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• ffmpeg creates empty mpd-file

  1er avril 2021, par Macster

  I'm trying to live stream a webm file using ffmpeg and Dash.js as a Player. Creating chunks with ffmpeg seems to work fine, but when want to create the manifest it says Could not find codec parameters for stream 0 (Video: vp9, none, 640x480): unspecified pixel format Consider increasing the value for the 'analyzeduration' and 'probesize' options and at the end Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used).

  


  Commands I use

  


  ffmpeg -re -r 25 -i Dash/strm.webm
 -map 0:v:0
 -pix_fmt yuv420p
 -c:v libvpx-vp9
 -s 640x480 -keyint_min 25 -g 25 
 -speed 6 -threads 8 -static-thresh 0 -max-intra-rate 300 
 -deadline realtime -lag-in-frames 0 -error-resilient 1
 -f webm_chunk 
 -header "Dash/glass_360.hdr"
 -chunk_start_index 1
 Dash\glass_360_%d.chk


  


  Manifest

  


  ffmpeg ^
 -f webm_dash_manifest -live 1
 -r 25
 -i Dash/glass_360.hdr
 -c copy
 -map 0
 -r 25
 -framerate 25
 -f webm_dash_manifest -live 1
 -adaptation_sets "id=0,streams=0"
 -chunk_start_index 1
 -chunk_duration_ms 1000
 -time_shift_buffer_depth 7200
 -minimum_update_period 7200
 Dash/glass_live_manifest.mpd


  


  Manifest Output

  


   libavutil      56. 49.100 / 56. 49.100
  libavcodec     58. 87.101 / 58. 87.101
  libavformat    58. 43.100 / 58. 43.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 83.100 /  7. 83.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[webm_dash_manifest @ 0000015f19f2ea40] Could not find codec parameters for stream 0 (Video: vp9, none, 640x480): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, webm_dash_manifest, from 'Dash/glass_360.hdr':
  Metadata:
    ENCODER         : Lavf58.43.100
  Duration: N/A, bitrate: N/A
    Stream #0:0(eng): Video: vp9, none, 640x480, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k tbc (default)
    Metadata:
      ALPHA_MODE      : 1
      ENCODER         : Lavc58.87.101 libvpx-vp9
      webm_dash_manifest_file_name: glass_360.hdr
      webm_dash_manifest_track_number: 1
Output #0, webm_dash_manifest, to 'stream_manifest.mpd':
  Metadata:
    encoder         : Lavf58.43.100
    Stream #0:0(eng): Video: vp9, none, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 1k tbr, 1k tbn, 1k tbc (default)
    Metadata:
      ALPHA_MODE      : 1
      ENCODER         : Lavc58.87.101 libvpx-vp9
      webm_dash_manifest_file_name: glass_360.hdr
      webm_dash_manifest_track_number: 1
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 Lsize=       1kB time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)


  


  glass_live_manifest.mpd

  


  &lt;?xml version="1.0" encoding="UTF-8"?>&#xA;&#xA;<period start="PT0S">&#xA;<adaptationset mimetype="video/webm" codecs="vp9" lang="eng" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">&#xA;<contentcomponent type="video"></contentcomponent>&#xA;<segmenttemplate timescale="1000" duration="1000" media="glass_$RepresentationID$_$Number$.chk" startnumber="1" initialization="glass_$RepresentationID$.hdr"></segmenttemplate>&#xA;<representation bandwidth="1000000" width="640" height="480" codecs="vp9" mimetype="video/webm" startswithsap="1"></representation>&#xA;</adaptationset>&#xA;</period>&#xA;&#xA;

  


  UPDATE

  


  I fixed the "warnings" by changing the comands like this :

  


  ffmpeg -re -r 25 -i Dash/strm.webm
-map 0:v:0
-pix_fmt yuv420p
-c:v libvpx
-s 640x480 -keyint_min 60 -g 60 -speed 6 -tile-columns 4 -frame-parallel 1 -threads 8 -static-thresh 0 -max-intra-rate 300 -deadline realtime -lag-in-frames 0 -error-resilient 1
-b:v 3000k
-f webm_chunk
-header "Dash/glass_360.hdr"
-chunk_start_index 1 Dash/glass_360_%d.chk
-map 0:a:0
-c:a libvorbis
-b:a 128k -ar 44100
-f webm_chunk
-audio_chunk_duration 2000
-header Dash/glass_171.hdr
-chunk_start_index 1 Dash/glass_171_%d.chk

ffmpeg
-f webm_dash_manifest -live 1
-i Dash/glass_360.hdr
-f webm_dash_manifest -live 1
-i Dash/glass_171.hdr
-c copy
-map 0 -map 1
-f webm_dash_manifest -live 1
-adaptation_sets "id=0,streams=0 id=1,streams=1"
-chunk_start_index 1
-chunk_duration_ms 2000
-time_shift_buffer_depth 7200
-minimum_update_period 7200 Dash/glass_video_manifest.mpd


  


  However, it's still not working.

  


• lavf/webm_dash : some fields should go into Representation

  1er octobre 2014, par Vignesh Venkatasubramanian

  lavf/webm_dash : some fields should go into Representation
  Width, Height and Sample Rate should be in the AdaptationSet tag
  
  only if all the contained representations have the same width,
  
  height and sampling rate. Otherwise they should go into the
  
  Representation tag. This patch adds this functionality and a fate
  
  test for the same.
  Signed-off-by : Vignesh Venkatasubramanian <vigneshv@google.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/webmdashenc.c
  • [DH] tests/fate/vpx.mak
  • [DH] tests/ref/fate/webm-dash-manifest-representations

• Live stream multi-bitrate video

  2 septembre 2017, par Rishabh

  Preface

  I have read this two part tutorial (Part-1 and Part-2) by Steamroot on MPEG-DASH, and below is my understanding (please correct me if I am wrong) :

  • The video needs to be encoded into multiple bit-rates using FFmpeg.
  • The encoded videos need to be transcoded (dashified) using MP4Box.
  • The dashified videos can be served using a web server.

  Problem

  I intend to live-stream an event and I need help to understand the following :

  1. Can I club the FFmpeg and MP4Box commands into a single step ? Maybe through a wrapper program so that I do not have to run them separately ? Is there any other or better solution ?
  2. How do I send the dashified content to the web server ? FTP ? Would any vanilla web server do ?
  3. Lastly, a friend had hinted that I could also use GStreamer to achieve my objective. But, I could not find any good resource on the internet for the same. So, where (and how) does GStreamer fit in the above process ?