Recherche avancée

Sur d’autres sites (9737)

• In ffmpeg, how do I scale dvdsub subtitles to match video size, using scale2ref filter ?

  24 janvier 2017, par Steve Moseley

  I have an mpeg file, recorded from live TV, containing video and multiple audio and subtitles streams. My eventual goal is to be able to create a smaller video file as the mpeg file is multi-gigabytes in size. My first step on that path is just to be able to select one each of the video, audio and subtitle streams and copy them to an mkv file, discarding the streams I’m not interested in. (I chose mkv as it will allow storing a dvdsub subtitle stream where other container formats wont.)

  The problem I’m having is that the dvdsub subtitles appear very small when I play the output video, when I researched this I found that ffmpeg doesn’t automatically scale the subtitles to match the source video : https://trac.ffmpeg.org/ticket/4744

  I have tried using the scale2ref filter, but I don’t understand the documentation, and the example they give makes no sense to me (see examples below).

  I have a command that selects the three streams and copies 1 minute to the output, as follows :

  ffmpeg -ss 00:28:00.200 -i Hillary-2016-08-21.mpg -t 00:01:00.000 -map 0:0 -c:v copy -map 0:3 -c:a copy -map 0:6 -c:s dvdsub cut.mkv

  Here’s the output :

  Input #0, mpegts, from 'Hillary-2016-08-21.mpg':
  
    Duration: 01:30:00.06, start: 20852.199389, bitrate: 6813 kb/s
  
    Program 1 
  
      Stream #0:0[0xfa]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x12c](eng): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
  
      Stream #0:2[0x131](ita): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired)
  
      Stream #0:3[0x191](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
      Stream #0:4[0x3ea]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:5[0x3ec]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:6[0x3fc](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:7[0x1f40]: Unknown: none ([5][0][0][0] / 0x0005)
  
  File 'cut.mkv' already exists. Overwrite ? [y/N] y
  
  Output #0, matroska, to 'cut.mkv':
  
    Metadata:
  
      encoder         : Lavf57.56.100
  
      Stream #0:0: Video: h264 (Main) (H264 / 0x34363248), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 50 tbr, 1k tbn, 90k tbc
  
      Stream #0:1(eng): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), 384 kb/s
  
      Stream #0:2(eng): Subtitle: dvd_subtitle (dvdsub) (hearing impaired)
  
      Metadata:
  
        encoder         : Lavc57.64.101 dvdsub
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:3 -> #0:1 (copy)
  
    Stream #0:6 -> #0:2 (dvb_subtitle (dvbsub) -> dvd_subtitle (dvdsub))
  
  Press [q] to stop, [?] for help
  
  frame= 2956 fps=0.0 q=-1.0 Lsize=   39612kB time=00:00:59.99 bitrate=5408.7kbits/s speed= 216x    
  
  video:36702kB audio:2896kB subtitle:23kB other streams:0kB global headers:0kB muxing overhead: unknown

  The documentation for scale2ref gives an example with an overlay, and I don’t want to overlay anything, I just want to resize the subtitles stream. Here’s their example :

  'scale2ref[b][a];[a][b]overlay'

  The closest I’ve got is something like this :

  ffmpeg -ss 00:28:00.200 -i Hillary-2016-08-21.mpg -t 00:01:00.000 -map 0:0 -c:v copy -map 0:3 -c:a copy -filter_complex "[0:6]scale2ref[b]" -map "[b]"   cut.mkv

  And the output is :

  Input #0, mpegts, from 'Hillary-2016-08-21.mpg':
  
    Duration: 01:30:00.06, start: 20852.199389, bitrate: 6813 kb/s
  
    Program 1 
  
      Stream #0:0[0xfa]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x12c](eng): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
  
      Stream #0:2[0x131](ita): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired)
  
      Stream #0:3[0x191](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
      Stream #0:4[0x3ea]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:5[0x3ec]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:6[0x3fc](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:7[0x1f40]: Unknown: none ([5][0][0][0] / 0x0005)
  
  Streamcopy requested for output stream 0:0, which is fed from a complex filtergraph. Filtering and streamcopy cannot be used together.

  And I don’t really understand how I can use a filter and direct my resized subtitle stream into the output file.

  Any help appreciated ! Thanks !

• Pointers returned by xlib don't match any existing window IDs

  1er septembre 2022, par Kroltan

  I'm using some X11 bindings to query some window information and later pass it to FFmpeg. FFmpeg expects a "window ID" given in hexadecimal notation.

  


  This notation seems somewhat standard, as it is returned by programs like xwininfo or wmctrl. I haven't found much information about it, but it seems to just be the hexadecimal representation of the window pointer ? If I take the ID string given by these programs and give it to FFmpeg, it is able to capture the window correctly :

  


  $ xwininfo

xwininfo: Please select the window about which you
          would like information by clicking the
          mouse in that window.

xwininfo: Window id: 0x2800014 "Desktop — Plasma"

$ ffmpeg -f x11grab -window_id 0x2800014 -i :0+0,0 -f apng -vframes 1 out.png
# works fine


  


  However, if I try listing all the windows in code :

  


  var root = Window.None;
var parent = Window.None;
Xlib.XQueryTree(_display, Xlib.XDefaultRootWindow(_display), ref root, ref parent, out var children);

var ids = children
    .Select(ptr => $"0x{(ulong) ptr:x}")
    .ToArray();


  


  I don't see 0x2800014 in the results (even disregardingleading zeroes), and if I try running FFmpeg on one of those results, it fails terribly :

  


  $ ffmpeg -f x11grab -window_id 0x4400003 -i :0+0,0 -f apng -vframes 1

# snipped for brevity

Trailing option(s) found in the command: may be ignored.
[x11grab @ 0x55b811a8da40] Cannot get the image data event_error: response_type:0 error_code:8 sequence:10 resource_id:167772160 minor_code:4 major_code:130.
[x11grab @ 0x55b811a8da40] Continuing without shared memory.
[x11grab @ 0x55b811a8da40] Cannot get the image data event_error: response_type:0 error_code:8 sequence:11 resource_id:71303171 minor_code:0 major_code:73.
Input #0, x11grab, from ':0+0,0':
  Duration: N/A, bitrate: 38361 kb/s
  Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 200x200, 38361 kb/s, 29.97 fps, 1000k tbr, 1000k tbn
At least one output file must be specified


  


  So I must conclude my guess that they are hex pointers is incorrect, or that the Window type is not the pointer itself, but then the question stands, how can I get the actual window IDs so I can pass them to FFmpeg ?

  


• PHP FFMPEG match Instagram aspect ratio requirements

  19 mai 2021, par Linesofcode

  As stated here, the Instagram API requirements to upload a video are :

  


  - Picture size
- - Maximum columns (horizontal pixels): 1920
- - Minimum aspect ratio [cols / rows]: 4 / 5
- - Maximum aspect ratio [cols / rows]: 16 / 9


  


  I'm having some problems figuring it out if the aspect ratio matches. I grab the width and height of the video like this :

  


  $ffprobe = \FFMpeg\FFProbe::create();
$video = $ffprobe->streams($file)->videos()->first();
$width = $video->get('width');
$height = $video->get('height');


  


  And then I know the ratio by dividing the width by height.

  


  The Instagram requirements about Portrait & Landscape videos are :

  


  Portrait - min: 0.8 ; max: 0.99
Landscape - min: 1.01 ; max: 1.78


  


  So why does a video of 848x480 (aspect ratio of 1.76) fails to upload to Instagram by returning "The video format is not supported" and how can I be completely sure that the aspect ratio matches the requirements before trying to upload ?

  


  Edit

  


  The full validation of Instagram requirements :

  


  $video = $ffprobe->streams($file)->videos()->first();
$audio = $ffprobe->streams($file)->audios()->first();
$codec = $video->get('codec_name');
$frameRate = eval('return ' . $video->get('avg_frame_rate') . ';'); // 30/1 -> 30
$width = $video->get('width');
$height = $video->get('height');
$duration = $video->get('duration');

$ratio = round($width / $height, 3);

// Portrait
if ($width < $height)
    if ($ratio < 0.8 || $ratio > 0.99)
        return false;
        
// Landscape
if ($width > $height)
    if ($ratio < 1.01 || $ratio > 1.78)
        return false;


if (!in_array($codec, ['h264', 'hevc']))
    return false;

if ($frameRate < 23 || $frameRate > 60)
    return false;

if ($width > 1920)
    return false;

if ($duration < 3 || $duration > 60)
    return false;

if ($audio)
{
    $aCodec = $audio->get('codec_name');

    if ($aCodec != 'aac')
        return false;
}

return true;


  


  Sample not uploading into Instagram :