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• How is video decoding corruption debugged ?

  20 novembre 2013, par TopGunCoder

  I just started working for a new company and my new role demands that I help debug the video corruption that they are receiving through decoding frames. As much as I intend on digging down deep into the code and looking into the specifics of my problem, it made me think about video debugging in general.

  Since handling videos is very new to me, the whole process seems pretty complex and it seems there are a lot of places for corruption to present itself. The way I see it there is at least three places where corruption could pop up (barring memory corruption from the machine) :

  • Transporting the data before it is decoded
  • decoding implementation that perpetuates corruption once it is encountered, or is all together incorrect (Which seems to be my problem)
  • Transportation to the monitor(which seems unlikely but possible)

  So what i'm really curious about is if/how people debug their video streams to determine the location of any potential corruption they are encountering. I'm sure there is no sure fire method but I am curious to see what problems are even possible and how they can be identified and triaged.

  P.S. - I'm not sure of the differences between different decoding methods but, if this question seems too vague maybe it helps to mention I am using ffmpeg and avcodec_decode_video2 for the decoding.

• ffmpeg error while converting to mp4 Error while opening encoder for output stream #0.0

  20 mars 2016, par Josh

  I am trying to convert various file types to mp4 to be displayed using ffmpeg, but i keep getting the error :

  Error while opening encoder for output stream #0.0 - maybe incorrect parameters such as bit_rate, rate, width or height

  Another piece that looks important is :

  [libx264 @ 0x93caef0] broken ffmpeg default settings detected

  [libx264 @ 0x93caef0] use an encoding preset (e.g. -vpre medium)

  [libx264 @ 0x93caef0] preset usage : -vpre -vpre

  [libx264 @ 0x93caef0] speed presets are listed in x264 —help

  [libx264 @ 0x93caef0] profile is optional ; x264 defaults to high

  The latest code I am running is :

  ffmpeg -i source -s 320x240 -r 30000/1001 -b 200k -bt 240k -vcodec libx264 -coder 0 -bf 0 -refs 1 -flags2 -wpred-dct8x8 -level 30 -maxrate 10M -bufsize 10M -acodec libfaac -ac 2 -ar 48000 -ab 192k destination

  I have seen a few other people with this issue, but their fixes didn’t work for some reason.

  In case it matters : ultimately this will be used in php, though I am trying to get it working first via putty

  EDIT: : Here is the full thing as requested(using a wmv, have tested wmv and flv) :

       ~ >> ffmpeg -i path.wmv -s 320x240 -r 30000/1001 -b 200k -r 29.97 -bt 240k -vcodec libx264 -coder 0 -bf 0 -refs 1 -flags2 -wpred-dct8x8 -level 30 -maxrate 10M -bufsize 10M -acodec libfaac -ac 2 -ar 48000 -ab 192k path.mp4
  
  FFmpeg version SVN-r26076, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Aug 28 2012 17:55:47 with gcc 4.1.2 20080704 (Red Hat 4.1.2-52)
  
    configuration: --enable-version3 --enable-gpl --enable-nonfree --enable-shared --enable-postproc --enable-avfilter --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvpx --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --disable-ffplay --disable-indevs --disable-outdevs --disable-demuxer=v4l --disable-demuxer=v4l2 --disable-mmx
  
    libavutil     50.36. 0 / 50.36. 0
  
    libavcore      0.16. 1 /  0.16. 1
  
    libavcodec    52.108. 0 / 52.108. 0
  
    libavformat   52.93. 0 / 52.93. 0
  
    libavdevice   52. 2. 3 / 52. 2. 3
  
    libavfilter    1.74. 0 /  1.74. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  
  
  Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 29.97 (30000/1001)
  
  Input #0, asf, from 'path.wmv':
  
    Metadata:
  
      SfOriginalFPS   : 299
  
      WMFSDKVersion   : 11.0.6001.7000
  
      WMFSDKNeeded    : 0.0.0.0000
  
      IsVBR           : 0
  
      title           : Wildlife in HD
  
      artist          :
  
      copyright       : © 2008 Microsoft Corporation
  
      comment         : Footage: Small World Productions, Inc; Tourism New Zealand | Producer: Gary F. Spradling | Music: Steve Ball
  
    Duration: 00:00:30.09, start: 8.000000, bitrate: 6977 kb/s
  
      Stream #0.0(eng): Audio: wmav2, 44100 Hz, 2 channels, s16, 192 kb/s
  
      Stream #0.1(eng): Video: vc1, yuv420p, 1280x720, 5942 kb/s, 29.97 tbr, 1k tbn, 1k tbc
  
  File 'path.mp4' already exists. Overwrite ? [y/N] y
  
  [buffer @ 0x9ce9eb0] w:1280 h:720 pixfmt:yuv420p
  
  [scale @ 0x9ce8f70] w:1280 h:720 fmt:yuv420p -> w:320 h:240 fmt:yuv420p flags:0x4
  
  [libx264 @ 0x9ce9ef0] broken ffmpeg default settings detected
  
  [libx264 @ 0x9ce9ef0] use an encoding preset (e.g. -vpre medium)
  
  [libx264 @ 0x9ce9ef0] preset usage: -vpre <speed> -vpre <profile>
  
  [libx264 @ 0x9ce9ef0] speed presets are listed in x264 --help
  
  [libx264 @ 0x9ce9ef0] profile is optional; x264 defaults to high
  
  Output #0, mp4, to 'path.mp4':
  
      Stream #0.0(eng): Video: libx264, yuv420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 29.97 tbc
  
      Stream #0.1(eng): Audio: libfaac, 48000 Hz, 2 channels, s16, 192 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
    Stream #0.0 -> #0.1
  
  Error while opening encoder for output stream #0.0 - maybe incorrect parameters such as bit_rate, rate, width or height
  
  </profile></speed>

  Thanks for any help

• Working way to make video from images in C#

  26 octobre 2013, par Jim Mischel

  Does anybody have a known reliable way to create a video from a series of image files ? Before you mod me down for not searching for the answer before posting the question, and before you fire off a simple message like "use FFMPEG," read the rest of this message.

  I'm trying to create a video, it doesn't matter too much what format as long as it's widely supported, from a series of images (.jpg, .bmp, etc.). My platform is Windows Server 2008, 64-bit. If I can make the video from within my C# program, that's great, but I'm not averse to writing a series of image files to a directory and then firing off an external program to make a video from those images.

  The only constraints are : it must work on my Windows Server 2008 system, and be scriptable. That is, no GUI programs that require operator intervention.

  I found a number of similar questions on StackOverflow, and have tried several of the solutions, all with varying degrees of frustration and none with anything like success.

  FFMPEG looks like a great program. Maybe it is, on Linux. The two Windows builds I downloaded are broken. Given this command line :

    ffmpeg -r 1 -f image2 -i jpeg\*.jpg video.avi

  One of the builds reads the images and then crashes due to data execution prevention. The other reads the first file and then spits out an error message that says "cannot find suitable codec for file jpeg/image2.jpg". Helpful, that. In any case, FFMPEG looks like a non-starter under Windows.

  One answer to a previous posting recommended Splicer . It looks like pretty good code. I compiled the samples and tried to run, but got some cryptic error message about a file not found. It looks like a COM class isn't registered. I suppose I need to install something (DirectShow, maybe, although I thought that was already installed ?). Depending on what's required, I might have a difficult time justifying its installation on a server. ("What ? Why do you need that on a server ?")

  Another answer suggested the AviFile library from Code Project. That looks simple enough : a wrapper around the Windows AviFile subsystem. Except that the AVI files the package creates appear to have all of the frames, but only the first frame shows when I play the AVI in Windows Media Player. Well, that and if you try to create a compressed video, the program throws an exception.

  So, I'm left wondering if there is a good, reliable way to do what I want : on a Windows system, create an AVI or other common video file format from a series of images, either through a .NET API or using an external program. Any help ?