ffmpeg转换任何用户视频文件以在手机上运行h264 mp4

Question

So, i have kind of accepted this task on work but im really not sure if its possible.

We are going to build a website where users can upload videos from their computers and mobile phone browsers. The video files can be a large range of aspect ratios, width, height, codex and file formats.

I will have access to ffmpeg from php exec command on a web server.

Is it possible to use this to convert the user files to one file format that works on computers, android and iphone.

The requirements is that we can set a max width, to witch the video will be scaled, dynamically to match height.

Does anyone know is this can be done, and be done in a reasonable amount of time. Will do project on 2 days. And if so some pointers in the right direction would be nice.

Answer 1

Had the same problem but solved by using HandBrake the open source video transcoder

https://handbrake.fr/

Answer 2

If your target can only be one file format, then I would choose mp4 baseline. (However some browsers won't play it, which is why the html tag offers multiple source flags, which usually include webm and ogg video...)

Using ffprobe -show_streams $uploadedFile you can get the dimensions (and aspect ratio) of the file. Using math you can get the new dimensions based on your needs.

$newDim=$new_width.":".$new_height;
$output  = shell_exec("/usr/bin/ffmpeg -i $uploadedFile -f mp4 \
-c:a libfdk_aac -b:a 128k -c:v libx264 -vprofile baseline \
-movflags faststart -vf scale=$newDim $output");```

Here is the breakdown:

f mp4              > format mp4
c:a libfdk_aac     > audio codec
c:v libx264        > video codec
vprofile baseline  > minimal codec usage for mobile
movflags faststart > put the moov atom at the beginning of file
$output            > should have '.mp4' as a file ending

Of course the devil is in the details (and the number of processing cores you can throw at an online converter), but this will get you up and running at least.

Edit: Actually answered the question. :)

By the way, ffmpeg does offer the vf flag: -vf scale=320,-1 , but sometimes it gives you a dimension not divisible by 2 which throws an error in x264 encoding. Its better to do the math yourself.