.051.mp4


  


  and

  


  ffmpeg -i video-raw/14425661295137552_duration11.666.mp4  -b:v 993k -b:a 128k -vf "scale=720x1280:force_original_aspect_ratio=decrease,pad=720:1280:(ow-iw)/2:(oh-ih)/2,setsar=1:1" video-proc/14425661295137552_duration11.666.mp4


  


  then running the following command to concat :

  


  ffmpeg -f concat -safe 0 -i video-concat/dogs-2021-04-17-06-46-id-1.txt -c:v copy -c:a copy ./output.mp4

  


  the resulting video starts properly but when getting to the second video the image stuck and and sound becomes slow.

  


  The ffprobe results are as follow :

  


  Before processing :

  


  ffprobe video-raw/14425661295137552_duration11.666.mp4 

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video-raw/14425661295137552_duration11.666.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:11.68, start: 0.000000, bitrate: 565 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 640x800 [SAR 1:1 DAR 4:5], 462 kb/s, 30 fps, 30 tbr, 90k tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 93 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


  for the second one :

  


  ffprobe video-raw/455848793538790988_duration18.051.mp4

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video-raw/455848793538790988_duration18.051.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:18.07, start: 0.000000, bitrate: 655 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, smpte170m/bt709/bt709), 576x1024 [SAR 1:1 DAR 9:16], 585 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 62 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


  after processing :

  


  ffprobe video-proc/14425661295137552_duration11.666.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video-proc/14425661295137552_duration11.666.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:11.70, start: 0.000000, bitrate: 1133 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x1280 [SAR 1:1 DAR 9:16], 993 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 130 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


  and the second one

  


  ffprobe video-proc/455848793538790988_duration18.051.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video-proc/455848793538790988_duration18.051.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:18.19, start: 0.000000, bitrate: 1044 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x1280 [SAR 1:1 DAR 9:16], 923 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 112 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


  any ideas whats wrong ? both videos play perfect separately after processing but not after the concat

  


• ffmpeg library - why does the Bitrate parameter change on encoding, and how do I force to preserve it ?

  22 avril 2021, par QRrabbit

  Hello forum and all the members of the community !

  


  I have this question on ffmpeg library, why does the bitrate parameter not retained after encoding, even though I explicitly specify the desired rate.

  


  Input file ffprobe :

  


    Duration: 00:00:10.01, start: 0.000000, bitrate: 534719 kb/s
    Stream #0:0(eng): Video: qtrle (rle  / 0x20656C72), argb(progressive), 1920x1080, 533881 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      creation_time   : 2021-04-13T16:35:16.000000Z
      handler_name    : Apple Video Media Handler
      encoder         : Animation
      timecode        : 00:00:00;00


  


  Here's the command I run :

  


  ffmpeg -i input.mov -map 0:a? -map 0:s? -pix_fmt argb -b:v 533881667 -maxrate 533881667 -minrate 533881667 -r 29.97 -top 1 -color_range 1 -colorspace 1 -color_primaries 1 -color_trc bt709 -map_metadata 0 -c:a copy -timecode 00:00:00.00 -c:v qtrle -c:s copy output.mov


  


  Output file ffprobe :

  


    Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    creation_time   : 2021-04-13T16:35:16.000000Z
  Duration: 00:00:10.01, start: 0.000000, bitrate: 100126 kb/s
    Stream #0:0: Video: qtrle (rle  / 0x20656C72), argb(progressive), 1920x1080, 100133 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 11988 tbn, 11988 tbc (default)
    Metadata:
      creation_time   : 2021-04-13T16:35:16.000000Z
      handler_name    : VideoHandler
      encoder         : Lavf58.58.100
      timecode        : 00:00:00;00


  


  As it is visible from the ffprobe from above, I go from :

  


  The Input's file bitrate : 534719 kb/s
to Output bitrate : 100126 kb/s

  


• How do you set framerate of AVStream in FFmpeg muxing ?

  16 avril 2021, par TheNeuronalCoder

  Almost everything works fine, this code at least produces playable video. The issue is basically with all time-related metadata about the video file. The FPS and bitrate of the video are WAY higher than what I specified and the duration is only milliseconds. I did some playing around with the framerate data and found this all ultimately stems from incorrectly specifying the framerate. What did I do wrong ? How do I fix this ? How do you properly set the framerate of a video stream in FFmpeg ?

  


  ffprobe version N-101948-g870bfe1 Copyright (c) 2007-2021 the FFmpeg developers
  built with Apple LLVM version 10.0.1 (clang-1001.0.46.4)
  configuration: --disable-asm --enable-shared --enable-libx264 --enable-gpl
  libavutil      56. 72.100 / 56. 72.100
  libavcodec     58.136.101 / 58.136.101
  libavformat    58. 78.100 / 58. 78.100
  libavdevice    58. 14.100 / 58. 14.100
  libavfilter     7.111.100 /  7.111.100
  libswscale      5. 10.100 /  5. 10.100
  libswresample   3. 10.100 /  3. 10.100
  libpostproc    55. 10.100 / 55. 10.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'animation.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.78.100
  Duration: 00:00:00.01, start: 0.000000, bitrate: 990171 kb/s
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 1082928 kb/s, 12409.66 fps, 12288 tbr, 12288 tbn, 48 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]


  


  class Camera {
 private:
  AVFrame* frame_;
  AVStream* stream_;
  AVPacket* packet_;
  AVCodecContext* context_;
  AVFormatContext* format_;

 public:
  const int fps_;
  bool recording_;
  std::string output_;

  Camera(std::string path, int fps) : fps_(fps), output_(path) {
    recording_ = false;
  }

  void Record() {
    if (recording_ == true)
      throw std::runtime_error(
        "you must close your camera before starting another recording"
      );
    recording_ = true;

    avformat_alloc_output_context2(&format_, NULL, "mp4", output_.c_str());
    if (!format_)
      throw std::runtime_error("failed to find output format");

    stream_ = avformat_new_stream(format_, NULL);
    if (!stream_)
      throw std::runtime_error("failed to allocate video stream");

    stream_->id = format_->nb_streams-1;
    stream_->codecpar->codec_id = AV_CODEC_ID_H264;
    stream_->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
    stream_->codecpar->width = 1920;
    stream_->codecpar->height = 1080;
    stream_->codecpar->bit_rate = 0.15 * fps_ * stream_->codecpar->width *
                                  stream_->codecpar->height;
    stream_->codecpar->format = AV_PIX_FMT_YUV420P;
    stream_->time_base = (AVRational){ 1, fps_ };

    AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
    if (!codec)
      throw std::runtime_error("failed to find codec");

    context_ = avcodec_alloc_context3(codec);
    if (!context_)
      throw std::runtime_error("failed to allocate video codec context");

    context_->width = stream_->codecpar->width;
    context_->height = stream_->codecpar->height;
    context_->bit_rate = stream_->codecpar->bit_rate;
    context_->time_base = stream_->time_base;
    context_->framerate = (AVRational){ fps_, 1 };
    context_->gop_size = 10;
    context_->max_b_frames = 1;
    context_->pix_fmt = AV_PIX_FMT_YUV420P;

    if (avcodec_open2(context_, codec, NULL) < 0)
      throw std::runtime_error("failed to open codec");

    if (format_->oformat->flags & AVFMT_GLOBALHEADER)
      context_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

    if (!(format_->flags & AVFMT_NOFILE))
      if (avio_open(&format_->pb, output_.c_str(), AVIO_FLAG_WRITE) < 0)
        throw std::runtime_error("failed to open video file");

    if (avformat_write_header(format_, NULL) < 0)
      throw std::runtime_error("failed to write headers");

    frame_ = av_frame_alloc();
    if (!frame_)
      throw std::runtime_error("failed to allocate video frame");

    frame_->width = context_->width;
    frame_->height = context_->height;
    frame_->format = AV_PIX_FMT_YUV420P;

    if (av_frame_get_buffer(frame_, 32) < 0)
      throw std::runtime_error("failed to allocate the video frame data");
  }

  void Encode(Frame frame) {
    if (av_frame_make_writable(frame_) < 0)
      throw std::runtime_error("failed to write to frame");

    for (int y = 0; y < frame.height_; ++y) {
      for (int x = 0; x < frame.width_; ++x) {
        int r = frame.pixels_[3 * frame.width_ * y + 3 * x];
        int g = frame.pixels_[3 * frame.width_ * y + 3 * x + 1];
        int b = frame.pixels_[3 * frame.width_ * y + 3 * x + 2];
        frame_->data[0][y * frame_->linesize[0] + x] = (uint8_t)((66*r+129*g+25*b+128) >> 8) + 16;
      }
    }

    for (int y = 0; y < frame.height_/2; ++y) {
      for (int x = 0; x < frame.width_/2; ++x) {
        int r = frame.pixels_[3 * frame.width_ * y + 3 * x];
        int g = frame.pixels_[3 * frame.width_ * y + 3 * x + 1];
        int b = frame.pixels_[3 * frame.width_ * y + 3 * x + 2];
        frame_->data[1][y * frame_->linesize[1] + x] = (uint8_t)((-38*r-74*g+112*b+128) >> 8) + 128;
        frame_->data[2][y * frame_->linesize[2] + x] = (uint8_t)((112*r-94*g-18*b+128) >> 8) + 128;
      }
    }

    if (avcodec_send_frame(context_, frame_) < 0)
      throw std::runtime_error("failed to send a frame for encoding");

    int ret = 0;
    while (ret >= 0) {
      AVPacket packet = { 0 };
      ret = avcodec_receive_packet(context_, &packet);
      if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
        break;
      else if (ret < 0)
        throw std::runtime_error("failed to encode frame");

      av_packet_rescale_ts(&packet, context_->time_base, stream_->time_base);
      packet.pos = -1;
      packet.stream_index = stream_->index;

      ret = av_interleaved_write_frame(format_, &packet);
      av_packet_unref(&packet);
    }
  }

  void Close() {
    if (recording_ == false)
      throw std::runtime_error(
        "you cannot close the camera without starting a recording"
      );
    recording_ = false;

    av_write_trailer(format_);

    avcodec_free_context(&context_);
    av_frame_free(&frame_);

    if (!(format_->oformat->flags & AVFMT_NOFILE))
      avio_closep(&format_->pb);
    avformat_free_context(format_);
  }
}