Recherche avancée

Sur d’autres sites (6230)

• What is the difference between yuv420p and yuv420p(tv) ?

  9 novembre 2018, par Aleksandr Shemetillo

  I am trying to implement Fairplay ready browser player (Apple’s DRM).
  A stream that has h264(Main) yuv420p(tv) settings becomes non-working after drm decryption (crashed picture of green color). Converting again the video with a "Main" ffmpeg profile changes the setting to a simple yuv420 and this solves the problem.
  Please explain the difference.
  Or maybe some other changes I don’t see can happen during the conversion ?

  Of course, since we are talking about Fairplay, the problem is observed in Safari on Os X

• Trouble writing mp3 into flv container

  8 février 2013, par Sriram

  I am encoding a raw pcm stream with LAME and writing the mp3 encoded samples to an flv container using a c program. For debugging purposes, I am also writing the mp3 encoded samples to a file separately. The following is observed :

  1. The mp3 written to another file is correct. There are no clicks or any other artefacts observed.

  2. The flv file does not play anything. Examining with ffmpeg like so :

     $ ./ffmpeg.exe -i temp_local_flv.flv

  The above command gives the following :

  ffmpeg version N-49352-gc46943e Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jan 26 2013 12:12:14 with gcc 4.7.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil      52. 17.100 / 52. 17.100
  
    libavcodec     54. 91.100 / 54. 91.100
  
    libavformat    54. 61.104 / 54. 61.104
  
    libavdevice    54.  3.102 / 54.  3.102
  
    libavfilter     3. 34.101 /  3. 34.101
  
    libswscale      2.  2.100 /  2.  2.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  [flv @ 0000000000307be0] Stream discovered after head already parsed
  
  [mp3 @ 000000000237d9c0] Header missing
  
  Input #0, flv, from 'temp_local_flv.flv':
  
    Duration: 00:00:00.07, start: 0.002000, bitrate: 643 kb/s
  
      Stream #0:0: Audio: mp3, 22050 Hz, mono, s16p, 32 kb/s
  
      Stream #0:1: Data: none
  
  At least one output file must be specified  

  My questions :
  1. What is this "Header missing" ? Is there a "special" mp3 header that needs to be written when writing encoded samples to an flv container ? If so, what does the header contain ? And given that the mp3 samples written to the file are decoded correctly by an audio player, what am I missing ?

• FFMPEG command runs forever even on using timelimit

  21 décembre 2017, par t6nand

  Mostly I use a java code to run FFMPEG bash commands for watermarking a logo on video. I am using the following FFmpeg command to overlay an image on video. I have observed that at times for some random videos, the process keeps on running even after the timelimit assigned to it expires. At times it’s more than a day or couple of days until not directly killed using kill -9 pid :

  ffmpeg -timelimit 900 -y -i
  input_video
  -i logoImage -filter_complex "[0:v]scale=trunc(iw/2)*2:trunc(ih/2)*2[even] ;[1:v][even]scale2ref=iw*0.25 :(iw*0.25)*(0.46446702)[2nd][ref] ;[ref][2nd]overlay=(main_w-overlay_w) :(main_h-overlay_h)"
  -c:v libx264 -b:v 300K -crf 28 -preset slow outputVideo

  But this command never completes even on using -timelimit flag at times for some videos.

  I have observed that for such processes output from ps aux|grep ffmpeg yeilds in something like :

  ubuntu 16620 0.6 6.7 1595044 515392 ? Sl Dec20 12:05
  ffmpeg -timelimit 900 -y -i
  input_video
  -i logoImage -filter_complex "[0:v]scale=trunc(iw/2)*2:trunc(ih/2)*2[even] ;[1:v][even]scale2ref=iw*0.25 :(iw*0.25)*(0.46446702)[2nd][ref] ;[ref][2nd]overlay=(main_w-overlay_w) :(main_h-overlay_h)"
  -c:v libx264 -b:v 300K -crf 28 -preset slow outputVideo

  It indicates that this process is in interruptible sleep state i.e. waiting for an event to complete. On using sudo strace -p 16620 to trace which system call is this process hung up on it results in something like :

  Process 16620 attached write(2, "frame= 4121 fps= 10 q=33.0 size="...,
  99

  i.e. it’s stuck writing to a file.

  What could be the reason for this problem ?
  And is there any other way to kill FFMPEG process which overshoots desired time limit ?