The format of iPhone video preview is changed from my NSHI Zheng ge.

First, clarify several basic concepts about video.

• A video file is composed of video streams and audio streams. It is packaged together. This involves three formats: video format, audio format, and package file format.
• Common File packaging formats include. MP4,. Avi,. mov, And. 3GP. The packaging format is not equal to the video format. Therefore, you cannot know the audio and video formats.
• Common video formats include: H.264, MPEG-4 video, H.263, MPEG-2 video and so on.
• Common audio formats include MP3, AAC, and Amr.

In other words, MP4, m4v, and 3GP are file packaging formats, not video encoding formats. It can be understood as ZIP or RAR compressed file packages. H.264, MPEG-4, H.263 and so on, these are video encoding formats. To play a video on a mobile phone, the mobile phone must be able to unbind the package file and decode the video stream. Just as if you send a RAR compressed Word file to someone else, that person must have the software to decompress RAR and word to view it.

Next, about MPEG-4, profile, and level

MPEG-4 is a series of standards on audio and video, including many parts. Among them, Part 1 defines a video format, called MPEG-4 video; Part 2 defines another video format, called MPEG-4 AVC, also called H. 264; Part 1 defines a file packaging format, called MP4; Part 2 defines an audio format, called AAC.

Because video encoding contains many features, some advanced features are not necessarily supported by all devices, each format is divided into several feature combinations based on the specific number of features ), from simple to complex. For example, MPEG-4 video includes simple profile, Advanced Simple Profile, and H.264 includes baseline profile, main profile, high profile and so on. Each device selects a combination of functions suitable for its own capabilities. For example, for H.264 video playback, the mobile phone may only support baseline profile decoding, while the computer may support Main
Profile decoding.

Because various devices have different playback capabilities, each profile is divided into several levels from low to high. The higher the level, the higher the video bit rate and the higher the definition.

Finally, the video formats supported by the iPhone

• IPhone supports H.264 video format (264x320, baseline profile, 240 level or lower), aac (low complexity profile) Audio Format
• IPhone supports H.264 video formats (264x640, low complexity of baseline profile) and aac (low complexity profile) audio formats
• The iPhone also supports MPEG-4 video format (Simple Profile), aac (low complexity profile) Audio Format
• The iPhone supports. MP4,. m4v, And. mov file packaging formats. 3GP is not supported.
• The cell phone number Nokia also supports .mp4 files, H.264 videos, and AAC audio. Therefore, theoretically, you only need to make a set of videos.

Some good video conversion tools

• Format Factory: http://www.formatoz.com/CN_index.html
• handbrake: http://handbrake.fr/downloads.php