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• Encoding QImage frames to video

  4 avril 2016, par keiivee

  Currently I can grab QImage frames from frames rendered using OpenGL. I am wanting to encode the QImage frames to video using ffmpeg and eventually stream this to a different machine in the network using live555 and display it on that machine with Qt window.

  I have found a wrapper qtffmpegwrapper, but this is no longer supported and has not been updated for 3 years that I can't even get the example program to compile.

• How to encode H.264 video using FFmpeg C API and then open the output with a media player ?

  4 avril 2016, par GummiB

  I'm trying to encode a H.264 video with the FFMPEG C API. I have successfully compiled and executed the decoding/encoding example provided by FFMPEG.

  The problem I'm facing is that the .mpg file (encoded with AV_CODEC_ID_MPEG1VIDEO) the example creates works. Windows creates a thumbnail and everything. On the other hand the .h264 (encoded with AV_CODEC_ID_H264) file does not. When I try to play the file in VLC the play/pause button just flickers, no thumbnail in windows, no nothing.

  During encoding libx264 reports the following:

  [libx264 @ 004b81a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  [libx264 @ 004b81a0] profile High, level 1.3
  [libx264 @ 004b81a0] frame I:3     Avg QP:26.79  size:  2116
  [libx264 @ 004b81a0] frame P:12    Avg QP:26.60  size:   789
  [libx264 @ 004b81a0] frame B:10    Avg QP:31.39  size:   499
  [libx264 @ 004b81a0] consecutive B-frames: 20.0% 80.0%
  [libx264 @ 004b81a0] mb I  I16..4: 78.3% 11.6% 10.1%
  [libx264 @ 004b81a0] mb P  I16..4: 77.4%  0.6%  0.1%  P16..4: 20.3%  0.7%  0.9%  0.0%  0.0%    skip: 0.0%
  [libx264 @ 004b81a0] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  9.4%  0.2%  0.0%  direct:11.0%  skip:79.4%  L0:25.4% L1:35.4% BI:39.2%
  [libx264 @ 004b81a0] final ratefactor: 17.03
  [libx264 @ 004b81a0] 8x8 transform intra:3.4% inter:31.3%
  [libx264 @ 004b81a0] direct mvs  spatial:0.0% temporal:100.0%
  [libx264 @ 004b81a0] coded y,uvDC,uvAC intra: 4.4% 35.8% 1.6% inter: 1.3% 34.5% 9.5%
  [libx264 @ 004b81a0] i16 v,h,dc,p:  0%  0%  0% 100%
  [libx264 @ 004b81a0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  7% 20% 17% 49%  0%  0%  0%  1%  6%
  [libx264 @ 004b81a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 14%  7% 18% 45%  2%  7%  2%  3%  2%
  [libx264 @ 004b81a0] i8c dc,h,v,p:  2%  6%  4% 88%
  [libx264 @ 004b81a0] Weighted P-Frames: Y:0.0% UV:0.0%
  [libx264 @ 004b81a0] ref P L0: 95.6%  1.6%  2.2%  0.5%  0.2%
  [libx264 @ 004b81a0] ref B L0: 67.5% 28.5%  3.2%  0.8%
  [libx264 @ 004b81a0] kb/s:166.45
  

  "ffprobe.exe test.h264 -show_streams" returns

  [STREAM]
  index=0
  codec_name=h264
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  profile=High
  codec_type=video
  codec_time_base=1/50
  codec_tag_string=[0][0][0][0]
  codec_tag=0x0000
  width=352
  height=288
  has_b_frames=1
  sample_aspect_ratio=0:1
  display_aspect_ratio=0:1
  pix_fmt=yuv420p
  level=13
  timecode=N/A
  id=N/A
  r_frame_rate=50/2
  avg_frame_rate=25/1
  time_base=1/1200000
  start_pts=N/A
  start_time=N/A
  duration_ts=N/A
  duration=N/A
  bit_rate=N/A
  nb_frames=N/A
  nb_read_frames=N/A
  nb_read_packets=N/A
  DISPOSITION:default=0
  DISPOSITION:dub=0
  DISPOSITION:original=0
  DISPOSITION:comment=0
  DISPOSITION:lyrics=0
  DISPOSITION:karaoke=0
  DISPOSITION:forced=0
  DISPOSITION:hearing_impaired=0
  DISPOSITION:visual_impaired=0
  DISPOSITION:clean_effects=0
  DISPOSITION:attached_pic=0
  [/STREAM]
  

  There you can see:

  start_time=N/A
  duration_ts=N/A
  duration=N/A
  

  I have tried countless changes to the AVCodecContext and multitude of parameters options to av_opt_set function. Still no luck getting a working H.264 video. I have even tried different builds of FFmpeg. No luck.

  I'm using the "FFmpeg git-0fb64da 32-bit Dev" build from Zeranoe and MinGw 4.7.2

• Unable to convert audio file format in php using shell commands

  4 avril 2016, par Sajeev C

  I'm trying to convert the uploaded audio file to .mp3 format using PHP. ffmpeg is enabled in my server.

  I try to execute shell commands, but it does not convert the file format of the audio file. exec() and shell_exec() are both enabled.

  <?php 
      $uploadpath = realpath('./') . '/musicfolder/';
  
      $filedata = $_FILES['filedata']['tmp_name'];
      $filename = $_POST['filename'];
      if ($filedata != '' && $filename != ''){
  
  
          list($name,$ext) = explode('.',$filename);
          $file_mp3=$name.".mp3";
          $file_wav=$name.".wav";
          shell_exec(' ffmpeg -i '.$filename.' -ac 1 -ab 16000 -ar 8000 '.$file_mp3.'');
  
  
  
          if($can_create){
              copy($filedata,$uploadpath.$filename);
              echo "-file_update_successful-";
          }
  
      }
  
  
  ?>
  

  I don't understand where I made mistake. Can I achieve this using system()?

• How to get keyframes of video ffmpeg for videos created by Red5 ?

  4 avril 2016, par akash777.sharma

  I had a task of getting keyframes information of a video i.e. getting time duration of all keyframes(seeking video via rtmp url). To get information of all the frames of video use following command:

  ffprobe -show_frames testVideo.mp4 > data.txt
  

  The information I get from data.txt file :

  “keyframe=1” signifies that it tried to make keyframe
  “pict_type=I” signifies a keyframe or I-frame
  here I get exact time duration of keyframe.
  

  actual fps of video

  fps = coded_picture_number(last frame that contains coded_picture_number) / pkt_pts_time
  

  Above information worked well for most of the videos.But for some videos that were created by Red5 were showing abnormal results. List of urls I have searched
  http://sinclairmediatech.com/using-ffprobe-to-evaluate-keyframes/
  http://ffmpeg-users.933282.n4.nabble.com/How-can-I-find-the-keyframe-information-for-a-mp4-video-td4349687.html

  please help if I am wrong or need any other command. Thanks in advance.

• Concat gives flickering result

  4 avril 2016, par Robin Castlin

  I really don't get this; I use ffmpeg concat one 2 files and the audio is concated well, but the videos aren't. The second video causes freeze/flicker/green screen instead.

  'ffmpeg -y -f concat -i concat.txt -c:v libx264 -pix_fmt yuv420p -c:a copy output.mkv

  Comparing the files, I have made them as identical as possible:

  • input.mkv1
    Video: MPEG4 Video (H264) 1280x720 60fps [V: h264 main L4.1, yuv420p, 1280x720 [default]] Audio: AAC 48000Hz stereo [A: aac, 48000 Hz, stereo [default]]
  • input2.mkv
    Video: MPEG4 Video (H264) 1280x720 60fps [V: English [eng] (h264 main L4.1, yuv420p, 1280x720) [default]] Audio: AAC 48000Hz stereo [A: English [eng] (aac, 48000 Hz, stereo) [default]]

  What could cause this behavior?