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• VP8 for Real-time Video Applications

  15 février 2011, par noreply@blogger.com (John Luther)

  With the growing interest in videoconferencing on the web platform, it’s a good time to explore the features of VP8 that make it an exceptionally good codec for real-time applications like videoconferencing.

  VP8 Design History & Features

  Real-time applications were a primary use case when VP8 was designed. The VP8 encoder has features specifically engineered to overcome the challenges inherent in compressing and transmitting real-time video data.
  

  • Processor-adaptive encoding. 16 encoder complexity levels automatically (or manually) adjust encoder features such as motion search strategy, quantizer optimizations, and loop filtering strength.
  • Encoder can be configured to use a target percentage of the host CPU.
    Ability to measure the time taken to encode each frame and adjust encoder complexity dynamically to keep the encoding time per frame constant
  • Robust error recovery (packet retransmission, forward error correction, recovery frame/new keyframe requests)
  • Temporal scalability (i.e., a single video bitstream that can degrade as needed depending on a participant’s available bandwidth)
  • Highly efficient decoding performance on low-power devices. Conventional video technology has grown to a state of complexity where dedicated hardware chips are needed to make it work well. With VP8, software-based solutions have proven to meet customer needs without requiring specialized hardware.

  For a more information about real-time video features in VP8, see the slide presentation by WebM Project engineer Paul Wilkins (PDF file).

  Commercially Available Products

  Millions of people around the world have been using VP7/8 for video chat for years. VP8 is deployed in some of today’s most popular consumer videoconferencing applications, including Skype (group video calling), Sightspeed, ooVoo and Logitech Vid. All of these vendors are active WebM project supporters. VP8’s predecessor, VP7, has been used in Skype video calling since 2005 and is supported in the new Skype app for iPhone. Other real-time VP8 implementations are coming soon, including ooVoo, and VP8 will play a leading role in Google’s plans for real-time applications on the web platform.

  Real-time applications will be extremely important as the web platform matures. The WebM community has made significant improvements in VP8 for real-time use cases since our launch and will continue to do so in the future.

  John Luther is Product Manager of the WebM Project.

  

• H.264 (MP4) video not play in IE9, but will play in Safari [closed]

  27 septembre 2011, par Austin S

  I have encoded a video using FFMPEG into three formats : WebM, MP4, and FLV. Chrome, Mozilla, and theoretically Opera (although I haven't tested it) should all use the WebM version. IE9, iOS devices, and Adriod should use the MP4 container. While all legacy browsers should default back to the flash version of the file. I'm using video-js to help serve the content. The content is set to preload and autoplay.

  I have found that everything is working as intended except for IE9, where all I get is the poster image and a white dot that typically spins indicating that the file is loading however it is not spinning in this scenario. The MP4 file opens in Safari, an iPad, an iPhone, and an Andriod - verifying that the file is infact legit.

  The following is the specs for the MP4 file when I stream it using VLC. I don't know if this is particularly useful, I'm just trying to provide as much detail as possible.

  VLC Codec Details

  • Stream 0

    Type : Video

    Codec : MPEG-4 Video (mp4v)

    Language : English

    Resolution : 480x270

    Frame rate : 2997

  • Stream 1

    Type : Audio

    Codec : MPEG AAC Audio (mp4a)

    Language : English

    Channels : Stereo

    Sample rate : 48000 Hz

  When accessing videojs.com from my coworkers computer, the video on their main page wouldn't play the video correctly in IE9, but we could hear the audio. When I went to another coworkers computer it played just fine. I'm wondering if IE9, or video-js, is tempermental depending on how updated your OS is.

  The fact that I'm working on XP with IE7 is making this all the more difficult to fix, so if you have any suggestions on what could point me in the right direction, I would greatly appreciate it !

  Thanks,

  Austin S

• Does ffmpeg play the entire video file to extract image

  21 mars 2012, par user735647

  I have a multimedia application which involves lot of videos. I use FFMPEG to generate the thumbnails from the video at a particular time duration. Now the problem is my console application which is used to extract the images from the video is consuming lot of memory when its being run.

  The doubt I have now is whether FFMPEG does play the entire video file when extracting the thumbnail image.Is it possible ?

  Following is the parameter being passed to FFMPEG,

    -i [input video file] -an -r 0.05 -y -ss 00:00:18 -vframes 1 [output thumbnail file path]

  I tried googling but with no success. Please provide your valuable thoughts.

  Thanks.