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• Android MediaRecorder setCaptureRate() and video playback speed

  7 novembre 2013, par spitzanator

  I've got a MediaRecorder recording video, and I'm very confused by the effect of setCaptureRate().

  Specifically, I prepare my MediaRecorder as follows :

  mMediaRecorder = new MediaRecorder();
  
  mCamera.stopPreview();
  
  mCamera.unlock();
  
  mMediaRecorder.setCamera(mCamera);
  
  mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
  
  mMediaRecorder.setProfile(CamcorderProfile.QUALITY_TIME_LAPSE_480P);
  
  mMediaRecorder.setCaptureRate(30f);
  
  mMediaRecorder.setOrientationHint(270);
  
  mMediaRecorder.setOutputFile(...);
  
  mMediaRecorder.setPreviewDisplay(...);
  
  mMediaRecorder.prepare();

  I record for five seconds (with a CountDownTimer, but that's irrelevant), and this is the file that gets generated :

  $ ffmpeg -i ~/CaptureRate30fps.mp4 
  
  ...
  
  Seems stream 0 codec frame rate differs from container frame rate: 180000.00 (180000/1) -> 30.00 (30/1)
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/mspitz/CaptureRate30fps.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 0
  
      compatible_brands: isom3gp4
  
      creation_time   : 2013-06-04 00:52:00
  
    Duration: 00:00:02.59, start: 0.000000, bitrate: 5238 kb/s
  
      Stream #0.0(eng): Video: h264 (Baseline), yuv420p, 720x480, 5235 kb/s, PAR 65536:65536 DAR 3:2, 30 fps, 30 tbr, 90k tbn, 180k tbc
  
      Metadata:
  
        creation_time   : 2013-06-04 00:52:00

  Note that the Duration is just about 3 seconds. The video also plays much faster, as if it were 5 seconds of video crammed into 3.

  Now, if I record by preparing my mediaRecorder exactly as above, but subtracting the setCaptureRate(30f) line, I get a file like this :

  $ ffmpeg -i ~/NoSetCaptureRate.mp4 
  
  ...
  
  Seems stream 0 codec frame rate differs from container frame rate: 180000.00 (180000/1) -> 90000.00 (180000/2)
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/mspitz/NoSetCaptureRate.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 0
  
      compatible_brands: isom3gp4
  
      creation_time   : 2013-06-04 00:50:41
  
    Duration: 00:00:04.87, start: 0.000000, bitrate: 2803 kb/s
  
      Stream #0.0(eng): Video: h264 (Baseline), yuv420p, 720x480, 2801 kb/s, PAR 65536:65536 DAR 3:2, 16.01 fps, 90k tbr, 90k tbn, 180k tbc
  
      Metadata:
  
        creation_time   : 2013-06-04 00:50:41

  Note that the Duration is as expected, about 5 seconds. The video also plays at a normal speed.

  I'm using setCaptureRate(30f) because 30 frames per second is the value of my CamcorderProfile's videoFrameRate. On my Galaxy Nexus S2 (4.2.1), omitting setCaptureRate() is fine, but when I tested on a Galaxy Nexus S3 (4.1.1), omitting setCaptureRate() results in the ever-helpful "start failed -22" error when I called mMediaRecorder.start().

  So, what am I missing ? I thought that the capture rate and the video frame rate were independent, but it's clear that they're not. Is there a way to determine programmatically what I need to set the capture rate at in order to determine that my video plays back at 1x speed ?

• ffplay : use start_time as next audio pts on flush when seeking is not supported

  13 juillet 2013, par Marton Balint

  ffplay : use start_time as next audio pts on flush when seeking is not supported
  Theoretically using start_time should also work if seeking is available and we
  
  could determine that the next packet after a flush packet is the first packet
  
  of a stream, but I could not think of an easy and clean way to do that, that is
  
  why I sticked to the no seeking available condition for now.
  Fixes ticket #2647.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] ffplay.c

• python ff-mpeg not working on VM

  2 août 2013, par Bob

  I have two Windows 2008 R2 64 bit servers with two different host providers (GoDaddy and company B). My python script runs successfully on GoDaddy's server. It doesn't run successfully on the server with company B.

  I installed the same software on both servers :

  • Python 2.7 for Windows 32 bit
  • NumPY module
  • SetupTools
  • EchoNest API for Windows

  The company B server is giving me an error related to an executable called en-ffmpeg.exe that uses the python ff-mpeg module. The exact error message is

  [dv @ 0x1449690]Can't determine profile of DV input stream.
  C :\Music\song1.mp3 : Error while opening file

  The song.mp3 file exists. I installed the latest Windows updates on the server with Company B but still I get the error. I believe the error is because something is not configured properly on this server (missing libraries or drivers ?). However, I don't know what that is !

  Please help :)

  UPDATED TO INCLUDE COMMAND AND ERROR OUTPUT FROM FFMPEG

  COMMAND :

  c :\Python27>en-ffmpeg -i "C :\Music\song1.mp3" -y -ac 2 -ar 44100
  "c :\users\x07 dmini 1\x07ppdata\local\temp\x02\tmpax82jf.wav"

  FULL ERROR :

  FFmpeg version SVN-r17988-Komeil, Copyright (c) 2000-2009 Fabrice Bellard, et al
  
  .
  
    configuration: --enable-memalign-hack --extra-cflags=-fno-common --enable-stat
  
  ic --disable-shared --disable-debug --enable-gpl --enable-nonfree --enable-avfil
  
  ter --enable-avfilter-lavf --enable-avisynth --enable-postproc --enable-pthreads
  
   --enable-libamr-nb --enable-libamr-wb --enable-libgsm --enable-libfaac --enable
  
  -libfaad --enable-libmp3lame --enable-libschroedinger --enable-libspeex --enable
  
  -libtheora --enable-libvorbis --enable-libx264 --enable-libxvid
  
    libavutil     50. 0. 0 / 50. 0. 0
  
    libavcodec    52.21. 0 / 52.21. 0
  
    libavformat   52.31. 1 / 52.31. 1
  
    libavdevice   52. 1. 0 / 52. 1. 0
  
    libavfilter    0. 4. 0 /  0. 4. 0
  
    libswscale     0. 7. 1 /  0. 7. 1
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
    built on Mar 15 2009 18:16:31, gcc: 4.3.0 20080305 (alpha-testing) mingw-20080
  
  502
  
  [dv @ 0x1449690]Can't determine profile of DV input stream.
  
  C:\\Music\\song1.mp3: Error while opening file

  I also tried removing the double back slashes from the command but got the same error.