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• FFMPEG - force webm clusters duration [closed]

  1er avril 2021, par Vlad Sineok

  in short, i'm modifying a game that uses a VP8 video format.
the original videos are at 25 fps and have all clusters of nice and perfect duration 0.96 seconds and contain 25 blocks each (except for that last cluster, which usually varies). also every cluster starts with a keyframe. (all that information i gathered using webm_info from google's libwebm repo)

  


  unless all of the requirements are met, the game struggles to play the webm file smoothly, so my own webm files stutter most of the time, because ffmpeg fails to create the correct clusters and mkclean doesn't help either.
so my question is : how would i force ffmpeg to make all clusters have that perfect duration ?
here's what my command currently looks like

  


  for %%f in (*.webm) do (
ffmpeg -y -i %%f -vcodec libvpx -cpu-used 1 -pass 1 -reserve_index_space 16384 -fflags +genpts -crf 15 -slices 8 -g 25 -keyint_min 25 -vprofile 1 -auto-alt-ref 1 -arnr-maxframes 5 -arnr-strength 3 -deadline good -vf scale=512:384,setsar=1:1 -vb 4000k -an -r 25 -movflags use_metadata_tags -f webm NUL && ^
ffmpeg -y -i %%f -vcodec libvpx -cpu-used 1 -pass 2 -reserve_index_space 16384 -fflags +genpts -crf 15 -slices 8 -g 25 -keyint_min 25 -vprofile 1 -auto-alt-ref 1 -arnr-maxframes 5 -arnr-strength 3 -deadline good -vf scale=512:384,setsar=1:1 -vb 4000k -an -r 25 -movflags use_metadata_tags -f webm %%~nf.webm
)


  


• FFmpeg : Frame sizes of the generated video are extremely larger than the expected [closed]

  8 février 2021, par bbasaran

  I am recording frames (screen buffer) as NumPy arrays during the game which runs on the resolution of "400x225". Each frame array is a size of 270.1 kB.

  


  After saving those frames, I create an mp4 file with the following bash command (The game runs in 35 FPS (frames/second)) :

  


  ffmpeg -r 35 -f image2 -i frame%05d.png -vcodec libx264 -crf 1 video.mp4


  


  Then I have used a tool to generate a CSV file of frame data from the video created with the command above. The output is here below. The weird this is that, if we sum those first 35 frames (video was recorded with "-r 35" parameter because game runs in 35 FPS), we get approximately 18k kbit.

  


  18k kbit/sec bitrate is super high for a 400x225 video. What am I doing wrong while generating the video ? I appreciate any help, thanks !

  


  

  


• FFmpeg does not save the mp4 clips to file

  31 janvier 2021, par oo92

  I'm using the FFmpeg Python library to save 60-second mp4 clips to a .mp4 file from Twitch live streams using its API. This is my code :

  


  current_dir = os.getcwd()

client = TwitchClient(client_id='')
streams_now = client.streams.get_live_streams(limit=100, offset=900)
epoch = str(math.ceil(time.time()))

if not os.path.exists(current_dir + '/twitch_videos/'):
    os.mkdir(current_dir + '/twitch_videos/')

for i in range(0, 100):
    try:
        username = streams_now[i]['channel']['name']
        id = streams_now[i]['id']
        game = streams_now[i]['game']
        game = game.translate(str.maketrans({':': '-', ' ': '-', "'": '', '!': '', '&': '_', '.': '', '+': '_'}))
        streaming = streamlink.streams('http://twitch.tv/' + username)
        stream = streaming["best"].url

        twitch_stream = ffmpeg.input(stream)

        twitch_stream = ffmpeg.filter(twitch_stream,
                                      'fps',
                                      fps=1,
                                      round='up')

        twitch_stream = ffmpeg.output(twitch_stream,
                                      current_dir + '/twitch_videos/' + '%d_' + username + '_' + epoch + '.mp4',
                                      sc_threshold='0',
                                      g='60',
                                      f='segment',
                                      segment_time='600',
                                      segment_format_options='movflags=+faststart',
                                      reset_timestamps='1')frl3dqgn21bbpp6tajjvg5pdevczac
        ffmpeg.run(twitch_stream)


    except:
        pass


  


  I am concatenating the path it should go to the name of the file but the folder is empty after I take a look. The reason why its in the try-catch block is because some streams do not have the best tag so I want to skip those.

  


  Update

  


  I put a bunch of print statements inside the try block and none of them get printed. I put similar if statements inside the except block and they are all printed. This means that there is something wrong with my code inside the try block. This tells me that the code inside the try block never gets executed.