Newest 'ffmpeg' Questions - Stack Overflow

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• Xcode cannot find symbol for particular source

  19 novembre 2014, par onemach

  I have an iOS project utilizing ffmpeg. The library is pre-built and copied to the project tree

  ffmpeg/ ├── include │   ├── libavcodec │   ├── libavdevice │   ├── libavfilter │   ├── libavformat │   ├── libavresample │   ├── libavutil │   ├── libpostproc │   ├── libswresample │   └── libswscale └── lib ├── libavcodec.a ├── libavdevice.a ├── libavfilter.a ├── libavformat.a ├── libavresample.a ├── libavutil.a ├── libpostproc.a ├── libswresample.a └── libswscale.a

  .h files are omitted above for clarity.

  In the Build Setting, the Header Search Paths and Library Search Paths are added respectively.

  When compiling, Xcode complains about tens of Undefined symbols for architecture x86_64, all about ffmpeg. All the errors come from the same source file. And in another source file, no error is given though it also utilize ffmpeg.

• Extracting chinese subtitle from video

  19 novembre 2014, par william007

  Given a video like: https://www.youtube.com/watch?v=cNHeiIM5xZI

  Is there any library or tool that supports extraction of subtitle?

  Extraction of subtitle in sequence would be sufficient, it would be plus if it can extracts the timestamp as well.

• Ffmpeg fade command and perl variable

  19 novembre 2014, par CRAIG

  I am trying to fade out some audio using ffmpeg in a Perl script.

  The command is the following:

   ffmpeg -i short.wav -af "afade=t=out:st=65:d=5" short.mp3
  

  With the 65 in the afade section being the time point where the fade should begin.

  However, I need to use a variable there, so instead of 65 I need to use $length and not hard code it. Any thing I try i.e.:

   ffmpeg -i short.wav -af "afade=t=out:st=" . $length . ":d=5" short.mp3
  

  Does not work and breaks the script.

  What would be the proper way to handle this?

• Have 2 blocking scripts interact with each other in linux

  18 novembre 2014, par Ortixx

  I have 2 blocking shell scripts which I want to have interact with each other. The scripts in question are peerflix (nodejs script) and ffmpeg (a simple bash script).

  What happens: Peerflix fires up, feeds data to ffmpeg bash scrip which terminates peerflix on completion.

  So once peerflix starts it outputs 2 lines and blocks immediately:

  [08:15 PM]-[vagrant@packer-virtualbox-iso]-[/var/www/test]-[git master] 
  $ node /var/www/test/node/node_modules/peerflix/app.js /var/www/test/flexget/torrents/test.torrent -r -q
  listening: http://10.0.2.15:38339/
  process: 9601
  

  I have to feed the listening address to the ffmpeg bash script:

  #!/bin/sh
  ffmpeg -ss 00:05:00 -i {THE_LISTENING_PORT} -frames:v 1 out1.jpg
  ffmpeg -ss 00:10:00 -i {THE_LISTENING_PORT} -frames:v 1 out2.jpg
  

  After the bash script is done I have to kill the peerflix script (hence me outputting the PID).

  My question is how do I achieve this?

• Concatenate chunk containg headers to another chunk in h264

  18 novembre 2014, par Ortixx

  I'm trying to extract thumbnails from a torrent stream by downloading the first couple of chunks to get the headers, another set of chunks from the middle and then concat them to have a single video file.

  For this I'm using nodejs but I'm having trouble with the concatenation part. Obviously the headers include the length of the video so if I simply concat another chunk to the end of the headers chunk, it won't work.

  In other words, I have 2 chunks of a video file: The first one contains the headers and some material and the other one is fully composed of a video stream. I want to combine the two to form a single video file So my question is how can I make this work properly if at all?