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• asfenc : fix some possible integer overflows

  4 mars 2016, par Anton Khirnov

  asfenc : fix some possible integer overflows
  Store the file duration in the same timebase it arrives (i.e.
  
  milliseconds) and only convert it to the file duration units (100ns)
  
  when it’s actually written, thus simplifying some calculations. Also,
  
  store the duration as unsigned, since it cannot be negative.
  CC : libav-stable@libav.org
  
  Bug-ID : CVE-2016-2326
  

  • [DBH] libavformat/asfenc.c

• ffmpeg video&audio streaming from webcam

  23 février 2016, par johncarrie

  I am new to ffmpeg and I want to stream webcam video&audio by using ffmpeg and ffserver.

  ffserver config is the following :

  <stream>
  
  Feed feed1.ffm
  
  Format avi
  
  VideoSize 176x128
  
  VideoFrameRate 15
  
  VideoBufferSize 40
  
  VideoBitRate 64
  
  AudioBitRate 32
  
  AudioChannels 1
  
  AudioSampleRate 11025
  
  VideoQMin 1
  
  VideoQMax 20
  
  NoDefaults
  
  </stream>

  ffmpeg process is the following :

  ffmpeg -vcodec mjpeg -v verbose -r 15 -s 176x128 -f video4linux2 -i /dev/video0 -f
  
   alsa -ac 1 -i hw:0 http://localhost:8090/feed1.ffm
  
  ffmpeg version N-77547-g2893dbf Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
  
    configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  
    libavutil      55. 11.100 / 55. 11.100
  
    libavcodec     57. 20.100 / 57. 20.100
  
    libavformat    57. 21.100 / 57. 21.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 22.100 /  6. 22.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [video4linux2,v4l2 @ 0xa6133a0] fd:3 capabilities:84000001
  
  [video4linux2,v4l2 @ 0xa6133a0] The V4L2 driver changed the video from 176x128 to 1280x720
  
  [mjpeg @ 0xa613ec0] Changing bps to 8
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 77139.395765, bitrate: N/A
  
  Stream #0:0: Video: mjpeg, 1 reference frame, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, -2 kb/s, 15 fps, 15 tbr, 1000k tbn, 1000k tbc
  
  Guessed Channel Layout for  Input Stream #1.0 : mono
  
  Input #1, alsa, from 'hw:0':
  
    Duration: N/A, start: 1456086923.213492, bitrate: 768 kb/s
  
  Stream #1:0: Audio: pcm_s16le, 48000 Hz, 1 channels, s16, 768 kb/s
  
  [tcp @ 0xa622000] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  [tcp @ 0xa61e140] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  [graph 0 input from stream 1:0 @ 0xa613220] tb:1/48000 samplefmt:s16 samplerate:48000 chlayout:0x4
  
  [audio format for output stream 0:0 @ 0xa62a620] auto-inserting filter 'auto-inserted resampler 0' between the filter 'Parsed_anull_0' and the filter 'audio format for output stream 0:0'
  
  [auto-inserted resampler 0 @ 0xa6229c0] ch:1 chl:mono fmt:s16 r:48000Hz -> ch:1 chl:mono fmt:s32p r:11025Hz
  
  [graph 1 input from stream 0:0 @ 0xa6244c0] w:1280 h:720 pixfmt:yuvj422p tb:1/15 fr:15/1 sar:0/1 sws_param:flags=2
  
  [scaler for output stream 0:1 @ 0xa623fc0] w:176 h:128 flags:'bicubic' interl:0
  
  [graph 1 input from stream 0:0 @ 0xa6244c0] TB:0.066667 FRAME_RATE:15.000000 SAMPLE_RATE:nan
  
  [swscaler @ 0xa63fe40] deprecated pixel format used, make sure you did set range correctly
  
  [scaler for output stream 0:1 @ 0xa623fc0] w:1280 h:720 fmt:yuvj422p sar:0/1 -> w:176 h:128 fmt:yuv420p sar:0/1 flags:0x4
  
  [mpeg4 @ 0xa626260] Either both buffer size and max rate or neither must be specified
  
  Output #0, ffm, to 'http://localhost:8090/feed1.ffm':
  
    Metadata:
  
      creation_time   : 2016-02-22 03:35:23
  
      Stream #0:0: Audio: mp3 (libmp3lame), 11025 Hz, mono, s32p, 32 kb/s
  
      Metadata:
  
        encoder         : Lavc57.20.100 libmp3lame
  
      Stream #0:1: Video: mpeg4, 1 reference frame, none, 176x128 (0x0), q=1-20, 64 kb/s, 15 fps, 15 tbc
  
      Metadata:
  
        encoder         : Lavc57.20.100 mpeg4
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
  
    Stream #0:0 -> #0:1 (mjpeg (native) -> mpeg4 (native))
  
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height

  I am using a FEBON168 UVC HDMI GRABBER CARD as Webcam.
  USB UVC output is the following :
  1. MJPEG 1280x720 up to 30fps (full screen)
  2. YUV 1280x720 up to 10fps (full screen)

  How can I fix it ? What am I doing wrong ?

• Changing the video file attribute without modifying it ffmpeg

  9 décembre 2017, par JoeSkurczysyn

  I am using a ffmpeg script to change the creation date of the file (access to the file) in the meta tag, parameter : creation_time. It’s just that the script that I use modifies the entire video file and change the normal parameter, not only that changes the parameters of the file, it still takes several hours.

  How to improve it ?

  ffmpeg -i 06.02.2017_PC.mp4 -c copy -map 0 -metadata creation_time="2016-02-06 18:10:27" 06.02.2017_PC2.mp4
  
  pause

  How to improve it ?