Sur d’autres sites (6361)

• How to use ffmpeg in JavaScript to decode H.264 frames into RGB frames

  17 juin 2020, par noel

  I'm trying to compile ffmpeg into javascript so that I can decode H.264 video streams using node. The streams are H.264 frames packed into RTP NALUs so any solution has to be able to accept H.264 frames rather than a whole file name. These frames can't be in a container like MP4 or AVI because then the demuxer needs to needs the timestamp of every frame before demuxing can occur, but I'm dealing with a real time stream, no containers.

  



  Streaming H.264 over RTP

  



  Below is the basic code I'm using to listen on a udp socket. Inside the 'message' callback the data packet is an RTP datagram. The data portion of the data gram is an H.264 frame (P-frames and I-frames).

  



  var PORT = 33333;
var HOST = '127.0.0.1';

var dgram = require('dgram');
var server = dgram.createSocket('udp4');

server.on('listening', function () {
    var address = server.address();
    console.log('UDP Server listening on ' + address.address + ":" + address.port);
});

server.on('message', function (message, remote) {
    console.log(remote.address + ':' + remote.port +' - ' + message);
    frame = parse_rtp(message);

    rgb_frame = some_library.decode_h264(frame); // This is what I need.

});

server.bind(PORT, HOST);  


  



  I found the Broadway.js library, but I couldn't get it working and it doesn't handle P-frames which I need. I also found ffmpeg.js, but could get that to work and it needs a whole file not a stream. Likewise, fluent-ffmpeg doesn't appear to support file streams ; all of the examples show a filename being passed to the constructor. So I decided to write my own API.

  



  My current solution attempt

  



  I have been able to compile ffmpeg into one big js file, but I can't use it like that. I want to write an API around ffmpeg and then expose those functions to JS. So it seems to me like I need to do the following :

  



  

  1. Compile ffmpeg components (avcodec, avutil, etc.) into llvm bitcode.

  


  2. Write a C wrapper that exposes the decoding functionality and uses EMSCRIPTEN_KEEPALIVE.

  


  3. Use emcc to compile the wrapper and link it to the bitcode created in step 1.

  


  



  I found WASM+ffmpeg, but it's in Chinese and some of the steps aren't clear. In particular there is this step :

  



  emcc web.c process.c ../lib/libavformat.bc ../lib/libavcodec.bc ../lib/libswscale.bc ../lib/libswresample.bc ../lib/libavutil.bc \


  



   :( Where I think I'm stuck

  



  I don't understand how all the ffmpeg components get compiled into separate *.bc files. I followed the emmake commands in that article and I end up with one big .bc file.

  



  2 questions

  



  1. Does anyone know the steps to compile ffmpeg using emscripten so that I can expose some API to javascript ?
  
 2. Is there a better way (with decent documentation/examples) to decode h264 video streams using node ?

  


• How to set up a cron job for ffmpeg in centOS 6

  9 mars 2018, par user27240

  I can convert from mp4 file to jpg file manually one by one with the below command on centOS 6 environment.

  Now, could anyone help me out how to set up a cron for any mp4 file in the directory to be converted automatically
  to jpg file with the same file name as mp4 file such as 03052022_5a9d28723d2da.jpg for the below environment ?

  OS：centos-6 (x86_64)

  ffmpeg version 2.2.2

  Plesk 17.0.17

  [root@server-xxxxxxxx-x ~]# ffmpeg -i                                \
  
    /var/www/vhosts/xxxxx.com/httpdocs/save/03052022_5a9d28723d2da.mp4 \
  
    /var/www/vhosts/xxxxx.com/httpdocs/save/03052022_5a9d28723d2da.jpg

  With ’s/.conf$/.jpg/p’ :

  [root@server-xxxxxx-x ~]# for i in `find /var/www/vhosts/xxxxxx.com/httpdocs/save/ -type f -name "*.mp4"`; do ffmpeg -i $i `echo $i | sed -En 's/.conf$/.jpg/p'`; done

  ffmpeg version 2.2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb 21 2018 03:03:24 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-18)
  configuration :
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ’/var/www/vhosts/xxxxxx.com/httpdocs/save/03081956_5aa116c836015.mp4’ :
  Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : isommp42
  creation_time : 2018-02-14 04:42:34
  Duration : 00:00:00.83, start : 0.000000, bitrate : 23270 kb/s
  Stream #0:0(eng) : Video : h264 (Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m), 1920x1080, 25370 kb/s, SAR 65536:65536 DAR 16:9, 29.73 fps, 30 tbr, 90k tbn, 180k tbc (default)
  Metadata :
  rotate : 90
  creation_time : 2018-02-14 04:42:34
  handler_name : VideoHandle
  Stream #0:1(eng) : Audio : aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
  Metadata :
  creation_time : 2018-02-14 04:42:34
  handler_name : SoundHandle
  At least one output file must be specified
  Conversion failed !

  With "s/.conf$/.jpg/p" :

  [root@server-xxxxxxx-x ~]# for i in `find /var/www/vhosts/xxxxxx.com/httpdocs/save/ -type f -name "*.mp4"`; do ffmpeg -i $i `echo $i | sed -En "s/.conf$/.jpg/p"`; done

  ffmpeg version 2.2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb 21 2018 03:03:24 with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-18)
  configuration :
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ’/var/www/vhosts/xxxxxx.com/httpdocs/save/03081956_5aa116c836015.mp4’ :
  Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : isommp42
  creation_time : 2018-02-14 04:42:34
  Duration : 00:00:00.83, start : 0.000000, bitrate : 23270 kb/s
  Stream #0:0(eng) : Video : h264 (Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m), 1920x1080, 25370 kb/s, SAR 65536:65536 DAR 16:9, 29.73 fps, 30 tbr, 90k tbn, 180k tbc (default)
  Metadata :
  rotate : 90
  creation_time : 2018-02-14 04:42:34
  handler_name : VideoHandle
  Stream #0:1(eng) : Audio : aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
  Metadata :
  creation_time : 2018-02-14 04:42:34
  handler_name : SoundHandle
  At least one output file must be specified
  Conversion failed !

  With "s/.mp4$/.jpg/p"

  [root@server-xxxxx-x ~]# for i in `find /var/www/vhosts/xxxxxx.com/httpdocs/save/ -type f -name "*.mp4"`; do ffmpeg -i $i `echo $i | sed -En "s/.mp4$/.jpg/p"`; done

  [image2 @ 0x2c488e0] Could not get frame filename number 2 from pattern ’/var/www/vhosts/xxxxxx.com/httpdocs/save/03100013_5aa2a49bb67bc.jpg’ (either set updatefirst or use a pattern like %03d within the filename pattern)
  av_interleaved_write_frame() : Invalid argument
  frame= 2 fps=0.0 q=3.2 Lsize=N/A time=00:00:00.06 bitrate=N/A
  video:289kB audio:0kB subtitle:0 data:0 global headers:0kB muxing overhead -100.007446%
  Conversion failed !

• FFmpeg - Concatenate all videos with similar file name ?

  24 décembre 2017, par Pan Hart

  Is there any way to use ffmpeg to concatenate all video files that have the exact same file name for the specified first few characters ?

  For example, if I set it to match the first 5 characters, it will match and concatenate video_1.flv, video_2.flv, video_3.flv and so on.

  But, at the same time, it can also match and concatenate tests_1.flv, tests_2.flv, tests_3.flv and so on.

  Any help will be appreciated !