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• More Weird VP8 Encodings

  10 décembre 2010, par Multimedia Mike — VP8

  When I announced that I had transitioned my VP8 encoder’s status from "toy" to "working", Jim L. lamented the loss of humorous posts about oddly encoded images output from my encoder. Not so ! There are still plenty of features that I have yet to implement, each of which carries the possibility of bizarre images.

  For example, I dusted off my work-in-progress intra 4x4 encoding, fixed a few of the more obvious bugs, and told the encoder to encode the first block in 4x4 mode and the rest in the usual, working, debugged 16x16 mode. The results of the first pass surprised me :

  
  
  

  The reason this surprised me was that I intuitively expected one of 2 outcomes :

  • Perfect image right away since everything is correct (very unlikely but not outside the realm of possibility)
  • Total garbage with, at most, the first macroblock looking somewhat legible ; this would be due to having some of the first macroblock correct but completely desynchronizing the bitstream for the purpose of decoding the rest of the coefficients.

  I absolutely did not expect the first macroblock to look messed up but for the rest of the picture to look fine. For fun, I reversed the logic and encoded the first block as 16x16 and the rest with the experimental 4x4 mode :

  
  
  

  If you examine carefully, you will see that the color planes are correct (though faint). There just isn’t much going on in the luma plane. This made sense when I noticed the encoder was encoding a blank (undefined, actually) set of luma coefficients for 4x4 mode macroblocks due to a bug. This helps to rationalize the first image as well— the first macroblock was encoding nonsense for the first macroblock which messed up the macroblocks which immediately surrounded it. Eventually, macroblock decoding got back on track when the prediction modes weren’t relying on the errantly decoded macroblocks.

  After I fixed that bug, I let the 4x4 mode rip through the whole image. That’s when I got what I am terming the "dark and gritty reboot of Big Buck Bunny" :

  
  
  

  Fortunately, this also turned out to be traceable to a pretty obvious code bug.

  One day, this VP8 encoder might do the right thing while implementing all of the algorithm’s features. In the meantime, it’s at least entertaining to watch it make mistakes.

• How can I render a video in real time with custom parameters ?

  18 décembre 2024, par Joaquín L. Robles

  Is it possible to render a video in real time with custom parameters ? I'm trying to inject some parameters (text, image and other video portions) into a video template depending on user parameters, like the "Facebook 10 Years video"..

  



  The output format should be any video format such as H.264.

  



  I've been googling and asking and the closest I got is to make a video from HTML5 canvas captures, which I think is totally inefficient.

  



  Any insight or guidance would be great, thanks

  


• FFmpeg fails to draw text

  6 avril 2024, par Edoardo Balducci

  I've rarely used ffmpeg before, so, sorry If the question is too dumb.
I have a problem adding a text layer to a video frame using ffmpeg.

  


  This is my current code :

  


  import subprocess
from PyQt5.QtGui import QPixmap, QImage
from PyQt5.QtWidgets import QLabel

class VideoThumbnailLabel(QLabel):
    def __init__(self, file_path, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.video = video
        video_duration = self.get_video_duration(file_path)
        thumbnail_path = self.get_thumbnail(file_path, video_duration)
        if thumbnail_path:
            self.setPixmap(QPixmap(thumbnail_path).scaled(160, 90, Qt.KeepAspectRatio))
        self.setToolTip(f"{video.title}\n{video.description}")

    def get_video_duration(self, video_path):
        """Returns the duration of the video in seconds."""
        command = [
            'ffprobe', '-v', 'error', '-show_entries',
            'format=duration', '-of',
            'default=noprint_wrappers=1:nokey=1', video_path
        ]
        try:
            result = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
            if result.returncode != 0:
                print(f"ffprobe error: {result.stderr}")
                return 0
            duration = float(result.stdout)
            return int(duration)  # Returning duration as an integer for simplicity
        except Exception as e:
            print(f"Error getting video duration: {e}")
            return 0

    def get_thumbnail(self, video_path, duration):
        """Generates a thumbnail with the video duration overlaid."""
        output_path = "thumbnail.jpg"  # Temporary thumbnail file
        duration_str = f"{duration // 3600:02d}:{(duration % 3600) // 60:02d}:{duration % 60:02d}"
        command = [
            'ffmpeg', '-i', video_path,
            '-ss', '00:00:01',  # Time to take the screenshot
            '-frames:v', '1',  # Number of frames to capture
            '-vf', f"drawtext=text='Duration: {duration_str}':x=10:y=10:fontsize=24:fontcolor=white",
            '-q:v', '2',  # Output quality
            '-y',  # Overwrite output files without asking
            output_path
        ]
        try:
            result = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            if result.returncode != 0:
                print(f"ffmpeg error: {result.stderr}")
                return None
            return output_path
        except Exception as e:
            print(f"Error generating thumbnail with duration: {e}")
            return None


  


  and it is used like this :

  


  for i, video in enumerate(self.videos):
    video_widget = VideoThumbnailLabel(video.file)
    video_widget.mousePressEvent = lambda event, v=video: self.onThumbnailClick(
        v
    )
    self.layout.addWidget(video_widget, i // 3, i % 3)


  


  I'm facing a problem where I am not able to get the thumbnail if I try to add the duration (I've tested it without the draw filter and worked fine)

  


  I get this error (from the result.returncode) that I'm not able to comprehend :

  


  ffmpeg error: b"ffmpeg version 6.1.1 Copyright (c) 2000-2023 the FFmpeg developers\n  built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)\n  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_4 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon\n  libavutil      58. 29.100 / 58. 29.100\n  libavcodec     60. 31.102 / 60. 31.102\n  libavformat    60. 16.100 / 60. 16.100\n  libavdevice    60.  3.100 / 60.  3.100\n  libavfilter     9. 12.100 /  9. 12.100\n  libswscale      7.  5.100 /  7.  5.100\n  libswresample   4. 12.100 /  4. 12.100\n  libpostproc    57.  3.100 / 57.  3.100\nInput #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/edoardo/Projects/work/test/BigBuckBunny.mp4':\n  Metadata:\n    major_brand     : mp42\n    minor_version   : 0\n    compatible_brands: isomavc1mp42\n    creation_time   : 2010-01-10T08:29:06.000000Z\n  Duration: 00:09:56.47, start: 0.000000, bitrate: 2119 kb/s\n  Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)\n    Metadata:\n      creation_time   : 2010-01-10T08:29:06.000000Z\n      handler_name    : (C) 2007 Google Inc. v08.13.2007.\n      vendor_id       : [0][0][0][0]\n  Stream #0:1[0x2](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 1991 kb/s, 24 fps, 24 tbr, 24k tbn (default)\n    Metadata:\n      creation_time   : 2010-01-10T08:29:06.000000Z\n      handler_name    : (C) 2007 Google Inc. v08.13.2007.\n      vendor_id       : [0][0][0][0]\n[Parsed_drawtext_0 @ 0x60000331cd10] Both text and text file provided. Please provide only one\n[AVFilterGraph @ 0x600002018000] Error initializing filters\n[vost#0:0/mjpeg @ 0x13ce0c7e0] Error initializing a simple filtergraph\nError opening output file thumbnail.jpg.\nError opening output files: Invalid argument\n"


  


  I've installed both ffmpeg and ffmprobe in my machine :

  


  ┌(edoardomacbook-air)-[~/Projects/work/tests-scripts]                                                                                                                                   
└─ $ ffmpeg -version && ffprobe -version                                                                                                                                                              2 ⚙ 
ffmpeg version 6.1.1 Copyright (c) 2000-2023 the FFmpeg developers
built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_4 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
libavutil      58. 29.100 / 58. 29.100
libavcodec     60. 31.102 / 60. 31.102
libavformat    60. 16.100 / 60. 16.100
libavdevice    60.  3.100 / 60.  3.100
libavfilter     9. 12.100 /  9. 12.100
libswscale      7.  5.100 /  7.  5.100
libswresample   4. 12.100 /  4. 12.100
libpostproc    57.  3.100 / 57.  3.100
ffprobe version 6.1.1 Copyright (c) 2007-2023 the FFmpeg developers
built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_4 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
libavutil      58. 29.100 / 58. 29.100
libavcodec     60. 31.102 / 60. 31.102
libavformat    60. 16.100 / 60. 16.100
libavdevice    60.  3.100 / 60.  3.100
libavfilter     9. 12.100 /  9. 12.100
libswscale      7.  5.100 /  7.  5.100
libswresample   4. 12.100 /  4. 12.100
libpostproc    57.  3.100 / 57.  3.100


  


  Does anyone see the problem ?

  


  ---

  


  P.S. : I know that I havent provided a minimal reproducible example, but since I don't know where the problem lies I didn't want to exclude anything