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• Anomalie #2834 (Fermé) : liens dans mails inutilisables pour les modérer

  3 septembre 2012, par cedric -

  Cette fonctionalité experimentale est liés au plugin notifications et ne concerne pas le core. Le message que tu reçois est lié a un lien périmé (les liens ne sont valables que quelques heures pour des raison de sécurité) 1/ Non la page est volontairement très légère car c’est un usage mobile qui est (...)

• ffmpeg API h264 encoded video does not play on all platforms

  19 juillet 2012, par TheSHEEEP

  Edit : In the previous version I used a very old ffmpeg API. I now use the newest libraries. The problem has only changed slightly, from "Main" to "High".

  I am using the ffmpeg C API to create a mp4 video in C++.

  I want the resulting video to be of the profile "Constrained Baseline", so that the resulting video can be played on as much platforms as possible, especially mobile, but I get "High" profile every time, even though I hard coded the codec profile to be FF_PROFILE_H264_CONSTRAINED_BASELINE. As a result, the video does not play on all our testing platforms.

  This is what "ffprobe video.mp4 -show_streams" tells about my video streams :

    Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  creation_time   : 1970-01-01 00:00:00
  
  encoder         : Lavf53.5.0
  
    Duration: 00:00:13.20, start: 0.000000, bitrate: 553 kb/s
  
  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 320x180,
  
  424 kb/s, 15 fps, 15 tbr, 15 tbn, 30 tbc
  
  Metadata:
  
    creation_time   : 1970-01-01 00:00:00
  
    handler_name    : VideoHandler
  
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16, 12
  
  kb/s
  
  Metadata:
  
    creation_time   : 1970-01-01 00:00:00
  
    handler_name    : SoundHandler
  
  -------VIDEO STREAM--------
  
  [STREAM] 
  
  index=0
  
  codec_name=h264
  
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  
  
  profile=High <-- This should be "Constrained Baseline"
  
  
  
  codec_type=video
  
  codec_time_base=1/30
  
  codec_tag_string=avc1
  
  codec_tag=0x31637661
  
  width=320
  
  height=180
  
  has_b_frames=0
  
  sample_aspect_ratio=N/A
  
  display_aspect_ratio=N/A
  
  pix_fmt=yuv420p
  
  level=30
  
  timecode=N/A
  
  is_avc=1
  
  nal_length_size=4
  
  id=N/A
  
  r_frame_rate=15/1
  
  avg_frame_rate=15/1
  
  time_base=1/15
  
  start_time=0.000000
  
  duration=13.200000
  
  bit_rate=424252
  
  nb_frames=198
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  TAG:creation_time=1970-01-01 00:00:00
  
  TAG:language=und
  
  TAG:handler_name=VideoHandler
  
  [/STREAM]
  
  -------AUDIO STREAM--------
  
  [STREAM]
  
  index=1
  
  codec_name=aac
  
  codec_long_name=Advanced Audio Coding
  
  profile=unknown
  
  codec_type=audio
  
  codec_time_base=1/44100
  
  codec_tag_string=mp4a
  
  codec_tag=0x6134706d
  
  sample_fmt=s16
  
  sample_rate=44100
  
  channels=2
  
  bits_per_sample=0
  
  id=N/A
  
  r_frame_rate=0/0
  
  avg_frame_rate=0/0
  
  time_base=1/44100
  
  start_time=0.000000
  
  duration=13.165714
  
  bit_rate=125301
  
  nb_frames=567
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  TAG:creation_time=1970-01-01 00:00:00
  
  TAG:language=und
  
  TAG:handler_name=SoundHandler
  
  [/STREAM]

  This is the function I use to add a video stream. All the values that come from ptr-> are defined from outside, do those values have to be specific values to get the correct profile ? :

  static AVStream *add_video_stream( Cffmpeg_dll * ptr, AVFormatContext *oc, enum   CodecID codec_id )
  
  {
  
  AVCodecContext *c;
  
  AVStream *st;  
  
  AVCodec* codec;
  
  
  
  // Get correct codec
  
  codec = avcodec_find_encoder(codec_id);
  
  if (!codec) {
  
      av_log(NULL, AV_LOG_ERROR, "%s","Video codec not found\n");
  
      exit(1);
  
  }
  
  
  
  // Create stream
  
  st = avformat_new_stream(oc, codec);
  
  if (!st) {
  
      av_log(NULL, AV_LOG_ERROR, "%s","Could not alloc stream\n");
  
      exit(1);
  
  }
  
  
  
  c = st->codec;
  
  
  
  /* Get default values */
  
  codec = avcodec_find_encoder(codec_id);
  
  if (!codec) {
  
      av_log(NULL, AV_LOG_ERROR, "%s","Video codec not found (default values)\n");
  
      exit(1);
  
  }
  
  avcodec_get_context_defaults3(c, codec);
  
  
  
  c->codec_id = codec_id;
  
  c->codec_type = AVMEDIA_TYPE_VIDEO;
  
  
  
  c->bit_rate = ptr->video_bit_rate;
  
  av_log(NULL, AV_LOG_ERROR, " Bit rate: %i", c->bit_rate);
  
  
  
      c->qmin = ptr->qmin;
  
      c->qmax = ptr->qmax;
  
      c->me_method = ptr->me_method;
  
      c->me_subpel_quality = ptr->me_subpel_quality;
  
      c->i_quant_factor = ptr->i_quant_factor;
  
      c->qcompress = ptr->qcompress;
  
      c->max_qdiff = ptr->max_qdiff;
  
  
  
      // We need to set the level and profile to get videos that play (hopefully) on all platforms
  
      c->level = 30;
  
      c->profile = FF_PROFILE_H264_CONSTRAINED_BASELINE;
  
  
  
  c->width = ptr->dstWidth; 
  
  c->height = ptr->dstHeight; 
  
  
  
  c->time_base.den = ptr->fps;
  
  c->time_base.num = 1;
  
  c->gop_size = ptr->fps;
  
  c->pix_fmt = STREAM_PIX_FMT;
  
  c->max_b_frames = 0;
  
  
  
  // some formats want stream headers to be separate
  
  if(oc->oformat->flags & AVFMT_GLOBALHEADER)
  
      c->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  return st;
  
  }

  Additional info :

  As a reference video, I use the gizmo.mp4 that Mozilla serves as an example that plays on every platform/browser. It definitely has the "Constrained Baseline" profile, and definitely works on all our testing smartphones. You can download it here. Our self-created video doesn't work on all platforms and I'm convinced this is because of the profile.

  I am also using qt-faststart.exe to move the headers to the start of the file after creating the mp4, as this cannot be done in a good way in C++ directly. Could that be the problem ?

  Obviously, I am doing something wrong, but I don't know what it could be. I'd be thankful for every hint ;)

• Why I became a HTML5 co-editor

  15 août 2012, par silvia

  A few weeks ago, I had the honor to be appointed as part of the editorial team of the W3C HTML5 specification.

  Since Ian Hickson had recently decided to focus solely on editing the WHATWG HTML living standard specification, the W3C started looking for other editors to take the existing HTML5 specification to REC level. REC level is what other standards organizations call a “ratified standard”.

  But what does REC level really mean for HTML ?

  In my probably somewhat subjective view, recommendation level means that a snapshot is taken of the continuously evolving HTML spec, which has a comprehensive feature set, that is implemented in a cross-browser interoperable way, has a complete test set for the features, and has received wide review. The latter implies that other groups in the W3C have had a chance to look at the specification and make sure it satisfies their basic requirements, which include e.g. applicability to all users (accessibility, internationalization), platforms, and devices (mobile, TV).

  Basically it means that we stop for a “moment”, take a deep breath, polish the feature set that we’ve been working on this far, and make sure we all agree on it, before we get back to changing the world with cool new stuff. In a software project we would call it a release branch with feature freeze.

  Now, as productive as that may sound for software – it’s not actually that exciting for a specification. Firstly, the most exciting things happen when writing new features. Secondly, development of browsers doesn’t just magically stop to get the release (REC) happening. And lastly, if we’ve done our specification work well, there should be only little work to do. Basically, it’s the unthankful work of tidying up that we’re looking at here.

  So, why am I doing it ? I am not doing this for money – I’m currently part-time contracting to Google’s accessibility team working on video accessibility and this editor work is not covered by my contract. It wasn’t possible to reconcile polishing work on a specification with the goals of my contract, which include pushing new accessibility features forward. Therefore, when invited, I decided to offer my spare time to the W3C.

  I’m giving this time under the condition that I’d only be looking at accessibility and video related sections. This is where my interest and expertise lie, and where I’m passionate to get things right. I want to make sure that we create accessibility features that will be implemented and that we polish existing video features. I want to make sure we don’t digress from implementations which continue to get updated and may follow the WHATWG spec or HTML.next or other needs.

  I am not yet completely sure what the editorship will entail. Will we look at tests, too ? Will we get involved in HTML.next ? This far we’ve been preparing for our work by setting up adequate version control repositories, building a spec creation process, discussing how to bridge to the WHATWG commits, and analysing the long list of bugs to see how to cope with them. There’s plenty of actual text editing work ahead and the team is shaping up well ! I look forward to the new experiences.