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• Encoding video for real time streaming

  15 septembre 2019, par lilroo

  Miguel Grinberg’s article video streaming with flask, covers sending multiple JPG formatted images to a client through a multipart response to stream video to the browser.

  After doing some reading, I quickly realized that MJPEG is not a real video format, JPEGs are not optimized for video streaming and MJPEG cannot be streamed to a HTML5 video element.

  for my application (a screen sharing application written in python), I need to be able to encode and stream relatively smooth video (smoother than MJPEG anyway) in semi-realtime to the browser.

  I think what I need to do is encode a video stream using a tool like FFmpeg and then send chunks of that output to a browser using a multipart response - however it doesn’t look like there is a way to get FFmpeg (using python bindings) to write to an in-memory buffer.

  Is ffmpeg up to this task ?

  I appreciate that this question may sound nieve, but I would be thankful for being pointed in the right direction.

• ffmpeg : audio + image to video : reduce time and space it takes

  9 septembre 2019, par Yashasvi

  I am using FFMPEG to convert an image and an audio to a video.

  I am able to achieve the final video using the following command (Attaching the output of the command too) :

  time ffmpeg -loop 1 -i inputImage.jpg -i inputAudio.mp3 -c:v libx264 -
  
  c:a copy -shortest output1.mp4
  
  ffmpeg version 4.1.3-0york1~16.04 Copyright (c) 2000-2019 the FFmpeg 
  
  developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.11) 20160609
  
    configuration: --prefix=/usr --extra-version='0york1~16.04' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-nonfree --enable-libfdk-aac --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, image2, from 'inputImage.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 32003 kb/s
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 4160x2340 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [mp3 @ 0x55cd4bed0f80] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, mp3, from 'inputAudio.mp3':
  
    Duration: 00:00:23.77, start: 0.000000, bitrate: 127 kb/s
  
      Stream #1:0: Audio: mp3, 44100 Hz, mono, fltp, 128 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
  
    Stream #1:0 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x55cd4bee9c80] using SAR=1/1
  
  [libx264 @ 0x55cd4bee9c80] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
  
  [libx264 @ 0x55cd4bee9c80] profile High, level 6.0
  
  [libx264 @ 0x55cd4bee9c80] 264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=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_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 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=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'output1.mp4':
  
    Metadata:
  
      encoder         : Lavf58.20.100
  
      Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuvj420p(pc), 4160x2340 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc58.35.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
      Stream #0:1: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 128 kb/s
  
  frame=  647 fps= 21 q=28.0 Lsize=    1302kB time=00:00:23.76 bitrate= 449.0kbits/s speed=0.778x    
  
  video:908kB audio:371kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.797463%
  
  [libx264 @ 0x55cd4bee9c80] frame I:3     Avg QP:12.36  size:235361
  
  [libx264 @ 0x55cd4bee9c80] frame P:163   Avg QP:17.66  size:   469
  
  [libx264 @ 0x55cd4bee9c80] frame B:481   Avg QP:20.95  size:   336
  
  [libx264 @ 0x55cd4bee9c80] consecutive B-frames:  0.8%  0.3%  0.0% 98.9%
  
  [libx264 @ 0x55cd4bee9c80] mb I  I16..4: 60.6% 37.5%  1.9%
  
  [libx264 @ 0x55cd4bee9c80] mb P  I16..4:  0.0%  0.0%  0.0%  P16..4:  0.3%  0.0%  0.0%  0.0%  0.0%    skip:99.7%
  
  [libx264 @ 0x55cd4bee9c80] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.2%  0.0%  0.0%  direct: 0.0%  skip:99.8%  L0:46.7% L1:53.3% BI: 0.0%
  
  [libx264 @ 0x55cd4bee9c80] 8x8 transform intra:36.9% inter:94.7%
  
  [libx264 @ 0x55cd4bee9c80] coded y,uvDC,uvAC intra: 29.0% 60.8% 5.5% inter: 0.0% 0.1% 0.0%
  
  [libx264 @ 0x55cd4bee9c80] i16 v,h,dc,p: 19% 67% 14%  0%
  
  [libx264 @ 0x55cd4bee9c80] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  8% 42% 41%  1%  0%  0%  0%  0%  8%
  
  [libx264 @ 0x55cd4bee9c80] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 35% 60%  5%  0%  0%  0%  0%  0%  0%
  
  [libx264 @ 0x55cd4bee9c80] i8c dc,h,v,p: 24% 56% 16%  5%
  
  [libx264 @ 0x55cd4bee9c80] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 0x55cd4bee9c80] ref P L0: 96.2%  0.0%  1.8%  2.0%
  
  [libx264 @ 0x55cd4bee9c80] ref B L0: 87.7%  8.6%  3.7%
  
  [libx264 @ 0x55cd4bee9c80] ref B L1: 98.5%  1.5%
  
  [libx264 @ 0x55cd4bee9c80] kb/s:291.81
  
  
  
  real    0m30.671s
  
  user    1m50.724s
  
  sys 0m0.348s

  Here are the respected sizes of inputs and output :

  inputImage.jpg : 160kb

  inputAudio.mp3 : 380.3kb

  output1.mp4 : 1.3MB

  The size of output video is pretty large as compared to the input audio. This is my first issue.

  Secondly, as you can see, this process takes 30sec, which is too much I think.

  How do I solve this two problems ?

  • reducing the output video file size

  • reducing the time this process takes.

  I’ve gone through numerous online links, including a lot of questions on this forum for the past several hours but still not able to solve this.
  Tried playing with framerate but disturbs the duration of the output video.

  Can someone please help here. Let me know if any other information is needed.

  1 thing that helped me reduce the size of final video from 3MB to 1.2MB was to compress the image that I am using.

• ffmpeg concat compressed video result in wrong time span

  15 juillet 2019, par Kris Roofe

  I use

  ffmpeg.exe -f concat -i file_path_list_txt -c copy out_out.mp4

  to concat

  for file in 1265_*; do ffmpeg -i $file -crf 30 -b:a 23k -b:v 96k -threads 3 -y 'out_'$file; done

  compressed video.

  When I play the generated video, the player shows the video length is much longer than the sum of compressed video pieces. And at the linkage between slices,the frame can play a very long time,time on the player is going on,but the frame is still.

  I use ffprobe to show the original video pieces and compressed video pieces. And found the original videos with same tbr,tbn,tbc, while the compressed not.

  Original videos :

  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, progressive), 1600x1144, 134 kb/s, 8.17 fps, 600 tbr, 600 tbn, 1200 tbc (default)
  
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, progressive), 1600x1144, 138 kb/s, 9.73 fps, 600 tbr, 600 tbn, 1200 tbc (default)

  Compressed videos :

  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1600x1144, 174 kb/s, 8.17 fps, 8.17 tbr, 245050 tbn, 16.33 tbc (default)
  
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1600x1144, 127 kb/s, 9.73 fps, 9.73 tbr, 1750800 tbn, 19.45 tbc (default)

  And when I concat, in the console,ffmpeg show below info :

  [mp4 @ 000001fe0193b700] Application provided duration: 2585263321 / timestamp: 6303355764 is out of range for mov/mp4 format
  
  [mp4 @ 000001fe0193b700] pts has no value
  
  [mp4 @ 000001fe0193b700] Application provided duration: 2585443321 / timestamp: 6303535765 is out of range for mov/mp4 format
  
  [mp4 @ 000001fe0193b700] pts has no value

  In my situation the video pieces are generated time by time, and I don’t know when it stops, so I cannot do concat before compress. Each time a video piece generated I comress it and append it.