Recherche avancée

Sur d’autres sites (6375)

• Blender VSE Audio out-of-sync when animation (video) is rendered

  21 août 2021, par Siddhant Shenoy

  Ok, so I found out that Blender has this really cool video-editing interface and I was beginning to love it. Until, I created this awesome project composition and when I exported the animation as a video file, the audio was out of sync :(.

  



  Actual Problem

  



  Audio is in-sync with video when the animation is played in Blender but is out-of-sync in the rendered video.

  



  Solutions I tried out and failed

  



  

  • I used the 'Audio-Sync' option in the sequencer but that made no difference.

  


  • Then I thought that my scene audio frequency might have been an issue since it was initially 48kHz and my videos were at 24kHz, so I changed the scene audio frequency to 24kHz, this still failed to solve the issue.

  


  • Initially, I was combining videos with different frame rates and thought that might have been an issue (although animation played as expected in Blender), so I recreated the source videos to ensure all videos I was using in my project had the same frame rate, but this also did not work.

  


  • Someone online suggested exporting the video and audio separately and then combining them using a command-line tool like FFMPEG, this also failed.

  


  



  What's really frustrating

  



  


  • This lag (audio is a few frames ahead of the video) is noticeable only in longer videos (>12 mins, my video is 1 hr long) suggesting a very small rendered rate difference between the video and the audio.

  


  • Also, note that the animation plays absolutely fine in Blender, so all I could figure out was that this was a rendering issue.

  


  



  So if anyone figured this out please let me know. I am a noob in video/audio codecs so please forgive me if I used some incorrect nomenclature above.

  


• Youtube processing stuck at 95%

  10 avril 2019, par lcssanches

  Well I’m trying to upload a video recorded with ffmpeg, but Youtube fail at processing it.

  Here’s the video information :

  

  
  Here’s the link https://www.youtube.com/watch?v=7XlxLh0usnY.

• Python buffered IO ending early streaming with multiple pipes

  5 octobre 2022, par Malibu

  I'm trying to make a continuous livestream of videos downloaded via yt-dlp. I need to port this (working) bash command into Python.

  


  (
    youtube-dl -v --buffer-size 16k https://youtube.com/watch?v=QiInzFHIDp4 -o - | ffmpeg -i - -f mpegts -c copy - ;
    youtube-dl -v --buffer-size 16k https://youtube.com/watch?v=QiInzFHIDp4 -o - | ffmpeg -i - -f mpegts -c copy - ;
) | ffmpeg -re -i - -c:v libx264 -f flv rtmp://127.0.0.1/live/H1P_x5WPF


  


  My Python attempt is cutting off the last 2 seconds of each video. My suspicion is that although the first pipe, yt-dlp, has an empty stdout, there is still data travelling between the second and third pipe. I haven't been able to figure out a way to properly handle the data between those two pipes at the end of the video.

  


  from subprocess import Popen, PIPE, DEVNULL

COPY_BUFSIZE = 65424

playlist = [
    {
        # 15 second video
        "url": "https://youtube.com/watch?v=QiInzFHIDp4"
    },
    {
        # 15 second video
        "url": "https://youtube.com/watch?v=QiInzFHIDp4"
    },
    {
        # 15 second video
        "url": "https://youtube.com/watch?v=QiInzFHIDp4"
    },
]

if __name__ == "__main__":
    stream_cmd = [
        "ffmpeg", "-loglevel", "error",
        "-hide_banner", "-re", "-i", "-",
        "-c:v", "libx264",
        "-f", "flv",
        "-b:v", "3000k", "-minrate", "3000k",
        "-maxrate", "3000k", "-bufsize", "3000k",
        "-r", "25", "-pix_fmt", "yuv420p",
        "rtmp://127.0.0.1/live/H1P_x5WPF"
    ]
    print(f'Stream command:\n"{" ".join(stream_cmd)}"')

    encoder_cmd = [
        "ffmpeg", "-re", "-i", "-", "-f", "mpegts",
        "-c", "copy", "-"
    ]
    print(f'Encoder command:\n"{" ".join(encoder_cmd)}"')

    stream_p = Popen(stream_cmd, stdin=PIPE, stderr=DEVNULL)

    for video in playlist:
        yt_dlp_cmd = [
            "yt-dlp", "-q",
            video["url"],
            "-o", "-"
        ]

        print("Now playing: " + video["url"])

        with Popen(yt_dlp_cmd, stdout=PIPE) as yt_dlp_p:
            with Popen(encoder_cmd, stdin=PIPE, stdout=PIPE, stderr=DEVNULL) as encoder_p:
                while True:
                    yt_dlp_buf = yt_dlp_p.stdout.read(COPY_BUFSIZE)
                    print("READ: yt_dlp")
                    if not yt_dlp_buf:
                        print("yt-dlp buffer empty")
                        # Handle any data in 2nd/3rd pipes before breaking?
                        break

                    written = encoder_p.stdin.write(yt_dlp_buf)
                    print("WRITE: encoder. Bytes: " + str(written))

                    encoder_buf = encoder_p.stdout.read(COPY_BUFSIZE)
                    # if not encoder_buf:
                    #     print("encoder_buf empty")
                    #     break
                    print("READ: encoder")

                    stream_bytes_written = stream_p.stdin.write(encoder_buf)
                    print("WRITE: stream, Bytes: " + str(stream_bytes_written))


  


  Running Python 3.6.9 on MacOS.