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• Debugging Video Frame Differences

  14 mai 2014, par jvenema

  I’m trying to decode an h264-encoded video frame using a decoder that has fairly limited capabilities (Broadway JS).

  Here’s the process I’m using for testing :

  1. Encode single image using h264 (output is 62KB) using OpenH264 from Cisco, write to disk
  2. Read file as binary in JS (loaded via XHR)
  3. Decode in JS using Broadway
  4. Display in canvas

  I actually have a functional example of this, but there’s a manual step at the moment between steps 1 and 2 - I have to call FFMPEG to force a small translation, and I can’t figure out why.

  I have successfully integrated Cisco’s Openh264 library into my project, and can encode the image as h264 and write it to disk. I’ve confirmed the encoding itself is valid by using FFMPEG to extract the frame back out as a JPEG (looks perfect).

  But, to make the frame decode properly in JS, I have to do a conversion using FFMPEG. It does some magic, the file size drops to 58KB, and voila, everything starts working.

  The Openh264 libraries only work with the baseline configuration, so I’m assuming I have some other random parameter set incorrectly. Problem is, if I use ffprobe to compare the frames - the settings are identical ! But the file sizes are different, so obviously something is different.

  So now the final question - what tool can I use to truly see what FFMPEG is doing behind the scenes here to make my "manually" encoded frame work ? Is there a tool that will let me compare all the details of two h264 frames ?

• FFMPEG - Scrambled Output converting from VOB with ffmpeg

  24 décembre 2013, par MattD

  I've concatenated a series of VOB files from a DVD into a single VOB file and I am trying to convert it to MP4 or other similar format. I see a lot of errors when converting and the output appears scrambled.

  >ffmpeg.exe" -i file.vob -sameq file.mp4
  
  FFmpeg version git-N-29181-ga304071, Copyright (c) 2000-2011 the FFmpeg develope
  
  rs
  
    built on Apr 18 2011 21:24:03 with gcc 4.5.2
  
    configuration: --enable-gpl --enable-version3 --enable-runtime-cpudetect --ena
  
  ble-memalign-hack --enable-avisynth --enable-bzlib --enable-frei0r --enable-libo
  
  pencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --
  
  enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger
  
   --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enabl
  
  e-libx264 --enable-libxavs --enable-libxvid --enable-zlib --cross-prefix=i686-w6
  
  4-mingw32- --target-os=mingw32 --arch=x86_32 --extra-cflags=-I/home/kyle/softwar
  
  e/ffmpeg/external-libraries/win32/include --extra-ldflags=-L/home/kyle/software/
  
  ffmpeg/external-libraries/win32/lib --pkg-config=pkg-config
  
    libavutil    50. 40. 1 / 50. 40. 1
  
    libavcodec   52.120. 0 / 52.120. 0
  
    libavformat  52.108. 0 / 52.108. 0
  
    libavdevice  52.  4. 0 / 52.  4. 0
  
    libavfilter   1. 79. 0 /  1. 79. 0
  
    libswscale    0. 13. 0 /  0. 13. 0
  
  [mpeg2video @ 01751A90] ac-tex damaged at 5 16
  
  [mpeg2video @ 01751A90] invalid mb type in I Frame at 0 1
  
  [mpeg2video @ 01751A90] invalid mb type in I Frame at 0 2
  
  [mpeg2video @ 01751A90] invalid mb type in I Frame at 0 3
  
  [mpeg2video @ 01751A90] invalid mb type in I Frame at 0 4
  
  
  
  [...]

  I'm guessing this is CSS scrambling and I need to do some sort of DeCSS. Does FFMpeg have an option for this ? Cringe if you'd like, but is there C# source to achieve this ?

  My end goal is really just to get some DVDs that I own onto my media server. I've tried a few demo-ware products with limited success including Acala DVD Ripper, Click to Disk, AVIDemux to name a few. I even paid for a couple of them to get the full version, but Acala only works for about half of my DVDs and Click to Disk can decode the VOB, but I need to use FFMpeg to convert. I'd like to have it all in one app that works and I am willing to write some code for it.

• Saving highest quality video from video-capture card

  23 décembre 2013, par DusteD

  I have a machine with 2x3 3ghz dual-core xeon and 4x10krpm scsi 320 disks in raid0.
  The capture card is an osprey 560 64 bit pci card.
  Operating system is currently Windows Server 2003.

  The video-stream that I can open with VLC using direct show is rather nice quality.
  However, trying to save this video-stream without loss of quality has proven quite difficult,
  using the h264 codec I am able to achieve a satisfying quality, however, all 4 cores jump to 100% load after a few second and then it start dropping frames, the machine is not powerful enough for realtime encoding. I've not been able to achieve satisfying mpeg1 or 4 quality, no matter which bitrate I set..

  Thing is, the disks in this machine are pretty fast even by todays standard, and they are bored.. I don't care about disk-usage, I want quality.
  I have searched in vain for a way to pump that beautiful videostream that I see in VLC onto the disk for later encoding, I reckon the disks would be fast enough, or maybe something which would apply a light compression, enough that the disks can keep up, but not so much as to loose visible quality.

  I have tried FFMPEG as it seems capable of streaming a yuv4 stream down to the disk, but ofcause FFMPEG is unable to open the dshow device ( same error as this guy Ffmpeg streaming from capturing device Osprey 450e fails )

  Please recommend a capable and (preferably) software which can do this.