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• audio extracted from flv file via ffmpeg is of shorter duration than the actual flv video [closed]

  11 janvier 2013, par user1961143

  I have extracted audio from flv file via ffmpeg using this command :-

  ffmpeg -i 164_29.flv v19.mp3

  The flv videos duration is 3 minutes but the audio is of 2 mins 20 seconds only. On searching i found that the silent pieces of audio are removed when generating audio from ffmpeg. But i need the audio file to be of exactly same duration as flv video as later i need to put this audio in the flv video itself. Please help as this is urgent for our project. I am running the FFMpeg via .net windows service, so in case you know any other tool which can extract the audio of same duration as video and can be run via .net, it would be useful too.

  Console output :

  C :\Users\ritika.thakur>ffmpeg -i 164_29.flv v19.mp3
  ffmpeg version N-47062-g26c531c Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
  configuration : —disable-static —enable-shared —enable-gpl —enable-version —disable-pthreads —enable-runtime-cpudetect —enable-avisynth —enable-bzlib —enable-frei0r —enable-libass —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libfreetype —enable-libgsm —enable-libmp3lame —enable-libnut -enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger -enable-libspeex —enable-libtheora —enable-libutvideo —enable-libvo-aacenc —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libx264 —enale-libxavs —enable-libxvid —enable-zlib
  libavutil 52. 9.100 / 52. 9.100
  libavcodec 54. 77.100 / 54. 77.100
  libavformat 54. 37.100 / 54. 37.100
  libavdevice 54. 3.100 / 54. 3.100
  libavfilter 3. 23.102 / 3. 23.102
  libswscale 2. 1.102 / 2. 1.102
  libswresample 0. 17.101 / 0. 17.101
  libpostproc 52. 2.100 / 52. 2.100
  Input #0, flv, from '164_29.flv' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  Duration : 00:03:04.08, start : 0.000000, bitrate : 283
  kb/s
  Stream #0:0 : Video : flv1, yuv420p, 320x240, 1k tbr, 1k tbn, 1k tbc
  Stream #0:1 : Audio : nellymoser, 22050 Hz, mono, flt
  Output #0, mp3, to 'v19.mp3' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  TSSE : Lavf54.37.100
  Stream #0:0 : Audio : mp3, 22050 Hz, mono, fltp
  Stream mapping :
  Stream #0:1 -> #0:0 (nellymoser -> libmp3lame)
  Press [q] to stop, [?] for help
  size= 567kB time=00:03:04.13 bitrate= 25.2kbits/s video:0kB audio:567kB subtitle:0 global headers:0kB muxing overhead 0.051503%

  This is the output of console for both video and audio file separately :-

  Microsoft Windows [Version 6.1.7601]
  Copyright (c) 2009 Microsoft Corporation. All rights reserved.

  C :\Users\ritika.thakur>ffmpeg -i v19.mp3

  ffmpeg version N-47062-g26c531c Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
  configuration : —disable-static —enable-shared —enable-gpl —enable-version3
  —disable-pthreads —enable-runtime-cpudetect —enable-avisynth —enable-bzlib
  — enable-frei0r —enable-libass —enable-libopencore-amrnb —enable-libopencore-
  amrwb —enable-libfreetype —enable-libgsm —enable-libmp3lame —enable-libnut -
   enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger -
   enable-libspeex —enable-libtheora —enable-libutvideo —enable-libvo-aacenc —
  enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libx264 —enab
  le-libxavs —enable-libxvid —enable-zlib
  libavutil 52. 9.100 / 52. 9.100
  libavcodec 54. 77.100 / 54. 77.100
  libavformat 54. 37.100 / 54. 37.100
  libavdevice 54. 3.100 / 54. 3.100
  libavfilter 3. 23.102 / 3. 23.102
  libswscale 2. 1.102 / 2. 1.102
  libswresample 0. 17.101 / 0. 17.101
  libpostproc 52. 2.100 / 52. 2.100
  [mp3 @ 0056e780] max_analyze_duration 5000000 reached at 5015510
  Input #0, mp3, from 'v19.mp3' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  encoder : Lavf54.37.100
  Duration : 00:02:25.14, start : 0.000000, bitrate : 32 kb/s
  Stream #0:0 : Audio : mp3, 22050 Hz, mono, s16, 32 kb/s
  At least one output file must be specified

  C :\Users\ritika.thakur>ffmpeg -i 164_29.flv

  ffmpeg version N-47062-g26c531c Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
  configuration : —disable-static —enable-shared —enable-gpl —enable-version3
  —disable-pthreads —enable-runtime-cpudetect —enable-avisynth —enable-bzlib
  — enable-frei0r —enable-libass —enable-libopencore-amrnb —enable-libopencore-
  amrwb —enable-libfreetype —enable-libgsm —enable-libmp3lame —enable-libnut -
   enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger -
   enable-libspeex —enable-libtheora —enable-libutvideo —enable-libvo-aacenc —
  enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libx264 —enab
  le-libxavs —enable-libxvid —enable-zlib
  libavutil 52. 9.100 / 52. 9.100
  libavcodec 54. 77.100 / 54. 77.100
  libavformat 54. 37.100 / 54. 37.100
  libavdevice 54. 3.100 / 54. 3.100
  libavfilter 3. 23.102 / 3. 23.102
  libswscale 2. 1.102 / 2. 1.102
  libswresample 0. 17.101 / 0. 17.101
  libpostproc 52. 2.100 / 52. 2.100
  Input #0, flv, from '164_29.flv' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  Duration : 00:03:04.08, start : 0.000000, bitrate : 283 kb/s
  Stream #0:0 : Video : flv1, yuv420p, 320x240, 1k tbr, 1k tbn, 1k tbc
  Stream #0:1 : Audio : nellymoser, 22050 Hz, mono, flt
  At least one output file must be specified

  If you see the duration of video is of 3:04 but audio extracted from it is of 2:25 only.
  Actually i am using ffmpeg overlay to show two videos side by side in our debate project for the client. Now ffmpeg takes audio from first video by default. But we want the audio from both videos together as a debate going on. Hence I thought of a solution to extract audio from both videos and merge them and than apply them to the overlayed video. This will all work perfectly only if I get the complete audio from the video file i.e. of equal duration.
  For more information i am writing here the overlay command we are using :-

   **ffmpeg -i 164_29.flv  -vf "[in] scale=359:320, pad=2*iw+6:ih
  
    [left];    movie=164_30.flv, scale=359:320 [right]; [left][right] 
  
    overlay=365:0  [out]" -b:v 3600k -y a1.flv**
  
  
  
   **This is the console output of this overlay command:-**

  C :\Users\ritika.thakur>ffmpeg -i 164_29.flv -vf "[in] scale=359:320, pad=2*iw+6
  :ih [left] ; movie=164_30.flv, scale=359:320 [right] ; [left][right] overlay=365:0
  [out]" -b:v 3600k -y a1.flv
  ffmpeg version N-47062-g26c531c Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
  configuration : —disable-static —enable-shared —enable-gpl —enable-version3
  —disable- pthreads —enable-runtime-cpudetect —enable- avisynth
  —enable-bzlib —enable
  -frei0r
  —enable-libass —enable-libopencore-amrnb —enable-libopencore-amrwb
  —enable- libfreetype —enable-libgsm —enable-libmp3lame —enable-libnut
  —enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger
  — enable-
  libspeex —enable-libtheora —enable- libutvideo
  —enable-libvo-aacenc —
  enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx
  —enable-libx264 —enab
  le-libxavs —enable-libxvid —enable-zlib
  libavutil 52. 9.100 / 52. 9.100
  libavcodec 54. 77.100 / 54. 77.100
  libavformat 54. 37.100 / 54. 37.100
  libavdevice 54. 3.100 / 54. 3.100
  libavfilter 3. 23.102 / 3. 23.102
  libswscale 2. 1.102 / 2. 1.102
  libswresample 0. 17.101 / 0. 17.101
  libpostproc 52. 2.100 / 52. 2.100
  Input #0, flv, from '164_29.flv' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  Duration : 00:03:04.08, start : 0.000000, bitrate : 283 kb/s
  Stream #0:0 : Video : flv1, yuv420p, 320x240, 1k tbr, 1k tbn, 1k tbc
  Stream #0:1 : Audio : nellymoser, 22050 Hz, mono, flt
  Output #0, flv, to 'a1.flv' :
  Metadata :
  canSeekToEnd : false
  createdby : FMS 4.0
  creationdate : Tue Jan 08 00:26:19 2013
  encoder : Lavf54.37.100
  Stream #0:0 : Video : flv1 ([2][0][0][0] / 0x0002), yuv420p, 724x320, q=2-31,
  3600 kb/s, 1k tbn, 1k tbc
  Stream #0:1 : Audio : mp3 ([2][0][0][0] / 0x0002), 22050 Hz, mono, fltp
  Stream mapping :
  Stream #0:0 -> #0:0 (flv -> flv)
  Stream #0:1 -> #0:1 (nellymoser -> libmp3lame)
  Press [q] to stop, [?] for help
  frame= 83 fps=0.0 q=4.1 size= 343kB time=00:00:07.01 bitrate= 401.2kbits/s
  frame= 149 fps=149 q=2.3 size= 861kB time=00:00:14.87 bitrate= 473.9kbits/s
  frame= 223 fps=148 q=2.0 size= 1492kB time=00:00:22.00 bitrate= 555.4kbits/s
  frame= 308 fps=153 q=2.0 size= 2195kB time=00:00:28.64 bitrate= 627.8kbits/s
  frame= 391 fps=156 q=2.0 size= 2858kB time=00:00:34.06 bitrate= 687.4kbits/s
  frame= 478 fps=159 q=2.0 size= 3541kB time=00:00:39.55 bitrate= 733.4kbits/s
  frame= 547 fps=156 q=2.0 size= 4293kB time=00:00:46.80 bitrate= 751.5kbits/s
  frame= 645 fps=161 q=2.0 size= 4896kB time=00:00:51.63 bitrate= 776.8kbits/s
  Buffer queue overflow, dropping.
  [Parsed_overlay_4 @ 0152ca80] Buffer queue overflow, dropping.
  Last message repeated 16 times
  frame= 731 fps=162 q=2.0 size= 5418kB time=00:00:56.61 bitrate= 784.0kbits/s
  Buffer queue overflow, dropping.
  [Parsed_overlay_4 @ 0152ca80] Buffer queue overflow, dropping.
  Last message repeated 49 times
  frame= 794 fps=158 q=2.0 size= 5802kB time=00:01:02.37 bitrate= 762.1kbits/s
  frame= 886 fps=160 q=2.0 size= 6363kB time=00:01:07.00 bitrate= 778.0kbits/s
  Buffer queue overflow, dropping.
  [Parsed_overlay_4 @ 0152ca80] Buffer queue overflow, dropping.
  Last message repeated 29 times
  frame= 954 fps=158 q=2.0 size= 6785kB time=00:01:13.31 bitrate= 758.2kbits/s
  frame= 1056 fps=162 q=2.0 size= 7377kB time=00:01:16.94 bitrate= 785.4kbits/s
  Buffer queue overflow, dropping.
  [Parsed_overlay_4 @ 0152ca80] Buffer queue overflow, dropping.
  Last message repeated 30 times
  frame= 1130 fps=161 q=2.0 size= 7789kB time=00:01:22.19 bitrate= 776.3kbits/s
  frame= 1217 fps=162 q=2.0 size= 8372kB time=00:01:27.68 bitrate= 782.1kbits/s
  frame= 1306 fps=163 q=2.0 size= 9074kB time=00:01:32.86 bitrate= 800.5kbits/s
  frame= 1393 fps=163 q=1.6 size= 9700kB time=00:01:38.41 bitrate= 807.3kbits/s
  frame= 1475 fps=163 q=2.0 size= 10278kB time=00:01:44.03 bitrate= 809.4kbits/s
  frame= 1568 fps=164 q=2.0 size= 10825kB time=00:01:48.52 bitrate= 817.1kbits/s
  frame= 1658 fps=165 q=2.0 size= 11439kB time=00:01:53.44 bitrate= 826.0kbits/s
  frame= 1734 fps=165 q=2.0 size= 12027kB time=00:01:58.31 bitrate= 832.7kbits/s
  frame= 1792 fps=162 q=2.0 size= 12579kB time=00:02:03.41 bitrate= 835.0kbits/s
  frame= 1851 fps=160 q=2.0 size= 13284kB time=00:02:10.74 bitrate= 832.3kbits/s
  frame= 1929 fps=160 q=2.0 size= 13922kB time=00:02:16.85 bitrate= 833.3kbits/s
  frame= 2010 fps=160 q=2.0 size= 14652kB time=00:02:23.39 bitrate= 837.1kbits/s
  frame= 2102 fps=161 q=2.0 size= 15329kB time=00:02:28.86 bitrate= 843.6kbits/s
  frame= 2200 fps=162 q=2.0 size= 15963kB time=00:02:34.08 bitrate= 848.7kbits/s
  frame= 2292 fps=163 q=2.0 size= 16554kB time=00:02:38.96 bitrate= 853.1kbits/s
  frame= 2378 fps=163 q=2.0 size= 17157kB time=00:02:44.50 bitrate= 854.4kbits/s
  frame= 2468 fps=164 q=2.0 size= 17826kB time=00:02:49.50 bitrate= 861.5kbits/s
  frame= 2564 fps=165 q=2.0 size= 18489kB time=00:02:54.43 bitrate= 868.3kbits/s
  Buffer queue overflow, dropping.
  [Parsed_overlay_4 @ 0152ca80] Buffer queue overflow, dropping.
  Last message repeated 15 times
  frame= 2647 fps=165 q=2.0 size= 19079kB time=00:02:59.53 bitrate= 870.6kbits/s
  frame= 2728 fps=165 q=2.0 Lsize= 19703kB time=00:03:04.13 bitrate= 876.6kbits/
  s video:19006kB audio:567kB subtitle:0 global headers:0kB muxing overhead 0.663315%

  Everything is working fine except that we want audio from both videos playing together in final overlayed file. I would be highly grateful if you can help in this and let me know if its possible to do via ffmpeg or not.

• Anomalie #2380 (Nouveau) : bandeau

  24 octobre 2011, par Alexandre C

  Un petit bug sur le bandeau de /ecrire en SPIP 3.0.0-beta [18629], pour le second niveau des raccourcis de création d’objets : Si l’on a mis dans ses préférences "Menu de navigation"=>Afficher uniquement le texte les mini-icones gauche restent, mais celles de droite disparaissent et se retrouvent (...)

• How To Play Hardware Accelerated Video on A Mac

  28 mai 2013, par Multimedia Mike — General

  I have a friend who was considering purchasing a Mac Mini recently. At the time of this writing, there are 3 desktop models (and 2 more “server” models).

  
  
  

  The cheapest one is a Core i5 2.5 GHz. Then there are 2 Core i7 models : 2.3 GHz and 2.6 GHz. The difference between the latter 2 is US$100. The only appreciable technical difference is the extra 0.3 GHz and the choice came down to those 2.

  He asked me which one would be able to play HD video at full frame rate. I found this query puzzling. But then, I have been “in the biz” for a bit too long. Whether or not a computer or device can play a video well depends on a lot of factors.

  Hardware Support
  First of all, looking at the raw speed of the general-purpose CPU inside of a computer as a gauge of video playback performance is generally misguided in this day and age. In general, we have a video standard (H.264, which I’ll focus on for this post) and many bits of hardware are able to accelerate decoding. So, the question is not whether the CPU can decode the data in real time, but can any other hardware in the device (likely the graphics hardware) handle it ? These machines have Intel HD 4000 graphics and, per my reading of the literature, they are capable of accelerating H.264 video decoding.

  Great, so the hardware supports accelerated decoding. So it’s a done deal, right ? Not quite…

  Operating System Support
  An application can’t do anything pertaining to hardware without permission from the operating system. So the next question is : Does Mac OS X allow an application to access accelerated video decoding hardware if it’s available ? This used to be a contentious matter (notably, Adobe Flash Player was unable to accelerate H.264 playback on Mac in the absence of such an API) but then Apple released an official API detailed in Technical Note TN2267.

  So, does this mean that video is magically accelerated ? Nope, we’re still not there yet…

  Application Support
  It’s great that all of these underlying pieces are in place, but if an individual application chooses to decode the video directly on the CPU, it’s all for naught. An application needs to query the facilities and direct data through the API if it wants to leverage the acceleration. Obviously, at this point it becomes a matter of “which application ?”

  My friend eventually opted to get the pricier of the desktop Mac Mini models and we ran some ad-hoc tests since I was curious how widespread the acceleration support is among Mac multimedia players. Here are some programs I wanted to test, playing 1080p H.264 :

  • Apple QuickTime Player
  • VLC
  • YouTube with Flash Player (any browser)
  • YouTube with Safari/HTML5
  • YouTube with Chrome/HTML5
  • YouTube with Firefox/HTML5
  • Netflix

  I didn’t take exhaustive notes but my impromptu tests revealed QuickTime Player was, far and away, the most performant player, occupying only around 5% of the CPU according to the Mac OS X System Profiler graph (which is likely largely spent on audio decoding).

  VLC consistently required 20-30% CPU, so it’s probably leveraging some acceleration facilities. I think that Flash Player and the various HTML5 elements performed similarly (their multi-process architectures can make such a trivial profiling test difficult).

  The outlier was Netflix running in Firefox via Microsoft’s Silverlight plugin. Of course, the inner workings of Netflix’s technology are opaque to outsiders and we don’t even know if it uses H.264. It may very well use Microsoft’s VC-1 which is not a capability provided by the Mac OS X acceleration API (it doesn’t look like the Intel HD 4000 chip can handle it either). I have never seen any data one way or another about how Netflix encodes video. However, I was able to see that Netflix required an enormous amount of CPU muscle on the Mac platform.

  Conclusion
  The foregoing is a slight simplification of the video playback pipeline. There are some other considerations, most notably how the video is displayed afterwards. To circle back around to the original question : Can the Mac Mini handle full HD video playback ? As my friend found, the meager Mac Mini can do an admirable job at playing full HD video without loading down the CPU.