Sur d’autres sites (8268)

• simple_idct : x86 : Drop disabled IDCT implementation

  1er août 2016, par Diego Biurrun

  simple_idct : x86 : Drop disabled IDCT implementation
  This gem has been disabled since 2001.
  

  • [DBH] libavcodec/x86/simple_idct.c

• 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 ?

• dashjs can't find initialization segment on manifest.mpd

  30 avril 2016, par Abelardo Mendoza

  I am following this tutorial to stream a WebM. I have no issues running the ffmpeg commands to generate the videos/audio/manifest files but when I try to run it locally, there’s no video or audio at all and dashjs floods the console with :

  Searching for initialization.    
  
  Start searching for initialization.     
  
  Perform init search: http://localhost:8080/video_1280x720_500k.webm    
  
  Perform SIDX load: http://localhost:8080/video_640x360_750k.webm     
  
  Perform SIDX load: http://localhost:8080/video_1280x720_500k.webm 

  Writing that to console until I stop the server. I have tried using other mpd files such as this, which is used on the dashjs quickstart and it plays the video without any problems.

  I used this guide to install the latest version of ffmpeg on Ubuntu 14.04 LTS :

  ffmpeg version N-79688-g3cb3ddd Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 5.3.0 (Ubuntu 5.3.0-3ubuntu1~14.04) 20151204
  
  configuration: --prefix=/home/ab/cpp/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/ab/cpp/ffmpeg_build/include --extra-ldflags=-L/home/ab/cpp/ffmpeg/lib --bindir=/home/ab/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
  
  libavutil      55. 23.100 / 55. 23.100
  
  libavcodec     57. 38.100 / 57. 38.100
  
  libavformat    57. 34.103 / 57. 34.103
  
  libavdevice    57.  0.101 / 57.  0.101
  
  libavfilter     6. 44.100 /  6. 44.100
  
  libswscale      4.  1.100 /  4.  1.100
  
  libswresample   2.  0.101 /  2.  0.101
  
  libpostproc    54.  0.100 / 54.  0.100

  When running on ffmpeg :

  ffmpeg \
  
   -f webm_dash_manifest -i video_160x90_250k.webm \
  
   -f webm_dash_manifest -i video_320x180_500k.webm \
  
   -f webm_dash_manifest -i video_640x360_750k.webm \
  
   -f webm_dash_manifest -i video_640x360_1000k.webm \
  
   -f webm_dash_manifest -i video_1280x720_500k.webm \
  
   -f webm_dash_manifest -i audio_128k.webm \
  
   -c copy -map 0 -map 1 -map 2 -map 3 -map 4 -map 5 \
  
   -f webm_dash_manifest \
  
   -adaptation_sets "id=0,streams=0,1,2,3,4 id=1,streams=5" \
  
   manifest.mpd

  It generates the following manifest.mpd :

  <?xml version="1.0" encoding="UTF-8"?>
  
  <mpd xmlns="urn:mpeg:DASH:schema:MPD:2011" type="static" mediapresentationduration="PT117.726S" minbuffertime="PT1S" profiles="urn:webm:dash:profile:webm-on-demand:2012">
  
    <period start="PT0S" duration="PT117.726S">
  
      <adaptationset mimetype="video/webm" codecs="vp9" lang="eng" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">
  
        <representation bandwidth="198155" width="160" height="90">
  
          <baseurl>video_160x90_250k.webm</baseurl>
  
          <segmentbase indexrange="2007834-2008211">
  
            <initialization range="0-437"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="459264" width="320" height="180">
  
          <baseurl>video_320x180_500k.webm</baseurl>
  
          <segmentbase indexrange="4459996-4460374">
  
            <initialization range="0-439"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="718495" width="640" height="360">
  
          <baseurl>video_640x360_750k.webm</baseurl>
  
          <segmentbase indexrange="6614036-6614414">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="931445" width="640" height="360">
  
          <baseurl>video_640x360_1000k.webm</baseurl>
  
          <segmentbase indexrange="8309082-8309460">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="821274" width="1280" height="720">
  
          <baseurl>video_1280x720_500k.webm</baseurl>
  
          <segmentbase indexrange="8728812-8729190">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
      </adaptationset>
  
      <adaptationset mimetype="audio/webm" codecs="vorbis" lang="eng" audiosamplingrate="44100" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">
  
        <representation bandwidth="107104">
  
          <baseurl>audio_128k.webm</baseurl>
  
          <segmentbase indexrange="1538710-1539184">
  
            <initialization range="0-4112"></initialization>
  
          </segmentbase>
  
        </representation>
  
      </adaptationset>
  
    </period>
  
  </mpd>

  The index.html has a few changes because dash.js changed the way the player gets initialized.

      
  
          
  
          
  
          <code class="echappe-js">&lt;script src=&quot;http://cdn.dashjs.org/latest/dash.all.debug.js&quot;&gt;&lt;/script&gt;
  
              
          
  

  And here is Chromium’s log file. I’m converting this webm from this site.

  If I missed out any other relevant information or if anyone can guide me into the right direction, please let me know.

  Edit :

  Like Will Law mentioned, using the Shaka Player worked without any issues with my current manifest. Hope this helps anyone else.