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• Wrapping a H264 stream into a mkv container manually

  12 juin 2012, par stackVidec

  I have a stream set up that I can play in applications like VLC using the sdp handler created.

  The stream is already encoded into h264 and I now basically have a raw h264 video being streamed in.

  I've been using live 555 + openRSTP to play the stream and it writes it to a file without a container. They have outputs for file types like mov and mp4 where (looking through the code) they seem to manually write the header information of the container and then throw the video blocks into it using an abstraction of the frames being sent in and iterating through them.

  I would like to do this but write it to an mkv. Since I already have the blocks of video encoded, I would assume that I would just have to write the rest of the mkv information (header and other meta data in line with the mkv specification), but I can't find anything anywhere pertaining to that.

  I realize I can use ffmpeg for this but it would really suite the needs of my application to avoid using ffmpeg.

  Any relevant help would be greatly appreciated.

• Can VLC's method for estimating the duration of a video be reproduced by the means of ffmpeg ?

  28 février, par archie

  This may seem to duplicate previous questions but it does not, as far as I can tell.

  


  I have a bash script for indexing images and videos to a thumbnails database. A user of my script complained that some videos of hers are skipped over with an error message "corrupted metadata" even though VLC can play them smoothly. These are about 10 videos out of some 15 thousand, but I'd like to solve the problem.

  


  I will focus on a single video from the bunch. File name : "Paper_and_discussion_M492.mkv", actual duration 02:03:47 (hh:mm:ss). The duration and bitrate fields in the video metadata are missing.

  


  ffmpeg  -hide_banner -i "Paper_and_discussion_M492.mkv" 2> ffmpeg_data.txt


  


  gives the following output :

  


    Input #0, matroska,webm, from 'Paper_and_discussion_M492.mkv':
  Metadata:
    COMPATIBLE_BRANDS: isomiso2avc1mp41
    MAJOR_BRAND     : isom
    MINOR_VERSION   : 512
    ENCODER         : Lavf58.76.100
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: hevc (Main), yuv420p(tv, progressive), 854x480 [SAR 1280:1281 DAR 16:9], 24 fps, 24 tbr, 1k tbn, 24 tbc (default)
    Metadata:
      HANDLER_NAME    : VideoHandler
      VENDOR_ID       : [0][0][0][0]
      ENCODER         : Lavc58.134.100 libx265
  Stream #0:1: Audio: vorbis, 44100 Hz, stereo, fltp (default)
    Metadata:
      HANDLER_NAME    : SoundHandler
      VENDOR_ID       : [0][0][0][0]
      ENCODER         : Lavc58.134.100 libvorbis
At least one output file must be specified


  


  Therefore, as expected,

  


  ffprobe -i <file> -show_entries format=duration -v quiet -of csv="p=0"&#xA;</file>

  


  returns "N/A".

  


  Decoding the whole file does work :

  


  ffprobe -show_entries stream=r_frame_rate,nb_read_frames -select_streams v -count_frames -of compact=p=0:nk=1 -v 0 "Paper_and_discussion_M492.mkv"


  


  but it obviously takes a lot of time, especially for a > 2 hours video.

  


  The "faster answer" proposed by LSerni in https://superuser.com/questions/1179000/ffmpeg-get-duration-of-video-file-without-meta-data should give an estimate of duration based on bitrate ; but bitrate is also "N/A" in the incriminated file(s). Their command-line solution based on ffmpeg ends with an error "division by zero".

  


  However, if I open the file with VLC, it plays ok and VLC immediately shows the duration of the file as 02:03:47. I have checked that duration is precise. Search and jump are also very fast : if I skip 1 hr, playback promptly resumes at the right time.

  


  So, a doubt is gnawing at me : How does VLC succeed where I consistently fail ? It must have a way for recovering data that I might also be able to use to produce a correct estimate of duration.

  


  My question is : is it possible to reproduce VLC's method (or equivalent) by means of ffmpeg ?

  


• Optimising video storage/encoding on server (J2EE)

  27 décembre 2014, par user2756260

  Please let me know if this question doesnt belong to stackoverflow so that i can move accordingly.

  Objective :
  i) I want to convert mp4 into mov and vice versa.
  ii) I want to create thumbnail for the video
  iii) Rotate the thumbnail if needed ( by looking at meta data information of image)

  Solution I tried until now :
  i) (http://www.xuggle.com/xuggler/ - Thumbnail
  ii) https://www.ffmpeg.org/ - Convert video formats.
  iii) Rotation : Java code.

  I am able to perform achieve all my objectives by using above solution but in above solution its reading stream 3 times and hence causing performance
  issues.

  Is there any single library or solution that does all of them but doesn’t slow us down and cause performance issues ?