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• FFMpeg Android Stagefright SIGSEGV error (h264 decode)

  19 avril 2013, par Sergey Ochkur

  I need to decode h264 file to YUV on Android 2.3+. As I understand I need to communicate with Stagefright, as it`s the only way now, after closing access with OpenMAX IL implementations. I have used FFmpeg 0.10 (and tried 0.9/0.9.1..) for this issue, compiled it with NDK7 (and also tried NDK6b with the same result) :

    ffmpeg version 0.10 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Jan 28 2012 14:42:37 with gcc 4.4.3
  
    configuration: --target-os=linux --cross-prefix=arm-linux-androideabi- --arch=arm --cpu=armv7-a --sysroot=/home/grid/Android/Android_NDK/platforms/android-9/arch-arm --disable-avdevice --disable-decoder=h264 --disable-decoder=h264_vdpau --enable-libstagefright-h264 --prefix=build/stagefright/armeabi-v7a --extra-cflags='-Iandroid-source/frameworks/base/include -Iandroid-source/system/core/include -Iandroid-source/frameworks/base/media/libstagefright -Iandroid-source/frameworks/base/include/media/stagefright/openmax -I/home/grid/Android/Android_NDK/sources/cxx-stl/system/include -march=armv7-a -mfloat-abi=softfp -mfpu=neon' --extra-ldflags='-Wl,--fix-cortex-a8 -Landroid-libs -Wl,-rpath-link,android-libs' --extra-cxxflags='-Wno-multichar -fno-exceptions -fno-rtti'
  
    libavutil      51. 34.101 / 51. 34.101
  
    libavcodec     53. 60.100 / 53. 60.100
  
    libavformat    53. 31.100 / 53. 31.100
  
    libavfilter     2. 60.100 /  2. 60.100
  
    libswscale      2.  1.100 /  2.  1.100
  
    libswresample   0.  6.100 /  0.  6.100
  
  Hyper fast Audio and Video encoder
  
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

  Hardware : Beagleboard-Xm + TI Android 2.3 (official)

  So, entering next command give me error with 480p :
  ffmpeg -i /sdcard/Video/480p.mp4

  Stopped (signal) ffmpeg -i /sdcard/Video/480p.mp4

  Full Android "answer" from ADB Logcat :
  http://pastebin.com/76JLgtXX

  Android-developers, does anybody know what this error means and how to deal with it ?
  I tried to make DSP window bigger, but with no luck.
  Commands like "stagefright /sdcard/Video/480p.mp4" works fine.

  P.S. Additionally I found that on some bigger files (720p) Android answers next :

  [libstagefright_h264 @ 0xd479b0] Decode failed : 80000000

• How to change stream metadata with ffmpeg ?

  13 juillet 2012, par Igor Grinfeld

  I have many video files and part of it have wrong size, or at least ffmpeg reports wrong size.
  For example, ffmpeg prints :

   Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isom
  
      creation_time   : 2009-10-11 15:04:33
  
      encoder         : HandBrake 0.9.3 2008112300
  
   Duration: 01:47:42.18, start: 0.000000, bitrate: 663 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x464 [
  
  SAR 43:36 DAR 215:116], 499 kb/s, 25 fps, 25 tbr, 48k tbn, 50 tbc
  
   Metadata:
  
      creation_time   : 2009-10-11 15:04:33
  
      handler_name    :
  
   Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, s16, 159
  
  kb/s
  
   Metadata:
  
       creation_time   : 2009-10-11 15:04:33
  
       handler_name    :

  However, when I configure media player to play the file without resizing it has 860x464 size.

  I want to write scripts that will fix the files, but I don't know how to do that. I've updated to last ffmpeg version and tried to use -metadata:s:v:0 Video="...860x464...", as I read in ffmpegh doc, but it doesn't work.
  What is my mistake ?

• YouTube's HD Video Streaming Server Technology ?

  30 septembre 2013, par bgentry

  Lately I've been researching different methods for streaming MP4s to the browser. Flash Media Server is an obvious choice here (using Cloudfront), and most solutions I've seen use the RTMP protocol.

  However, I spent some time on YouTube with Firebug and Chrome debugger figuring out how their streaming worked and I discovered some interesting differences between some of their videos and quality rates.

  My two sample videos are A and B. A is available up to 480p and B is available up to 1080p. For both videos, all rates up to 480p are served in an FLV container with H.264 video and AAC audio, over HTTP. What's interesting here is that if you have not yet downloaded (cached) the entire video, and you try to skip forward to an uncached part of the video, a new request will be made with a 'begin' parameter equal to the target offset in milliseconds. Example from Video A at 480p :

  http://v11.lscache8.c.youtube.com/videoplayback?ip=0.0.0.0&sparams=id%2Cexpire%2Cip%2Cipbits%2Citag%2Calgorithm%2Cburst%2Cfactor%2Coc%3AU0dWTldQVF9FSkNNNl9PSlhJ&fexp=904806%2C902906%2C903711&algorithm=throttle-factor&itag=35&ipbits=0&burst=40&sver=3&expire=1279756800&key=yt1&signature=D2D704D63C242CF187CAA5B5D5BAFB8DFACAC5FF.39180C01559C976717B651A7EB1D0C6249231EB7&factor=1.25&id=8568eb3135971f6f&begin=111863
  
  
  
  Response Headers:
  
  Cache-Control:public,max-age=23472
  
  Connection:close
  
  Content-Length:14320637
  
  Content-Type:video/x-flv
  
  Date:Wed, 21 Jul 2010 17:23:48 GMT
  
  Expires:Wed, 21 Jul 2010 23:55:00 GMT
  
  Last-Modified:Wed, 19 May 2010 12:31:41 GMT
  
  Server:gvs 1.0
  
  X-Content-Type-Options:nosniff

  The file returned by this URL is a fully valid FLV containing only the portion of the video after the requested offset.

  I did the same kind of test on the higher resolution versions of Video B. At 720p and 1080p, YouTube will return a video in an MP4 container, also with H.264 video and AAC audio. What's impressive to me is that their server takes the same type of offset for an MP4 video (via the 'begin' parameter) and returns a valid, streamable MP4 (moov atom at the front of the file with correct offsets) that also only includes the requested portion of the video.

  So, how does YouTube do this ? How do they generate the FLV or MP4 container on the fly with the correct headers and only the desired segment of the requested video ? I know this can be accomplished using FFMPEG to seek to the desired start point and the qt-faststart script to reposition the moov atom to the front of the stream, but it seems like this would be too slow to handle on-demand for millions of YouTube viewers.

  Ideas ?

  Thanks in advance !

  Footnote : I am not allowed to include more than 1 link at this point, so here is Video A's URL : http:// www.youtube .com/watch ?v=hWjrMTWXH28 "Video available up to 480p"