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• How to generate video as fast as possible with subtitles and audio on node.js + ffmpeg ?

  12 septembre 2018, par DSeregin

  Intro :

  We receive from the site some pieces of text
  Pieces arrive to node.js-server

  At the output we need to get a video, merged from all the pieces of text, voiced by the machine voice, with the added subtitles and audio substrate. So that user could be share this video in the social networks. MKV format doesn`t supported by VK.com

  The options that we have tried :
  1. Get all the text at once, generate the entire speech, create a file with subtitles, burn subtitles in the video .mp4 (vk.com does not support the .mkv container). It took 12 seconds of operations for a 45-second video on the local computer.
  2. Generate audio and video files for each piece of text (with added subtitles). It took one second for one piece of text. At the final request, we merge all pieces together. The last request (merging) took 2-3 seconds, which is already bearable.

  The second variant looks acceptable in terms of speed, but if you run 50 clients at the same time, then the computer (tested on a MacBook PRO 2013, 2.4 GHz i7, 8gb 1600 Mhz DDR3, SSD 256gb) processed only 1 piece from 1 client in 60 seconds (60 times slower), then the computer hung tight.

  • Generation of audio is done through Amazon Polly
  • Generate subtitles via https://github.com/gsantiago/subtitle.js#readme
  • From node.js we call ffmpeg using https://github.com/fluent-ffmpeg/node-fluent-ffmpeg
  • Resolution for video - 1280x720

  The commands we used :

  • Burn video subtitles and trim up to conditional 6 seconds (in the code send unix timestamp)

  ffmpeg -i import / back.mov -i export_0 / tmp.srt -scodec mov_text -t 6 export_0 / output.mov

  • Merging all audio

  ffmpeg -i audio1.mp3 .... -i audio15.mp3 merged.mp3

  • Overlay audio-substrate on the text

  ffmpeg -i merged.mp3 -i back.mp3 -filter_complex amerge -ac 2-c: a libmp3lame -q: a 4 -shortest audio.mp3

  • Merging all videos

  ffmpeg -i video.txt -f concat -c copy video.mp4

  • Overlay audio on video

  ffmpeg -i audio.mp3 -i video.mp4 -i test.mp4 -i export / output.mp3 -c: v copy -c: a aac -map 0: v: 0 -map 1: a: 0 -shortest output .mp4

  Questions that torment :

  1. Is it faster ?

  2. Can I use other codecs or methods of gluing without re-encoding ?

  3. Try to call ffmpeg directly without a wrapper ? (in fact, it gives 50-100 ms of speed)

  4. Try not to save to disk, and write data to Stream and have them glue together in the end ?

• avformat/hlsenc : fix handling of delete_segments when %v is present

  11 avril 2018, par Bela Bodecs

  avformat/hlsenc : fix handling of delete_segments when %v is present
  When var_stream_map option is used, %v must appear either in segment
  
  name template or in the directory path. This latter case currently is
  
  not handled and delete_segments flag of hls_flags is broken now. This
  
  patch fix this. The root cause of the bug was that HLSSegment struct
  
  only stores the final filename part, but not the final directory path.
  
  Most of the cases, final path info is unneded, It only necessary when
  
  you want to delete old segments (e.g in case of live streaming).
  
  Without variant streams it was unnecessary to store the final directory
  
  path, because all segment were stored into the same directory. But
  
  introducing %v in directory names either require to store the final
  
  directory path into HLSSegment or associate segments with their variant
  
  streams to be able deleting them later. I have choosen the second
  
  solution and introduced a variant index data member into the segment
  
  struct.
  Signed-off-by : Bela Bodecs <bodecsb@vivanet.hu>
  
  Signed-off-by : Steven Liu <lq@onvideo.cn>
  

  • [DH] libavformat/hlsenc.c

• Creating HLS variants with FFMPEG [closed]

  14 février 2024, par user2491463

  I am starting with a high res video file and I would like to create 3 variants, low quality, mid quality, and high quality for mobile streaming. I want these mid/low/high variants to be segmented into ts pieces that the m3u8 file will be pointing that. Is there a way to do this in one line in ffmpeg ?

  



  I have successfully generated an m3u8 file and ts segments with ffmpeg, do I need to do this 3x and set specs for low/mid/high ? If so, how do I get the singular m3u8 file to point to all variants as opposed to one for each variant ?

  



  This is the command I used to generate the m3u8 file along with the ts segments.

  



  ffmpeg -i C:\Users\george\Desktop\video\hos.mp4 -strict -2 -acodec aac -vcodec libx264 -crf 25 C:\Users\user\Desktop\video\hos_Phone.m3u8