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• How the data stream file written .h264 [on hold]

  29 octobre 2015, par lzyroot

  NSData Type：

  00000001 67640014 ad84010c 20086100 43080218 4010c200 842b50b0 4b200000 000168ee 3cb00000 000106e5 01a68000 00000165 b800001b a6cfd4d4 42abb9be 53b371b4 f0521134 f587a131 ffc5c6ea 0eeacc08 303ad194 687f364d 544c4fc6 be97519d 33883bd3 53caac97 ec9be9c1 6e218225 8259354d eea7eb4a efabcb73 394a9339 6d229a1a a910fcea e1229f0a 04421f0a bae52c85 43d58fad dc9b6d60 2ea82fb2 727f5dba d39247cc edfe9d23 f210018d 4336a937 0aad66fb 2865bbd7 794e0870 8f0a974b bf9ad770 123ca915 a7567bcd c1a887ac addf08e8 93d7777a f7969670 274dbcd8 afa873ef b125fe97 dc0c7762 be21c5e3 69aa1527 73ef484f b927f78c 514bbff5 ce3adb8b ff606f43 41972c37 22473a3b d7fa380f 8a14166d ee8f2704 a5130315 525959f8 9e364583 8a34e2fd 9cf0ddd9 b9d31f3f 028eac69 9860a752 bcf61606 52aa1d78 c45939b0 15562287 f226bb6b 683e5a07 209c63af caea040a a89ba69d c787bd62 38a751d7 b0b56ada 2af998fe 0489ac0a 4d14ba6f f04c92dc 9f0d7e74 491a72e2 623477f2 62b2d939 7d62c504 1c5f94d1 314fbb1d 3ec0a79a 1f3ac297 9e2985a8 d2a9bbdc d30ba3c0 38dc8d19 6056f9f2 1c5c88b5 c030890e 7809a0c5 431264ec d2cf5eaa b47525c7 62b5beb6 506b7d05 b5f2dd3d 11d713f5 3340961a 29191bbc a1929050 7cb8f651 5aa23fbf

  write to .h264 file

• mp4 video written with ffmpeg has different first frame based on total number of frames

  26 janvier 2023, par Nitzan Weissman

  I'm trying to read and write videos using ffmpeg, and I got an interesting phenomenon where the first frame is not the same in videos I create that are made from the same frames, only with different lengths.

  


  The commands I'm running to reproduce the problem :

  


  ffmpeg -i .mp4 -frames:v 20 -q:v 3 resource_images/00%04d.png

ffmpeg -hide_banner -loglevel error -framerate 30 -y -i resource_images/00%04d.png  -c:v libx264 -pix_fmt yuv420p -frames:v 20 long_video.mp4 -y

ffmpeg -hide_banner -loglevel error -framerate 30 -y -i resource_images/00%04d.png  -c:v libx264 -pix_fmt yuv420p -frames:v 10 short_video.mp4 -y

ffmpeg -i long_video.mp4 -vf "select=eq(n,0)" -q:v 3 long_frame0.png -y

ffmpeg -i short_video.mp4 -vf "select=eq(n,0)" -q:v 3 short_frame0.png -y


  


  The images long_frame0.png and short_frame0.png are different (I loaded them using Python and compared them, there are many differences).

  


  I find it very peculiar, since I create very short videos, it's those videos first frames, and they are keyframes of those videos (I checked it using ffprobe)

  


  What is the cause of this issue and how do I overcome it to create a consistent first frame for a video, regardless of the video length ?

  


• Capture video from webcam using ffmpeg - finish streaming without any data to written it

  7 septembre 2017, par Robert

  I have webcam in my computer and ffmpeg 3.3.0
  I run this command :

  ffmpeg -y -f vfwcap -r 25 -i 0 out1.mp4

  I have no errors but the output file is empty.

  c:\..\bin>ffmpeg -y -f vfwcap -r 25 -i 0 out1.mp4
  
  ffmpeg version N-87130-g2b9fd15 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 7.1.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --e
  
  nable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --
  
  enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv
  
  --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-li
  
  bfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug -
  
  -enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enabl
  
  e-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-li
  
  bsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolam
  
  e --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
  
   --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable
  
  -libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-zlib
  
    libavutil      55. 74.100 / 55. 74.100
  
    libavcodec     57.104.100 / 57.104.100
  
    libavformat    57. 79.100 / 57. 79.100
  
    libavdevice    57.  8.100 / 57.  8.100
  
    libavfilter     6.101.100 /  6.101.100
  
    libswscale      4.  7.103 /  4.  7.103
  
    libswresample   2.  8.100 /  2.  8.100
  
    libpostproc    54.  6.100 / 54.  6.100
  
  Input #0, vfwcap, from '0':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480, 25 fps,
  
  1k tbr, 1k tbn, 1k tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  Finishing stream 0:0 without any data written to it.
  
  [libx264 @ 00000000004f5160] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2
  
  AVX FMA3 BMI2 AVX2
  
  [libx264 @ 00000000004f5160] profile High 4:2:2, level 3.0, 4:2:2 8-bit
  
  [libx264 @ 00000000004f5160] 264 - core 152 r2851 ba24899 - H.264/MPEG-4 AVC cod
  
  ec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=1 r
  
  ef=3 deblock=1:0:0 analyse=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_pski
  
  p=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 deci
  
  mate=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=2
  
  5 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.6
  
  0 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'out1.mp4':
  
    Metadata:
  
      encoder         : Lavf57.79.100
  
      Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv422p, 640x480, q=
  
  -1--1, 25 fps, 12800 tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc57.104.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  frame=    0 fps=0.0 q=0.0 Lsize=       0kB time=00:00:00.00 bitrate=N/A speed=
  
   0x
  
  video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing ove
  
  rhead: unknown
  
  Exiting normally, received signal 2.
  
  
  
  c:\..\bin>

  My operating system is Windows 7.