How the iPhone 3GS records videos

Here are some technical details an analysis about the formats used by the Apple iPhone 3GS to record video.

This is an annotated screenshot of the excellent Mediainfo by Jerome Martinez.

Mediainfo screenshot analysing an iPhone recorded video
Some notes:

  1. Apple always uses MOV as the extension for standard MP4 files. The recorded video uses an MP4 container so it is capable of holding modern content and tags. Read on.
  2. Very cool: the iPhone ads geotagging to the video file with latitude, longitude and altitude information.
  3. Video is compressed and encoded with one of the most modern codecs available: H.264. The compression profile used is Baseline at level 3, the one optimized for low power CPUs.
  4. 3.5mbps average bitrate. Quite high but expected for a low power device compressing on demand. Lower bitrates with minimal quality loss can only be achieved by multipass compressions with higher level proviles.
  5. The video is a standard VGA 640×480 pixels per frame, with average of 30 frames per second. This is almost DVD quality.
  6. Audio is compressed and encoded with the MPEG-4’s AAC low complexity codec, the same used by popular M4A audio files. But it is mono, only one channel, no stereo audio.

Having said that, videos generated by the iPhone are ready for streaming over the Internet directly to Flash multimedia players. You may need conversion/recompression/transcoding only if you want to reduce the file size and bit rate. Otherwise, current popular Flash players that you already have installed in your browser are capable of playing these video files.

Here is a more detailed analysis generated by mp4dump utility on Linux, from the mpeg4ip Open Source project.

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