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• How can ffmpeg be made as efficient as Android's built-in video viewer ?

  6 janvier 2016, par Nicholas

  I have a project based off of https://ikaruga2.wordpress.com/2011/06/15/video-live-wallpaper-part-1/, which uses an older copy of the ffmpeg libraries from http://bambuser.com/opensource. Within the C++ code in this project we have the following lines of code :

          unsigned long long current = GetCurrentTimeInNanoseconds();
  
          avcodec_decode_video(pCodecCtx, pFrame, &frameFinished, packet.data, packet.size);
  
          __android_log_print(ANDROID_LOG_DEBUG, "getFrame>>>>", "decode video time: %llu", (GetCurrentTimeInNanoseconds() - current)/1000000);

  This code continually reports between 60 and 90 ms to decode each frame on an Xperia Ion, using a 1280x720 h264 source video file. Other processing to get the frame out to the screen takes an average of 30ms more with very little variation. This leads to frame rates of 10-11fps.

  Ignoring that other processing, a decode that takes an average of 75ms would result in 13fps. However, when I browse my SD card and click on that mp4 file to open it in the native viewer, it shows at a full 30fps. Further, when I open a 1920x1080 version of the same mp4 in the native viewer it also runs at a full 30fps without stutter or lag. This implies (to my novice eye) that something is very very wrong, as the hardware is obviously capable of decoding many times faster.

  What flags or options can be passed to avcode_decode_video to optimize decode speed to match that of the native viewer ? Can optimizations be made elsewhere to optimize speed further ? Is there a reason that the native viewer can decode almost an order of magnitude faster (taking into account the 1920x1080 source results) ?

  EDIT

  The answer below is very helpful, but is not practical for me at this time. In the mean time I have managed to decrease decoding time by 70% with some optimal encoding flags found through many many hours of trial and error. Here are the ffmpeg arguments I’m using for encoding in case it helps anyone else who stumbles across this post :

          ffmpeg.exe -i "#inputFilePath#" -c:v libx264 -preset veryslow -g 2 -y -s 910x512 -b 5000k -minrate 2000k -maxrate 8000k -pix_fmt yuv420p -tune fastdecode -coder 0 -flags -loop -profile:v main -x264-params subme=5:ref=4 "#ouputFilePath#"

  With these settings ffmpeg is decoding frames in 20-25 seconds, though with the sws_scale and then writing out to the texture I’m still hovering at 22 FPS on an Xperia Ion at a lower resolution than I’d like.

• How to split a .mkv file into sound and video files ?

  27 août 2024, par Ken Yip

  I have a mkv file which contains 3 streams. I use ffprobe to get the info of my mkv file.

  


  ffprobe ./demo/test2.mkv 


  


  I got this output

  


  Input #0, matroska,webm, from './demo/test2.mkv':
Metadata:
encoder         : libebml v0.7.7 + libmatroska v0.8.1
creation_time   : 2011-02-16T16:06:17.000000Z
Duration: 00:03:41.08, start: 0.000000, bitrate: 1363 kb/s
Stream #0:0: Video: rv40, yuv420p, 720x480, SAR 1:1 DAR 3:2, 29.97 tbr, 1k tbn, 1k tbc (default)
Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp (default)
Stream #0:2: Audio: aac (LC), 48000 Hz, stereo, fltp


  


  The audio streams should be vocal and background music. I would like to extract them from the video.

  


  I have tried to do so with this command

  


  ffmpeg -i ./demo/test2.mkv -map_channel 0.1.0 -y ch0.wav -map_channel 0.2.0 -y ch1.wav


  


  However, it outputs the same audio file. Is there any mistake I have made ? Thanks a lot.

  


• Where to store the .mpd file on django to play on a dash player ?

  3 janvier 2019, par enigmaVada

  I am trying to build a video player on django. I am using MPEG-DASH for adaptive streaming of the video file. I have chosen a sample video in the beginning. Then, using ffmpeg commands, I have encoded the video into 240p, 360p, 480p and 720p videos. Also have encoded audio separately.

  Then, using mp4box, I have generated the .mpd file. I have read that mpd files cannot be run from the local file system and need to be hosted on a server. I have a dash player setup as follows :

    
  
      
  
      
  
      <code class="echappe-js">&lt;script src=&quot;https://cdn.dashjs.org/latest/dash.all.min.js&quot;&gt;&lt;/script&gt;
  
         
     
  

  The url in the src field is a random manifest file that i used to test the player out. It works fine.

  Then, on my django project, I have created a media folder which stores the media files uploaded via a form(root included in settings.py).
  My question is where do i store the video, audio and .mpd file so that i can play them using the html code which resides in the templates folder. I have tried using the media url of .mpd file in the source but I am unable to play the video.

  Here is the generated mpd file for reference :

  <?xml version="1.0"?>
  
  
  
  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" minbuffertime="PT1.500S" type="static" mediapresentationduration="PT0H1M9.869S" maxsegmentduration="PT0H0M9.985S" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011,http://dashif.org/guidelines/dash264">
  
   <programinformation moreinformationurl="http://gpac.io">
  
    
  
   </programinformation>
  
  
  
   <period duration="PT0H1M9.869S">
  
    <adaptationset segmentalignment="true" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="audio/mp4" codecs="mp4a.40.2" audiosamplingrate="44100" startwithsap="1" bandwidth="130920">
  
      <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
  
      <baseurl>sample_audio_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="902-1017">
  
        <initialization range="0-901"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="426" maxheight="240" maxframerate="30" par="426:240" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.640015" width="426" height="240" framerate="30" sar="1:1" startwithsap="1" bandwidth="590708">
  
      <baseurl>sample_video_240_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="640" maxheight="480" maxframerate="30" par="4:3" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.64001E" width="480" height="360" framerate="30" sar="1:1" startwithsap="1" bandwidth="883873">
  
      <baseurl>sample_video_360_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
     <representation mimetype="video/mp4" codecs="avc1.64001E" width="640" height="480" framerate="30" sar="1:1" startwithsap="1" bandwidth="1188712">
  
      <baseurl>sample_video_480_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="913-1052">
  
        <initialization range="0-912"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="1280" maxheight="720" maxframerate="30" par="16:9" lang="und" subsegmentalignment="true" subsegmentstartswithsap="1">
  
     <representation mimetype="video/mp4" codecs="avc1.64001F" width="1280" height="720" framerate="30" sar="1:1" startwithsap="1" bandwidth="2365717">
  
      <baseurl>sample_video_720_dashinit.mp4</baseurl>
  
      <segmentbase indexrangeexact="true" indexrange="914-1053">
  
        <initialization range="0-913"></initialization>
  
      </segmentbase>
  
     </representation>
  
    </adaptationset>
  
   </period>
  
  </mpd>