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• Converting `webm` to `mov` format using ffmpeg loses transparency - how can I keep it ?

  10 mars 2023, par M.A Shahbazi

  I am trying to convert a webm video to mov format without losing quality and transparency using the following command :

  


  ffmpeg -c:v libvpx-vp9 -i input.webm ouput.mov


  


  The video gets converted, but it loses transparency and the background of video is black.

  


  I also tried the following command :

  


  ffmpeg -c:v png -i input.webm output.mov


  


  But it gives me the following error output :

  


    libavutil      58.  3.100 / 58.  3.100
  libavcodec     60.  4.100 / 60.  4.100
  libavformat    60.  4.100 / 60.  4.100
  libavdevice    60.  2.100 / 60.  2.100
  libavfilter     9.  4.100 /  9.  4.100
  libswscale      7.  2.100 /  7.  2.100
  libswresample   4. 11.100 /  4. 11.100
  libpostproc    57.  2.100 / 57.  2.100
[png @ 0000028041ca7000] Invalid PNG signature 0x824983420031F031.
[matroska,webm @ 0000028041c91240] Could not find codec parameters for stream 0 (Video: png, none(pc, progressive), 800x800): unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, matroska,webm, from 'hero.webm':
  Metadata:
    COMPATIBLE_BRANDS: qt
    creation_time   : 2023-02-23T10:43:46.703800Z
    MAJOR_BRAND     : qt
    MINOR_VERSION   : 537199360
    ENCODER         : Lavf59.35.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 1378 kb/s
  Stream #0:0: Video: png, none(pc, progressive), 800x800, SAR 1:1 DAR 1:1, 24 fps, 24 tbr, 1k tbn
    Metadata:
      alpha_mode      : 1
      ENCODER         : Lavc59.56.100 libvpx-vp9
      DURATION        : 00:00:09.000000000
Stream mapping:
  Stream #0:0 -> #0:0 (png (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[png @ 0000028041ca7680] Invalid PNG signature 0x824983420031F031.
Error while decoding stream #0:0: Invalid data found when processing input
Cannot determine format of input stream 0:0 after EOF
Error marking filters as finished
Conversion failed!


  


  How can I maintain transparency when converting from webm to mov format ?

  


  Here's the video info in case it can be helpful :

  


  {
    "streams": [
        {
            "index": 0,
            "codec_name": "vp9",
            "codec_long_name": "Google VP9",
            "profile": "Profile 0",
            "codec_type": "video",
            "codec_tag_string": "[0][0][0][0]",
            "codec_tag": "0x0000",
            "width": 800,
            "height": 800,
            "coded_width": 800,
            "coded_height": 800,
            "closed_captions": 0,
            "film_grain": 0,
            "has_b_frames": 0,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "1:1",
            "pix_fmt": "yuv420p",
            "level": -99,
            "color_range": "tv",
            "field_order": "progressive",
            "refs": 1,
            "r_frame_rate": "24/1",
            "avg_frame_rate": "24/1",
            "time_base": "1/1000",
            "start_pts": 0,
            "start_time": "0.000000",
            "disposition": {
                "default": 0,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0,
                "captions": 0,
                "descriptions": 0,
                "metadata": 0,
                "dependent": 0,
                "still_image": 0
            },
            "tags": {
                "alpha_mode": "1",
                "ENCODER": "Lavc59.56.100 libvpx-vp9",
                "DURATION": "00:00:09.000000000"
            }
        }
    ],
    "format": {
        "filename": ".\\hero.webm",
        "nb_streams": 1,
        "nb_programs": 0,
        "format_name": "matroska,webm",
        "format_long_name": "Matroska / WebM",
        "start_time": "0.000000",
        "duration": "9.000000",
        "size": "1550466",
        "bit_rate": "1378192",
        "probe_score": 100,
        "tags": {
            "COMPATIBLE_BRANDS": "qt  ",
            "creation_time": "2023-02-23T10:43:46.703800Z",
            "MAJOR_BRAND": "qt  ",
            "MINOR_VERSION": "537199360",
            "ENCODER": "Lavf59.35.100"
        }
    }
}


  


• FFMPEG - How to reduce frame rate without slow motion effect ? [closed]

  4 avril 2024, par crater33

  I have an MP4 video that's 21 minutes long, that was shot on a GoPro Hero 9 Black at 2.7k and 240 frames per second using HEVC.

  


  I would like to use FFMPEG to reduce the frame rate, with the output being a video that is also 21 minutes long and 2.7k ... but with a frame rate of 120 frames per second. But when I use the command "ffmpeg -i input.mp4 -filter:v fps=120 output.mp4 I get a video that is 42 minutes long.

  


  I would like to tell FFMPEG to simply delete every other frame of the input video, while keeping the total length of the video the same. What command would I use to do that ?

  


  Also, how would I modify this command if I wanted the output to be encoded in AVC ?

  


  Thank you.

  


• FFMPEG color key filter applied, output to a transparent HEVC mov file, speed is different

  2 mars 2023, par Patrick Vellia

  I have an original recording that has the following ffprobe output :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  Metadata:
    major_brand     : mp41
    minor_version   : 538120216
    compatible_brands: mp41
    creation_time   : 2023-02-28T19:06:41.000000Z
    firmware        : H21.01.01.50.00
  Duration: 00:00:08.15, start: 0.000000, bitrate: 60160 kb/s
  Stream #0:0(eng): Video: hevc (Main) (hvc1 / 0x31637668), yuvj420p(pc, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 59891 kb/s, 119.88 fps, 119.88 tbr, 120k tbn, 119.88 tbc (default)
    Metadata:
      creation_time   : 2023-02-28T19:06:41.000000Z
      handler_name    : GoPro H.265
      vendor_id       : [0][0][0][0]
      encoder         : GoPro H.265 encoder
      timecode        : 19:05:32:105
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 189 kb/s (default)
    Metadata:
      creation_time   : 2023-02-28T19:06:41.000000Z
      handler_name    : GoPro AAC  
      vendor_id       : [0][0][0][0]
      timecode        : 19:05:32:105
  Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
    Metadata:
      creation_time   : 2023-02-28T19:06:41.000000Z
      handler_name    : GoPro TCD  
      timecode        : 19:05:32:105
  Stream #0:3(eng): Data: bin_data (gpmd / 0x646D7067), 76 kb/s (default)
    Metadata:
      creation_time   : 2023-02-28T19:06:41.000000Z
      handler_name    : GoPro MET  
Unsupported codec with id 0 for input stream 2
Unsupported codec with id 100359 for input stream 3


  


  This video is chroma keyed, so I ran the following command the key out the green and export it to a HEVC mov container (the Apple HEVC supports alpha channel via the videotoolbox codec) :

  


  ffmpeg -i test.mp4 -vf colorkey=0x00b140:0.3:0.1 -vcodec hevc_videotoolbox -alpha_quality 0.5 -tag:v hvc1 output1.mov


  


  which results in this ffprobe :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output1.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf58.76.100
  Duration: 00:00:08.15, start: 0.000000, bitrate: 366946 kb/s
  Stream #0:0(eng): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, gbr/bt709/bt709, progressive), 3840x2160 [SAR 1:1 DAR 16:9], 367188 kb/s, 119.88 fps, 119.88 tbr, 120k tbn, 120k tbc (default)
    Metadata:
      handler_name    : GoPro H.265
      vendor_id       : FFMP
      encoder         : Lavc58.134.100 hevc_videotoolbo
      timecode        : 19:05:32:105
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 118 kb/s (default)
    Metadata:
      handler_name    : GoPro AAC  
      vendor_id       : [0][0][0][0]
  Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s
    Metadata:
      handler_name    : GoPro H.265
      timecode        : 19:05:32:105
Unsupported codec with id 0 for input stream 2


  


  When the play the original video inside a web browser, it will play normally. As in, the video doesn't play in slo-mo but at "normal speed" which is what I actually want. User can slow it down and still have the frames necessary to keep the clarity when desired.

  


  However, when I play the second video, it is unnaturally slow even at 2x the speed.

  


  The only difference I can see above is that the export didn't include the second data stream (input 3).

  


  This was recorded on a GoPro Hero 10. I am using FFMPEG 4.6.

  


  Any help would be appreciated to fine tune the command.