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• How do I use ffmpeg to deliver the video

  19 juin 2014, par user3750991

  Our destination :

  We want to install camera on our device of arm architecture with capture real-time video and send them to ffserver, then we can watch this video from h ttp ://172.16.51.29:8090/stat.html on the other computer in the same time.

  Device IP address : 172.16.51.29
  computer IP address : 172.16.51.26

  1 I start the server on device

  ffserver -f /etc/ffserver.conf

  2 Camera start to capture video on device

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 h ttp ://127.0.0.1:8090/cam1.ffm

  3 I got the messages

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

  4 Test

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 cam1.asf

  Command above is perfect to produce video named cam1.asf

  5 Fix incorrect parameters such as bit_rate, rate, width or height

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 -b 100k h ttp ://127.0.0.1:8090/cam1.ffm

  But use the command above produce the message presented below

  Input #0, video4linux2, from ’/dev/video0’ :
  Duration : N/A, start : 24300.069612, bitrate : 36864 kb/s
  Stream #0.0 : Video : rawvideo, yuyv422, 320x240, 36864 kb/s, 30 tbr, 1000k tbn, 30 tbc
  Sat Jan 1 07:09:07 2000 127.0.0.1 - - [GET] "/cam1.ffm HTTP/1.1" 200 4149
  [buffer @ 0x2f1a0] w:320 h:240 pixfmt:yuyv422
  [avsink @ 0x2f7e0] auto-inserting filter ’auto-inserted scaler 0’ between the filter ’src’ and the filter ’out’
  [scale @ 0x2ea60] w:320 h:240 fmt:yuyv422 -> w:320 h:240 fmt:yuv420p flags:0x4
  Sat Jan 1 07:09:07 2000 127.0.0.1 - - [POST] "/cam1.ffm HTTP/1.1" 200 0
  Segmentation fault

  What should I do to fix this issue ? Thanks.

• Compiling FFMpeg libraries for Visual Studio

  20 janvier 2015, par LostBoy

  I’m trying to use the FFMpeg libraries in a Windows application. I use MingW-w64 to compile FFMpeg with static libraries with architecture once with x86 and once with x86_64.
  Currently I’m trying to link the 32bit x86 libraries with my VS2008 application.
  The libraries are added to the library path and VS does not complain about being unable to load a .a file.

  However I get several uneresolved symbol errors like
  ait_rtp_receiver.lib(ait_decoder_lib.obj) : error LNK2001 : unresolved external symbol _av_free

  I import the FFMpeg header files as extern C and I can see the symbols in the .a without the leading underscore.
  What can I do to make the name decoration of Mingw-w64’s gcc and of the VS compiler suite compatible ?

• arm : Detect 32 bit cpu features on ARMv8 when running on a 64 bit kernel

  23 juin 2014, par Martin Storsjö

  arm : Detect 32 bit cpu features on ARMv8 when running on a 64 bit kernel
  When running on a 64 bit kernel, /proc/cpuinfo lists different
  
  optional features than on 32 bit kernels (because some of them
  
  are mandatory in the 64 bit implemenations).
  The kernel does list the old features properly if they are queried
  
  via /proc/self/auxv though - however this file is not always readable
  
  (e.g. on most android systems). The getauxval function could also
  
  provide the same info as /proc/self/auxv even if this file isn’t
  
  readable, but this function is not always available (and thus would
  
  need to be loaded with dlsym for compatibility with older android
  
  versions).
  The android cpufeatures library does this slightly differently,
  
  by assuming that these are available if the "CPU architecture"
  
  line is >= 8, see [1] for details.
  It has been suggested to include the old, non-optional features in
  
  /proc/cpuinfo as well, but that suggested patch never was merged.
  
  See [2] for the discussion around this suggestion.
  [1] https://android-review.googlesource.com/91380
  
  [2] http://marc.info/?l=linux-arm-kernel&m=139087240101974
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavutil/arm/cpu.c