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• Transcoding fMP4 to HLS while writing on iOS using FFmpeg

  29 avril 2017, par bclymer

  TL ;DR

  I want to convert fMP4 fragments to TS segments (for HLS) as the fragments are being written using FFmpeg on an iOS device.

  Why ?

  I’m trying to achieve live uploading on iOS while maintaining a seamless, HD copy locally.

  What I’ve tried

  1. Rolling AVAssetWriters where each writes for 8 seconds, then concating the MP4s together via FFmpeg.

     What went wrong - There are blips in the audio and video at times. I’ve identified 3 reasons for this.

     1) Priming frames for audio written by the AAC encoder creating gaps.

     2) Since video frames are 33.33ms long, and audio frames 0.022ms long, it’s possible for them to not line up at the end of a file.

     3) The lack of frame accurate encoding present on Mac OS, but not available for iOS Details Here

  2. FFmpeg muxing a large video only MP4 file with raw audio into TS segments. The work was based off the Kickflip SDK

     What Went Wrong - Every once in a while an audio only file would get uploaded, with no video whatsoever. Never able to reproduce it in-house, but it was pretty upsetting to our users when they didn’t record what they thought they did. There were also issues with accurate seeking on the final segments, almost like the TS segments were incorrectly time stamped.

  What I’m thinking now

  Apple was pushing fMP4 at WWDC this year (2016) and I hadn’t looked into it much at all before that. Since an fMP4 file can be read, and played while it’s being written, I thought that it would be possible for FFmpeg to transcode the file as it’s being written as well, as long as we hold off sending the bytes to FFmpeg until each fragment within the file is finished.

  However, I’m not familiar enough with the FFmpeg C API, I only used it briefly within attempt #2.

  What I need from you

  1. Is this a feasible solution ? Is anybody familiar enough with fMP4 to know if I can actually accomplish this ?
  2. How will I know that AVFoundation has finished writing a fragment within the file so that I can pipe it into FFmpeg ?
  3. How can I take data from a file on disk, chunk at a time, pass it into FFmpeg and have it spit out TS segments ?

• Recording desktop with gdigrab ffmeg to mp4 file with too high video_size don't working

  4 juillet 2016, par tagry

  I try to recording my desktop with ffmpeg using the command :

  ffmpeg -f gdigrab -framerate 10 -video_size 1920x1200 -i desktop -pix_fmt yuv420p -vcodec libx264 -preset ultrafast output.mp4

  The problem is when the video_size option is higher than some size, (for example height higher 1089), the video can’t be read with Windows Media. I noticed that with this high size, the video which be recorded doesn’t have informations about size. I don’t understand why the record don’t work with a too big size. If somebody can help me.
  Thank you very much and very sorry for my English.

  [edit]

      ffmpeg version N-78758-g5156578 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.3.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --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-decklink --enable-zlib
  
    libavutil      55. 19.100 / 55. 19.100
  
    libavcodec     57. 27.100 / 57. 27.100
  
    libavformat    57. 26.100 / 57. 26.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 37.100 /  6. 37.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [gdigrab @ 00861860] Capturing whole desktop as 1920x1200x16 at (0,0)
  
  Input #0, gdigrab, from 'desktop':
  
    Duration: N/A, start: 1467631308.011542, bitrate: 368644 kb/s
  
      Stream #0:0: Video: bmp, rgb555le, 1920x1200, 368644 kb/s, 10 tbr, 1000k tbn, 10 tbc
  
  [libx264 @ 00863fe0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 00863fe0] profile Constrained Baseline, level 5.0
  
  [libx264 @ 00863fe0] 264 - core 148 r2665 a01e339 - H.264/MPEG-4 AVC codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=10 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      encoder         : Lavf57.26.100
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1920x1200, q=-1--1, 10 fps, 10240 tbn, 10 tbc
  
      Metadata:
  
        encoder         : Lavc57.27.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (bmp (native) -> h264 (libx264))
  
  Press [q] to stop, [?] for help
  
  frame=    6 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    
  
  frame=   11 fps= 11 q=10.0 size=     277kB time=00:00:00.40 bitrate=5664.4kbits/s speed=0.396x    
  
  frame=   16 fps= 11 q=9.0 size=     393kB time=00:00:00.90 bitrate=3578.8kbits/s speed=0.595x    
  
  frame=   21 fps= 10 q=9.0 size=     429kB time=00:00:01.40 bitrate=2507.4kbits/s speed=0.695x    
  
  frame=   26 fps= 10 q=9.0 size=     429kB time=00:00:01.90 bitrate=1849.3kbits/s speed=0.754x    
  
  frame=   31 fps= 10 q=18.0 size=     430kB time=00:00:02.40 bitrate=1466.1kbits/s speed=0.793x    
  
  frame=   36 fps= 10 q=10.0 size=     511kB time=00:00:02.90 bitrate=1442.6kbits/s speed=0.823x    
  
  frame=   41 fps= 10 q=10.0 size=     562kB time=00:00:03.40 bitrate=1353.0kbits/s speed=0.844x    
  
  frame=   46 fps= 10 q=10.0 size=     565kB time=00:00:03.90 bitrate=1185.9kbits/s speed=0.861x    
  
  frame=   51 fps= 10 q=9.0 size=     575kB time=00:00:04.40 bitrate=1070.8kbits/s speed=0.874x    
  
  frame=   56 fps= 10 q=12.0 size=     582kB time=00:00:04.90 bitrate= 972.3kbits/s speed=0.885x    
  
  frame=   61 fps= 10 q=10.0 size=     598kB time=00:00:05.40 bitrate= 907.7kbits/s speed=0.893x    
  
  frame=   66 fps= 10 q=10.0 size=     601kB time=00:00:05.90 bitrate= 834.5kbits/s speed=0.901x    
  
  frame=   71 fps= 10 q=10.0 size=     603kB time=00:00:06.40 bitrate= 772.3kbits/s speed=0.907x    
  
  frame=   76 fps= 10 q=12.0 size=     606kB time=00:00:06.90 bitrate= 719.8kbits/s speed=0.913x    
  
  frame=   81 fps= 10 q=10.0 size=     625kB time=00:00:07.40 bitrate= 691.8kbits/s speed=0.917x    
  
  frame=   86 fps= 10 q=10.0 size=     629kB time=00:00:07.90 bitrate= 652.2kbits/s speed=0.922x    
  
  frame=   91 fps= 10 q=12.0 size=     634kB time=00:00:08.40 bitrate= 618.2kbits/s speed=0.926x    
  
  frame=   97 fps= 10 q=10.0 size=     757kB time=00:00:09.00 bitrate= 689.3kbits/s speed=0.94x    
  
  frame=  100 fps= 10 q=-1.0 Lsize=     772kB time=00:00:10.00 bitrate= 632.8kbits/s speed=0.998x    
  
  video:771kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.153975%
  
  [libx264 @ 00863fe0] frame I:1     Avg QP:20.00  size:242961
  
  [libx264 @ 00863fe0] frame P:99    Avg QP:10.67  size:  5517
  
  [libx264 @ 00863fe0] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 00863fe0] mb P  I16..4:  0.8%  0.0%  0.0%  P16..4:  2.9%  0.0%  0.0%  0.0%  0.0%    skip:96.3%
  
  [libx264 @ 00863fe0] coded y,uvDC,uvAC intra: 23.6% 15.1% 13.9% inter: 1.2% 1.3% 0.8%
  
  [libx264 @ 00863fe0] i16 v,h,dc,p: 65% 33%  1%  1%
  
  [libx264 @ 00863fe0] i8c dc,h,v,p: 61% 25% 13%  0%
  
  [libx264 @ 00863fe0] kb/s:631.31

• Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  6 juillet 2016, par olega

  Found a lot of helpful answers. But could not find for my problem.
  I am trying to convert .mp4 to .webm. I tried with parameters, without them (like below), but always got same result :

  ================

  ---

  Converting (dseoFRQrJehleLDHPdcB.mp4) started - Tue - Jul 05, 2016 @ 06:29 PM

  ---

  /usr/local/bin/ffmpeg -i public_html/uploads/avi/dseoFRQrJehleLDHPdcB.mp4 public_html/uploads/dseoFRQrJehleLDHPdcB.webm

  ffmpeg version N-80913-gd915b6e Copyright (c) 2000-2016 the FFmpeg developers

  built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-16)

  configuration : —enable-libvpx —enable-libvorbis

  libavutil 55. 28.100 / 55. 28.100

  libavcodec 57. 48.101 / 57. 48.101

  libavformat 57. 41.100 / 57. 41.100

  libavdevice 57. 0.102 / 57. 0.102

  libavfilter 6. 47.100 / 6. 47.100

  libswscale 4. 1.100 / 4. 1.100

  libswresample 2. 1.100 / 2. 1.100

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
  ’/home/supergirl/public_html/uploads/avi/dseoFRQrJehleLDHPdcB.mp4’ :

  Metadata :

  major_brand     : isom
  
  
  
  minor_version   : 512
  
  
  
  compatible_brands: isomiso2avc1mp41
  
  
  
  creation_time   : 1970-01-01 00:00:00
  
  
  
  encoder         : Lavf53.24.2

  Duration : 00:00:05.31, start : 0.000000, bitrate : 1589 kb/s

  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1205 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
  
  
  
  Metadata:
  
  
  
    creation_time   : 1970-01-01 00:00:00
  
  
  
    handler_name    : VideoHandler
  
  
  
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 384 kb/s (default)
  
  
  
  Metadata:
  
  
  
    creation_time   : 1970-01-01 00:00:00
  
  
  
    handler_name    : SoundHandler

  [libvpx @ 0x21fd880] v1.2.0

  [libvpx @ 0x21fd880] Failed to initialize encoder : ABI version mismatch

  Output #0, webm, to ’/home/supergirl/public_html/uploads/dseoFRQrJehleLDHPdcB.webm’ :

  Metadata :

  major_brand     : isom
  
  
  
  minor_version   : 512
  
  
  
  compatible_brands: isomiso2avc1mp41
  
  
  
  encoder         : Lavf53.24.2
  
  
  
  Stream #0:0(und): Unknown: none, SAR 1:1 DAR 0:0 (default)
  
  
  
  Metadata:
  
  
  
    creation_time   : 1970-01-01 00:00:00
  
  
  
    handler_name    : VideoHandler
  
  
  
    encoder         : Lavc57.48.101 libvpx
  
  
  
  Stream #0:1(und): Unknown: none (default)
  
  
  
  Metadata:
  
  
  
    creation_time   : 1970-01-01 00:00:00
  
  
  
    handler_name    : SoundHandler
  
  
  
    encoder         : Lavc57.48.101 libvorbis

  Stream mapping :

  Stream #0:0 -> #0:0 (h264 (native) -> vp8 (libvpx))

  Stream #0:1 -> #0:1 (aac (native) -> vorbis (libvorbis))

  Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  ================

  Any suggestions, please ?