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• FFMPEG Conversion improve quality

  1er octobre 2019, par user726720

  I have some questions regarding ffmpeg :

  I need to convert the XDCAM HD422 (yuv422p) to AVC (h.264, mp4). I’m doing it as follows :

  ffmpeg.exe -y -i path\abc.mxf  -ab 128k -acodec aac -ac 2 -strict -2 -b:v 12000k -f mp4 -g 34 -pix_fmt yuv420p -r 25 -s 1920x1080 -vcodec h264 -preset ultrafast h264file.mp4

  I have check the mp4 on a broadcast monitor and there are some visible color saturation issue’s. The quality doesn’t match the original XDCAM HD422

  1. What changes do I need to make in the above parameters to fix this ?
  2. My original file is a yuv422p and I’m using yuv420p in the above ffmpeg command, does this make a difference in the quality.
  3. Should change the preset from ultrafast to Fast make a difference.
  4. Will using the libx264 make any difference ?
  5. How does ffmeg encode from one format to another. Does it simply do a direct conversion or does it extract the RAW (yuv) from the XDCAM and then encode it into MP4 ?

  I’m just brainstorming how to improve the quality so it matches the that of XDCAM, any suggestions would be highly appreciated.

• Android HLS : Any way to edit the m3u8 file so that I know which segment is currently streaming/playing in my player using HLS

  1er août 2014, par hclee

  I am now working on a VOD project using HLS.

  I use the VideoViewBuffer in VitamioDemo to stream my video that is stored in my local server.
  The Vitamio library is awesome that I am able to stream the video, getting the bit rate, buffering percentage and some metadata.

  We use ffmpeg to convert the video into m3u8 and the corresponding ts files.
  But now our team want to know which segment (which ts file) of the video the HLS is currently streaming.

  That’s a very important part in our project but we get stuck in this point.

  I tried to use the MediaMetadata in Vitamio but only the Duration of the video is found.
  I am wondering if we can add some metadata in the m3u8 file so that we can retrieve the name of the current segment during streaming.
  eg :
  The original m3u8 is like this :
  #EXTINF:10.500000,
  stream00000.ts

  Is it possible for me to change it as follows :
  #EXTINF:10.500000, name of segment
  stream00000.ts

  But all I can get using MediaMetaDataRetriever is null except for the duration.

  It seems that no body have done this before so I can’t find any very useful information about this.

  Do anybody how to implement this ?
  Or should I use some packet sniffer to monitor the network traffic by myself ?
  Or Would MediaScanner be helpful ?
  Or I need to use code in android.os ?

  Thanks in advance !

• Is there a way to control ffplay audio volume from command line and from key commands on Mac OSX ?

  20 avril 2023, par smartblonde

  We want to use ffplay to monitor live RTMP feeds. We have a script to open an instance of ffplay for each feed. We would like to control the initial volume of the video to be around 30 out of 100. We would also like to be able to raise or lower the volume via key commands during the stream. We are referring to this doc : http://ffmpeg.org/ffplay.html

  



  We've tried the main option -volume 30, to try and start the volume at 30/100. FFplay says unrecognized option when it sees -volume on the command line.

  



  Also, we've tried using 9 and 0 to lower or raise the volume once the player is up and playing the live RTMP feed. These key commands seem to have no effect on the player's volume.

  



  Are there other shell parameters, and other key commands, that are known to work on all builds/OS's for ffplay ? If not, why change these basic functions from release and O/S ato other release ? In any case what works on MacOSX ? Thank you !