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• Synchronize video subtitle with text-to-speech voice

  8 décembre 2015, par Ahmad

  I try to create a video of a text in which the text is narrated by text-to-speech.

  To create the video file, I use the VideoFileWriter of Aforge.Net as the following :

  VideoWriter = new VideoFileWriter();
  
  
  
  VideoWriter.Open(CurVideoFile, (int)(Properties.Settings.Default.VideoWidth),
  
      (int)(Properties.Settings.Default.VideoHeight), 25, VideoCodec.MPEG4, 800000);

  To read aloud the text I use SpeechSynthesizer class and write the output to a wave stream

  AudioStream = new FileStream(CurAudioFile, FileMode.Create);
  
  synth.SetOutputToWaveStream(AudioStream);

  I want to highlight the word is spoken in the video, so I synchronize them by the SpeakProgress event :

      void synth_SpeakProgress(object sender, SpeakProgressEventArgs e)
  
      {
  
  
  
          curAuidoPosition = e.AudioPosition;
  
          using (Graphics g = Graphics.FromImage(Screen))
  
          {
  
               g.DrawString(e.Text,....); 
  
          }                    
  
          VideoWriter.WriteVideoFrame(Screen, curAuidoPosition);
  
      }

  And finally, I merge the video and audio using ffmpeg

  using (Process process = new Process())
  
  {
  
            process.StartInfo.FileName = exe_path;
  
            process.StartInfo.Arguments = string.Format(@"-i ""{0}"" -i ""{1}"" -y -acodec copy -vcodec copy ""{2}""",
  
                                             avi_path, mp3_path, output_file);
  
  ......

  The problem is that for some voices like Microsoft Hazel, Zira and David, the video is not synchronized with the audio, and the audio is much faster than the shown subtitle. In windows 7, it works for Mircrosoft Sam

  How can I synchronize them so that it works for any text-to-speech voices ?

• Why Do Some of the Codecs in FFMPEG's Supported Codec List Show "encoders :" or "decoders :" in Parenthesis ?

  4 mai 2020, par spaceman

  If you open the Command Prompt, and run ffmpeg -codecs,
  
you will get a long list of Codecs that FFMPEG supports.

  



  Here's a small sample of the list :

  



   DEV.L. h261                 H.261
 DEV.L. h263                 H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2
 D.V.L. h263i                Intel H.263
 DEV.L. h263p                H.263+ / H.263-1998 / H.263 version 2
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)
 D.V.LS hevc                 H.265 / HEVC


  



  Now If you briefly go over the whole list,
  
you see that most Codecs in this list appear with their Name and Description,
  
but some of the Codecs also include parenthesis in the Description, and in the parenthesis,
  
they specify "encoders :" or "decoders :".

  



  For example :

  



  1)

  



   DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)


  



  2)

  



   DEVILS jpeg2000             JPEG 2000 (decoders: jpeg2000 libopenjpeg) (encoders: jpeg2000 libopenjpeg)


  



  3)

  



   DEV.L. msmpeg4v3            MPEG-4 part 2 Microsoft variant version 3 (decoders: msmpeg4) (encoders: msmpeg4)


  



  4)

  



   DEA.L. aac                  AAC (Advanced Audio Coding) (encoders: aac libvo_aacenc)


  



  5)

  



   DEA.L. amr_nb               AMR-NB (Adaptive Multi-Rate NarrowBand) (decoders: amrnb libopencore_amrnb) (encoders: libopencore_amrnb)
 DEA.L. amr_wb               AMR-WB (Adaptive Multi-Rate WideBand) (decoders: amrwb libopencore_amrwb) (encoders: libvo_amrwbenc)


  



  My question :

  



  Why do some Codecs have those parenthesis, specifying Encoders/Decoders,
  
while other (in fact : most) codecs don't have these parenthesis ?

  


• swscale : make yuv2interleavedX more asm-friendly

  26 avril 2020, par Nelson Gomez

  swscale : make yuv2interleavedX more asm-friendly
  Extracting information from SwsContext in assembly is difficult, and
  
  rearranging SwsContext just for asm access didn't look good. These
  
  functions only need a couple of fields from it anyway, so just make
  
  them parameters in their own right.
  Signed-off-by : Nelson Gomez <nelson.gomez@microsoft.com>
  

  • [DH] libswscale/output.c
  • [DH] libswscale/swscale_internal.h
  • [DH] libswscale/vscale.c