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• Adding a text overlay with constant size to a video with varying resolutions using ffmpeg

  22 décembre 2020, par BetaLixT

  I have a video with different resolutions at different points of the video and need to add a text overlay to it. I'm new with ffmpeg, the following is one of the commands I've tried

  


  ffmpeg -i input.mp4 -vf "drawtext=text='Hello World'" -c:a copy output.mp4


  


  But the output has blurry text with it resizing every few seconds (I'm guessing because of the various resolutions in the video) and some parts of the video have their aspect ratios altered.

  


  Information on input file

  


  The input.mp4 video is generated from some .h264 raw data converted to mp4 and some blank mp4 generated that are all concatenated together, following are the commands

  


  h264 to mp4 :

  


  ffmpeg a.h264 -c copy a.mp4


  


  blank mp4

  


  ffmpeg -t 5 -f lavfi -i color=c=black:s=200x200 -c:v libx264 -tune stillimage -pix_fmt yuv420p -video_track_timescale 1200000 b.mp4


  


  Concat :

  


  ffmpeg -safe 0 -f concat -i list.txt -s 720x960 -c copy input.mp4


  


  I'd be thankful for any advice on how I could achieve this

  


• Google cloud speech to text not giving output for OGG & MP3 files

  27 avril 2021, par Vedant Jumle

  I am trying to perform speech to text on a bunch of audio files which are over 10 mins long. I don't want to waste storage on the cloud bucket by straight-up uploading wav files on it. So I am using ffmpeg to convert the files either to ogg or mp3 like :
ffmpeg -y -i audio.wav -ar 12000 -r 16000 audio.mp3

  


  ffmpeg -y -i audio.wav -ar 12000 -r 16000 audio.ogg

  


  For testing purpose I ran the speech to text service on a dummy wav file and it seemed to work, I got the text as expected. But for some reason it isn't detecting any speech when I use the ogg or mp3 file. I could not give amr files to work either.

  


  My code :

  


  def transcribe_gcs(gcs_uri):
    client = speech.SpeechClient()

    audio = speech.RecognitionAudio(uri=gcs_uri)
    config = speech.RecognitionConfig(
        encoding="OGG_OPUS", #replace with "LINEAR16" for wav, "OGG_OPUS" for ogg, "AMR" for amr
        sample_rate_hertz=16000,
        language_code="en-US",
    )
    print("starting operation")
    operation = client.long_running_recognize(config=config, audio=audio)
    response = operation.result()
    print(response)


  


  I have set up the authentication properly, so that is not a problem.

  


  When I run the speech to text service on the same audio but in ogg or mp3(I just comment out the encoding setting from the config for mp3) format, it gives no response, just prints out a line break and done.

  


  What can I do to fix this ?

  


• html text overlay with ffmpeg [closed]

  28 septembre 2020, par Tom

  I have a web page where a user can write html text with online editor tool, ckeditor.com. I want to overlay the html text to a video. My understanding is that ffmpeg doesn't support text overlay with html.

  


  Here are some possible options. I haven't tried any of them. I want to find out which is the better way to doing it.

  


  


  1. Parse the html text and convert it to text and settings that ffmpeg supports ? Is it doable ? How difficult is this ?

     


  


  2. Use puppeteer (server side rendering) to create a png image for image overlay. Would the font rendering on the server side matches 100% with the client side ?

     


  


  3. Someone suggests to do HTML->PDF->image using imagemagick + mpdf lib to image for image overlay. Many conversions are involved. Sound complex with many points of failure.

     


  


  


  Are there other better options ?