Recherche avancée

Sur d’autres sites (12421)

• Revision 393a8ccef9 : Remove avoid_frame_with_high_error from RD loop The feature undergoes prior ass

  6 janvier 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_block.h

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Remove avoid_frame_with_high_error from RD loop

  The feature undergoes prior assumption that the recursive partition
  size search from 4x4 to 64x64, hence utilizing information from small
  blocks to determine early termination in large block rate-distortion
  optimization search. The current codebase is now going from top down.
  The previous function might go with not properly initialized values,
  hence removed.

  Tested on pedestrian_area_1080p at 4000 kbps running under speed 2.
  No visible difference in runtime observed.

  Change-Id : I553df415c6191413762db7ae34e8790c71d8118e

• Accurate FFmpeg capture start time

  28 juillet 2016, par Adam

  I’m using ffmpeg from the command line to capture from a webcam to a file using the following :

  ffmpeg -y -rtbufsize 702000k -f dshow -s 320x240 -r 25 -i video="<device>" -t 10 -vcodec mjpeg -q:v 2 out.mp4
  
  </device>

  There is a slight delay between executing the command and the start of the capture ( 0.5 sec).
  I’m trying to find a way to accurately determine the start time (UTC/GMT) of the capture.

  My initial thought was to use the file-creation time as this might accurately reflect when the first frame was encoded (as opposed to when the command was executed). Unfortunately the file creation time is only accurate to the second which is not precise enough (and I’m not sure this would have given an accurate result anyway).

  My next thought was to use ffmpegs timestamp option. According to the documentation (http://www.ffmpeg.org/ffmpeg.html) :

  ‘-timestamp time (output)’

  Set the recording timestamp in the container. The syntax for time is:
  
  
  
  now|([(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...])|(HHMMSS[.m...]))[Z|z])

  If the value is "now" it takes the current time. Time is local time unless ’Z’ or
  ’z’ is appended, in which case it is interpreted as UTC. If the year-month-day part
  is not specified it takes the current year-month-day.

  So I added the option :

  ffmpeg -y -rtbufsize 702000k -f dshow -s 320x240 -r 25 -i video="<device>" -t 10 -vcodec mjpeg -q:v 2 -timestamp now out.mp4
  
  </device>

  Unfortunately ffmpeg doesn’t seem to like this :

  Option timestamp (set the recording timestamp (’now’ to set the
  current time)) cannot be applied to output file out.mp4 — you are
  trying to apply an input option to an output file or vice versa. Move
  this option before the file it belongs to.

  Error parsing options for output file out.mp4.

  Error opening output files : Error number -22 occurred

  The documentation says -timestamp is an output option and it appears to be applied to the output file so I’m confused by this error.

  Can anyone suggest a way to accurately determine the capture start time ?

  Does anyone know why the -timestamp option gives an error ?

• libavformat/mpegts : expose raw packet size

  31 janvier 2014, par Leandro Dorileo

  libavformat/mpegts : expose raw packet size
  We cannot easily determine if an mpeg TS’s packet size is DVHS, FEC
  
  or so on, for that we need to expose the internal raw_packet_size
  
  field.
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] libavformat/mpegts.c