php和ffmpeg-执行智能视频转换

这对我很有用:

$data = 'ffmpeg output';
$matches = array();

if (!preg_match('/Stream #(?:[0-9\.]+)(?:.*)\: Video: (?P<videocodec>.*) (?P<width>[0-9]*)x(?P<height>[0-9]*)/',$data,$matches)
   preg_match('/Could not find codec parameters \(Video: (?P<videocodec>.*) (?P<width>[0-9]*)x(?P<height>[0-9]*)\)/',$data,$matches)

这可能不会 总是 工作,但大多数时候都是有效的,这在我看来已经足够好了:)

好啊。我有一个功能齐全的解决方案。这是为任何人谁发现这个问题想做同样的事情。我的代码可能不太优雅,但它可以完成任务。

获取ffmpeg的输出

首先,我必须从ffmpeg-i获得输出,这本身就是一个挑战。多亏黑格尔蒙的回答 my other question ,我终于能够让它与 2>&1 在我的命令结束时。感谢Evert对这个问题的回答,我能够用 preg_match 查找原始文件的高度和宽度。

function get_vid_dim($file)
{
    $command = '/usr/bin/ffmpeg -i ' . escapeshellarg($file) . ' 2>&1';
    $dimensions = array();
    exec($command,$output,$status);
    if (!preg_match('/Stream #(?:[0-9\.]+)(?:.*)\: Video: (?P<videocodec>.*) (?P<width>[0-9]*)x(?P<height>[0-9]*)/',implode('\n',$output),$matches))
    {
        preg_match('/Could not find codec parameters \(Video: (?P<videocodec>.*) (?P<width>[0-9]*)x(?P<height>[0-9]*)\)/',implode('\n',$output),$matches);
    }
    if(!empty($matches['width']) && !empty($matches['height']))
    {
        $dimensions['width'] = $matches['width'];
        $dimensions['height'] = $matches['height'];
    }
    return $dimensions;
}

确定最佳尺寸

我编写这个函数是为了确定用于转换的最佳维度。它采用原始尺寸、目标尺寸以及是否强制转换为目标纵横比(由其宽度/高度决定)。目标维度将始终是此函数可以返回的最大结果。

function get_dimensions($original_width,$original_height,$target_width,$target_height,$force_aspect = true)
{
    // Array to be returned by this function
    $target = array();
    // Target aspect ratio (width / height)
    $aspect = $target_width / $target_height;
    // Target reciprocal aspect ratio (height / width)
    $raspect = $target_height / $target_width;

    if($original_width/$original_height !== $aspect)
    {
        // Aspect ratio is different
        if($original_width/$original_height > $aspect)
        {
            // Width is the greater of the two dimensions relative to the target dimensions
            if($original_width < $target_width)
            {
                // Original video is smaller.  Scale down dimensions for conversion
                $target_width = $original_width;
                $target_height = round($raspect * $target_width);
            }
            // Calculate height from width
            $original_height = round($original_height / $original_width * $target_width);
            $original_width = $target_width;
            if($force_aspect)
            {
                // Pad top and bottom
                $dif = round(($target_height - $original_height) / 2);
                $target['padtop'] = $dif;
                $target['padbottom'] = $dif;
            }
        }
        else
        {
            // Height is the greater of the two dimensions relative to the target dimensions
            if($original_height < $target_height)
            {
                // Original video is smaller.  Scale down dimensions for conversion
                $target_height = $original_height;
                $target_width = round($aspect * $target_height);
            }
            //Calculate width from height
            $original_width = round($original_width / $original_height * $target_height);
            $original_height = $target_height;
            if($force_aspect)
            {
                // Pad left and right
                $dif = round(($target_width - $original_width) / 2);
                $target['padleft'] = $dif;
                $target['padright'] = $dif;
            }
        }
    }
    else
    {
        // The aspect ratio is the same
        if($original_width !== $target_width)
        {
            if($original_width < $target_width)
            {
                // The original video is smaller.  Use its resolution for conversion
                $target_width = $original_width;
                $target_height = $original_height;
            }
            else
            {
                // The original video is larger,  Use the target dimensions for conversion
                $original_width = $target_width;
                $original_height = $target_height;
            }
        }
    }
    if($force_aspect)
    {
        // Use the target_ vars because they contain dimensions relative to the target aspect ratio
        $target['width'] = $target_width;
        $target['height'] = $target_height;
    }
    else
    {
        // Use the original_ vars because they contain dimensions relative to the original's aspect ratio
        $target['width'] = $original_width;
        $target['height'] = $original_height;
    }
    return $target;
}

用法

下面是一些你将从中得到什么的例子 get_dimensions() 使事情更清楚:

get_dimensions(480,360,640,480,true);
-returns: Array([width] => 480, [height] => 360)

get_dimensions(480,182,640,480,true);
-returns: Array([padtop] => 89, [padbottom] => 89, [width] => 480, [height] => 360)

get_dimensions(480,182,640,480,false);
-returns: Array([width] => 480, [height] => 182)

get_dimensions(640,480,480,182,true);
-returns: Array([padleft] => 119, [padright] => 119, [width] => 480, [height] => 182)

get_dimensions(720,480,640,480,true);
-returns: Array([padtop] => 27, [padbottom] => 27, [width] => 640, [height] => 480)

get_dimensions(720,480,640,480,false);
-returns: Array([width] => 640, [height] => 427)

成品

现在,把它们放在一起:

$src = '/var/videos/originals/original.mpg';
$original = get_vid_dim($src);
if(!empty($original['width']) && !empty($original['height']))
{
    $target = get_dimensions($original['width'],$original['height'],640,480,true);
    $command = '/usr/bin/ffmpeg -i ' . $src . ' -ab 96k -b 700k -ar 44100 -s ' . $target['width'] . 'x' . $target['height'];
    $command .= (!empty($target['padtop']) ? ' -padtop ' . $target['padtop'] : '');
    $command .= (!empty($target['padbottom']) ? ' -padbottom ' . $target['padbottom'] : '');
    $command .= (!empty($target['padleft']) ? ' -padleft ' . $target['padleft'] : '');
    $command .= (!empty($target['padright']) ? ' -padright ' . $target['padright'] : '');
    $command .= ' -acodec mp3 /var/videos/converted/target.flv 2>&1';

    exec($command,$output,$status);

    if($status == 0)
    {
        // Success
        echo 'Woohoo!';
    }
    else
    {
        // Error.  $output has the details
        echo '<pre>',join('\n',$output),'</pre>';
    }
}

我不熟悉PHP,但几个月前我写了一个实用程序来使用C语言中的ffmpeg。我用正则表达式来做这个。有一些正则表达式可以帮助您:

// this is for version detection
"FFmpeg version (?<version>(\w|\d|\.|-)+)"
// this is for duration parsing
"Duration: (?<hours>\d{1,3}):(?<minutes>\d{2}):(?<seconds>\d{2})(.(?<fractions>\d{1,3}))?"

// these are connected:
// 0) this is base for getting stream info
"Stream #(?<number>\d+?\.\d+?)(\((?<language>\w+)\))?: (?<type>.+): (?<data>.+)"
// 1) if the type is audio:
"(?<codec>\w+), (?<frequency>[\d]+) (?<frequencyUnit>[MK]?Hz), (?<chanel>\w+), (?<format>\w+)(, (?<bitrate>\d+) (?<bitrateUnit>[\w/]+))?"
// 2) if the type is video:
"(?<codec>\w+), (?<format>\w+), (?<width>\d+)x(?<height>\d+), (?<bitrate>\d+(\.\d+)?) (?<bitrateUnit>[\w\(\)]+)"

因此,获得宽度和高度可以计算纵横比。

注意:我知道在某些情况下表达式可能会失败。