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• ffmpeg "select" filter not working with MPEG-4 and "-vcodec copy"

  5 novembre 2013, par Simone Palazzo

  I have an MPEG-4 video, which mediainfo describes as :

  Format                                   : MPEG-4
  
  Format profile                           : Base Media
  
  Codec ID                                 : isom
  
  Overall bit rate                         : 6 772 Kbps
  
  Writing application                      : Lavf54.6.100
  
  
  
  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L4.1
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Bit rate                                 : 25.0 Mbps
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 29.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.554
  
  Stream size                              : 500 MiB (98%)
  
  Writing library                          : x264 core 125
  
  Encoding settings                        : cabac=1 / ref=3 / deblock=1:0:0 /     nalyse=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=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=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=25000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00

  (I removed some useless information)

  What I'd like to do is remove the first, say, 200 frames from the video.

  However, if I try with ffmpeg (version 0.11.1, compiled from source)

  ffmpeg -i video.mp4 -vf select='gte(n\,200)' -vcodec copy -strict -2 out.mp4

  it doesn't work, the frames are exactly the same. If I remove the -vcodec copy part, what happens is that the first 190 frames are all the same (equal to the 190th one) ; so, they're not removed, but replaced with the 190th one.

  If I try the select filter to extract single images from the video, with

  ffmpeg -i video.mp4 -vf "select=gte(n\,200)" %d.jpg

  it works alright.

  Does anybody have an idea why this happens ?

  Thank you !

• Android NDK : Getting java.lang.UnsatisfiedLinkError : dlopen failed : cannot locate symbol "signal" referenced by "libffmpeg.so"

  27 février 2015, par Gaganpreet Singh

  I have a video trimmer application code .

  Its Android.mk file code is mentioned below :

  MY_LOCAL_PATH := $(call my-dir)

  include $(all-subdir-makefiles)

  LOCAL_PATH :=$(MY_LOCAL_PATH)
  
  include $(CLEAR_VARS)
  
  LOCAL_MODULE    := video-trimmer
  
  LOCAL_SRC_FILES := video-trimmer.c
  
  LOCAL_C_INCLUDES := $(MY_LOCAL_PATH) $(MY_LOCAL_PATH)/ffmpeg
  
  LOCAL_SHARED_LIBRARIES := ffmpeg 
  
  LOCAL_LDLIBS += -lz -llog
  
  include $(BUILD_SHARED_LIBRARY)

  and Application.mk file code is :

  APP_MODULES      := ffmpeg video-trimmer
  
  APP_OPTIM := debug

  When I try to run this application, I get following error :

  02-26 16:06:05.779: E/AndroidRuntime(4092): FATAL EXCEPTION: main
  
  02-26 16:06:05.779: E/AndroidRuntime(4092): Process: net.video.trimmer, PID: 4092
  
  02-26 16:06:05.779: E/AndroidRuntime(4092): java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "signal" referenced by "libffmpeg.so"...
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at java.lang.Runtime.loadLibrary(Runtime.java:364)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at java.lang.System.loadLibrary(System.java:526)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at net.video.trimmer.service.VideoTrimmingService.onCreate(VideoTrimmingService.java:29)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.app.ActivityThread.handleCreateService(ActivityThread.java:2585)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.app.ActivityThread.access$1800(ActivityThread.java:139)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.os.Handler.dispatchMessage(Handler.java:102)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.os.Looper.loop(Looper.java:136)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at android.app.ActivityThread.main(ActivityThread.java:5086)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at java.lang.reflect.Method.invokeNative(Native Method)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at java.lang.reflect.Method.invoke(Method.java:515)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
  
  02-26 16:06:05.779: E/AndroidRuntime(4092):     at dalvik.system.NativeStart.main(Native Method)

  My video-trimmer.so and ffmpeg.so are generated in \libs\armeabi .

  Thanks in advance.

• How to mimic Audacity's "truncate silence" with ffmpeg "silenceremove" filter

  16 juin 2024, par Cara Duf

  I want to remove completely silence parts from wav files with ffmpeg.

  


  Input wav can be like :


  


  I am using the following ffmpeg command to remove silence part ffmpeg -i input.wav -af silenceremove=stop_periods=-1:stop_duration=0.2:stop_threshold=-45dB output.wav because I understand from the doc that it will remove all silence parts longer than 0.2 s (silence being below -45dB).

  


  But I get that where silence part has only been reduced to around 0.1 wheras I want it to be 0 (no remaining silence).

  


  In Audacity I will use "truncate audio" filter and choose the above parameters to detect silence and in the action part I will choose to truncate to 0 : .

  


  This will yield to what I want (ie an audio with no silence part remaining) :


  


  Searching on the internet only lead me to what I already do.

  


  So how can I reproduce the output I get from Audacity "Truncate Silence" filter with ffmpeg and remove all silence parts from audio ?

  


  Edit : The output from silencedetect filter is correct : ffmpeg -i input.wav -af silencedetect=0.2:n=-45dB -f null - detects exactly what audacity detects.

  


  Thanks in advance for your help