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• Not able to play video file in Qt5 based Web browser on Linux ARM machine

  20 février 2016, par user3436349

  I am using Yocto Buildsystem to generate customized Linux Image with Qt5.4
  support in it for TI AM335x based ARM platform, here in Yocto I have selected
  components those are required for Qt5 based Webbrowser so as to play HTML5 audio
  and video files such as :
   qtmultimedia
   gstreamer (1.0)
   qtscript
   qtwebsockets
   qtimageformats
   libgles-omap3
   lighttpd
   gst-ffmpeg
   gst-fluendo-mp3
   gstreamer (0.10)

  Here after building the final image. I found that there are
  both gstreamer and gstreamer-1.0 directories in /usr/lib, also the
  required ffmpeg libs are located in /usr/lib/gstreamer directory.
  But I suspect the webkit by default links to /usr/lib/gstreamer-1.0
  directory and hence cannot find required libs.

  When I tried the manually copy the ffmepg related libs in /usr/lib/gstreamer-1.0
  directory from /usr/lib/gstreamer, then I got the libav related version error.

  Please guide me regarding who to configure webkit or webcore .bb file so that
  it links to both the gstreamer directories in /usr/lib and can thus play
  HTML5 audio and video files in qt5 based web-browser.

• M4a (mp4) audio file encoded with pydub+ffmpeg doesn't play on Android

  6 juillet 2020, par Evelyn

  I have a python script to split up some wav files and export to m4a using pydub. I'm able to get these files to play on several devices, but not on an Android device (using Google Pixel 3). When I try encoding with straight ffmpeg in terminal, that works fine on the Android device.

  


  What is the difference in these two files, and since pydub is using ffmpeg, what do I need to change to make it do exactly the same as the ffmpeg command ?

  


  Not working

  


  from pydub import AudioSegment
>>> audio = AudioSegment.from_wav("input.wav")
>>> slice = audio[1000:3000]
>>> slice.export("pydub_export.m4a", format="mp4", parameters=["-ac", "1", "-c:a", "libfdk_aac", "-profile:a", "aac_he", "-vbr", "2"])


  


  mediainfo output :

  


  General
Complete name                            : pydub_export.m4a
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/mp41)
File size                                : 11.7 KiB
Duration                                 : 2 s 115 ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 45.1 kb/s
Writing application                      : Lavf58.29.100

Audio
ID                                       : 1
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 2 s 115 ms
Duration_LastFrame                       : -22 ms
Bit rate mode                            : Constant
Bit rate                                 : 41.4 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 10.7 KiB (92%)
Default                                  : Yes
Alternate group                          : 1


  


  Working

  


  $ffmpeg -i input.wav -acodec copy -ss 1 -to 3 input_slice.wav
$ffmpeg -i input_slice.wav -ac 1 -c:a libfdk_aac -profile:a aac_he -vbr 2 ffmpeg_export.m4a


  


  mediainfo output :

  


  General
Complete name                            : ffmpeg_export.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (isom/iso2)
File size                                : 11.2 KiB
Duration                                 : 2 s 112 ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 43.6 kb/s
Writing application                      : Lavf58.29.100

Audio
ID                                       : 1
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 2 s 112 ms
Duration_LastFrame                       : -25 ms
Bit rate mode                            : Constant
Bit rate                                 : 39.9 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 10.3 KiB (91%)
Default                                  : Yes
Alternate group                          : 1


  


  I already tried moving metadata to the front with -movflags faststart on the broken file and it didn't make a difference.

  


• Play audio out through specific output device with ffplay

  4 février 2018, par ComedicChimera

  I just have a quick question regarding ffplay (extension of ffmpeg) for Windows. I am trying to get it to allow me to play audio out of specific device (ie. a virtual audio cable), and I cannot find any documentation on how to do it.

  Here is my current command :

  "ffplay -loglevel panic -nodisp -volume volume -i url"

  I could not find any documentation of how to do this.

  If it is not possible to do this ffplay, I would like to ask if there is away to set a specific audio output device in Python 3 (as that is the language I am using to call ffplay)

  Thanks