Newest 'ffmpeg' Questions - Stack Overflow

Les articles publiés sur le site

• how to pause the video in FFmpeg [on hold]

  17 février 2014, par Hadi M.NourAllah

  I am using IFrameExtractor and I want to make pause button how can i make it

• ffmpeg trimming video with -ss and -t working only with audio

  16 février 2014, par user3197974

  I am trying to extract 5 seconds out of a TS stream using the command below:

  ffmpeg -ss 780 -t 5 -i "D:\TS\stream_457.ts" -map 0:17 -map 0:7 -qscale 6 -y -async 1 "D:\1_O.ts"
  

  The trimming seems to work on the audio track, the output file plays only 5 seconds of audio but the video starts at second 780 and continues until the end of the stream. So i end up with 5 seconds of audio and 37 seconds of video.

  How can i trim both audio and video?

  Thanks

• FFmpeg force_key_frames expression variables

  16 février 2014, par user1704620

  I am writing a Bash script, and I am trying to figure out a way to get FFmpeg to recognize a global variable in the -force_key_frames option. The -force_key_frames option can take a regular expression as an argument, allowing functionality such as forcing a key frame every 5 seconds:

  -force_key_frames 'expr:gte(t,n_forced*5)'
  

  This works fine for forcing a key frame every 5 seconds, but I don't know how to force a key frame every x seconds, x being an input variable from the user gotten by the rest of the script. The exact FFmpeg command that I'm trying is:

  ffmpeg -i "video.mp4" -vcodec: libx264 -b:v 500k \
  -force_key_frames 'expr:gte(t,n_forced*${SEG_TIME})' -s:v 640x480 \
  -r 29.97 -pix_fmt yuv420p -map 0 -f segment -segment_time ${SEG_TIME} \
  -reset_timestamps 1 -y "output%01d.mp4"
  

  The variable $SEG_TIME is set to 5 by the script, but the regular expression in the -force_key_frames option doesn't seem to like the $SEG_TIME variable.

• Is it Possible To hide an information in a Image and convert it to video and decrypt it back with FFMPEG

  16 février 2014, par Ivan

  I am doing my project with the help of ffmpeg. I initially convert a video file in to images and hide some information in one of the images and convert it back to video. and in the receiver side the user should again convert the video containing the encrypted message in to images and get back the information from the image in which we have previously hided the information.

  I have done all these but after convert the encrypted image into video and then i convert back to image i am not able to get the hidden information from the converted image...How do i do this. Is there any way to hide infor mation in a image other than this...

• How to Buffer Audio Streams for an Android Internet Radio Application

  16 février 2014, par burakk

  We have a radio application that streams MP3 over HTTP using an instance of the MediaPlayer class. In devices running new Android versions (i.e, Note 3 running Android 4.3), the music plays for about half a second, and then waits (buffers?) for up to 10 seconds, and plays again. I guess this unwanted behavior is due to the increased buffer size of the MediaPlayer in newer Android versions. Since there's no way to set the buffer size, there are few options left:

  • Stream Proxy
  • AudioTrack + MP3 Decoder
  • OpenSL

  I have read many posts about those, and concluded that the best way would be using AudioTrack with an MP3 decoder like FFMPEG. However, I am open to suggestions and any guidances since I do not have any knowledge about Android NDK, JNI and FFMPEG...