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• Why won't some MP4 videos start streaming until the entire file is downloaded ?

  28 janvier 2016, par Sujeet

  I’m working on an application where users upload a video and play it back the browser using jwplayer, jplayer, flowplayer, etc. Some videos play immediately, while others wait until the entire video file has been downloaded.

  I’m using ffmpeg to convert the video to mp4 format.

  Here is some detailed information about one of the video files I tried.

  General
  
  Complete name                    : 429183132058337290450_AutoFF.mp4
  
  Format                           : MPEG-4
  
  Format profile                   : Base Media
  
  Codec ID                         : isom
  
  File size                        : 10.2 MiB
  
  Duration                         : 24s 333ms
  
  Overall bit rate                 : 3 501 Kbps
  
  
  
  Video
  
  ID                               : 1
  
  Format                           : AVC
  
  Format/Info                      : Advanced Video Codec
  
  Format profile                   : High@L4.1
  
  Format settings, CABAC           : Yes
  
  Format settings, ReFrames        : 3 frames
  
  Codec ID                         : avc1
  
  Codec ID/Info                    : Advanced Video Coding
  
  Duration                         : 24s 333ms
  
  Bit rate mode                    : Variable
  
  Bit rate                         : 3 351 Kbps
  
  Width                            : 1 024 pixels
  
  Height                           : 560 pixels
  
  Display aspect ratio             : 16:9
  
  Frame rate mode                  : Constant
  
  Frame rate                       : 30.000 fps
  
  Color space                      : YUV
  
  Chroma subsampling               : 4:2:0
  
  Bit depth                        : 8 bits
  
  Scan type                        : Progressive
  
  Bits/(Pixel*Frame)               : 0.195
  
  Stream size                      : 9.72 MiB (96%)
  
  Language                         : Japanese

• Post processing in ffmpeg to move 'moov atom' in MP4 files (qt-faststart)

  12 septembre 2014, par siliconpi

  Is it possible to run ffmpeg from the command line which will either place the ’moov atom’ metadata in the beginning of the MP4 file or run the qt-faststart as a post processing operation in ffmpeg so the generated file is stream-able through the internet ?

  I can of course run it as a separate command, but would prefer it to be something

  • as an option within ffmpeg, or
  • as part of a post conversion, command line option when converting the video files via ffmpeg

  ---

  Edit 1

  http://ffmpeg.org/ffmpeg.html#mov

  MOV / MP4 muxer

  The muxer options are :

  ‘-moov_size bytes’

  Reserves space for the moov atom at the beginning of the file instead of 
  
  placing the moov atom at the end. If the space reserved is insufficient, 
  
  muxing will fail.

• Thread count option in FFmpeg for FASTEST conversion to h264 ?

  5 septembre 2013, par Saptarshi Biswas

  I need to maximize speed while converting videos using FFmpeg to h264

  • Any input format of source videos
  • User's machine can have any number of cores
  • Power and memory consumption are non-issues

  Of course, there are a whole bunch of options that can be tweaked but this question is particularly about choosing the best -thread <count></count> option. I am trying to find an ideal thread count as a function of

  • no. of cores
  • input video format
  • h264-friendly values maybe ?
  • anything else missed above ?

  I am aware the default -thread 0 follows one-thread-per-core approach which is supposed to be optimal. But I am not sure if this is time or space-optimized. Also, on certain testcases, I've seen more threads (say 4 threads on my dual core test machine) finishes quicker than the default.

  Any other direction, say configure options w.r.t. threads, worth pursuing ?