Recherche avancée

Sur d’autres sites (8766)

• Generate individual HLS-compatible .ts segments on-demand by downloading as little bytes as possible from a remote input file

  27 janvier 2017, par Romain Cointepas

  I’m trying to generate individual HLS-compatible .ts segments on-demand by downloading/reading as little bytes as possible from a remote input file (hosted on a server supporting byte-ranges requests).

  One of the application for this would be to be able to transcode and play on Apple TV (via Airplay) a remote file that is not Airplay compatible, without having to download the entire file first.

  I am generating the playlist myself, and I have access to the ffprobe results for the remote file (that gives video duration, etc.).

  I have something working that plays via Airplay but with small video and audio glitches between each segments when I use the following command to generate each segment :

  ffmpeg -ss 60 -t 6 -i http://s3.amazonaws.com/misc-12345/avicii.vob -f mpegts -map 0:v:0 -map 0:a:0 -c:v libx264 -bsf:v h264_mp4toannexb -force_key_frames "expr:gte(t,n_forced*6)" -forced-idr 1 -pix_fmt yuv420p -colorspace bt709 -c:a aac -async 1 -preset ultrafast pipe:1

  Note : above command is for segment 11.ts, and in the m3u8 playlist I advertise each segment duration as 6 seconds.

  Here is a Youtube video showing the audio/video glitches between segments :
  https://www.youtube.com/watch?v=0vMwgbSfsu0

  The segment or hls modules of ffmpeg can’t be used because they both generate all the segments at once.

  I’ve been struggling on this for some days now and I would really appreciate some help !

• Calculate PSNR and MSE for individual frames using ffmpeg

  26 juin 2015, par Mayank Agarwal

  I have an avi file.i am converting avi file to .mp4 codec H.264 and ain second case to .mp4 file codec H.265.Now i want to calculate the PSNR/MSE/MSAD between the ref file(avi file) and the converted mp4 file using ffmpeg.Came across ffmpeg command line filters for PSNR and SSIM calculation but it gives the average PSNR value not the PSNR value frame by frame.Also i want to do it using code and not using command line.Read several examples in demuxing.c it is separating the whole file into frames in av_read_frame before calling decode
  but how can i convert pkt to frame and able to calculate PSNR or MSE values.

  Regards
  Mayank

• avutil/tx_template : Don't waste space for inexistent factors

  22 octobre 2022, par Andreas Rheinhardt

  avutil/tx_template : Don't waste space for inexistent factors
  It is possible to avoid the factors array for the power-of-two
  
  tables for which said array is unused by using a different
  
  structure for initialization for power-of-two tables than for
  
  non-power-of-two-tables. This saves 3*15*16B from .data.
  Reviewed-by : Lynne <dev@lynne.ee>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavutil/tx_template.c