在后台运行ffmpeg进程 [英] Run a ffmpeg process in the background
问题描述
我想使用ffmpeg将视频转换为php中的.flv。目前我有这个工作，但它挂起浏览器，直到文件上传并完成。我一直在查看关于如何在后台运行exec（）进程的php文档，同时使用返回的PID更新进程。这是我发现的：
I am wanting to use ffmpeg to convert video to .flv in php. Currently I have this working, but it hangs the browser until the file is uploaded and is finished. I have been looking at the php docs on how to run an exec() process in the background, while updating the process using the returned PID. Here is what I found:
//Run linux command in background and return the PID created by the OS
function run_in_background($Command, $Priority = 0)
{
if($Priority)
$PID = shell_exec("nohup nice -n $Priority $Command > /dev/null & echo $!");
else
$PID = shell_exec("nohup $Command > /dev/null & echo $!");
return($PID);
}
还有一个技巧，我用来跟踪后台任务是否正在运行使用返回的PID：
There is also a trick which I use to track if the background task is running using the returned PID :
//Verifies if a process is running in linux
function is_process_running($PID)
{
exec("ps $PID", $ProcessState);
return(count($ProcessState) >= 2);
}
我想创建一个单独的.php文件，然后从php运行cli执行这些功能之一？
Am I suppose to create a separate .php file which then runs from the php cli to execute one of these functions? I just need a little nudge in getting this working and then I can take it from there.
谢谢！
推荐答案
我想创建一个单独的.php
文件，然后从php cli
运行以执行这些函数之一？
Am I suppose to create a separate .php file which then runs from the php cli to execute one of these functions?
这可能是我会这样做的：
This is probably the way I would do it :
- PHP页面在数据库中添加一条记录，以指示该文件必须处理
- 并向用户显示一条消息;像你的文件将很快被处理
- 首先，将记录标记为处理
- 执行ffmpeg事件
- 标记文件作为已处理
- 如果尚未处理
- 如果正在处理
- 或者是已被处理，然后可以给他链接到新的视频文件。
这里有几个其他想法：
- 您的应用程序变大的一天，您可以拥有：
- 一个web服务器
- 许多处理服务器;在您的应用程序中，这是ffmpeg的事情，将需要大量的CPU，不提供网页;因此，能够缩放该部分是好的（这是另一个锁定文件，指示它们在数据库中为处理：这样，您将不会有多个处理服务器尝试处理相同的文件）
- 重要/长时间的处理不是Web服务器的工作！
- 您将要转换为除PHP之外的其他部分的处理部分，这将会更容易。
您的处理脚本每隔几分钟发射一次;您可以使用 cron ，如果您位于类似Linux的计算机上。
Your "processing script" would have to be launch every couple of minutes ; you can use cron for that, if you are on a Linux-like machine.
编辑：看到评论后有更多的信息
由于处理部分是从CLI完成的，而不是从Apache完成，您不需要任何背景操作：您可以使用
shell_exec，当完成这项工作后，该命令将返回到您的PHP脚本的整个输出。As the processing part is done from CLI, and not from Apache, you don't need anykind of "background" manipulations : you can just use
shell_exec, which will return the whole ouput of the command to your PHP script when it's finished doing it's job.对于观看网页的用户来说处理，看起来像后台处理;在某种程度上，这将是另一个进程的处理（甚至可能在另一台机器上）。
For the user watching the web page saying "processing", it will seem like background processing ; and, in a way, it'll be, as the processing will be done by another processus (maybe even on another machine).
但是，对于你来说，简单一点：
But, for you, it'll be much simpler :
- 一个网页（没有背景）
- 一个CLI脚本，没有背景资料。
您的处理脚本可能看起来像这样，我想：
Your processing script could look like something like this, I suppose :
// Fetch informations from DB about one file to process // and mark it as "processing" // Those would be fetched / determined from the data you just fetched from DB $in_file = 'in-file.avi'; $out_file = 'out-file.avi'; // Launch the ffmpeg processing command (will probably require more options ^^ ) // The PHP script will wait until it's finished : // No background work // No need for any kind of polling $output = shell_exec('ffmpeg ' . escapeshellarg($in_file) . ' ' . escapeshellarg($out_file)); // File has been processed // Store the "output name" to DB // Mark the record in DB as "processed"真的比你想象的更容易，不是吗？ ;-)
只需不要担心背景的东西：只有重要的是处理脚本是定期从crontab启动的。Really easier than what you first thought, isn't it ? ;-)
Just don't worry about the background stuff anymore : only thing important is that the processing script is launched regularly, from crontab.
希望有助于： - ）
Hope this helps :-)这篇关于在后台运行ffmpeg进程的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
