Recherche avancée

Sur d’autres sites (14723)

• ffmpeg slows down as I run it

  14 septembre 2022, par Bambi2k21

  I edit a video such that it speeds up by 8x where the speaker is silent and by 2x when he is speaking. And to do that I use ffmpeg in such a manner :

  


  ffmpeg -i C:\Users\TheD4\Desktop\uni1.mp4 -filter_complex "[0:v]trim=0:0.98,setpts=1*(PTS- 
STARTPTS)[v0]; [0:a]atrim=0:0.98,asetpts=PTS-STARTPTS,atempo=1[a0] 
[0:v]trim=0.98:1.598,setpts=0.5*(PTS-STARTPTS)[v1]; [0:a]atrim=0.98:1.598,asetpts=PTS- STARTPTS,atempo=2[a1]; [0:v]trim=1.598:1.946,setpts=1*(PTS-STARTPTS)[v2]; 
[0:a]atrim=1.598:1.946,asetpts=PTS-STARTPTS,atempo=1[a2]; [0:v]trim=1.946:1.975,setpts=0.5*(PTS- 
STARTPTS)[v3]; [0:a]atrim=1.946:1.975,asetpts=PTS-STARTPTS,atempo=2[a3];............ 
[0:v]trim=1529.04:1537.34,setpts=1*(PTS-STARTPTS)[v1652]; [0:a]atrim=1529.04:1537.34,asetpts=PTS- 
STARTPTS,atempo=1[a1652]; [0:v]trim=1537.34:1537.55,setpts=0.5*(PTS-STARTPTS)[v1653]; 
[0:a]atrim=1537.34:1537.55,asetpts=PTS-STARTPTS,atempo=2[a1653]; 
[0:v]trim=1537.55:1538.73,setpts=1*(PTS-STARTPTS)[v1654]; [0:a]atrim=1537.55:1538.73,asetpts=PTS- 
STARTPTS,atempo=1[a1654]; [0:v]trim=1538.73:1539.15,setpts=0.5*(PTS-STARTPTS)[v1655]; 
[0:a]atrim=1538.73:1539.15,asetpts=PTS-STARTPTS,atempo=2[a1655]; [v0][a0][v1][a1][v2][a2][v3] 
[a3]..........[v1652][a1652][v1653][a1653][v1654][a1654][v1655][a1655]concat=n=1656:v=1:a=1" -preset 
superfast -profile:v baseline


  


  But the thing is, as you might have noticed the filter goes into the thousands, and so the total number of caracters is high(in this example there are around 200000), but cmd(8000) or powershell(30000) have less than that. So to get around that limitation, I divided all of that into smaller parts, but here is where the problem starts, as I run more and more of the "parts code" and ffmpeg does work on later and later parts of the video, the process of making the video from those smaller parts becomes slower as well, even though the size of the video is the same. To see what is wrong, I ran the code from a couple of hundred seconds(so instead of starting from 0s it start from let's say 500s) and I noticed the same effect. So what I think happens is that ffmpeg goes through the entirety of the video until it reaches the specified start. So here is my question is there a way to tell ffmpeg to ignore the start of the video and to start immediately from where I need it to, maybe something like this :

  


  ffmpeg -i C:\Users\TheD4\Desktop\uni1.mp4[500:] -filter_complex ........


  


• avformat/movenc : limit ISOBMFF AC-3 mapping to bsids <=8

  22 juin 2022, par Jan Ekström

  avformat/movenc : limit ISOBMFF AC-3 mapping to bsids <=8
  This leaves out RealAudio DolbyNet, which utilizes bsids 9 and 10,
  It is not clear whether the interpreted bit rate value (divided by
  
  2 or 4 depending on the variant), or the original bit rate value
  
  should be utilized to receive the bit_rate_code index.
  Signed-off-by : Jan Ekström <jan.ekstrom@24i.com>
  

  • [DH] libavformat/movenc.c

• How to export mestimate filter motion vectors into a separate file with ffmpeg binary ?

  20 juin 2022, par Hitokage

  So mestimate filter can be used to compute the motion vectors in a video. They can also be displayed. Is there a way to export them into a separate file using the ffmpeg binary ? I would love to have them for example in an image like 2-component color values representing the 2D vectors for each block (so the resolution would be the original one divided by the block size) or something.&#xA;Given a sequence of png frames, I can do :

  &#xA;

  ffmpeg -i %04d.png -vf "mestimate" test.mkv


  &#xA;

  And as I understand it, the vectors are then stored in the frames' side data which can be extracted using libav. Is there a simple way with the ffmpeg tool alone ? Thanks.

  &#xA;