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• ffmpeg replacing audio track with track from another video but different length (sync audio)

  27 août 2019, par Matt

  Background

  I have digitized some old Canon Video8 tapes. I used a SONY Digital8 camera (which is backwards compatible with Video8) to output DV (using it’s inbuilt ADC). The conversion process worked well for the video but the audio came through jumpy/distorted in places. This left me with a problem, was it the Camera or the tape ? So I bought another Samsung Video8 camera (just analog) and using the SONY’s passthrough feature output from the Samsung (Composite & mono audio) into the SONY which output the DV. Much to my delight it worked ! The audio was clear.

  Result

  DV01.avi - Good Video / Crap Audio
  
  DV02.avi - Crap Video / Good Audio

  Ok so obviously what I would like to do is take the video track from DV01 and the audio track from DV02 and join/mux ? them WITHOUT re-encoding.

  Problem 1 : They have different start times so just copying over the audio track will result it not being in sync.

  After some googling I found you can use ffmpeg to take care of this :

  Firstly here is the Video info using : ffmpeg -i DV01.avi

  Input #0, avi, from 'DV01.avi':
  
    Duration: 02:53:06.68, start: 0.000000, bitrate: 28878 kb/s
  
      Stream #0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15 DAR 4:3], 25000 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
      Stream #0:1: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s
  
      Stream #0:2: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s

  Muxing :

  ffmpeg -itsoffset 4 -i DV01.avi -i DV02.avi -map 0:v -map 1:a -c copy output.avi

  In the example above I am delaying the start of the video 4 seconds (I think ?) This is just an example I haven’t actually tried it as the file sizes are 40Gb !

  So my QUESTION is :

  Given the background above what would be the best way to join/mux the two streams together (without re-encoding) with the audio being in sync. Given that syncing the audio to the video may need millisecond tweaking I don’t believe trial and error is a good idea (I don’t want to tweak it by 10ms then rinse and repeat for a 40Gb file) ?

  I just had a thought, could I say create a 10 second clip (from the start) of each video and use them to find the reference/sync start point then use that when muxing the 40Gb versions ?

  Anyway, you get the idea. Looking for ways to solve this problem. Thanks !

• ffserver : fix some comments

  13 février 2014, par Reynaldo H. Verdejo Pinochet

  ffserver : fix some comments
  Signed-off-by : Reynaldo H. Verdejo Pinochet <r.verdejo@sisa.samsung.com>
  

  • [DH] ffserver.c

• ffserver : cosmetics

  13 février 2014, par Reynaldo H. Verdejo Pinochet

  ffserver : cosmetics
  Signed-off-by : Reynaldo H. Verdejo Pinochet <r.verdejo@sisa.samsung.com>
  

  • [DH] ffserver.c