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• WebRTC books – a brief review

  1er janvier 2014, par silvia

  I just finished reading Rob Manson’s awesome book “Getting Started with WebRTC” and I can highly recommend it for any Web developer who is interested in WebRTC.

  Rob explains very clearly how to create your first video, audio or data peer-connection using WebRTC in current Google Chrome or Firefox (I think it also now applies to Opera, though that wasn’t the case when his book was published). He makes available example code, so you can replicate it in your own Web application easily, including the setup of a signalling server. He also points out that you need a ICE (STUN/TURN) server to punch through firewalls and gives recommendations for what software is available, but stops short of explaining how to set them up.

  Rob’s focus is very much on the features required in a typical Web application :

  • video calls
  • audio calls
  • text chats
  • file sharing

  In fact, he provides the most in-depth demo of how to set up a good file sharing interface I have come across.

  Rob then also extends his introduction to WebRTC to two key application areas : education and team communication. His recommendations are spot on and required reading for anyone developing applications in these spaces.

  —

  Before Rob’s book, I have also read Alan Johnson and Dan Burnett’s “WebRTC” book on APIs and RTCWEB protocols of the HTML5 Real-Time Web.

  Alan and Dan’s book was written more than a year ago and explains that state of standardisation at that time. It’s probably a little out-dated now, but it still gives you good foundations on why some decisions were made the way they are and what are contentious issues (some of which still remain). If you really want to understand what happens behind the scenes when you call certain functions in the WebRTC APIs of browsers, then this is for you.

  Alan and Dan’s book explains in more details than Rob’s book how IP addresses of communication partners are found, how firewall holepunching works, how sessions get negotiated, and how the standards process works. It’s probably less useful to a Web developer who just wants to implement video call functionality into their Web application, though if something goes wrong you may find yourself digging into the details of SDP, SRTP, DTLS, and other cryptic abbreviations of protocols that all need to work together to get a WebRTC call working.

  —

  Overall, both books are worthwhile and cover different aspects of WebRTC that you will stumble across if you are directly dealing with WebRTC code.

• WebRTC books – a brief review

  30 décembre 2013, par silvia

  I just finished reading Rob Manson’s awesome book “Getting Started with WebRTC” and I can highly recommend it for any Web developer who is interested in WebRTC.

  Rob explains very clearly how to create your first video, audio or data peer-connection using WebRTC in current Google Chrome or Firefox (I think it also now applies to Opera, though that wasn’t the case when his book was published). He makes available example code, so you can replicate it in your own Web application easily, including the setup of a signalling server. He also points out that you need a ICE (STUN/TURN) server to punch through firewalls and gives recommendations for what software is available, but stops short of explaining how to set them up.

  Rob’s focus is very much on the features required in a typical Web application :

  • video calls
  • audio calls
  • text chats
  • file sharing

  In fact, he provides the most in-depth demo of how to set up a good file sharing interface I have come across.

  Rob then also extends his introduction to WebRTC to two key application areas : education and team communication. His recommendations are spot on and required reading for anyone developing applications in these spaces.

  —

  Before Rob’s book, I have also read Alan Johnson and Dan Burnett’s “WebRTC” book on APIs and RTCWEB protocols of the HTML5 Real-Time Web.

  Alan and Dan’s book was written more than a year ago and explains that state of standardisation at that time. It’s probably a little out-dated now, but it still gives you good foundations on why some decisions were made the way they are and what are contentious issues (some of which still remain). If you really want to understand what happens behind the scenes when you call certain functions in the WebRTC APIs of browsers, then this is for you.

  Alan and Dan’s book explains in more details than Rob’s book how IP addresses of communication partners are found, how firewall holepunching works, how sessions get negotiated, and how the standards process works. It’s probably less useful to a Web developer who just wants to implement video call functionality into their Web application, though if something goes wrong you may find yourself digging into the details of SDP, SRTP, DTLS, and other cryptic abbreviations of protocols that all need to work together to get a WebRTC call working.

  —

  Overall, both books are worthwhile and cover different aspects of WebRTC that you will stumble across if you are directly dealing with WebRTC code.

• No video steam played with the ffmpeg script from avi to mp4 on Centos 8.2/ffmpeg 8 [duplicate]

  27 septembre 2020, par user27240

  The mp4 file that was transformed from the avi file with the script below running on Centos 8.2/ffmpeg gcc 8 does not play video stream and it only play audio on chrome/edge/firefox/opera and Windows10.
Could anyone please help me out ?

  


  for i in /var/www/html/xxxxx/xxxxx/479.AVI; do ffmpeg -i "$i" -pix_fmt yuv420p -movflags +faststart -ss 0.03 "/var/www/html/xxxxx/xxxxx/$(basename "$i" .avi).mp4"; done

  


  The log for the ffmpeg transform script :

  


  peg -i "$i" -pix_fmt yuv420p -movflags +faststart -ss 0.03 "/var/www/html/xxxxx/xxxxx/$(basename "$i" .avi).mp4"; done
ffmpeg version N-99260-g6401a5d4b8 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (GCC)
  configuration: --disable-x86asm
  libavutil      56. 59.100 / 56. 59.100
  libavcodec     58.106.100 / 58.106.100
  libavformat    58. 58.100 / 58. 58.100
  libavdevice    58. 11.102 / 58. 11.102
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, avi, from '/var/www/html/xxxxx/xxxxx/479.AVI':
  Metadata:
    creation_time   : 1980-01-01 00:00:18
    encoder         : CanonMVI06
  Duration: 00:00:04.63, start: 0.000000, bitrate: 15522 kb/s
    Stream #0:0: Video: mjpeg (Baseline) (MJPG / 0x47504A4D), yuvj422p(pc, bt470                                                                                                                                                             bg/unknown/unknown), 640x480, 14916 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc
    Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16,                                                                                                                                                              705 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> mpeg4 (native))
  Stream #0:1 -> #0:1 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
[swscaler @ 0x37e3c80] deprecated pixel format used, make sure you did set range                                                                                                                                                              correctly
Output #0, mp4, to '/var/www/html/xxxxx/xxxxx/479.AVI.mp4':
  Metadata:
    encoder         : Lavf58.58.100
    Stream #0:0: Video: mpeg4 (mp4v / 0x7634706D), yuv420p, 640x480, q=2-31, 200                                                                                                                                                              kb/s, 30 fps, 65521 tbn, 30 tbc
    Metadata:
      encoder         : Lavc58.106.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 69 k                                                                                                                                                             b/s
    Metadata:
      encoder         : Lavc58.106.100 aac
frame=   61 fps=0.0 q=24.8 size=       0kB time=00:00:02.90 bitrate=   0.1kbits/                                                                                                                                                             frame=  126 fps=125 q=31.0 size=     256kB time=00:00:04.55 bitrate= 460.9kbits/                                                                                                                                                             [mp4 @ 0x376e700] Starting second pass: moving the moov atom to the beginning of                                                                                                                                                              the file
frame=  138 fps=125 q=31.0 Lsize=     379kB time=00:00:04.62 bitrate= 671.2kbits                                                                                                                                                             /s speed=4.17x
video:335kB audio:38kB subtitle:0kB other streams:0kB global headers:0kB muxing                                                                                                                                                              overhead: 1.401716%
[aac @ 0x377d2c0] Qavg: 2088.382


  


  ffmpeg version :

  


  ffmpeg version N-99260-g6401a5d4b8 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (GCC)
configuration: --disable-x86asm
libavutil      56. 59.100 / 56. 59.100
libavcodec     58.106.100 / 58.106.100
libavformat    58. 58.100 / 58. 58.100
libavdevice    58. 11.102 / 58. 11.102
libavfilter     7. 87.100 /  7. 87.100
libswscale      5.  8.100 /  5.  8.100
libswresample   3.  8.100 /  3.  8.100


  


  CentOS version :
CentOS Linux release 8.2.2004 (Core)

  


  Clinet OS :
Windows10

  


  Browsers :
Chrome, Edge, Firefox, Opera

  


  ffprobe -loglevel error :

  


  [root@xxxxxxx xxxxxxx]# ffprobe -loglevel error -show_streams 479.AVI.mp4                                                                                                                                                      
[STREAM]
index=0
codec_name=mpeg4
codec_long_name=MPEG-4 part 2
profile=Simple Profile
codec_type=video
codec_time_base=2184/65521
codec_tag_string=mp4v
codec_tag=0x7634706d
width=640
height=480
coded_width=640
coded_height=480
closed_captions=0
has_b_frames=0
sample_aspect_ratio=1:1
display_aspect_ratio=4:3
pix_fmt=yuv420p
level=1
color_range=unknown
color_space=unknown
color_transfer=unknown
color_primaries=unknown
chroma_location=left
field_order=unknown
timecode=N/A
refs=1
quarter_sample=false
divx_packed=false
id=N/A
r_frame_rate=65521/2184
avg_frame_rate=65521/2184
time_base=1/65521
start_pts=0
start_time=0.000000
duration_ts=301392
duration=4.599930
bit_rate=596840
max_bit_rate=596840
bits_per_raw_sample=N/A
nb_frames=138
nb_read_frames=N/A
nb_read_packets=N/A
DISPOSITION:default=1
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
DISPOSITION:timed_thumbnails=0
TAG:language=und
TAG:handler_name=VideoHandler
[/STREAM]
[STREAM]
index=1
codec_name=aac
codec_long_name=AAC (Advanced Audio Coding)
profile=LC
codec_type=audio
codec_time_base=1/44100
codec_tag_string=mp4a
codec_tag=0x6134706d
sample_fmt=fltp
sample_rate=44100
channels=1
channel_layout=mono
bits_per_sample=0
id=N/A
r_frame_rate=0/0
avg_frame_rate=0/0
time_base=1/44100
start_pts=0
start_time=0.000000
duration_ts=202992
duration=4.602993
bit_rate=67677
max_bit_rate=69000
bits_per_raw_sample=N/A
nb_frames=200
nb_read_frames=N/A
nb_read_packets=N/A
DISPOSITION:default=1
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
DISPOSITION:timed_thumbnails=0
TAG:language=und
TAG:handler_name=SoundHandler
[/STREAM]