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• Record a video conference application

  11 août 2014, par Matin Lotfaliee

  I want to record a video conference (e.g skype, oovoo, ...) with a program written in C#. I searched a lot about how to do this :

  • Here suggests Windows Media Encoder, but none of their samples work correctly on my Win7. I installed the SDK but even the links to Microsoft are somehow broken or old.
  • Here suggests creating a video stream from a series of screenshots using ffmpeg. but it is probably impossible to keep the audio,mic and screenshots synced.
  • Here seems to be a great solution but it is not free...

  Compression is not important to me because a video conference uses CPU a lot.

  Can you help me find a good solution ?

• FFMpegCore .Net cuts off the fist few ( 1.5) seconds of audio

  28 mai 2024, par Tim

  I want to use FFMpegCore to convert some audio files to raw pcm. I noticed that this always cuts off 1.5 seconds of my audio from the start. I check my input stream, saved it to HD all good. If use it from cli with the same arguments everything seem fine. I tried -ss 0, no luck. This behavior is observed with .wav (RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, stereo 44100 Hz), same issue with different sample rate. I tested mp3 works fine.

  


  public async Task<memorystream> ConvertToPcmStreamAsync(Stream inputStream)&#xA;{&#xA;    var outputStream = new MemoryStream();&#xA;    &#xA;    var audioInput = new StreamPipeSource(inputStream);&#xA;    var audioOutput = new StreamPipeSink(outputStream);&#xA;&#xA;    await FFMpegArguments&#xA;        .FromPipeInput(audioInput)&#xA;        .OutputToPipe(audioOutput, options => options&#xA;            .WithCustomArgument("-ss 0 -f s16le -acodec pcm_s16le -ac 1"))&#xA;        .ProcessAsynchronously();&#xA;&#xA;    // Reset the position of the memory stream to the beginning&#xA;    outputStream.Position = 0;&#xA;&#xA;    return outputStream;&#xA;}&#xA;</memorystream>

  


• ffprobe failing on certain videos

  19 mars 2020, par griswoldbar

  I work on a platform that uses ffprobe as part of a video transcoding pipeline. One of our users is trying and failing to upload video clips extracted from a CCTV system, and it seems the failure is occurring when we parse the clips with ffprobe.

  When I run ffprobe from the command line, I get this :

  $ ffprobe file.avi
  
  ffprobe version 4.2.2 Copyright (c) 2007-2019 the FFmpeg developers
  
    built with Apple clang version 11.0.0 (clang-1100.0.33.17)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  [avi @ 0x7fc22280b800] Invalid sample_size -1 at stream 1 setting it to 0
  
  [avi @ 0x7fc22280b800] Invalid sample_size -1 at stream 2 setting it to 0
  
  [avi @ 0x7fc22280b800] wav header size < 14 is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
  
  [avi @ 0x7fc22280b800] If you want to help, upload a sample of this file to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
  
  file.avi: Invalid data found when processing input

  I am however able to parse it with mediainfo, which outputs this :

  $ mediainfo file.avi
  
  General
  
  Complete name                            : file.avi
  
  Format                                   : AVI
  
  Format/Info                              : Audio Video Interleave
  
  File size                                : 11.3 MiB
  
  Duration                                 : 5 min 0 s
  
  Overall bit rate                         : 316 kb/s
  
  
  
  Video
  
  ID                                       : 0
  
  Format                                   : MPEG-4 Visual
  
  Codec ID                                 : MP43
  
  Codec ID/Info                            : Microsoft MPEG-4 v3 (pre-standard)
  
  Codec ID/Hint                            : Microsoft
  
  Duration                                 : 5 min 0 s
  
  Source duration                          : 5 min 0 s
  
  Bit rate                                 : 308 kb/s
  
  Width                                    : 640 pixels
  
  Height                                   : 480 pixels
  
  Display aspect ratio                     : 4:3
  
  Frame rate                               : 16.000 FPS
  
  Compression mode                         : Lossy
  
  Bits/(Pixel*Frame)                       : 0.063
  
  Stream size                              : 11.0 MiB (97%)

  I’m guessing/hoping that there’s a way to make this work by passing appropriate flags to ffprobe - can anyone point me in the right direction ?