testanki1.github.io/video_capture.html at main · BattleOfTheForces/testanki1.github.io · GitHub

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<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>视频帧精确提取器</title>
    <style>
        body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; text-align: center; margin: 20px; background-color: #f4f7f9; color: #333; }
        h1 { color: #0056b3; }
        p { max-width: 720px; margin: 10px auto; }
        video { max-width: 100%; height: auto; border: 2px solid #ccc; background-color: #000; border-radius: 8px; margin-bottom: 15px;}
        .controls-container { max-width: 720px; margin: 20px auto; padding: 20px; background-color: #fff; border-radius: 8px; box-shadow: 0 4px 8px rgba(0,0,0,0.1); border-top: 3px solid #007bff; }
        button { padding: 10px 20px; margin: 10px 5px; font-size: 16px; cursor: pointer; border-radius: 5px; border: 1px solid #007bff; background-color: #007bff; color: white; transition: background-color 0.2s, transform 0.1s; }
        button:hover:not(:disabled) { background-color: #0056b3; }
        button:active:not(:disabled) { transform: scale(0.98); }
        button:disabled { cursor: not-allowed; background-color: #a0a0a0; border-color: #a0a0a0; opacity: 0.7; }
        #status { font-weight: bold; color: #0056b3; min-height: 20px; margin-top: 15px; }
        .input-group { display: flex; align-items: center; justify-content: center; margin: 15px 0; }
        .time-input { text-align: center; font-size: 1.2em; width: 120px; margin: 0 10px; padding: 8px; border: 1px solid #ccc; border-radius: 4px; }
        #framePreviewContainer { margin-top: 20px; padding: 10px; border: 1px dashed #ddd; min-height: 100px; background-color: #f9f9f9; border-radius: 8px; }
        #framePreview { max-width: 100%; height: auto; border: 1px solid #eee; display: none; margin: 0 auto; }
    </style>
</head>
<body>

<h1>视频帧精确提取器</h1>
<p>加载视频后，暂停或拖动进度条，即可在下方工具中看到对应时间的预览帧，并可进行微调和保存。</p>

<input type="file" id="videoFile" accept="video/*">
<br><br>
<video id="videoPlayer" controls>
    <source id="videoSource" type="video/mp4">
    你的浏览器不支持 HTML5 视频播放。
</video>
<br>

<div class="controls-container">
    <h2>精确时间帧预览与保存</h2>
    <div class="input-group">
        <button id="timeDecreaseBtn" title="减小 0.01 秒" disabled>&laquo; -0.01s</button>
        <input type="number" id="timeInput" class="time-input" min="0" step="0.001" placeholder="时间 (秒)" disabled>
        <button id="timeIncreaseBtn" title="增加 0.01 秒" disabled>&raquo; +0.01s</button>
    </div>

    <div id="framePreviewContainer">
        <p id="previewPlaceholder">此处将显示提取的帧</p>
        <img id="framePreview" alt="提取的帧预览">
    </div>

    <button id="saveFrameBtn" disabled>保存预览中的帧</button>
</div>

<div id="status"></div>

<script>
    // --- DOM Elements ---
    const videoFileInput = document.getElementById('videoFile');
    const videoPlayer = document.getElementById('videoPlayer');
    const videoSource = document.getElementById('videoSource');
    const statusDiv = document.getElementById('status');

    const timeInput = document.getElementById('timeInput');
    const timeDecreaseBtn = document.getElementById('timeDecreaseBtn');
    const timeIncreaseBtn = document.getElementById('timeIncreaseBtn');
    const framePreview = document.getElementById('framePreview');
    const previewPlaceholder = document.getElementById('previewPlaceholder');
    const saveFrameBtn = document.getElementById('saveFrameBtn');

    // --- State Variables ---
    let videoFileName = '';
    let currentFrameUrl = null;
    let isSeeking = false;
    let timeUpdateTimeout;
    const TIME_STEP = 0.01;

    // --- Canvas Setup ---
    const hiddenCanvas = document.createElement('canvas');
    const context = hiddenCanvas.getContext('2d');

    // --- Event Listeners ---

    videoFileInput.addEventListener('change', function(event) {
        resetUI();
        const file = event.target.files[0];
        if (file) {
            videoFileName = file.name.split('.').slice(0, -1).join('.') || 'video';
            const url = URL.createObjectURL(file);
            videoSource.src = url;
            videoPlayer.load();
        }
    });

    videoPlayer.addEventListener('loadedmetadata', function() {
        if (videoPlayer.videoWidth > 0) {
            hiddenCanvas.width = videoPlayer.videoWidth;
            hiddenCanvas.height = videoPlayer.videoHeight;
        }
        timeInput.max = videoPlayer.duration.toFixed(3);
        timeInput.value = "0.000";
        updateButtonStates();
        statusDiv.textContent = '视频已加载。';
    });

    // 当视频播放或暂停时更新按钮状态
    videoPlayer.addEventListener('play', updateButtonStates);
    videoPlayer.addEventListener('pause', () => {
        updateButtonStates();
        syncTimeAndPreview();
    });

    // 【关键改动】监听seeked事件，处理拖动进度条的情况
    videoPlayer.addEventListener('seeked', () => {
        // 只有当视频处于暂停状态时，拖动进度条才更新预览
        if (videoPlayer.paused) {
            updateButtonStates();
            syncTimeAndPreview();
        }
    });

    videoPlayer.addEventListener('error', function() {
        alert('加载或播放视频时发生错误。');
        resetUI();
    });

    // --- 精确时间控制交互 ---
    timeInput.addEventListener('input', () => {
        clearTimeout(timeUpdateTimeout);
        timeUpdateTimeout = setTimeout(() => {
            let targetTime = parseFloat(timeInput.value);
            if (!isNaN(targetTime)) {
                targetTime = Math.max(0, Math.min(targetTime, videoPlayer.duration));
                timeInput.value = targetTime.toFixed(3);
                updateFramePreview(targetTime);
            }
        }, 300);
    });

    timeDecreaseBtn.addEventListener('click', () => {
        let currentTime = parseFloat(timeInput.value) || 0;
        let newTime = Math.max(0, currentTime - TIME_STEP);
        timeInput.value = newTime.toFixed(3);
        updateFramePreview(newTime);
    });

    timeIncreaseBtn.addEventListener('click', () => {
        let currentTime = parseFloat(timeInput.value) || 0;
        let newTime = Math.min(videoPlayer.duration, currentTime + TIME_STEP);
        timeInput.value = newTime.toFixed(3);
        updateFramePreview(newTime);
    });

    saveFrameBtn.addEventListener('click', () => {
        if (!currentFrameUrl) {
            alert('没有可保存的预览帧。');
            return;
        }
        const timestamp = parseFloat(timeInput.value).toFixed(3).replace('.', '_');
        const filename = `${videoFileName}_frame_at_${timestamp}s.png`;

        const link = document.createElement('a');
        link.href = currentFrameUrl;
        link.download = filename;
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);

        statusDiv.textContent = `已保存预览中的帧: ${filename}`;
    });

    // --- Helper Functions ---

    /**
     * 【新增】同步视频当前时间到输入框并更新预览
     */
    function syncTimeAndPreview() {
        if (isSeeking || videoPlayer.readyState < videoPlayer.HAVE_METADATA) return;
        const currentTime = videoPlayer.currentTime;
        // 更新输入框的值
        timeInput.value = currentTime.toFixed(3);
        // 更新预览图像
        updateFramePreview(currentTime);
    }

    async function updateFramePreview(targetTime) {
        if (isSeeking || videoPlayer.readyState < videoPlayer.HAVE_METADATA) return;

        isSeeking = true;
        updateButtonStates();
        statusDiv.textContent = `正在定位到 ${targetTime.toFixed(3)}s 并提取...`;

        try {
            await seekToTime(targetTime);
            const frameBlob = await captureFrameAsBlob();

            if (currentFrameUrl) URL.revokeObjectURL(currentFrameUrl);

            currentFrameUrl = URL.createObjectURL(frameBlob);
            framePreview.src = currentFrameUrl;
            framePreview.style.display = 'block';
            previewPlaceholder.style.display = 'none';

            statusDiv.textContent = `已成功提取 ${targetTime.toFixed(3)}s 处的帧。`;

        } catch (error) {
            console.error('更新帧预览时出错:', error);
            statusDiv.textContent = `提取失败: ${error.message}`;
            alert(`提取帧时出错: ${error.message}`);
        } finally {
            isSeeking = false;
            updateButtonStates();
        }
    }

    function resetUI() {
        statusDiv.textContent = '请选择一个视频文件。';
        isSeeking = false;
        if(videoPlayer.src && videoPlayer.src.startsWith('blob:')) {
            URL.revokeObjectURL(videoPlayer.src);
        }
        videoSource.src = '';
        videoFileName = '';
        videoPlayer.load();

        resetFramePreview();
        timeInput.value = '';
        timeInput.max = null;

        updateButtonStates();
    }

    function resetFramePreview() {
        if (currentFrameUrl) {
            URL.revokeObjectURL(currentFrameUrl);
            currentFrameUrl = null;
        }
        framePreview.src = '';
        framePreview.style.display = 'none';
        previewPlaceholder.style.display = 'block';
    }

    function updateButtonStates() {
        const videoLoaded = videoPlayer.readyState >= videoPlayer.HAVE_METADATA;
        const disableAllPreciseControls = !videoLoaded || isSeeking;

        timeInput.disabled = disableAllPreciseControls;
        timeDecreaseBtn.disabled = disableAllPreciseControls;
        timeIncreaseBtn.disabled = disableAllPreciseControls;
        saveFrameBtn.disabled = disableAllPreciseControls || !currentFrameUrl;
        videoFileInput.disabled = isSeeking;
    }

    function seekToTime(time) {
        return new Promise((resolve) => {
            const onSeeked = () => {
                videoPlayer.removeEventListener('seeked', onSeeked);
                requestAnimationFrame(() => resolve());
            };

            if (Math.abs(videoPlayer.currentTime - time) < 0.01) {
                 requestAnimationFrame(() => resolve());
                 return;
            }

            videoPlayer.addEventListener('seeked', onSeeked);
            videoPlayer.currentTime = time;
        });
    }

    function captureFrameAsBlob() {
        return new Promise((resolve, reject) => {
            try {
                if (hiddenCanvas.width !== videoPlayer.videoWidth || hiddenCanvas.height !== videoPlayer.videoHeight) {
                    hiddenCanvas.width = videoPlayer.videoWidth;
                    hiddenCanvas.height = videoPlayer.videoHeight;
                }
                context.drawImage(videoPlayer, 0, 0, hiddenCanvas.width, hiddenCanvas.height);
                hiddenCanvas.toBlob(blob => {
                    if (blob) resolve(blob);
                    else reject(new Error('无法将Canvas转换为Blob。'));
                }, 'image/png');
            } catch (e) {
                reject(new Error(`捕获帧时出错: ${e.message}`));
            }
        });
    }

    // --- Initial State ---
    updateButtonStates();

</script>

</body>
</html>