Recherche avancée

Sur d’autres sites (10368)

• ffmpeg audio and video gradually go out of sync when recorded with shell script and make

  6 août 2020, par cgmil

  I wrote the following shell script for making streamcasts for recording streams using ffmpeg :

  


  [ -z $1 ] && { echo "No recording device selected!" 2>&1 && exit ; } || DEV=$1
VIDFILE=video/bvid.mkv
AUDFILE=audio/baud.wav
DIM=$(xdpyinfo | grep dimensions: | awk '{print $2;}')
(sleep 10 && echo "Streaming...") &
ffmpeg -nostdin -loglevel panic -f x11grab -s $DIM -i $DISPLAY.0 -c:v libx264 "$VIDFILE" &
ffmpeg -nostdin -loglevel panic -f alsa -i hw:$DEV -c:a libmp3lame  "$AUDFILE" &
sleep 1
[ -f $VIDFILE ] && (echo "Created video" 1>&2) || (echo "No video!" 1>&2)
sleep 1
[ -f $AUDFILE ] && (echo "Created audio" 1>&2) || (echo "No audio!" 1>&2)

wait
trap "killall background -s 2" SIGINT


  


  This produces a video and audio file that can then be used to make a stream via make using the command make stream. Here is the Makefile (note that there is a 3-minute long audio file and a file with images that is used to make an opening splash screen) :

  


  FULLAUDIO=audio/full.wav
AUDSTART=84
TITLE="Stats Aside:\\nInterpreting\\nProbability"
SIZEW=1920
SIZEH=1080

audio/clip.wav : $(FULLAUDIO)
        ffmpeg -ss $(AUDSTART) -i $< -t 6 -af "afade=t=in:st=0:d=3:curve=qsin,afade=t=out:st=3:d=3:curve=qsin" -c:a libmp3lame $@

img/thumb.png : img/bg.png img/ico.png
        convert -stroke white -fill white -background black -transparent "#000000" \
                 -font "URWBookman-Light" -gravity Center -size 928x1080 \
                label:$(TITLE) png:- | composite -gravity west -geometry +64+0 - \
                img/bg.png $@
        convert img/ico.png -transparent "#ffffff" png:- | composite \
                 -gravity southeast -geometry +32+32 - $@ $@
        convert $@ -resize $(SIZEW)x$(SIZEH) $@

video/intro.mp4 : img/thumb.png audio/clip.wav
        ffmpeg -i audio/clip.wav -loop 1 -t 6 -i img/thumb.png -vf "fade=t=in:st=0:d=1,fade=t=out:st=5:d=1:c=white,scale=$(SIZEW):$(SIZEH)" -c:v libx264 -c:a libmp3lame $@

ProbabilityInterpretation.mp4 : video/bvid.mkv video/intro.mp4 audio/baud.wav
        ffmpeg -i video/intro.mp4 -ss 11 -i video/bvid.mkv \
                 -ss 10 -i audio/baud.wav \
                 -filter_complex \
                "[1]fade=t=in:st=0:d=1:c=white,scale=$(SIZEW):$(SIZEH)[bvid];\
                 [2]afftdn=nr=20[baud];\
                 [0:v][0:a][bvid][baud]concat=n=2:v=1:a=1[v][a]" -map "[v]" -map "[a]" \
                 -c:v libx264 -c:a libmp3lame $@

stream : ProbabilityInterpretation.mp4

clean:
        -rm ProbabilityInterpretation.mp4
        -rm video/intro.mp4
        -rm audio/clip.wav
        -rm img/thumb.png

veryclean:
        make clean
        -rm video/bvid.mkv
        -rm audio/baud.wav



  


  Because of lag between my webcam and what appears on screen, I do intentionally start the video and audio at different times so that they can eventually become in sync. However, the end result is a video that starts with the video and audio synced together, but eventually become out of sync, with the video lagging well behind the audio. Here is a link to the video with the end result ; it's long, but notice that the video starts in sync and ends out-of-sync. I should probably also note that the operating system is living in a virtual machine (VirtualBox).

  


  Why is this happening and what can I do to prevent or correct ?

  


• How to convert the AVPacket of ffmpeg to the webm stream with c++ code ?

  2 décembre 2020, par MichaelGD

  I am confused how to convert the ffmpeg AVPacket to a living stream in order to I can play it with HTML5.

  


  I have already got the AVPacket of ffmpeg with avcodec_encode_video2

  


  AVPacket pkt_;    
ret = avcodec_encode_video2(c_, &pkt_, picture_, &got_frame);


  


  And I also know how to dump the packet to webM file.

  


  file_.write(reinterpret_cast<char>(&amp;(pkt_.size)), sizeof(int));&#xA;file_.write(reinterpret_cast<char>(&amp;timestamp), sizeof(uint64_t));&#xA;file_.write(reinterpret_cast<char>(pkt_.data), pkt_.size);&#xA;</char></char></char>

  


  But, How can I create a stream server with the packets for front-end playing ?

  


• Pipe ffmpeg process with node js

  20 juin 2022, par Max

  When I make request to route, spawn process and pipe it directly to response, it works perfectly fine and creates livestream. However, it takes some time to start process and buffer some data to start playing video.

  


  app.get("/stream", async (req, res) => {
  const url = "rtsp://213.3.38.11/axis-media/media.amp";

  const cmd = [
    "-re",
    "-loglevel",
    "debug",
    "-reorder_queue_size",
    "5",
    "-rtsp_transport",
    "tcp",
    "-i",
    `${url}`,
    "-c:v",
    "copy",
    "-c:a",
    "aac",
    "-f",
    "mp4",
    "-movflags",
    "+frag_keyframe+empty_moov+default_base_moof",
    "pipe:1",
  ];

  const child = spawn("ffmpeg", cmd, {
    stdio: ["ignore", "pipe", process.stderr],
  });

  child.stdio[1].pipe(res)l

  res.on("close", () => {
    child.stdio[1].unpipe(res);
  });
});



  


  I would like to create process while starting server so I can pipe it whenever I make request to that route, but when I do so, process is living for a few seconds then stops using cpu. Sometimes it lives, but dies when I make request and try piping it.