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• Inconsistent crop and overflay ffmpeg result with drawImage canvas

  21 juin 2022, par yuno saga

  i try to encode the video block frame to specific pattern order, then in front-end it decode back to normal. I test it in back-end by decode back with same function, it back to normal. but in front-end with canvas the order of block not in right position. if you look into front-end function. it have same pattern. i try to check output from for generate, it equal to for in backend overlay builder command.
  
whats wrong with this ?

  


  ffmpeg config

  


  const { spawn } = require('child_process');

function hflip(width) {
    const sizeBlock = 16;
    let filterCommands = '';
    const length = Math.floor(width / sizeBlock);

    for (let i=0; i < length; i++) { 
        filterCommands += `[0]crop=${sizeBlock}:480:${(i*sizeBlock)}:0[c${i}];`;
    }
    
    for (let i=0; i < length; i++) {
        if (i == 0) filterCommands += '[0]';
        if (i != 0) filterCommands += `[o${i}]`;
    
        filterCommands += `[c${i}]overlay=x=${(width - sizeBlock)-(i*sizeBlock)}:y=0`;
    
        if (i != (length - 1)) filterCommands += `[o${i+1}];`;
    }

    return filterCommands;
}

const crops = spawn('ffmpeg', [
    '-i',
    'C:/Software Development/project/blackpink.mp4',
    '-filter_complex',
    hflip(854),
    '-c:a',
    'copy',
    '-c:v',
    'libx264',
    '-crf',
    '30',
    '-preset',
    'ultrafast',
    '-pix_fmt',
    'yuv420p',
    'C:/Software Development/project/hflip.mp4',
    '-y'
], {
    cwd: 'C:/Software Development/ffmpeg'
})


  


  front-end

  


  


  


  &#xA;&#xA;    &#xA;    &#xA;        <button>play</button>&#xA;        <code class="echappe-js">&lt;script&gt;&amp;#xA;            const canvas = document.createElement(&amp;#x27;canvas&amp;#x27;);&amp;#xA;            document.body.appendChild(canvas)&amp;#xA;            const context = canvas.getContext(&amp;#x27;2d&amp;#x27;);&amp;#xA;            const video = document.createElement(&amp;#x27;video&amp;#x27;);&amp;#xA;            video.src = &amp;#x27;https://drive.google.com/uc?export=download&amp;amp;id=1Z0aFg_N3kP0SUO_xOFB0UBjTRH6_mSmb&amp;amp;confirm=t&amp;#x27;&amp;#xA;&amp;#xA;&amp;#xA;            function hflip(video) {&amp;#xA;                const widthBlock = 16;&amp;#xA;                const heightBlock = 480;&amp;#xA;                const length = Math.floor(video.videoWidth / widthBlock);&amp;#xA;&amp;#xA;                for (let i=0; i &lt; length; i&amp;#x2B;&amp;#x2B;) {&amp;#xA;                    console.log({&amp;#xA;                        cX: (i*widthBlock),&amp;#xA;                        oX: (video.videoWidth - widthBlock) - (i*widthBlock)&amp;#xA;                    });&amp;#xA;&amp;#xA;                    context.drawImage(video, (i*widthBlock), 0, widthBlock, heightBlock,  (video.videoWidth - widthBlock) - (i*widthBlock), 0, widthBlock, heightBlock)&amp;#xA;                }&amp;#xA;            }&amp;#xA;&amp;#xA;            video.onloadedmetadata = () =&gt; {&amp;#xA;                context.canvas.width = video.videoWidth;&amp;#xA;                context.canvas.height = video.videoHeight;&amp;#xA;            }&amp;#xA;&amp;#xA;            video.onplay = () =&gt; {&amp;#xA;                const updateCanvas = () =&gt; {&amp;#xA;                    hflip(video);            &amp;#xA;&amp;#xA;                    video.requestVideoFrameCallback(updateCanvas);&amp;#xA;                }&amp;#xA;&amp;#xA;                updateCanvas();&amp;#xA;            }&amp;#xA;&amp;#xA;            function play() { video.play() }&amp;#xA;        &lt;/script&gt;&#xA;    &#xA;

  


  


  



• af_hdcd : detect and report encoding errors and oddities

  12 juillet 2016, par Burt P

  af_hdcd : detect and report encoding errors and oddities
  Count and report when a code is signaled but fails to match a known pattern.
  
  For example try Līve - Secret Samadhi.
  Signed-off-by : Burt P <pburt0@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavfilter/af_hdcd.c

• libavcodec/mpegaudiodecheader.h : detect reserved mpeg id

  8 juillet 2018, par Karsten Otto

  libavcodec/mpegaudiodecheader.h : detect reserved mpeg id
  Check the MPEG version ID for the reserved bit pattern 01, and abort the
  
  header check in that case. This reduces the chance of misinterpreting
  
  arbitrary data as a valid header, and prevents resulting audio artifacts.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mpegaudiodecheader.h