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• Create animated gif from a set of png images

  12 avril 2020, par Zizi96

  I'm trying to use ffpmeg to convert a list of png to a gif.

  



  Running C:\Users\Me\Art\Animations\wubz\output> dir shows my files :

  



  12/04/2020  16:48    <dir>          ..&#xA;12/04/2020  16:45           136,706 wubz_0001.png&#xA;12/04/2020  16:45           136,180 wubz_0002.png&#xA;12/04/2020  16:45           136,413 wubz_0003.png&#xA;12/04/2020  16:45           136,099 wubz_0004.png&#xA;12/04/2020  16:45           136,309 wubz_0005.png&#xA;12/04/2020  16:45           137,172 wubz_0006.png&#xA;</dir>

  



  The code I'm running in command prompt from C:\Users\Me\Art\Animations\wubz\output> :

  



  ffmpeg-f image2 -framerate 30 -i wubz_%d.png video.flv


  



  gives the error message :
[image2 @ 000001efd6c4bac0] Could find no file with path 'wubz_%d.png' and index in the range 0-4
wubz_%d.png: No such file or directory

  



  Can someone explain what I'm doing wrong, I don't get why ffmpeg isn't seeing the png files in the output directory.

  


• FFmpeg, videotoolbox and avplayer in iOS

  9 janvier 2017, par Hwangho Kim

  I have a question how these things are connected and what they exactly do.

  FYI, I have a few experience about video player and encoding and decoding.

  In my job I deal udp streaming from server and take it with ffmpeg and decodes it and draw it with openGL. And also using ffmpeg for video player.

  These are the questions...

  1. Only ffmpeg can decodes UDP streaming (encoded with ffmpeg from the server) or not ?

  I found some useful information about videotoolbox which can decode streaming with hardware acceleration in iOS. so could I also decode the streaming from the server with videotoolbox ?

  2. If it is possible to decode with videotoolbox (I mean if the videotoolbox could be the replacement for ffmpeg), then what is the videotoolbox source code in ffmpeg ? why it is there ?

  In my decoder I make AVCodecContext from the streaming and it has hwaccel and hwaccel_context field which set null both of them. I thought this videotoolbox is kind of API which can help ffmpeg to use hwaccel of iOS. But it looks not true for now...

  3. If videotoolbox can decode streaming, Does this also decode for H264 in local ? or only streaming possible ?

  AVPlayer is a good tool to play a video but if videotoolbox could replace this AVPlayer then, what’s the benefit ? or impossible ?

  4. FFmpeg only uses CPU for decoding (software decoder) or hwaccel also ?

  When I play a video with ffmpeg player, CPU usage over 100% and Does it means this ffmpeg uses only software decoder ? or there is a way to use hwaccel ?

  Please understand my poor english and any answer would be appreciated.

  Thanks.

• python 3 using ffmpeg in a subprocess getting stderr decoding error

  4 mai 2024, par jdauthre

  I am running ffmpeg as a subprocess and using the stderr to get various bits of data like the subtitles stream Id's. It works fine for most videos, but one with japanese subtitles results in an error :

  


  'charmap' codec can't decode byte in position xxx : character maps to

  


  Much googling suggests the problem is that the japanese requires unicode, whereas English does not. Solutions offered refer to problems with files, and I cannot find a way of doing the same with the stderr. Relevent Code is below :

  


  command = [ffmpeg,"-y","-i",fileSelected,"-acodec","pcm_s16le",
                  "-vn","-t","3", "-f",            "null","-"]
print(command)   
proc = subprocess.Popen(command,stderr=PIPE,Jstdin=subprocess.PIPE,
                            universal_newlines=True,startupinfo=startupinfo)
  
stream = ""    
for line in proc.stderr:
    try:
        print("line",line)
    except exception as error:
        print("print",error)
        line = line[:-1]
        if "Stream #" in line:
            estream = line.split("#",1)[1]
            estream =estream.split(" (",1)[0]
            print("estream",estream)
            stream = stream + estream +"\n"  #.split("(",1)[0] 
            stream = stream + estream +"\n"