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• Audio drift in Premiere (not VFR)

  22 octobre 2019, par petaire

  I’m getting audio drift in Premiere, and it’s not related (or is it ?) to VFR. I honestly really dont know where this is coming from, but, oh God, Premiere… Obviously, when I read the file in VLC or any other player, it’s fine. But in Premiere…

  Here’s my media informations :

  General
  
  Complete name                            : /Users/petaire/Desktop/LCI-2019-10-16_10-00-00h.mp4
  
  Format                                   : MPEG-4
  
  Format profile                           : Base Media
  
  Codec ID                                 : isom (isom/iso2/avc1/mp41)
  
  File size                                : 831 MiB
  
  Duration                                 : 2h 0mn
  
  Overall bit rate                         : 968 Kbps
  
  Writing application                      : Lavf57.83.100
  
  
  
  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L3.1
  
  Format settings                          : CABAC / 4 Ref Frames
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 2h 0mn
  
  Bit rate                                 : 832 Kbps
  
  Width                                    : 900 pixels
  
  Height                                   : 720 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 25.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.051
  
  Stream size                              : 715 MiB (86%)
  
  Writing library                          : x264 core 152 r2854 e9a5903
  
  Encoding settings                        : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=16 / lookahead_threads=5 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=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=1 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
  
  Codec configuration box                  : avcC
  
  
  
  Audio
  
  ID                                       : 2
  
  Format                                   : AAC LC
  
  Format/Info                              : Advanced Audio Codec Low Complexity
  
  Codec ID                                 : mp4a-40-2
  
  Duration                                 : 1h 59mn
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 129 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel layout                           : L R
  
  Sampling rate                            : 48.0 KHz
  
  Frame rate                               : 46.875 fps (1024 SPF)
  
  Compression mode                         : Lossy
  
  Stream size                              : 111 MiB (13%)
  
  Language                                 : French
  
  Default                                  : Yes
  
  Alternate group                          : 1

  Premiere…

  I think it might be related to this line :

  Frame rate                               : 46.875 fps (1024 SPF)

  I’m using this line for ffmpeg encoding :

  ffmpeg -err_detect ignore_err -i $1 -preset veryfast -strict -2 -c:v libx264 -vf scale=-1:720 -threads $numberOfThreads $2

  Do you know how to force SPF to 25FPS (of the SPF equivalent) ?

• FFmpeg raw video size parameter

  3 novembre 2019, par Yanick Salzmann

  I am using libavformat in my library to read a stream of raw i420 images and transform them into an mp4 video. I’ve found CLI commands that perform this but since I am using the library in my program I need to reconstruct the same thing.

  Currently the code that is having a problem is looking like this :

          const auto raw_format = av_find_input_format("rawvideo");
  
          if (raw_format == nullptr) {
  
              log->error("Could not find RAW input parser in FFmpeg");
  
              throw std::runtime_error("RAW not found");
  
          }
  
  
  
          _format_context->pb = _io_context.get();
  
  
  
          AVDictionary *input_options = nullptr;
  
          av_dict_set(&input_options, "framerate", std::to_string(fps).c_str(), 0);
  
          av_dict_set(&input_options, "pix_fmt", "yuv420p", 0);
  
          av_dict_set(&input_options, "s:v", fmt::format("{}x{}", width, height).c_str(), 0);
  
          av_dict_set(&input_options, "size", fmt::format("{}x{}", width, height).c_str(), 0);
  
  
  
          auto formatPtr = _format_context.get();
  
          auto res = avformat_open_input(&formatPtr, "(memory file)", raw_format, &input_options);

  Finding the rawvideo is no problem, but it fails in avformat_open_input with the error : [2019-11-03 15:03:22.953] [11599:11663] [ffmpeg] [error] Picture size 0x0 is invalid

  I assumed the sizes are something I can insert using the input options, since in the CLI version it is passed using -s:v 1920x1080, however this does not seem to be true.

  Where do I have to specify the dimensions of my raw input stream ?

• ffmpeg : precisely cut a video

  19 octobre 2019, par Santhosh Yedidi

  I am tring to cut a video in linux OS

  $ ffmpeg -i dhol.mkv 
  
  ffmpeg version n4.1.2 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 8.2.1 (GCC) 20181127
  
    configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, matroska,webm, from 'dhol.mkv':
  
    Metadata:
  
      ENCODER         : Lavf58.20.100
  
    Duration: 00:03:56.18, start: -0.007000, bitrate: 2688 kb/s
  
      Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv, bt709/unknown/unknown), 1920x1080, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        DURATION        : 00:03:56.167000000
  
      Stream #0:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        DURATION        : 00:03:56.181000000

  I was trying to precisely cut the video file :

  But using ffmpeg I was not successfull. It cuts from the nearest key frames to the given start time

  ffmpeg -y -i dhol.mkv -ss $shift   -t $duration -c:v copy -an output.mkv

  ONE OF THE REASONS HERE IS H.264 Video format (YUV420p vs YUV420sp). I am using -c:v copy so it has to use the same format YUV420p, so it has to start from nearest keyframe

  Now the only reliable software that i can fully depend if avidemux.

  Even in that i have to select

  video-codec: MJPEG
  
  audio-codec: vorbis

  But the cut video size will be large.

  I tried in avidemux

  video-codec: copy
  
  audio-codec: copy

  It will cut from nearest keyframe than precisely.

  One conclusion :
  So irrespective of ffmpeg or avidemux, the output video format yuv420p will not allow precise formatting

  Only option currently possible :

  Using avidemux and with

  video-codec: MJPEG
  
  audio-codec: vorbis

  Cons :

  1) bigger video size.
  
  2) no proper command line examples available for avidemux to do the same as gui does

  I tried command line in avidemux :

  avidemux3_cli --video-codec MJPEG --audio-codec AAC --output-format AVI --load dhol.mkv --begin 137.633 --end 141.334 --save dhol2.mkv

  It tries to convert the whole file rather than from the start to end time

  My requirement :
  I want to do it command line.

  I didnt try with ffmpeg (with video codec : MJPEG and audio : vorbis). I never saw any example

  How to precisely cut a video (even the output format can be different (like MJPEG instead of yuv420p, and also bigger sizes, its ok) using command line