Recherche avancée

Sur d’autres sites (6183)

• Batch Merge Large Number of Video Files by Pair

  16 février 2021, par dellyice

  I have a directory full of 1000+ short h.264 video clips that I'd like to batch merge via ffmpeg one pair at a time in Windows (eg, file1.mp4 is concatenated with file2.mp4, then file3.mp4 is concatenated with file4.mp4, etc, to ultimately produce half as many resultant videos, each containing two merged parent clips), and everything I've tried from fudging together scripts from other answers on the site has resulted in messes too embarrassing to mention.

  


  Each pair of videos is cut from a common source vid, so the concat demuxer should be fine for merging them. If it helps, each set of videos follows the naming scheme "filename"_1.mp4 and "filename"_2.mp4, so they're correctly paired alphabetically, and the _1 and _2 files can obviously be easily separated into different folders if need be.

  


  Sorry if any of this is terribly vague. If I had any productive work to show, I'd do so. Many thanks for any help.

  


• ffmpeg cut the video and get accurate begining time of the result

  1er décembre 2022, par Pavlo Sharhan

  I do the cut via :

  


  ffmpeg -i  long_clip.mp4 -ss 00:00:10.0 -c copy -t 00:00:04.0 short_clip.mp4


  


  I need to know the precise time where did the ffmpeg do the cut (Time of the closest keyframe before the 00:00:10.0)

  


  Currently, I'm using the following ffprobe command to list all the keyframes and select the closest before 00:00:10.0

  


  ffprobe -show_frames -skip_frame nokey long_clip.mp4


  


  It works extremely slow (I run It on Jetson Nano, and It is a few minutes to list the keyframes for 30 sec video, although the cutting is done in 0.2seconds)

  


  I hope there is the much faster way to know the time of the keyframe where ffmpeg does the cut, at least because ffmpeg seeks to this keyframe and cuts the video less than in half a second.

  


  So in other words the question is : How to get the time of the keyframe where ffmpeg does the cut not listing all the keyframes ?

  


• Building FFmpeg for android to run command line args

  11 septembre 2012, par Zargoon

  I am trying to build the FFmpeg library to use in my android app with the NDK. The reason for this is because I am using the native video capture feature in android because I really don't want to write my own video recorder. However, the native video capture only allows for either high-quality encoding, or low quality encoding. I want something in between, and I believe that the solution is to use the FFmpeg library to re-encode the high quality video to be lighter.

  So far I have been able to build the FFmpeg library according to this guide : http://www.roman10.net/how-to-build-ffmpeg-for-android/ and which a few tweaks I have been able to get it to work.

  However, everything that I've found seems to be about writing your own encoder, which seems like overkill to me. All that I really want to do is send a string in command line format to the main() function of FFmpeg and re-encode my video. However, I can't seem to figure out how I build FFmpeg to give me access to the main method. I found this post : Compile ffmpeg.c and call its main() via JNI which links to a project doing what I want more of less, but for the life of me I cannot figure out what is going on. It also seems like he is compiling more than I want, and I would really like to keep my application as light weight as possible.

  Some additional direction would be extremely helpful. Thank you.