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• How to write RTP/H264 stream as a file

  2 octobre 2012, par Jun

  I couldn't find a solution for my previous question so I decided to try it step by step.

  The thing that I wanna do now is to store the RTP/H264 stream as a file.

  What I found so far is the below :

  (firstly my RTP/H264 is FU-A which is the form of)

  | RTP HEADER 12bytes long | FU INDICATOR 1byte | FU HEADER 1byte | FU payload |

  As I understood RFC 6184 document, I'm starting a NAL with a packet which has '1' at the first bit of FU Header and appending following packets that set '0' at the first bit until the last packet which has '1' at the second bit of FU Header.

  I think that's how to get a complete NAL before the FU-A packetization and also what I found is I need to put the 'starting bits' (0x00000001) at the front of each complete NAL.

  But no luck so far. The below is part of log

   ========= the new NAL is as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
  
   ========= adding the next NAL as 716
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]7C/1111100 [5]85/10000101 [6]B8/10111000 [7]40/1000000 ...
  
   ========= a NAL is summed up as 4866
  
   ========= the new NAL is as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= adding the next NAL as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= adding the next NAL as 139
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E2/11100010 [7]20/100000 ...
  
   ========= a NAL is summed up as 7061
  
   ========= the new NAL is as 1377
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]41/1000001 [5]E4/11100100 [6]40/1000000 [7]1A/11010 ...
  
   ========= a NAL is summed up as 1369
  
   ========= the new NAL is as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E6/11100110 [7]60/1100000 ...
  
   ========= adding the next NAL as 94
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]E6/11100110 [7]60/1100000 ...
  
   ========= a NAL is summed up as 1472
  
   ========= the new NAL is as 447
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]41/1000001 [5]E8/11101000 [6]80/10000000 [7]16/10110 ...
  
   ========= a NAL is summed up as 439
  
   ========= the new NAL is as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EA/11101010 [7]A0/10100000  ...
  
   ========= adding the next NAL as 1174
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EA/11101010 [7]A0/10100000 ...
  
   ========= a NAL is summed up as 2552
  
   ========= the new NAL is as 1400
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EC/11101100 [7]C0/11000000 ...
  
   ========= adding the next NAL as 1364
  
   [0]0/0 [1]0/0 [2]0/0 [3]1/1 [4]5C/1011100 [5]81/10000001 [6]EC/11101100 [7]C0/11000000 ...
  
   ========= a NAL is summed up as 2742
  
   ========= the new NAL is as 1400
  
   ...

  my question is,

  1. if I can get the complete NALs from the fragmented packets by FU-A, how can I make it as a file which is able to run by VLC or other player ?

  2. I'm still confused if I have to keep the FU indicator and FU header or not. Somebody said I need to take them only for the very first packet (starting with '1' at the FU header)

  Any advice will be really appreciated.

  Thanks.

• How can i create ffmpeg code with video and audio filter in one command line

  15 septembre 2014, par aligokayduman

  i can add a background image behind the video and change scale and position with this code

  ffmpeg -loop 1 -i 360.png -i input.mp4 -filter_complex "[1]scale=362:218[over]; [0][over]overlay=200:117" -shortest -y output.mp4

  and i can change audio and volume speed %10 faster

   ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.9*PTS[v]; [0:a]atempo=1.1[a]" -map "[v]" -map "[a]" output.mp4

  i wanna do this 2 step in one code but i couldn’t do that

  Do you know any solution ?

• Trying to concat videos from different sources with ffmpeg and get different broken results every time (partly no audio and/or fast forward video)

  30 octobre 2022, par Oliver

  I am using ffmpeg for years to create (merge and render) big video files from the (vaction) clips my sony camcorder produces. My basic workflow is to copy the mp4 files from the camcorder over to my pc, put the names in a file (file 'filename') and use the following command to create one big file that is playable by my apple tv :

  


  ffmpeg -f concat -safe 0 -i filelist.txt -c:v libx265 -preset slow -x265-params strong-intra-smoothing=0:merange=58 -crf 24 -c:a aac -b:a 320k -tag:v hvc1 output.mp4


  


  i cannot explain most of the arguments in total detail but i know that it works.
My problem occurred as i wanted to prepend some video clips recorded with an iphone to one of those files. So the first part seemed easy, the sony camcorder files have a resolution of 3840x2160 and the iphone video clips have a resolution of 1280x720 so at first i upscaled the iphone files using this command (i would have rather done in just one step but i do not know how to do that) :

  


  ffmpeg -i IMG_1182.MP4 -vf scale=3840:2160 IMG_1182_3840x2160.MP4


  


  then i just tried to add those upscaled video files to the filelist from the first command and ran the command for all clips again. Sadly that did not worked, as the resulting file contained all clips but only the iphone part had audio ! For the rest of the video the audio was missing. At this point i also did not noticed that the second part was played much faster (like played in fast forward mode). So guessed that i have to render the iphone and sony camcorder clips separately using the first command. That worked and i got two video files with perfect audio and video. My next step was to concatenate the resulting files using the following simple command :

  


  ffmpeg -f concat -safe 0 -i concatlist.txt -c copy output.mp4


  


  where concatlist contained both files.
Sadly that also did not worked. I do got a file containing both parts, this time with audio, but the video of the second part still was fast forward !

  


  I do not know what to do at this point, and i also do not understand enough to experiment with the options any more. Can someone explain to my what could be the problems here and how to solve them ?