php - 使用 php、ffmpeg 和 proc_open 逐帧读取视频

Question

我想使用 proc_open 从使用 ffmpeg 的视频中读取每一帧，然后使用 PHP 对这些帧进行处理。
这是一个相反的例子——它从 PHP 逐帧发送到 ffmpeg:

$descriptors = array(
    0 => array("pipe", "r"),

    1 => array("pipe", "w"), 
    2 => array("file", "C:/error-output.txt", "a")  
);

$frames = glob('Q:/images/*.jpg');


$command = "ffmpeg -f image2pipe -pix_fmt rgb24 -framerate 10 -c:v mjpeg -i - ".
                "-r 10 -vcodec libx264 -pix_fmt yuv420p  -preset faster -crf 17 ".
                "-y test.mp4";

$ffmpeg = proc_open($command, $descriptors, $pipes);

if (!is_resource($ffmpeg))
{
    die('Could not run ffmpeg');

}

foreach ($frames AS $frame)
{

    fwrite($pipes[0], file_get_contents($frame) );
}

fclose($pipes[0]);

这就是我正在尝试但无法正确解决的方法:

$descriptors = array(
    0 => array("pipe", "r"),

    1 => array("pipe", "w"),  write to
    2 => array("file", "C:/error-output.txt", "a") 
);


$command = "ffmpeg -i 1.gif -ss 00:00:3 -s 650x390 -vframes 100 -c:v png -f image2pipe -";

$ffmpeg = proc_open($command, $descriptors, $pipes);

if (!is_resource($ffmpeg))
{
    die('Could not run ffmpeg');

}

while (!feof($pipes[1]))
{
    $frame = fread($pipes[1], 5000);
}

fclose($pipes[1]);

最大的问题是我不知道要从 ffmpeg 读取多少数据才能获得整个帧。

Answer 1

$descriptors = array(
    0 => array("pipe", "r"),    
    1 => array("pipe", "w"), 
    2 => array("file", "C:/path/error-output.txt", "a") 
);

$command = 'ffmpeg -i INPUT.mp4 -ss 00:00:10 -t 120 -c:v png -f image2pipe  -compression_level 0 -';

$ffmpeg = proc_open($command, $descriptors, $pipes);

if (!is_resource($ffmpeg))
{
    die('Could not run ffmpeg');

}

$k = 0;

$buff = '';

$blend = 0; 

while (!feof($pipes[1]))
{
    $buff .= fread($pipes[1], 50000);

    $pos = strpos($buff, chr(137).'PNG', 1);

    if ($pos !== false)
    {
        $frame = substr($buff, 0, $pos);
        $buff = substr($buff, $pos);

        handleFrame($frame, $k);    

        $k++;       
    }
}

handleFrame($buff, $k);

fclose($pipes[0]);
fclose($pipes[1]);



function handleFrame(&$str, $num)
{
    $im = imagecreatefromstring($str);
    ...
}