如何将 iOS 应用预览视频放大到 1080 x 1920?

问题描述

我刚刚使用 QuickTime Player 和 Lightning 数据线拍摄了我在 iPhone 6 上运行的新应用的视频.之后我在 iMovie 中创建了一个 App Preview 项目，将其导出并成功上传到 iTunes Connect.

I just captured a video of my new app running on an iPhone 6 using QuickTime Player and a Lightning cable. Afterwards I created an App Preview project in iMovie, exported it and could successfully upload it to iTunes Connect.

Apple 要求开发者根据屏幕尺寸上传不同分辨率的应用预览，即:

Apple requires developers to upload App Previews in different resolutions dependent on screen size, namely:

• iPhone 5(S):1080 x 1920 或 640 x 1136
• iPhone 6:750 x 1334(我拥有的)
• iPhone 6+:1080 x 1920

• iPhone 5(S): 1080 x 1920 or 640 x 1136
• iPhone 6: 750 x 1334 (what I have)
• iPhone 6+: 1080 x 1920

显然，1080 x 1920 一石二鸟.我知道升级不是完美的解决方案，但它满足了我的需求.因为我没有 6+，另一个录音会话不会成功.

Obviously, 1080 x 1920 is killing two birds with one stone. I know that upscaling isn't the perfect solution, but it's meeting my needs. Since I don't own a 6+, another recording session won't do the trick.

不幸的是，iTunes Connect 对接受什么非常挑剔.这是我尝试过的，但无济于事:

Unfortunately, iTunes Connect is extremely picky about what to accept. Here's what I tried, to no avail:

• Handbrake、iMovie、QuickTime 不支持放大
• MPEG 流剪辑
• ffmpeg -i input.mp4 -acodec copy -vf scale=1080:1920 output.mp4

奇怪的是，当我尝试上传 ffmpeg 的 output.mp4 时，iTunes Connect 一直抱怨分辨率错误.

Strangely enough, iTunes Connect keeps complaining about the wrong resolution when I try to upload the output.mp4 of ffmpeg.

推荐答案

最后，ffmpeg -i input.mp4 -acodec copy -crf 12 -vf scale=1080:1920,setsar=1:1 output.mp4 成功了！

事实证明 ffmpeg 试图对纵横比进行智能处理，因此实际尺寸为 1079x1920，纵横比为 2000:2001.

Turns out that ffmpeg tries to be smart about aspect ratio, so that the actual size is 1079x1920 with an aspect ratio of 2000:2001.

• setsar=1:1 强制长宽比为 1:1，因此正确分辨率
• -crf 12 作为所需的质量大致与 iMovie 创建的原始文件相同的文件大小，所以它应该是一个安全的赌注比特率

• setsar=1:1 forces an aspect ratio of 1:1 and hence, the right resolution
• -crf 12 as desired quality roughly results in the same file size as the original file created by iMovie, so it should be a safe bet bit rate-wise

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