Recherche avancée

Sur d’autres sites (6071)

• Merge commit ’b141c7b37eb52aca41ac83738f159b63b9c09d5c’

  8 février 2014, par Michael Niedermayer

  Merge commit ’b141c7b37eb52aca41ac83738f159b63b9c09d5c’
  * commit ’b141c7b37eb52aca41ac83738f159b63b9c09d5c’ :
  
    h264 : give numbers to nalus
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/h264.h

• Problem with ffmpeg function avformat_seek_file()

  19 avril 2013, par Kael

  I am trying to seek the given frame in the video using ffmpeg library. I knew that there is av_seek_frame() function but it was recommended to use avformat_seek_file()instead. Something similar mentioned here. I know that avformat_seek_file() can't always take you to exact frame you want, but this is ok for me. I just want to jump to the nearest keyframe. So i open the video, find videostream and calling it like this :
  avformat_seek_file( formatContext, streamId, 0, frameNumber, frameNumber, AVSEEK_FLAG_FRAME ). It always returns 0, so i understand it as correct finish. However, it doesn't work as it should to. I check byte position like here before and after calling avformat_seek_file(). Actually it changes, but it changes always in the same way whenever i'm trying to put different target frame numbers ! I mean that byteposition after this call is always same even with different frameNumber values. Obviously, i'm doing something wrong but i don't know what exactly. I don't know if it does matter but i'm using .h264 files for that. I tried different flags, different files, using timestamps instead of frames, flushing buffers before and after and so on but it doesn't work for me. I will be very grateful if someone could show me what is wrong with it.

• ffmpeg Decoding Progress during Frame Extarction

  4 avril 2013, par Isantipov

  I scan input video to extract certain frames using ffmpeg's select filter. The selection is based on a complex creteria and the number of extracted frames can't be predicted (I'm doing scene detection, but this can be something different - e.g. selecting all the I frames, etc).

  What I need is to display the percentage of scanned (decoded) video (e.g. 10% or 90%).

  ---

  I tried several ways to do this parsing console output as people usually do when dealing with encoding, but it doesn't help with the progress of scanning (e.g. Can ffmpeg show a progress bar ? or ffmpeg Progress Bar - Encoding Percentage in PHP)

  ffmpeg -progress sceneProgr.txt -i input.wmv -vsync passthrough -an -vf select='gt(scene\,0.2)',showinfo scene%%05d.png

  The output this produces is as follows :

  <..>    
  
  frame=    0 fps=0.0 q=0.0 size=N/A time=00:00:00.00 bitrate=N/A    
  
  n:0 pts:16550 pts_time:16.55 pos:4205325 fmt:rgb24 sar:0/1 s:640x480 i:P iskey:1 type:I checksum:95895BC9 plane_checksum:[95895BC9]
  
  frame=    1 fps=0.7 q=0.0 size=N/A time=00:00:00.00 bitrate=N/A    
  
  n:1 pts:24591 pts_time:24.591 pos:6685325 fmt:rgb24 sar:0/1 s:640x480 i:P iskey:0 type:P checksum:FF4CC015 plane_checksum:[FF4CC015]
  
  'frame=...' and 'n:...' lines are repeated for each of the extracted frames.

  Both frame=... and n:... lines refer to the numbers in the output and therefore can't be used to calculate progress the way people usually do this (as I can't predict how many frames will be found beforehead and besides, they are not uniformly spread across the input video).

  ---

  If I specify -progress progress.txt parameter, the progress.txt file is as follows :

  frame=5
  
  fps=1.2
  
  stream_0_0_q=0.0
  
  total_size=N/A
  
  out_time_ms=43209833
  
  out_time=00:00:43.209833
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue
  
  
  
  
  
  frame=6
  
  fps=1.3
  
  stream_0_0_q=0.0
  
  total_size=N/A
  
  out_time_ms=52252200
  
  out_time=00:00:52.252200
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue
  
  
  
  frame=6
  
  fps=1.2
  
  stream_0_0_q=0.0
  
  total_size=N/A
  
  out_time_ms=52252200
  
  out_time=00:00:52.252200
  
  dup_frames=0
  
  drop_frames=0
  
  progress=continue

  New portion is written approximately every second and refers to the last extracted frame.
  Which is somewhat helpful as out_time refers to the last extracted frames' position in the input video, so I can calculate the progress of the scan from it as

  progress = out_time_ms/total_input_time 

  But this is not ideal as it will be updated only when the new frame which matches the select criteria is extracted. So, If I have a large portion of video with no matching frames, the progress won't change for a lot of time.

  ---

  Wrapping-up :

  I am looking for a way to calculate the progress of video scanning when using select filter.

  Any ideas are strongly appreciated.