短视频系统源码,如何限制视频分辨率?
导言:
在短视频系统源码的许多场景下,我们需要确保用户上传的视频满足一定的分辨率要求,以保证在后续的处理中能够获得良好的视觉效果。在短视频系统源码开发时需要对用户上传的视频分辨率进行限制,以确保页面加载和播放的性能。
技术实现步骤:
1、创建视频元素和 Canvas:
const video = document.createElement('video'); const canvas = document.createElement('canvas'); const context = canvas.getContext('2d');
2、加载视频文件
video.preload = 'metadata'; video.src = URL.createObjectURL(videoFile);
3、获取视频元数据
video.onloadedmetadata = () => { const videoWidth = video.videoWidth; const videoHeight = video.videoHeight; // 进行分辨率校验... };
4.分辨率校验逻辑:
// 校验最小分辨率 if (minResolution && (videoWidth < minResolution[0] || videoHeight < minResolution[1])) { reject(`分辨率太小,最小要求 ${minResolution[0]}x${minResolution[1]}`); return; } // 校验最大分辨率 if (maxResolution && (videoWidth > maxResolution[0] || videoHeight > maxResolution[1])) { reject(`分辨率太大,最大允许 ${maxResolution[0]}x${maxResolution[1]}`); return; } // 通过校验 resolve(true);
5、异常处理:
video.onerror = () => { reject('无法读取视频信息'); };
6、使用 Canvas 提取视频帧:
video.onloadeddata = () => { canvas.width = video.videoWidth; canvas.height = video.videoHeight; context.drawImage(video, 0, 0, canvas.width, canvas.height); };
4. 示例用法:
const videoFile: File = /* 从文件输入获取的 File 对象 */; const minResolution: Resolution = [640, 480]; const maxResolution: Resolution = [1920, 1080]; validateResolutionInBrowser(videoFile, minResolution, maxResolution) .then((isValid: boolean) => { console.log(isValid ? '分辨率符合要求' : '分辨率不符合要求'); }) .catch((error: string) => { console.error(`校验失败: ${error}`); });
完整代码
type Resolution = [number, number]; function validateResolutionInBrowser(videoFile: File, minResolution?: Resolution, maxResolution?: Resolution): Promise<boolean> { return new Promise((resolve, reject) => { const video = document.createElement('video'); const canvas = document.createElement('canvas'); const context = canvas.getContext('2d'); video.preload = 'metadata'; video.src = URL.createObjectURL(videoFile); video.onloadedmetadata = () => { const videoWidth = video.videoWidth; const videoHeight = video.videoHeight; // 校验最小分辨率 if (minResolution && (videoWidth < minResolution[0] || videoHeight < minResolution[1])) { reject(`分辨率太小,最小要求 ${minResolution[0]}x${minResolution[1]}`); return; } // 校验最大分辨率 if (maxResolution && (videoWidth > maxResolution[0] || videoHeight > maxResolution[1])) { reject(`分辨率太大,最大允许 ${maxResolution[0]}x${maxResolution[1]}`); return; } // 通过校验 resolve(true); }; video.onerror = () => { reject('无法读取视频信息'); }; video.onloadeddata = () => { // 使用 Canvas 提取视频帧 canvas.width = video.videoWidth; canvas.height = video.videoHeight; context.drawImage(video, 0, 0, canvas.width, canvas.height); }; }); } // 示例用法: const videoFile: File = /* 从文件输入获取的 File 对象 */; const minResolution: Resolution = [640, 480]; const maxResolution: Resolution = [1920, 1080]; validateResolutionInBrowser(videoFile, minResolution, maxResolution) .then((isValid: boolean) => { console.log(isValid ? '分辨率符合要求' : '分辨率不符合要求'); }) .catch((error: string) => { console.error(`校验失败: ${error}`); });
结论:
通过结合 TypeScript 和 HTML5 中的视频元素,我们可以更好地在 短视频系统源码中处理用户上传的视频文件,提高用户体验和整体性能。
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