Recherche avancée
Autres articles (95)
-
Le profil des utilisateurs
12 avril 2011, parChaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...) -
Configurer la prise en compte des langues
15 novembre 2010, parAccéder à la configuration et ajouter des langues prises en compte
Afin de configurer la prise en compte de nouvelles langues, il est nécessaire de se rendre dans la partie "Administrer" du site.
De là, dans le menu de navigation, vous pouvez accéder à une partie "Gestion des langues" permettant d’activer la prise en compte de nouvelles langues.
Chaque nouvelle langue ajoutée reste désactivable tant qu’aucun objet n’est créé dans cette langue. Dans ce cas, elle devient grisée dans la configuration et (...) -
XMP PHP
13 mai 2011, parDixit Wikipedia, XMP signifie :
Extensible Metadata Platform ou XMP est un format de métadonnées basé sur XML utilisé dans les applications PDF, de photographie et de graphisme. Il a été lancé par Adobe Systems en avril 2001 en étant intégré à la version 5.0 d’Adobe Acrobat.
Étant basé sur XML, il gère un ensemble de tags dynamiques pour l’utilisation dans le cadre du Web sémantique.
XMP permet d’enregistrer sous forme d’un document XML des informations relatives à un fichier : titre, auteur, historique (...)
Sur d’autres sites (6940)
-
Why convert wav to mp3 get different length
13 avril 2022, par sybilI use NAudio and NAudio.Lame to convert a wav file to mp3 file,code like that :


using var reader = new WaveFileReader(file);
using var ms = new MemoryStream();
var writer = new LameMP3FileWriter(ms, reader.WaveFormat, 32);
reader.CopyTo(writer);
writer.Flush();
File.WriteAllBytes(file.Replace("wav", "mp3"), ms.ToArray());


the wav file length is 1500ms,but the mp3 file length is 1557ms.


And I do the same thing by using ffmpeg.exe,command like that :


ffmpeg -i c:\2\xxx.wav c:\2\xxx.mp3


the output info :


ffmpeg version 5.0.1-essentials_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
 built with gcc 11.2.0 (Rev7, Built by MSYS2 project)
 configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-sdl2 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libgme --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libtheora --enable-libvo-amrwbenc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-librubberband
 libavutil 57. 17.100 / 57. 17.100
 libavcodec 59. 18.100 / 59. 18.100
 libavformat 59. 16.100 / 59. 16.100
 libavdevice 59. 4.100 / 59. 4.100
 libavfilter 8. 24.100 / 8. 24.100
 libswscale 6. 4.100 / 6. 4.100
 libswresample 4. 3.100 / 4. 3.100
 libpostproc 56. 3.100 / 56. 3.100
Guessed Channel Layout for Input Stream #0.0 : mono
Input #0, wav, from 'c:\2\xxx.wav':
 Duration: 00:00:01.50, bitrate: 768 kb/s
 Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, mono, s16, 768 kb/s
Stream mapping:
 Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
Press [q] to stop, [?] for help
Output #0, mp3, to 'c:\2\xxx.mp3':
 Metadata:
 TSSE : Lavf59.16.100
 Stream #0:0: Audio: mp3, 48000 Hz, mono, s16p
 Metadata:
 encoder : Lavc59.18.100 libmp3lame
size= 12kB time=00:00:01.51 bitrate= 66.2kbits/s speed= 137x
video:0kB audio:12kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.928711%


And I get a mp3 file which length is 1536ms.
So,why the length changed ?
Thanks for reading.


-
How correctly show video with transparency in Qt with OpenCV + FFMpeg
11 avril 2022, par TheEnigmistI'm trying to show a video with transparency in a Qt6 application using OpenCV + FFMPEG.
Actually those are tool versions :


- 

- Win 11
- Qt 6.3.0
- OpenCV 4.5.5 (built with CMake)
- FFMPEG 2022-04-03-git-1291568c98-full_build-www.gyan.dev










I've used a base .mov video with transparency as test (link provided below).
First of all I've converted .mov video to .webm video (VP9) and I see in output text that alpha channel remains




ffmpeg -i '.\Retro Bars.mov' -c:v libvpx-vp9 -crf 30 -b:v 0 output.webm




Input #0, mov,mp4,m4a,3gp,3g2,mj2,
 ...
 Stream #0:0[0x1](eng): Video: qtrle (rle / 0x20656C72), argb(progressive),
 ...

Output #0, webm, 
 ...
 Stream #0:0(eng): Video: vp9, yuva420p(tv, progressive),
 ...


But when I show info of output file with ffmpeg it loses alpha channel :




ffmpeg -i .\output.webm




Input #0, matroska,webm,
 ...
 Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv, progressive),
 ...


If I open output.webm with OBS it is shown correctly without a background, as shown in picture :



If I try to open it with OpenCV + FFMPEG it shows a black background under bars, as shown in picture :



This is how I load video in Qt :


cv::VideoCapture capture;
capture.open(filename, cv::CAP_FFMPEG);
capture.set(cv::CAP_PROP_CONVERT_RGB, false); // try forcing load alpha channel
... //in a thread
while (capture.read(frame)) {
 qDebug() << "c" << frame.channels() << "t" << frame.type() << "d" << frame.depth(); // output: c 3 t 16 d 0
 cv::cvtColor(frame, frame, cv::COLOR_BGR2RGBA); //useless since no alpha channel is detected
 img = QImage(frame.data, frame.cols, frame.rows, QImage::Format_RGBA8888);
 emit processedImage(img); // to show image in a QLabel with QPixmap::fromImage(img)
}


I think the problem is when I load the video with OpenCV, it doens't detect alpha channel, since I can load correctly in other player (obs, html5, etc.)


What I'm wrong with all process to show this video in Qt with transparency ?


EDIT : Added dropbox link with test video + ffmpeg outputs :
sample items


-
ffmpeg "Time code of first frame" not making sense [closed]
23 janvier, par Kevin VaskoI can't seem to make sense of where ffmpeg is coming up with the "Time code of first frame" value.


My original file that I am using.


This video has the general timestamps of the original encoding date (aka the start time of the video the way I understanding it) and a duration of 8 min and 52s


$ mediainfo GL0100002_output.mp4 
General
Complete name : GL0100002_output.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 93.7 MiB
Duration : 8 min 52 s
Overall bit rate : 1 476 kb/s
Encoded date : UTC 2022-02-23 15:18:42
Tagged date : UTC 2022-02-23 15:18:42
Writing application : Lavf58.29.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 8 min 52 s
Bit rate : 1 342 kb/s
Width : 848 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.138
Stream size : 85.2 MiB (91%)
Title : GoPro AVC 
Writing library : x264 core 155 r2917 0a84d98
Encoding settings : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language : English
Encoded date : UTC 2022-02-23 15:18:42
Tagged date : UTC 2022-02-23 15:18:42
Color range : Full
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 8 min 52 s
Bit rate mode : Constant
Bit rate : 129 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 8.16 MiB (9%)
Title : GoPro AAC 
Language : English
Default : Yes
Alternate group : 1
Encoded date : UTC 2022-02-23 15:18:42
Tagged date : UTC 2022-02-23 15:18:42

Other
ID : 3
Type : Time code
Format : QuickTime TC
Duration : 8 min 52 s
Frame rate : 23.976 (24000/1001) FPS
Time code of first frame : 15:57:41:15
Time code, striped : Yes
Title : GoPro AVC 
Language : English
Default : No
Encoded date : UTC 2022-02-23 15:18:42
Tagged date : UTC 2022-02-23 15:18:42


Now if I run


ffmpeg -y -nostdin -v error -ss 00:00:00.042 -i GL0100002_output.mp4 -t 00:00:25.192 -map 0 -map -0:d -c:v libx264 -preset fast -crf 21 -c:a aac -sn GL0100002_test.DSME_0001.mp4

I get the following mediainfo


$ mediainfo GL0100002_test.DSME_0001.mp4 
General
Complete name : GL0100002_test.DSME_0001.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 4.54 MiB
Duration : 25 s 234 ms
Overall bit rate : 1 510 kb/s
Writing application : Lavf58.29.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 25 s 234 ms
Bit rate : 1 376 kb/s
Width : 848 pixels
Height : 480 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.141
Stream size : 4.14 MiB (91%)
Title : GoPro AVC 
Writing library : x264 core 155 r2917 0a84d98
Encoding settings : cabac=1 / ref=2 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=6 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=30 / rc=crf / mbtree=1 / crf=21.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language : English
Color range : Full
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 25 s 214 ms
Duration_LastFrame : -3 ms
Bit rate mode : Constant
Bit rate : 129 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 398 KiB (9%)
Title : GoPro AAC 
Language : English
Default : Yes
Alternate group : 1

Other
ID : 3
Type : Time code
Format : QuickTime TC
Duration : 25 s 234 ms
Frame rate : 23.976 (24000/1001) FPS
Time code of first frame : 15:57:41:15
Time code, striped : Yes
Title : GoPro AVC 
Language : English
Default : No


But what I don't understand is where
Time code of first frameis coming from. I would expect it would be00:00:00.042or evenUTC 2022-02-23 15:18:42+ .042 but appear to be.

Time code of first frame : 15:57:41:15


Is this potentially clobbering together something to get this time that isn't obvious ?


Syndiquer tout le site
