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• How to use ffmpeg to overlay waveforms on xstack mosaics and specify specific audio for playback

  1er mai 2022, par kellib

  I would like to make a mosaic of multiple titled streams, 1) specifying which of the audio streams to play and 2) overlay waveforms at the bottom of each of the video tiles for the audio that they belong to.

  


  I'm successfully able to create the titled mosaic of streams with the code below.

  


  However :

  


  

  1. I'm having a hard time figuring out how to specify just one of the specific audio sources. I found amix, but I don't really want to mix them, I just want to specify audio [a0], or [a1], or [a2], etc.

  


  


  and

  


  

  2. I'm having a hard time figuring out how to overlay the wave forms at the bottom of the video for each of the tiles. I struggled trying to figure out putting showwaves into the mix. Is it possible ?

  


  


  I want each tile to look like this, but since these are rtmp streams, they need to play-out the matching waveforms dynamically with each stream. https://dragonquest64.blogspot.com/2020/01/ffmpeg-audio-waveform.html

  


  If someone could point me in the right direction, that would be great. I'm getting close, but I'm pretty new to all of this, and have already spent way more time than I should have, so would love a little help.

  


  ffmpeg \
-i rtmp://my.cdn.com/srcEncoders/STREAM-1 \
-i rtmp://my.cdn.com/srcEncoders/STREAM-2 \
-i rtmp://my.cdn.com/srcEncoders/STREAM-3 \
-i rtmp://my.cdn.com/srcEncoders/STREAM-4 \
  -filter_complex " \
      [0:v] setpts=PTS-STARTPTS, scale=qvga \
    , drawtext=text=STREAM-1:fontsize=20:x=10:y=10:fontcolor=white:box=1:boxcolor=black@0.5:boxborderw=5 [a0]; \
      [1:v] setpts=PTS-STARTPTS, scale=qvga \
    , drawtext=text=STREAM-2:fontsize=20:x=10:y=10:fontcolor=white:box=1:boxcolor=black@0.5:boxborderw=5 [a1]; \
      [2:v] setpts=PTS-STARTPTS, scale=qvga \
    , drawtext=text=STREAM-3:fontsize=20:x=10:y=10:fontcolor=white:box=1:boxcolor=black@0.5:boxborderw=5 [a2]; \
      [3:v] setpts=PTS-STARTPTS, scale=qvga \ 
    , drawtext=text=STREAM-4:fontsize=20:x=10:y=10:fontcolor=white:box=1:boxcolor=black@0.5:boxborderw=5 [a3]; \
      [a0][a1][a2][a3]xstack=inputs=4:layout=0_0|0_h0|w0_0|w0_h0[out]; \
    amix=inputs=1
      " \
  -map "[out]" \
 -c:v libx264 -b:v 1000k -g 30 -keyint_min 120 -profile:v baseline -preset veryfast -f mpegts "udp://127.0.0.1:1234?pkt_size=1316"


  


• How to convert from .srt to .ass with FFmpeg without decoding errors

  10 avril 2020, par symonxd

  When I try the following command with FFmpeg (v. git-2020-03-24-e5d25d1) : ffmpeg -i subs.srt subs.ass, I get a bunch of the following errors :

  



  [srt @ 0000028ea78fa780] Invalid UTF-8 in decoded subtitles text; maybe missing -sub_charenc option
Error while decoding stream #0:0: Invalid data found when processing input


  



  and :

  



  [ass @ 0000028ea78ffe40] ReadOrder gap found between 3 and 4


  



  I found that my .srt file contains the following char : ë
I tried adding the flag -sub_charenc UTF-8 as stated here with no success.

  



  How can I successfully convert .srt to .ass ?

  


• How to generate a PDF (1.7) from a MP4 movie (Rich Media annotation) ?

  19 août 2020, par malat

  I am a happy user of img2pdf. This tool does the minimal amount of work to put a series of JPEG 2000/JPEG/PNG images into a PDF "enveloppe". However I am now faced with a new challenge : embed a MP4 file into a PDF "enveloppe".

  


  I see that commercial tool can do it, as seen at :

  


  

  • Add audio, video, and interactive objects to PDFs

  


  


  It seems to have been introduced in ISO 32000-1 (PDF 1.7 Extension Level 5)

  


  I am looking for a solution which will use the Rich Media annotation inside the PDF stream.

  


  There are dozen of duplicated questions on superuser/stackoverflow, which all pretty much refer to imagemagick/convert command line tool. But in my case, convert expand the images into a multi-page PDF (which is not my desired behavior) :

  


  $ convert input.mp4 output.pdf
$ pdfinfo output.pdf 
Title:          out
Producer:       https://imagemagick.org
CreationDate:   Wed Aug 19 15:38:01 2020 CEST
ModDate:        Wed Aug 19 15:38:01 2020 CEST
Tagged:         no
UserProperties: no
Suspects:       no
Form:           none
JavaScript:     no
Pages:          1601
Encrypted:      no
Page size:      352 x 288 pts
Page rot:       0
File size:      534407296 bytes
Optimized:      no
PDF version:    1.3


  


  with :

  


  $ convert --version
Version: ImageMagick 6.9.10-23 Q16 x86_64 20190101 https://imagemagick.org
Copyright: © 1999-2019 ImageMagick Studio LLC
License: https://imagemagick.org/script/license.php
Features: Cipher DPC Modules OpenMP 
Delegates (built-in): bzlib djvu fftw fontconfig freetype jbig jng jpeg lcms lqr ltdl lzma openexr pangocairo png tiff webp wmf x xml zlib


  


  and

  


  $ file input.mp4 
input.mp4: ISO Media, MP4 Base Media v1 [IS0 14496-12:2003]
$ ffprobe -v quiet -print_format json  -show_streams input.mp4 | grep codec_long_name
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",