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• 32BGRA to AVFrame(ffmpeg) and viceversa ? for IOS

  8 février 2012, par Asta ni enohpi

  Am working Video Processing in IOS(iphone/ipod/ipad) Using Objective c. i am using AVFoundation Framework to Capture Video . i want to Encode/decode those video frame using ffmpeg-libx264. i have compiled ffmpeg-x264 lib for ios. i got kCVPixelFormatType_32BGRA from AVFoundation.

  my problem is
  1.How to convert kCVPixelFormatType_32BGRA to AVFrame for enode using avcodec_encode_video ?

  2.How to convert AVFrame to kCVPixelFormatType_32BGRA @ decode side from avcodec_decode_video2 ?

  Please help me to start above process or give path for working tutorial .Thanks in advance.

• FFmpeg mp4 videos load very slow outside of network

  6 juin 2014, par user3550401

  I used ffmpeg to convert my videos to mp4 using libx264 and qt fast start. Im playing my videos through the HTML tag, and when im inside my network where my website is, everything plays fast. But when i try to play the video from an outside network, I have to wait about 10 seconds before a 5 second video is played. And even when its playing, its super choppy. Any reason on why this is ? I am playing the videos in Safari on my iPhone.

  Here is how im encoding my videos :

  ffmpeg -i video.ts -i css/watermark.png -filter_complex overlay=10:main_h-overlay_h-10 -shortest -b:v 800k -vcodec libx264 -acodec libfaac -ar 44100 -ac 2 -b:a 128k -movflags faststart -map_metadata -1 video.mp4

• 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.