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• rtsp : Only interpret $ as interleaved packet indicator at the start of replies

  21 janvier 2015, par Martin Storsjö

  rtsp : Only interpret $ as interleaved packet indicator at the start of replies
  Allow $ as character anywhere within normal RTSP replies - both
  
  within the lines, and as the first character of RTSP header lines.
  
  (The existing old comment indicated that an inline packet could
  
  start at any line within a RTSP reply header, but that doesn’t
  
  sound valid to me, and I’m not sure if the existing code
  
  handled that correctly either.)
  CC : libav-stable@libav.org
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/rtsp.c

• FFMPEG avoid_negative_ts makes video start not from keyframe

  7 mars 2019, par Void Floyd

  Let’s say I want to cut part of the mp4 video and resize it from 1280x720 to 854x480.

  My command looks like this :

  ffmpeg -ss 45 -i source.mp4 -ss 10 -to 20 \
  
  -acodec aac -ar 44100 -ac 2 -c:v libx264 \
  
  -crf 26 -vf scale=854:480:force_original_aspect_ratio=decrease,pad=854:480:0:0,setsar=1/1,setdar=16/9 \
  
  -video_track_timescale 29971 -pix_fmt yuv420p \
  
  -map_metadata 0 -avoid_negative_ts 1 -y dest.mp4

  The problem is, when I don’t use option avoid_negative_ts, resulting video has some issues with time bases etc, therefore it cannot be later converted by other libs, for example Swift’s AVFoundation.

  But when I use this option - video does not start with keyframe.
  By using ffprobe I see start_time=0.065997 or other times other than 0.

  How can I use option avoid_negative_ts and have a video that starts with keyframe ?

• Python subprocesses only start once I Ctrl-C the program ?

  4 février 2016, par slhck

  I’m trying to run a few ffmpeg commands in parallel, using Cygwin and Python 2.7.

  This is roughly what I have :

  import subprocess
  
  processes = set()
  
  
  
  commands = ["ffmpeg -i input.mp4 output.avi", "ffmpeg -i input2.mp4 output2.avi"] 
  
  
  
  for cmd in commands:
  
    processes.add(
  
      subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
  
    )
  
  
  
  for process in processes:
  
    if process.poll() is None:
  
      process.wait()

  Now, once I am at the end of this code, the whole program waits. All the ffmpeg processes are created, but they’re idle, i.e., using 0% CPU. And the Python program just keeps waiting. Only when I hit Ctrl-C, it suddenly starts encoding.

  What am I doing wrong ? Do I have to "send" something to the processes to start them ?