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• Fragmented MP4 not playing in ffplay/QuickTime/Safari, but in VLC

  6 août 2020, par Stack64

  I encoded a fMP4-Video (HEVC) in Swift using VideoToolbox and CoreMedia. The resulting fragmented MP4 is only playing in VLC.

  


  The library I am using to write the fMP4 is an HEVC-adapted version of this GitHub-Project : https://github.com/krad/morsel

  


  Process of encoding and writing :

  


  

  1. VideoToolbox : Encoding SampleBuffer from the camera (VTCompressionSession, as described in WWDC 2014 Session 513)

  


  2. Using CoreMedia-Functions (e.g. CMVideoFormatDescriptionGetHEVCParameterSetAtIndex, CMVideoFormatDescriptionGetDimensions) to get the encoded streams metadata. I am writing the content of CMFormatDescriptionGetExtension(description, extensionKey: "SampleDescriptionExtensionAtoms" as CFString)["hvcC"] directly to the hvcC box. This box is obviously written correctly, when I alter one bit of the box of the mp4, QuickTime throws an error.

  


  3. I am appending the sample buffer data to the morsel-library, which manages fragmentation and creates the moof and mdat atoms.

  


  


  The result file is playable in VLC, when I just let the playback "run" without doing anything. When I scroll the time in VLC, VLC crashes and the playback stops.

  


  It is also sort of "playable" in Safari and QuickTime (no error message shown, the playback window opens and the correct length of the file is shown, I can even change to playback time / play/pause, but there is no video shown. The window remains empty. And that is the problem I have. I need to get an fMP4 running in Safari and QuickTime.

  


  The file is not playing at all in ffplay (same problem when converting with ffmpeg). The line where the playback time is shown remains nan M-V:    nan fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0 , there are no error messages. The playback just does not start.
When playing the file with ffplay, this is the output :

  


  ffplay version 4.3 Copyright (c) 2003-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: mp41mp42isomhlsf
    creation_time   : 2020-08-03T20:41:08.000000Z
  Duration: N/A, bitrate: N/A
    Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv), 1920x1080, SAR 1:1 DAR 16:9, 1000000000.00 tbr, 1000000000.00 tbn, 1000000000.00 tbc (default)
    Metadata:
      creation_time   : 2020-08-03T20:41:08.000000Z
      handler_name    : video
    nan M-V:    nan fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0 


  


  My file has this structure :

  


  ftyp
moov
    mvhd
    trak
        tkhd
        mdia
            mdhd
            hdlr
            minf
                vmhd
                dinf
                    dref
                stbl
                    stsd
                    stts
                    stsc
                    stsz
                    stco
    mvex
        trex
moof-(1)
mdat
moof-(2)
mdat 
...


  


  The result file I want to create should be like the fMP4 served within this HLS playlist : (Example : https://developer.apple.com/streaming/examples/advanced-stream-hevc.html, Playlist : https://devstreaming-cdn.apple.com/videos/streaming/examples/bipbop_adv_example_hevc/master.m3u8)
This file has the following structure :

  


  ftyp
moov
    mvhd
    trak
        tkhd
        mdia
            mdhd
            hdlr
            minf
                vmhd
                dinf
                    dref
                stbl
                    stsd
                    stts
                    stsc
                    stsz
                    stco
    trak (same structure as above)
    mvex
        trex
moof-(1)
mdat
moof-(2)
mdat 
...


  


  This file from Apple plays perfectly in ffmpeg and QuickTime/Safari. Except for the second trak atom, it has the same structure.

  


  The "good" file is : https://devstreaming-cdn.apple.com/videos/streaming/examples/bipbop_adv_example_hevc/v14/main.mp4 (It is intended for use in a HLS Playlist I've downloaded it with curl)

  


  The "bad" file is : https://www.transfernow.net/ddl/fmp4_bad (link should work, tested it just now :) ). The video shows a slowly rotating sheet of paper.

  


  Any suggestions what the problem with my file is ?
Thanks in advance !

  


• Revision f600b50a6e : Fix avx builds on macosx with clang 5.0. The macosx release of clang v5.0 ident

  9 avril 2014, par Tom Finegan

  Changed Paths :
   Modify /vp9/common/x86/vp9_subpixel_8t_intrin_avx2.c

  
  
  Fix avx builds on macosx with clang 5.0.

  The macosx release of clang v5.0 identifies itself as :
  Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)

  This version of clang uses the older _mm_broadcastsi128_si256, like
  v3.3, as given away in the LLVM svn version above.

  Change-Id : I4d6d59d5454efd57d2ae9e75f5eb7486af7cbd0c

• Ffmpeg to duplicate an audio stream and encode this new stream

  6 décembre 2015, par Sam

  I have some video files that I need to re-encode due to compatibility issues. They are currently mkv files with h.264 video and ac3-a52 audio. I want to keep the h.264 video, convert the container to m4v and create two audio tracks, one with the original ac3-a52 and one copied from that but in aac stereo.

  I assume there has to be some sort of audio stream mapping command but I don’t know how to map and re-encode at the same time. What command should I enter into ffmpeg to achieve this ?

  Also, what is the difference between ac3 and ac3-a52 ? Will an apple TV still be able to pass through ac3-a52 or does that have to be converted to ac3 ?