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• qt-faststart never finish

  19 avril 2012, par Shakti Singh

  I am trying to use qt-faststart on MP4 videos to make the streaming fast but the qt-faststart command is never get finish, It is running from the last one and half hour and video file is of 14MB only.

  The command is showing the ftyp and free as output

  the output look like this

  ftyp 2324322  32
  
  free 2324456   8

  and the number is keep increasing with the output. No error is shown.

  The MP4 video is converted from FLV video using the FFMPEG.

  Generally it show the output like this but with my installation of qt-faststart I never get this ouput

      patching stco atom...
  
      patching stco atom..
  
      writing ftyp atom...
  
      writing moov atom...
  
      copying rest of file ...

  What could be the issue ?
  Is there anything wrong with the installation of qt-faststart ?

  I am on Linux 2.6.18-128.2.1.el5PAE i686

• How can I capture audio AND video simultenaous with ffmpeg from an USB capture device

  5 octobre 2011, par oban

  I'm capturing a video by means of an USB Terratec Grabster AV350 (which is based on the em2860 chip).

  I don't succeed to get the audio when it is played . If I play the captured video with vlc or with ffplay I got only 3 seconds sound and then a silence for the rest of the video ...

  During the capturing I don't get any errors. At the end it indicates the size of the video and audio captured ....

  I'm using the ffmpeg command for this :

  ffmpeg -f alsa -ac 2 -i hw:3 -f video4linux2 -i /dev/video0 -acodec ac3 -ab 128k -vcodec mpeg4 -b 6000k -r 25 test5.avi

  The log is :

  [alsa @ 0x9bcd420]Estimating duration from bitrate, this may be inaccurate
  Input #0, alsa, from 'hw:3' :
  Duration : N/A, start : 69930.998994, bitrate : N/A
  Stream #0.0 : Audio : pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  [video4linux2 @ 0x9bf5d30]Estimating duration from bitrate, this may be inaccurate
  Input #1, video4linux2, from '/dev/video0' :
  Duration : N/A, start : 1307111377.654173, bitrate : -2147483 kb/s
  Stream #1.0 : Video : rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc
  [ac3 @ 0x9bf9590]No channel layout specified. The encoder will guess the layout, but it might be incorrect.
  Output #0, avi, to 'test5.avi' :
  Metadata :
  ISFT : Lavf52.64.2
  Stream #0.0 : Video : mpeg4, yuv420p, 720x576, q=2-31, 6000 kb/s, 25 tbn, 25 tbc
  Stream #0.1 : Audio : ac3, 44100 Hz, stereo, s16, 128 kb/s
  Stream mapping :
  Stream #1.0 -> #0.0
  Stream #0.0 -> #0.1
  Press [q] to stop encoding
  frame= 1283 fps= 25 q=2.3 Lsize= 38677kB time=51.32 bitrate=6173.9kbits/s
  video:37755kB audio:846kB global headers:0kB muxing overhead 0.198922%

  If I reduce the command for only capturing audio, then the audio file can be played successfully :

  ffmpeg -f alsa -ac 2 -i hw:3,0 -acodec ac3 -ab 128k test5.avi

  [alsa @ 0x8ede420]Estimating duration from bitrate, this may be inaccurate
  Input #0, alsa, from 'hw:3,0' :
  Duration : N/A, start : 70395.998935, bitrate : N/A
  Stream #0.0 : Audio : pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  [ac3 @ 0x8eebac0]No channel layout specified. The encoder will guess the layout, but it might be incorrect.
  Output #0, avi, to 'test5.avi' :
  Metadata :
  ISFT : Lavf52.64.2
  Stream #0.0 : Audio : ac3, 44100 Hz, stereo, s16, 128 kb/s
  Stream mapping :
  Stream #0.0 -> #0.0
  Press [q] to stop encoding
  size= 227kB time=13.62 bitrate= 136.8kbits/s
  video:0kB audio:213kB global headers:0kB muxing overhead 6.902375%

  If I run the command for only video capturing then vlc or ffplay can play the video successfully :

  ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -b 12000k -r 25 test5.avi

  [video4linux2 @ 0x91d6420]Estimating duration from bitrate, this may be inaccurate
  Input #0, video4linux2, from '/dev/video0' :
  Duration : N/A, start : 1307112044.025687, bitrate : -2147483 kb/s
  Stream #0.0 : Video : rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc
  Output #0, avi, to 'test5.avi' :
  Metadata :
  ISFT : Lavf52.64.2
  Stream #0.0 : Video : mpeg4, yuv420p, 720x576, q=2-31, 12000 kb/s, 25 tbn, 25 tbc
  Stream mapping :
  Stream #0.0 -> #0.0
  Press [q] to stop encoding
  frame= 388 fps= 25 q=2.0 Lsize= 12963kB time=15.52 bitrate=6842.5kbits/s
  video:12949kB audio:0kB global headers:0kB muxing overhead 0.114584%

  Strange behaviour I noticed is that when I tried capturing video and audio, I can not capture the audio afterwards any more,
  unless I unplug the AV350 first.

  The G350 is located at card 3 :

  htpc@htpc-01 :/proc/asound/G350/pcm0c$ more info
  card : 3
  device : 0
  subdevice : 0
  stream : CAPTURE
  id : USB Audio
  name : USB Audio
  subname : subdevice #0
  class : 0
  subclass : 0
  subdevices_count : 1
  subdevices_avail : 1

  The OS is a Linux 2.6.38-8-generic with the Ubuntu Natty Narwhal version

  Any help on how to tackle this issue would be great ....

  Thanks !

• lavf : use a fixed width type

  13 janvier 2014, par Anton Khirnov

  lavf : use a fixed width type
  It’s shorter and more consistent with the rest of the code.
  

  • [DBH] libavformat/utils.c