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• Slow seek in MKV videos with FFmpeg C/C++

  14 juin 2019, par Igor

  Seeking in any large MKV H.264 video works very slow.

  Call of av_seek_frame() in my code using FFmpeg LibAV takes about 3-10 seconds to jump to a middle position in 1-2 hours video.

  I tried all combinations of flags : AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE, AVSEEK_FLAG_ANY, AVSEEK_FLAG_FRAME

  However VLC seeks very fast in same MVK videos.

  Seeking in MP4 H.264 works instantly. The problem is only with MKV.

  Latest FFmpeg 4.1.3.

• How can I download videos from reddit using praw

  9 octobre 2023, par rabbibillclinton

  So I want to download videos from reddit, I've seen projects on github but I'm very new to python and don't know how it works, if someone could explain I'd appreciate it, I found this project It works but it seperates audio and video and I want it all in one, I think you can combine those using ffmpeg but I don't know how that works either, also how do I configure some of this stuff like where the videos save and quality, here's my code.

  


  from redvid import Downloader
import praw

reddit = praw.Reddit(client_id = "a", client_secret = "b", user_agent = "c")

subreddit = reddit.subreddit("learnpython")
hot = subreddit.hot(limit=5)

downloader = Downloader(max_q=True)

for submission in hot:
    downloader.url = submission.url
    reddit.download()


  


• Merging four videos with different resolution in a Grid with ffmpeg

  5 juillet 2015, par Taufiq

  I want to marge four videos in to one as show below. I have achieve the correct output given all the videos have the same resolution. But I get an undesirable result with different resolution. See below for more details.

  i need ffmpeg code to get to merge 4 videos of different resolution in a grid format

  ffmpeg.exe -i "1.avi" -vf "[in] scale=iw:ih, pad=2*iw:ih [left];movie=2.avi, scale=iw:ih [right]; [left][right] overlay=main_w/2:0 [out]" -b:v 768k "Output1.mp4"
  
  ffmpeg.exe -i "3.avi" -vf "[in] scale=iw:ih, pad=2*iw:ih [left];movie=4.avi, scale=iw:ih [right]; [left][right] overlay=main_w/2:0 [out]" -b:v 768k "Output2.mp4"
  
  ffmpeg.exe -i "Output1.mp4" -vf "pad=iw:2*ih [top]; movie=Output2.mp4 [bottom]; [top][bottom] overlay=0:main_h/2" "Output_Stacked.mp4"

  Code above gives the follow output.

  

  But the problem arises when I rotate one of the videos and merge them.
  .

  Please tell me what I need to change to get the desired result. Thanks