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• extracting image with ffmpeg-api much slowlier than with ffmpeg cmd

  13 avril 2021, par Tangtoo

  i want to extract frame from video with time interval 1s and saving as .jpg. Before I use ffmpeg cmd like followed :

  


  ffmpeg -i video.webm -vf fps=1 -q:v -start_number 0 %d.jpg


  


  It cost about 2 seconds when the video is 25 min long.

  


  Because some reason I try to do the same thing with ffmpeg-api. The code is like this(the code is fake code, it just show what I have done) :

  


  while(1)
{
    auto ret = av_read_frame(input_format_context, &input_pkt);  //read packet from input format context
    if(ret ==  AVERROR_EOF){
         break;
    }
    
    ret = avcodec_send_packet(input_codec_context, input_pkt);  //send packet in decoder
    ret = avcodec_receive_frame(input_codec_context, input_frame); // read frame frome decoder
    if(current_pts - last_pts > 1000)  //if 1 second passed
    {
        //encoder the frame to jpg
    }
 }


  


  But now it cost about 7 8s when the video is the same.

  


  Should I use any other method e.g. multithread decoding, or try to extract only key frame ?

  


  Thank you.

  


• Save live video stream .m3u8 to MP4. Video freezes for a few seconds

  11 octobre 2020, par Frodo Baggins

  I am trying to save in MP4 an .m3u8 live stream using FFMPEG.

  


  The version in use is the following : $ ffmpeg -v
ffmpeg version 3.4.8-0ubuntu0.2 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 7 (Ubuntu 7.5.0-3ubuntu1 18.04)

  


  While the command used for saving the stream in MP4 is the the one below :

  


  ffmpeg -y -i https://stream.m3u8 —map 0 —vcodec copy -acodec copy / output.mp4

  


  The file can be successfully opened and played with VLC even though every 3-5 seconds I see that the video freezes every few seconds.

  


  I wonder if it's something that I am missing in the above command.

  


  I also verified whether the issue was related to the connection in use but it does not seem related.

  


• ffmpeg merge audio and video streams on the fly

  19 décembre 2022, par Kiko

  I'm trying to get a stream from Youtube and stream it via HTTP, but I have to use separate audio and video streams to get good quality. I don't know how to merge the streams on the fly with ffmpeg. (I'm using pytube)

  


  I know I can do this by saving the streams, then merging them, and then streaming the output, but I would like to do it on the fly. This is my current code (which uses the old progressive streams) :

  


  yt = YouTube(f"https://www.youtube.com/watch?v={url}")
video = yt.streams.filter(file_extension='mp4', progressive=True).first()
async def stream(response):
    for chunk in pytube_request.stream(video.url):
        await response.write(chunk)
return ResponseStream(stream, content_type="audio/mp4")