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• Introducing WebM, an open web media project

  19 mai 2010, par noreply@blogger.com (christosap)

  A key factor in the web’s success is that its core technologies such as HTML, HTTP, TCP/IP, etc. are open and freely implementable. Though video is also now core to the web experience, there is unfortunately no open and free video format that is on par with the leading commercial choices. To that end, we are excited to introduce WebM, a broadly-backed community effort to develop a world-class media format for the open web.

  WebM includes :
  

  • VP8, a high-quality video codec we are releasing today under a BSD-style, royalty-free license
  • Vorbis, an already open source and broadly implemented audio codec
  • a container format based on a subset of the Matroska media container

  The team that created VP8 have been pioneers in video codec development for over a decade. VP8 delivers high quality video while efficiently adapting to the varying processing and bandwidth conditions found on today’s broad range of web-connected devices. VP8’s efficient bandwidth usage will mean lower serving costs for content publishers and high quality video for end-users. The codec’s relative simplicity makes it easy to integrate into existing environments and requires less manual tuning to produce high quality results. These existing attributes and the rapid innovation we expect through the open-development process make VP8 well suited for the unique requirements of video on the web.

  A developer preview of WebM and VP8, including source code, specs, and encoding tools is available today at www.webmproject.org.

  We want to thank the many industry leaders and web community members who are collaborating on the development of WebM and integrating it into their products. Check out what Mozilla, Opera, Google Chrome, Adobe, and many others below have to say about the importance of WebM to the future of web video.

  
  

  AMD

  ARM

  Brightcove

  Broadcom

  Collabora

  Digital Rapids

  Encoding.com

  Grab Networks

  iLinc

  INLET

  Kaltura

  Logitech

  MIPS

  Nvidia

  Ooyala

  Qualcomm

  Skype

  Sorenson

  Telestream
  

  Texas Instruments

  Verisilicon

  ViewCast

  Wildform

  
  

  Posted by Jeremy Doig, Engineering Director of video and Mike Jazayeri, Group Product Manager, Google

  

• Revision 576c2bb021 : Fix bug in segment skip. Wrong max data size (skip has no data) and use of vp9_

  7 juin 2013, par Paul Wilkins

  Changed Paths :
   Modify /vp9/common/vp9_seg_common.c

  
   Modify /vp9/decoder/vp9_detokenize.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
  
  Fix bug in segment skip.

  Wrong max data size (skip has no data) and use of vp9_get_segdata()
  when it should be vp9_segfeature_active().

  Change-Id : I1eb97d33df6e2a42cc589049f704266fe3639902

• How can I make ffmpeg output proper SDP data for a data stream

  8 juillet 2021, par Shalom Crown

  I have a program based on the FFMPEG libraries, to add KLV data to a video stream. When I try to sent the output to an RTSP server (rtsp-simple-server), I get a 400 response.

  


  The apparent reason is that the SDP data for the KLV stream is missing the rtpmap.

  


  I would like to add the missing data either by setting the proper parameters in the contexts, or by specifying the data explicitly.

  


  This is the ANNOUNCE captured with Wireshark

  


  ANNOUNCE rtsp://0.0.0.0:8554/test RTSP/1.0
Content-Type: application/sdp
CSeq: 2
User-Agent: Lavf58.29.100
Content-Length: 270

v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 58.29.100
m=video 0 RTP/AVP 96
b=AS:10000
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1
a=control:streamid=0
m=application 0 RTP/AVP 97
b=AS:90
a=control:streamid=1


  


  Code fragment for initializing the data stream :

  


  AVStream* data_track = avformat_new_stream(muxer, nullptr);

if (data_track == nullptr) {
    LOG_ERROR << "failed to open data output stream";
    return nullptr;
}

muxer->oformat->video_codec = AV_CODEC_ID_H264;

AVCodec *klvEncoder = avcodec_find_encoder(AV_CODEC_ID_SMPTE_KLV);

if (klvEncoder == nullptr) {
    klvEncoder = avcodec_find_encoder(AV_CODEC_ID_BIN_DATA);
}

if (klvEncoder == nullptr) {
    klvEncoder = avcodec_find_encoder(AV_CODEC_ID_TEXT);
}

if (klvEncoder != nullptr) {
    klvEncoderContext = avcodec_alloc_context3(encoder);

    avcodec_parameters_from_context(data_track->codecpar, encoderContext);
} else {
    avcodec_parameters_copy(data_track->codecpar, pVideoStream->codecpar);
}

data_track->codecpar->codec_tag =  KLV_ID_TAG;
data_track->codecpar->codec_type = AVMEDIA_TYPE_DATA;
data_track->codecpar->codec_id = AV_CODEC_ID_SMPTE_KLV;
data_track->codecpar->bit_rate = 90000;
data_track->codecpar->format =  AV_SAMPLE_FMT_U8;
data_track->stream_identifier = KLV_ID_TAG;
data_track->id = 0x101;
data_track->time_base = video_track->time_base;
data_track->avg_frame_rate = video_track->time_base;