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• Revision 5d2f6baac3 : thumb : Adjust the conversion of the position independent switch This is require

  15 mai 2013, par Martin Storsjo

  Changed Paths :
   Modify /build/make/thumb.pm

  
  
  thumb : Adjust the conversion of the position independent switch

  This is required since the microsoft assembler claims that
  add.w r12, pc, #10
  generated unpredictable behaviour.

  Change-Id : Ia8e1830def965c88ca4e2f48a24107bac6a4cb9d

• Need help on handling MPEG4V1 data

  14 septembre 2011, par Gediminas

  I'm in situation where I need to get a chunk of MPEG4V1 (Microsoft MPEG-4 VKI
  Codec V1) data located in the beginning of a packet (that was sent by some DVR unit).

  Packet structure looks something like this :

  • Compressed MPEG4 data.
  • Long integer - Number of events and tripwires.
  • Long integer - Number of events.
  • Event - Event's sequence.
  • Long integer - Number of tripwires.
  • Tripwire - Tripwires sequence.
  • Long integer - Cyclical redundant code (CRC).

  So there is no indication of how to know where does the MPEG4 data ends (Or is there ?),
  and from where should I start reading this additional data like "Number of events and tripwires" and etc...

  I uploaded two packet's so you could see how the actual data looks like :
  recvData1.txt,
  recvData2.txt.

  I've tried to decode those packets using FFmpeg library with avcodec_decode_video function and by removing byte by byte from the end of my recvData buffer in a hope for any results,
  but FFmpeg just allways returned with an error messages like this :

  "[msmpeg4v1 @ 038865a0] invalid startcode",
  "[msmpeg4v1 @ 038865a0] header damaged".

  I'm not that good specialist on knowing of how does the MPEG4 works from the inside,
  but judging by the error messages it's clearly seen that I'm missing some data for decoding at the start of the buffer.

  So I'm not sure of what part / kind of MPEG data I'm getting here..
  Maybe it's some kind of MPEG's "frame" data with it's "end" indication or something ?

  I've even compared the start of my recvData buffer to some of MPEG4V1 encoded video files I found on the net "http://www.trekmania.net/clips/video_clips4.htm" to check if the start of my buffer really contains the MPEG data ..and not some kind of DVR vendor specific stuff..

  And I noticed that there are about 20bytes of data
  (at the start of my packet data, and in .avi files right after about 180bytes..)
  that looks like some kind of header or something..

  Please check this image : "http://ggodis.gamedev.lt/stackOverflow/recvData.jpg"

  Maybe someone knows what this part of MPEG4V1 data represents ?

  P.S. ..I've checked the CRC values for my received packets and they were correct..

• .mov conversion to .mp4 using ffmpeg doesn't convert the entire video

  5 février 2013, par user504879

  I am trying to convert a mov file which I got from saving my powerpoint presentation to a movie file. However only a part of the presentation is converted not the entire one and also running qt-start doesn't make the exported mp4 to stream over rtmp. Is there something which I am missing ?

  I am attaching the output which i get when I am trying to convert the file using ffmpeg

  $ export LD_LIBRARY_PATH=/usr/local/lib; /usr/local/bin/ffmpeg -y -i /data/tmp/vialogues_prez.mov -r 20 -g 40 -acodec libfaac -ar 44100  -ab 96k -vcodec libx264 -s 640x480 -vpre medium /data/videos/vialogues_prez.mp4
  
  
  
  FFmpeg version 0.6.1, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Feb 19 2011 19:03:56 with gcc 4.4.5
  
    configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x186f460]max_analyze_duration reached
  
  
  
  Seems stream 0 codec frame rate differs from container frame rate: 600.00 (600/1) -> 0.08 (1/12)
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/data/tmp/vialogues_prez.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      comment         : Microsoft PowerPoint Movie
  
      comment-eng     : Microsoft PowerPoint Movie
  
    Duration: 00:04:47.00, start: 0.000000, bitrate: 22 kb/s
  
      Stream #0.0(eng): Video: qtrle, bgra, 640x480, 21 kb/s, 0.01 fps, 0.08 tbr, 600 tbn, 600 tbc
  
      Stream #0.1(eng): Video: 0x0000, 600 tbr, 600 tbn, 600 tbc
  
      Stream #0.2(eng): Video: 0x0000, 600 tbr, 600 tbn, 600 tbc
  
  [libx264 @ 0x1873b50]using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
  
  [libx264 @ 0x1873b50]profile High, level 3.0
  
  [libx264 @ 0x1873b50]264 - core 114 - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=200 ratetol=20.0 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.41 aq=1:1.00
  
  Output #0, mp4, to '/data/videos/vialogues_prez.mp4':
  
    Metadata:
  
      encoder         : Lavf52.64.2
  
      Stream #0.0(eng): Video: libx264, yuv420p, 640x480, q=10-51, 200 kb/s, 20 tbn, 20 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  frame=    4 fps=  0 q=32766.0 Lsize=      50kB time=45.05 bitrate=   9.0kbits/s    
  
  video:49kB audio:0kB global headers:0kB muxing overhead 1.740573%
  
  [libx264 @ 0x1873b50]frame I:1     Avg QP:32.73  size:  8427
  
  [libx264 @ 0x1873b50]frame P:3     Avg QP:20.68  size: 13640
  
  [libx264 @ 0x1873b50]mb I  I16..4: 60.8% 14.6% 24.7%
  
  [libx264 @ 0x1873b50]mb P  I16..4: 28.7%  7.2% 15.4%  P16..4:  2.0%  1.3%  1.4%  0.0%  0.0%    skip:43.9%
  
  [libx264 @ 0x1873b50]final ratefactor: -16.67
  
  [libx264 @ 0x1873b50]8x8 transform intra:14.2% inter:5.0%
  
  [libx264 @ 0x1873b50]coded y,uvDC,uvAC intra: 25.2% 18.4% 13.0% inter: 5.3% 7.4% 7.2%
  
  [libx264 @ 0x1873b50]i16 v,h,dc,p: 63% 34%  1%  2%
  
  [libx264 @ 0x1873b50]i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 41% 31%  1%  1%  1%  1%  1%  4%
  
  [libx264 @ 0x1873b50]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 29% 33% 19%  2%  3%  3%  4%  3%  4%
  
  [libx264 @ 0x1873b50]i8c dc,h,v,p: 75% 20%  4%  1%
  
  [libx264 @ 0x1873b50]Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 0x1873b50]ref P L0: 57.0% 12.2% 26.2%  4.7%
  
  [libx264 @ 0x1873b50]kb/s:1.14

  any help is appreciated.