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• FFmpeg meaningful video thumbnails

  18 avril 2015, par Maverick

  I know this question has been discussed already here. However, it did not solve the problem completely. I trying to retrieve meaning thumbnails from video and while executing the following command.

  ffmpeg -ss 3 -i input.avi -vf "select=gt(scene\,0.4)" -frames:v 5 -vsync vfr -vf "fps=fps=1/600" out%02d.jpg

  As a result, I am only able to get 1 image out of this video. I am not sure, what is going wrong over here.

  Also, it would be great, if someone kindly give a quick explanation of this command parameters and filters. The command originally comes from here

  FFMPEG console output :

  ffmpeg version 2.6 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.6 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libfreetype --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libass --enable-ffplay --enable-libspeex --enable-libschroedinger --enable-libfdk-aac --enable-libopus --enable-frei0r --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1_1/include/openjpeg-1.5 ' --enable-nonfree --enable-vda
  
    libavutil      54. 20.100 / 54. 20.100
  
    libavcodec     56. 26.100 / 56. 26.100
  
    libavformat    56. 25.101 / 56. 25.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 11.102 /  5. 11.102
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, avi, from 'tagesschau.avi':
  
    Metadata:
  
      encoder         : Lavf56.25.101
  
    Duration: 00:00:20.03, start: 0.000000, bitrate: 4357 kb/s
  
      Stream #0:0: Video: mpeg4 (Simple Profile) (xvid / 0x64697678), yuv420p, 720x540 [SAR 1:1 DAR 4:3], 4190 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn, 29.97 tbc
  
      Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 44100 Hz, stereo, fltp, 160 kb/s
  
  [swscaler @ 0x7fcb2a00f600] deprecated pixel format used, make sure you did set range correctly
  
  [mjpeg @ 0x7fcb2a803c00] bitrate tolerance 4000000 too small for bitrate 200000, overriding
  
  Output #0, image2, to 'out%02d.jpg':
  
    Metadata:
  
      encoder         : Lavf56.25.101
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc), 720x540 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 0k fps, 0k tbn, 0k tbc
  
      Metadata:
  
        encoder         : Lavc56.26.100 mjpeg
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mpeg4 (native) -> mjpeg (native))
  
  Press [q] to stop, [?] for help
  
  frame=    1 fps=0.0 q=6.9 Lsize=N/A time=00:10:00.00 bitrate=N/A    
  
  video:44kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown 

• lavc : Make AVPacket.duration int64, and deprecate convergence_duration

  26 septembre 2015, par wm4

  lavc : Make AVPacket.duration int64, and deprecate convergence_duration
  Note that convergence_duration had another meaning, one which was in
  
  practice never used. The only real use for it was a 64 bit replacement
  
  for the duration field. It’s better just to make duration 64 bits, and
  
  to get rid of it.
  Signed-off-by : Vittorio Giovara <vittorio.giovara@gmail.com>
  

  • [DBH] doc/APIchanges
  • [DBH] libavcodec/audio_frame_queue.c
  • [DBH] libavcodec/audio_frame_queue.h
  • [DBH] libavcodec/avcodec.h
  • [DBH] libavcodec/avpacket.c
  • [DBH] libavcodec/parser.c
  • [DBH] libavcodec/version.h
  • [DBH] libavformat/framecrcenc.c
  • [DBH] libavformat/matroskadec.c
  • [DBH] libavformat/matroskaenc.c
  • [DBH] libavformat/md5enc.c
  • [DBH] libavformat/mov.c
  • [DBH] libavformat/r3d.c
  • [DBH] libavformat/utils.c

• Problems of using MediaCodec.getOutputFormat() for an encoder in Android 4.1/4.2 devices

  13 mars 2014, par Mark

  I'm trying to use MediaCodec to encode frames (either by camera or decoder) into a video.
  When processing the encoder output by dequeueOutputBuffer(), I expect to receive the return index = MediaCodec.INFO_OUTPUT_FORMAT_CHANGED, so I can call getOutputFormat() to get the encoder output format as the input of the currently used ffmpeg muxer.

  I have tested some pad/phone devices with Android version 4.1 4.3. All of them have at least one hardware video AVC encoder and is used in the test. On the devices with version 4.3, the encoder gives MediaCodec.INFO_OUTPUT_FORMAT_CHANGED before writing the encoded data as expected, and the output format returned from getOutputFormat() can be used by the muxer correctly. On the devices with 4.2.2 or lower, the encoder never gives MediaCodec.INFO_OUTPUT_FORMAT_CHANGED while it can still output the encoded elementary stream, but the muxer cannot know the exact output format.

  I want to ask the following questions :

  1. Does the behavior of encoder (gives MediaCodec.INFO_OUTPUT_FORMAT_CHANGED or not before outputing encoded data) depend on the Android API Level or the chips on individual devices ?
  2. If the encoder writes data before MediaCodec.INFO_OUTPUT_FORMAT_CHANGED appears, is there any way to get the output format of the encoded data ?
  3. The encoder still output the codec config data (with flag MediaCodec.BUFFER_FLAG_CODEC_CONFIG) on the devices before the encoded data. It is mostly used to config a decoder, but can I derive the output format by the codec config data ?

  I have tried these solutions to get the output format but failed :

  • Call getOutputFormat() frequently during the whole encode process. However, all of them throw IllegalStateException without the appearance of MediaCodec.INFO_OUTPUT_FORMAT_CHANGED.

  • Use the initial MediaFormat use to config the encoder at the beginning, like the example :

    m_init_encode_format = MediaFormat.createVideoFormat(m_encode_video_mime, m_frame_width, m_frame_height);
    
    int encode_bit_rate = 3000000;
    
    int encode_frame_rate = 15;
    
    int encode_iframe_interval = 2;
    
    
    
    m_init_encode_format.setInteger(MediaFormat.KEY_COLOR_FORMAT, m_encode_color_format);
    
    m_init_encode_format.setInteger(MediaFormat.KEY_BIT_RATE, encode_bit_rate);
    
    m_init_encode_format.setInteger(MediaFormat.KEY_FRAME_RATE, encode_frame_rate);
    
    m_init_encode_format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, encode_iframe_interval);
    
    
    
    m_encoder = MediaCodec.createByCodecName(m_video_encoder_codec_info.getName());
    
    m_encoder.configure(m_init_encode_format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
    
    
    
    // Assume m_init_encode_format is the output format of the encoder

    However it fails since the output format of the encoder is still "changed" from the initial one.

  Please help me to realize the behavior of an encoder, and if there is any solution to query the output format if the required MediaCodec.INFO_OUTPUT_FORMAT_CHANGED is missing.

  ---

  By comparing the output format and the codec config data, the missing fields are csd-0, csd-1, and a "what" field with value = 1869968451.
  (I do not understand the "what" field. It seems to be a constant and is not required. Can anyone tell me about its meaning ?)

  If I parse the codec config data as the csd-1 field (last 8 bytes) and csd-0 field (remaining bytes), it seems that the muxer can work correctly and output a video playable on all of the testing devices.
  (But I want to ask : is this 8-byte assumption correct, or there is more reliable way to parse the data ?)

  However, I got another problem that If I decode the video by Android MediaCodec again, the BufferInfo.presentationTimeUs value get by dequeueOutputBuffer() is 0 for most of the decoded frames. Only the last few frames has correct time. The sample time get by MediaExtractor.getSampleTime() is correct and exactly the value I set to the encoder/muxer, but the decoded frame time is not. This issue only happen on 4.2.2 or lower device.

  It is strange that the frame time is incorrect but the video can be playback in correct speed on the device. (Most of the devices with 4.2.2 or lower I've tested has only 1 Video AVC decoder.) Do I need to set other fields that may affect the presentation time ?