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• 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 :


  


• FFmpeg and QuickTime Player dimensions of video do not match [duplicate]

  31 mai 2020, par GRS

  I have a video.mp4, which I scaled using FFmpeg to get out.mp4. The new video has the following probe :

  



  {'streams': [{'index': 0,
   'codec_name': 'h264',
   'codec_long_name': 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
   'profile': 'High',
   'codec_type': 'video',
   'codec_time_base': '1/50',
   'codec_tag_string': 'avc1',
   'codec_tag': '0x31637661',
   'width': 886,
   'height': 1920,
   'coded_width': 896,
   'coded_height': 1920,
   'has_b_frames': 2,
   'sample_aspect_ratio': '5120:1329',
   'display_aspect_ratio': '16:9',
   'pix_fmt': 'yuv420p',
   'level': 40,
   'chroma_location': 'left',
   'refs': 1,
   'is_avc': 'true',
   'nal_length_size': '4',
   'r_frame_rate': '25/1',
   'avg_frame_rate': '25/1',
   'time_base': '1/12800',
   'start_pts': 0,
   'start_time': '0.000000',
   'duration_ts': 384512,
   'duration': '30.040000',
   'bit_rate': '490832',
   'bits_per_raw_sample': '8',
   'nb_frames': '751',
   'disposition': {'default': 1,
    'dub': 0,
    'original': 0,
    'comment': 0,
    'lyrics': 0,
    'karaoke': 0,
    'forced': 0,
    'hearing_impaired': 0,
    'visual_impaired': 0,
    'clean_effects': 0,
    'attached_pic': 0,
    'timed_thumbnails': 0},
   'tags': {'language': 'und', 'handler_name': 'VideoHandler'}}],
 'format': {'filename': 'out.mp4',
  'nb_streams': 1,
  'nb_programs': 0,
  'format_name': 'mov,mp4,m4a,3gp,3g2,mj2',
  'format_long_name': 'QuickTime / MOV',
  'start_time': '0.000000',
  'duration': '30.040000',
  'size': '1852948',
  'bit_rate': '493461',
  'probe_score': 100,
  'tags': {'major_brand': 'isom',
   'minor_version': '512',
   'compatible_brands': 'isomiso2avc1mp41',
   'encoder': 'Lavf58.20.100'}}}


  



  I am expecting my video player to say the video is 886 x 1920, however, it is 3413:1920.


  



  What could be the error ? I am using pix_frmt=yuva420p and codec=libx264 to create the video.

  



  The error is that my ascpect ratio remains 16:9, which is the original input video, when it should automatically change to 9:19. E.g. 3413 = 1920 * 16 / 9. So why isn't the ascpect ratio changed when the video is scaled ?