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• Old TV : ffmpeg-converted file not working

  29 décembre 2016, par senseiwa

  I have an old Full-HD TV (Philips) that supports USB reading with some video formats. However, it just supports one audio stream (the first), so in case I have two with the first that is not english, I need to remove the first one. I am doing this via ffmpeg, but the TV cannot read the converted file, although they are identical (except for one audio track).

  The conversion command I am using is is

   ffmpeg -i filename.IN -map 0:0 -map 0:2 -acodec copy -vcodec copy  filename.OUT

  to just copy the video/audio stream, but keeping only the second audio track. The original file is this one (output of ffprobe) and it works perfectly reproducing the video with the first audio track :

  Input #0, avi, from 'ORIG.avi':
  
    Metadata:
  
      encoder         : X
  
    Duration: 01:40:57.18, start: 0.000000, bitrate: 2695 kb/s
  
      Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 656x368 [SAR 1:1 DAR 41:23], 1914 kb/s, 23.98 fps, 23.98 tbr, 23.98 tbn, 23.98 tbc
  
      Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
      Stream #0:2: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 384 kb/s

  and the converted not working one is

  Input #0, avi, from 'CONV.avi':
  
    Metadata:
  
      encoder         : Lavf57.56.100
  
    Duration: 01:40:57.18, start: 0.000000, bitrate: 2309 kb/s
  
      Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 656x368 [SAR 1:1 DAR 41:23], 1914 kb/s, 23.98 fps, 23.98 tbr, 23.98 tbn, 23.98 tbc
  
      Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 384 kb/s

  On a PC, however, they both work.

  The question is, how can I convert, keeping eventually just one audio track, in a format that my TV supports without losing quality ?

  I do not have the list of supported codecs, but I have a list of videos that the TV is able to reproduce.

• What parameter should use to create adaptive hls videos in different scale using ffmpeg and shaka packager for VOD streaming ?

  25 juin 2019, par Rahul

  I am trying to package HLS with shaka packager in a different scale from 144x256 to 1080x1920 for adaptive streaming using hevc, It is working fine, but Is there some more parameter required to put for good video quality and optimization.

  Below are the command I used :

  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=144:256 144_256_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=360:640 360_640_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=720:1280 720_1280_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=1080:1920 1080_1920_h265.mp4 -hide_banner
  
  
  
  HLS Packaging Using shaka packager.
  
  packager-osx in=144_256_h265.mp4,stream=audio,output=hls/audio.mp4,playlist_name=audio.m3u8,hls_group_id=audio,hls_name=ENGLISH in=144_256_h265.mp4,stream=video,output=hls/h265_144p.mp4,playlist_name=h265_144p.m3u8,iframe_playlist_name=h265_144p_iframe.m3u8 in=360_640_h265.mp4,stream=video,output=hls/h265_360p.mp4,playlist_name=h265_360p.m3u8,iframe_playlist_name=h265_360p_iframe.m3u8 in=720_1280_h265.mp4,stream=video,output=hls/h265_720p.mp4,playlist_name=h265_720p.m3u8,iframe_playlist_name=h265_720p_iframe.m3u8  in=1080_1920_h265.mp4,stream=video,output=hls/h265_1080p.mp4,playlist_name=h265_1080p.m3u8,iframe_playlist_name=h265_1080p_iframe.m3u8 --hls_master_playlist_output hls/h265_master.m3u8

• Learn Multimedia Programming By Writing A JPEG Decoder

  6 janvier 2011, par Multimedia Mike — Programming

  For those of you who hack on multimedia tech, how did you get started ? Did you begin by studying the mathematical underpinnings of multimedia codec algorithms ? Or did you find a practical problem and jump right in by writing code ? (Personally, I was always more of a nuts & bolts hacker than a math guy.) I ask because I occasionally get emails from aspiring multimedia hackers who want to know where to begin. Invariably, they want to go the math-first route. I heavily discourage this approach.

  I have a crazy idea for anyone who wants a crash course on multimedia hacking : write a JPEG decoder. In doing so, you will be exposed to a lot of key domain concepts such as bitstream parsing, Huffman decoding, dequantization, zigzagging, the dreaded (inverse) discrete cosine transform, YUV vs. RGB colorspaces, macroblock organization, delta coding, and run length coding.

  Sure, JPEG decoding is a solved problem. But that’s hardly the point. Why would you enter an unfamiliar field and hope to come up to speed on the basics by leaping straight into the domain’s unsolved problems ? If you are successful in this exercise, no one will ever use the fruits of your labor, but that doesn’t really matter.

  So, do you want to learn multimedia hacking quickly ? Then grab a JPEG file (maybe create a few contrived ones that are small, have friendly dimensions, and feature predictable patterns), grab a good JPEG reference, and implement the decoding algorithm in the language and platform of your choice.

  On the matter of the reference, my personal favorite reference has always been A note about the JPEG decoding algorithm by Cristi Cuturicu. The English grammar is a bit dodgy but overall, it might be the best reference you’ll find on the matter— as simple as it needs to be, but no simpler.

  Good luck !