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• Multicast video captured via VLC show a gray background for first 1/2 second

  28 juillet 2014, par DavidG

  I am capturing multicast video using VLC.exe and performing some processing/converting using FFmpeg.exe. The resulting video starts with a gray background with some of the moving objects moving through the gray background. This seems to me that the video is not starting on an I-Frame, but on a B-Frame or a P-Frame. However, when I run ffprobe, it states the first frame is a key frame. After about 1/2 second, the video plays fine.

  Here is the command I’m using to capture the video :

  vlc.exe -I curses --run-time=10 "my.sdp" --sout=video.mp4

  I’m not using anything special when I convert to an mp4 file using FFmpeg :

  ffmpeg.exe -i video.mp4 -s 400x300 final.mp4

  I tried to post an image of the first frame or two, but Stackoverflow gave me an error stating I need at least 10 reputation to post images. Sorry about that, an image would have helped.

  I ran the command "ffprobe show_frames " and it looks like the first frame is a key frame. Of course I’m new to all this and I don’t know what I’m doing or seeing.

  Here is beginning of the output to the "ffprobe show_frames " command :

  [FRAME]
  
  media_type=video
  
  key_frame=1
  
  pkt_pts=0
  
  pkt_pts_time=0.000000
  
  pkt_dts=0
  
  pkt_dts_time=0.000000
  
  pkt_duration=1001
  
  pkt_duration_time=0.033367
  
  pkt_pos=48
  
  pkt_size=756
  
  width=400
  
  height=300
  
  pix_fmt=yuv420p
  
  sample_aspect_ratio=1:1
  
  pict_type=I
  
  coded_picture_number=0
  
  display_picture_number=0
  
  interlaced_frame=0
  
  top_field_first=0
  
  repeat_pict=0
  
  reference=3
  
  [/FRAME]

  Is there any way to either tell VLC.exe to start capturing on an I-Frame (This would be the best solution as I specify a duration to capture the video) or is there a way to tell FFmpeg.exe to start converting the input video starting at the first I-Frame encountered ?

  Thanks,
   David

• How can I show that a frame has been duplicated to extend the video framerate using ffprobe ?

  14 juillet 2023, par Brandon J

  As the title suggests I have a video.mp4 which I know visually has been extended from 5fps to 20fps. I know this because there are 256 frames and when I run ffprobe it reports 20fps and the video is 12.8 sec long. I also run

  


  ffprobe -v 0 -select_streams v -show_entries stream=duration_ts,time_base,nb_frames video.mp4

  


  reports to me 256 frames, 1/20 timebase adn 256 duration. This matches the expected 12.8 s duration. When I manually sort through the extracted frames I can see the frames have been held for 4 ticks. So it should be 5fps.

  


  I then run the below to view the packets and the frames (cmd not typed)

  


  ffprobe -show_packets -select_streams v:0 video.mp4

  


  and the packets or frames don't seem to give me a huge indication that the frames have been duplicated.

  


  With the -show_packets cmd the only possible indication of duplication I can see is that every 0.2 seconds, (consistent with 5fps) the size of the packets go from a consistent 150-300 size to around 16000 or so. Is there a way I can better articulate what I am seeing with the packet size change ? Why has their compression or encoder (forgive any error in verbiage) decided to duplicate frames to achieve 20fps vs extending the pts to 0.2 seconds for each packet ? It seems like simply defining a longer pts would reduce overall file size anyways ?

  


  All that said, is there something within ffprobe or other tool I can use to more efficiently confirm what I am visually seeing to say yep these frames were just duplicated from another program ? Thanks !

  


• How to show a watermark for 3 second on a MP4 using FFmpeg

  6 février 2014, par b1izzard

  I need to add a 3-second watermark to a Camera recorded video in Android. I'm using FFmpeg static build to execute the commands.

  Approach I

  I had tried the below command using latest version of FFmpeg(version N-60108-gda25a65) in my Desktop running Linux Mint, the command works fine.

  ffmpeg -y -itsoffset 3 -i input.mp4 -i myImage.jpg -filter_complex "[0:v][1:v]overlay=0:0:enable=between(t\,0\,3)"  -codec:a copy output.mp4

  In Android I'm using the FFmpegv1.2 with below config to execute the command.

   *******Starting FFMPEG
  
      ***ffmpeg version 1.2 Copyright (c) 2000-2013 the FFmpeg developers***
  
      ***  built on Mar 31 2013 23:44:57 with gcc 4.6 (GCC) 20120106 (prerelease)***
  
      ***  configuration: --arch=arm --target-os=linux --enable-runtime-cpudetect --enable-pic --disable-shared --enable-static --cross-prefix=/opt/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi- --sysroot=/opt/android-ndk-r8e/platforms/android-8/arch-arm --extra-cflags='-march=armv6' --extra-ldflags= --enable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-network***
  
      ***  libavutil      52. 18.100 / 52. 18.100***
  
      ***  libavcodec     54. 92.100 / 54. 92.100***
  
      ***  libavformat    54. 63.104 / 54. 63.104***
  
      ***  libavdevice    54.  3.103 / 54.  3.103***
  
      ***  libavfilter     3. 42.103 /  3. 42.103***
  
      ***  libswscale      2.  2.100 /  2.  2.100***
  
      ***  libswresample   0. 17.102 /  0. 17.102***

  Java Code to run the FFmpeg command :

  String[] ffmpegCommandToAddWatermark = { 
  
              mFfmpegInstallPath, "-y", "-itsoffset","3",
  
               "-i", INPUT_VIDEO_PATH, "-i", WATERMARK_IMAGE_PATH,
  
               "-filter_complex","[0:v][1:v]overlay=0:0:between(t\\,0\\,3)",
  
               "-strict","-2",
  
               "-codec:a","copy",OUTPUT_VIDEO_PATH};          
  
          try {
  
          Process ffmpegProcess = new ProcessBuilder(ffmpegCommandToAddWatermark)
  
              .redirectErrorStream(true).start();
  
  
  
          String line;
  
  
  
          BufferedReader reader = new BufferedReader(
  
              new InputStreamReader(ffmpegProcess.getInputStream()));
  
          Log.d(TAG, "*******Starting FFMPEG");
  
          while ((line = reader.readLine()) != null ) {
  
  
  
              Log.d(TAG, "***" + line + "***");
  
          }
  
          Log.d(null, "****ending FFMPEG****");
  
  
  
          } catch (Exception e) {
  
          e.printStackTrace();
  
          }

  The command execution failed with following error :

  ***[overlay @ 0x271f770] No option name near 'between(t,0,3)'***
  
  ***[AVFilterGraph @ 0x2711530] Error initializing filter 'overlay' with args '0:0:between(t,0,3)'***
  
  ***Error configuring filters.***

  The same command executes successfully when :enable=between(t\,0\,3) is removed, but the resulting output video has the watermark throughout the timeline, but I need watermark only for the starting 3 seconds.

  Approach II :

  I tried to convert WaterMarkImage to WaterMarkVideo

  ffmpeg -y -loop 1 -r 30 -i WaterMarkImage.jpg -b:v "4096k" -vf "scale=640:480" -t 3 WaterMarkVideo.mp4

  And then merge the WaterMarkVideo.mp4+CameraRecordedVideo.mp4 using the concat command :

  ffmpeg -y -f concat -i inputs.txt -c copy output.mp4

  The resulting output is corrupt due to BitRate,FrameRate,etc., mismatch. Any idea to solve the problem ?.