How to convert video files to MP4 format using PHP

PHP is a commonly used scripting language used for website development and creating dynamic web pages. However, Php can also be used for video conversion. In this article, we will learn how to convert video files to MP4 format using PHP.

First of all, we need to understand several concepts. A video file consists of multiple frames, each frame representing a moment of video sampling. These frames are compressed into a certain sequence and stored in a file in a special format. Converting video files mainly involves the process of decoding these frames, editing them, and then re-encoding them to a new format.

To achieve video conversion, we need to use two PHP libraries: FFmpeg and FFprobe. FFmpeg is an open source library for processing audio and video. It provides many functions to decode, edit and encode videos. FFprobe is a tool for detecting video files and extracting information.

In order to use these two libraries, you need to install them on the server. This usually requires using the command line interface of the Linux system. You can install them through the following command:

sudo apt-get install ffmpeg
sudo apt-get install ffprobe

After the installation is completed, we can use PHP to call these two libraries to perform video conversion operations. Here is a simple PHP script to convert video files to MP4 format:

<?php $ffmpeg_command = &#39;/usr/bin/ffmpeg&#39;;
$ffprobe_command = &#39;/usr/bin/ffprobe&#39;;

$input_file = &#39;input_video.mp4&#39;;
$output_file = &#39;output_video.mp4&#39;;

// 获取视频信息
$cmd = "$ffprobe_command -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 $input_file";
exec($cmd, $output, $retval);
$duration = floor($output[0]);

// 转换视频文件
$cmd = "$ffmpeg_command -i $input_file -vcodec h264 -acodec mp3 -shortest -preset fast -strict experimental -t $duration -f mp4 -y $output_file";
exec($cmd, $output, $retval);

?>

Let’s see how this script works. First, we defined two variables $ffmpeg_command and $ffprobe_command to specify the locations of FFmpeg and FFprobe. Next, we specify the names of the input and output files, as well as the format of the output file (MP4).

In the next step, we use FFprobe to get the duration of the input video file. We use a system command to run FFprobe, execute the command through the -exec() function and capture the output. The duration value obtained from FFmpeg is stored in the $duration variable.

Finally, we use FFmpeg for the actual video conversion. We specified the names of the input and output files and used the -h264 encoder and -mp3 audio encoder. We set the length to the duration of the video and use the -fast preset to speed up the conversion. We also specified the -strict experimental option to ensure that the latest codecs are used during conversion.

By using FFmpeg and FFprobe like this, we can convert video files to almost any format and perform a variety of editing operations. This makes PHP a very powerful platform for audio and video editing and processing applications.

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