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• convert video with ffmpeg command line. but the video stream and audio stream are out of sync

  24 juin 2016, par zack chen

  I use ffmpeg cmd to convert some mkv video files to flv.

  The source files are downloaded from this site : Sample mkv files

  ffmpeg -i input.mkv -c:v libx264 -crf 20 -preset ultrafast -c:a aac -ar 22050 -y output.flv

  However the output video seems lose some frames, the FPS dropped from 25 to 5 suddenly and The video stream and audio stream are out of sync.

  I tested some mkv files downloaded from another site, the output file could play well.
  So, I guess it may be caused by the mkv files downloaded from the site : http://www.sample-videos.com/index.php#sample-mkv-video

  But i couldn’t find the reason. Could you help me ?

  I get the video info by ffprobe, as below.

  {
  
  "streams": [
  
      {
  
          "index": 0,
  
          "codec_name": "h264",
  
          "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
  
          "profile": "Main",
  
          "codec_type": "video",
  
          "codec_time_base": "1/50",
  
          "codec_tag_string": "[0][0][0][0]",
  
          "codec_tag": "0x0000",
  
          "width": 320,
  
          "height": 240,
  
          "coded_width": 320,
  
          "coded_height": 240,
  
          "has_b_frames": 0,
  
          "sample_aspect_ratio": "1:1",
  
          "display_aspect_ratio": "4:3",
  
          "pix_fmt": "yuv420p",
  
          "level": 20,
  
          "chroma_location": "left",
  
          "refs": 1,
  
          "is_avc": "true",
  
          "nal_length_size": "4",
  
          "r_frame_rate": "25/1",
  
          "avg_frame_rate": "25/1",
  
          "time_base": "1/1000",
  
          "duration_ts": 9818,
  
          "duration": "9.818000",
  
          "bits_per_raw_sample": "8",
  
          "disposition": {
  
              "default": 1,
  
              "dub": 0,
  
              "original": 0,
  
              "comment": 0,
  
              "lyrics": 0,
  
              "karaoke": 0,
  
              "forced": 0,
  
              "hearing_impaired": 0,
  
              "visual_impaired": 0,
  
              "clean_effects": 0,
  
              "attached_pic": 0
  
          }
  
      },
  
      {
  
          "index": 1,
  
          "codec_name": "aac",
  
          "codec_long_name": "AAC (Advanced Audio Coding)",
  
          "profile": "LC",
  
          "codec_type": "audio",
  
          "codec_time_base": "1/48000",
  
          "codec_tag_string": "[0][0][0][0]",
  
          "codec_tag": "0x0000",
  
          "sample_fmt": "fltp",
  
          "sample_rate": "48000",
  
          "channels": 6,
  
          "channel_layout": "5.1",
  
          "bits_per_sample": 0,
  
          "r_frame_rate": "0/0",
  
          "avg_frame_rate": "0/0",
  
          "time_base": "1/1000",
  
          "duration_ts": 9818,
  
          "duration": "9.818000",
  
          "disposition": {
  
              "default": 1,
  
              "dub": 0,
  
              "original": 0,
  
              "comment": 0,
  
              "lyrics": 0,
  
              "karaoke": 0,
  
              "forced": 0,
  
              "hearing_impaired": 0,
  
              "visual_impaired": 0,
  
              "clean_effects": 0,
  
              "attached_pic": 0
  
          }
  
      }
  
  ],
  
  "format": {
  
      "filename": "big_buck_bunny_240p_1mb.mkv",
  
      "nb_streams": 2,
  
      "nb_programs": 0,
  
      "format_name": "matroska,webm",
  
      "format_long_name": "Matroska / WebM",
  
      "duration": "9.818000",
  
      "size": "1055721",
  
      "bit_rate": "860233",
  
      "probe_score": 100,
  
      "tags": {
  
          "ENCODER": "Lavf53.24.2"
  
      }
  
  }
  
  }

• asp.net ffmpeg : The system cannot find the file specified

  19 juin 2016, par Malik

  I am doing code for extracting image from video using ffmpeg. But gone stuck what this means. I also have checked

  ffmpeg -i F:\MIC\stream\finalstream\casper\small.mp4  -an -ss 00:00:03 -s 108*80 -vframes 1 -f image2 -vcodec mjpeg F:/MIC/stream/finalstream/caspe
  
  r/output11.png 

  on cmd line and working fine but dont understand why this is not happening in asp.net ?

  here is my code this function happens on button click event :

  protected void Capture(object sender, EventArgs e)
  
          {
  
  
  
              string InputFile = @"F:\MIC\stream\finalstream\casper\small.mp4";
  
              string ThumbnailsPath = @"F:\MIC\stream\finalstream\casper\testimage.jpg";
  
              System.Diagnostics.Process proc = new System.Diagnostics.Process();
  
              proc.EnableRaisingEvents = false;
  
              proc.StartInfo.FileName = Page.MapPath("~/ffmpeg.exe");
  
              proc.StartInfo.Arguments = "-i F:/MIC/stream/finalstream/casper/small.mp4  -an -ss 00:00:03 -s 108*80 -vframes 1 -f image2 -vcodec mjpeg F:/MIC/stream/finalstream/casper/ output11.png";
  
              proc.Start();
  
  
  
  
  
          }

  while running i got this Error :
  

  Any idea ????

• FFMpeg on Android, undefined references to libavcodec functions, although it is listed on command line

  1er juin 2016, par dimsuz

  I have a problem with unresolved references to ffmpeg’s libavcodec functions, so far failed to find the answer in other places (including my mind) :)

  Let me describe my setup - it takes space, but is really basic, it might be that I’m failing to see some error...

  I built an FFMPeg with ndk r5 toolchain, ffmpeg port I got from http://bambuser.com/opensource (as recommended in other questions here). It built fine, so I put several static libraries in my project like this :

  <project>/jni/bambuser_ffmpeg/libavcodec.a
  
  <project>/jni/bambuser_ffmpeg/libavformat.a
  
  <project>/jni/bambuser_ffmpeg/libavcore.a
  
  <project>/jni/bambuser_ffmpeg/libavutil.a
  
  </project></project></project></project>

  Next, I created an Android.mk in bambuser_ffmpeg folder to list these libs as a prebuilt ones :

  LOCAL_PATH := $(call my-dir)
  
  
  
  include $(CLEAR_VARS)
  
  LOCAL_MODULE := bambuser-libavcore
  
  LOCAL_SRC_FILES := libavcore.a
  
  include $(PREBUILT_STATIC_LIBRARY)
  
  
  
  include $(CLEAR_VARS)
  
  LOCAL_MODULE := bambuser-libavformat
  
  LOCAL_SRC_FILES := libavformat.a
  
  include $(PREBUILT_STATIC_LIBRARY)
  
  
  
  (same for other two libs)

  Next, I have another module which references these libs in its Android.mk, sets up include paths, etc :

  LOCAL_PATH := $(call my-dir)
  
  
  
  include $(CLEAR_VARS)
  
  
  
  LOCAL_MODULE := ffmpegtest
  
  LOCAL_STATIC_LIBRARIES := bambuser-libavcodec bambuser-libavcore bambuser-libavformat bambuser-libavutil
  
  LOCAL_SRC_FILES := ffmpeg_test.cpp
  
  LOCAL_C_INCLUDES := $(LOCAL_PATH)/../bambuser_ffmpeg/include
  
  LOCAL_LDLIBS    := -llog -lz
  
  
  
  include $(BUILD_SHARED_LIBRARY)

  And finally I have my ffmpeg_test.cpp which is really basic, like this :

  #include 
  
  
  
  extern "C" {
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  extern "C" {
  
      JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName);
  
  }
  
  
  
  JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName)
  
  {
  
      av_register_all();
  
      return 0;
  
  }

  When I run ndk-build, it compiles fine, but when linking it prints an unresolved reference to almost every function in libavcodec. Looks like only this lib’s functions are failing to be located :

  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(allformats.o) :
  In function

  av_register_all':
 /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/allformats.c:47:
 undefined reference to
 

  avcodec_register_all’
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o) :
  In function

  parse_frame_rate':
 /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3240:
 undefined reference to
 

  av_parse_video_rate’
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o) :
  In function

  parse_image_size':
 /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3234:
 undefined reference to
 

  av_parse_video_size’
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o) :
  In function

  flush_packet_queue':
 /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1277:
 undefined reference to
 

  av_free_packet’
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1283 :
  undefined reference to

  av_free_packet'
 /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o):
 In function

  get_audio_frame_size’ :
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:766 :
  undefined reference to

  av_get_bits_per_sample'
 /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o):
 In function
 

  ff_interleave_add_packet’ :
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:2909 :
  undefined reference to `av_dup_packet’

  and so on...

  I fail to figure why this is happening. I tried running ndk-build V=1 to check the actual linking command, and libavcodec is sitting there perfectly right, like it should. All other ffmpeg libs are there too.

  Any hints ?