Common Video Formats (Part 1)
Video formats are likely familiar to everyone; most people can name a few offhand, such as MOV, FLV, MP4, and so on. But how much do you really know about these video formats? Probably not much. Today, let's explore some of the video formats we frequently encounter in daily life.
AVI stands for Audio Video Interleaved, an audio-video interleaved format. It is a file format that synchronizes voice and video together. It uses a lossy compression method for video files, but with a relatively high compression ratio. Although the image quality is not the best, its application range remains very broad. AVI supports 256 colors and RLE compression. AVI information is mainly used on multimedia CDs to store various video information such as TV shows and movies.
It was introduced by Microsoft in 1992 and became known alongside Windows 3.1. The term "audio video interleaved" means that video and audio can be interwoven for synchronized playback. The advantage of this video format is good image quality and cross-platform usability. Its disadvantages include excessively large file sizes and, worse, inconsistent compression standards. A common issue is that higher versions of Windows Media Player cannot play AVI videos encoded with early codecs, while lower versions cannot play AVI videos encoded with the latest codecs. Therefore, when playing AVI format videos, problems often arise due to video encoding issues, such as inability to play, inability to adjust playback progress, or playback with only sound but no image. If users encounter these problems while playing AVI videos, they can resolve them by downloading the corresponding codec. AVI remains a mainstream video file format. Such files are ubiquitous, for example, in game or educational software intros and multimedia CDs.
WMV is a streaming media format introduced by Microsoft, evolved from its "sibling" ASF (Advanced Stream Format). At the same video quality, WMV files are very small in size, making them ideal for online playback and transmission. AVI files encapsulate video and audio in a single file and allow audio to synchronize with video playback. Similar to DVD video formats, AVI files support multiple video and audio streams.
RealMedia is an audio-video compression specification developed by RealNetworks. Users can use RealPlayer or RealOnePlayer to broadcast network audio/video resources that comply with RealMedia technical specifications in real time. RealMedia can also set different compression ratios based on different network transmission rates, enabling real-time transmission and playback of video data over low-speed networks. Another feature of this format is that users can use RealPlayer or RealOnePlayer to play online without downloading the audio/video content. Additionally, as a mainstream network video format, RM can convert other video formats into RM video via its RealServer, which then publishes and plays the content. RM and ASF formats each have their own merits; typically, RM video is softer, while ASF video is relatively clearer.
RMVB is a video file format. The VB in RMVB stands for Variable Bit Rate (VBR). Compared to the previous generation RM format, the image quality is much clearer because it reduces the bit rate for static scenes. It can be played using RealPlayer software.
TP files are a type of HDTV file format. HDTV files circulating on the internet mainly exist in two categories: one is compressed using the MPEG-2 standard, with file suffixes .tp and .ts, and the other is compressed using the WMV-HD (Windows Media Video High Definition) standard, with the suffix .wmv. A few files have suffixes .avi or .mpg, but their nature is identical to .wmv. HDTV files are very large; even re-encoded .wmv files are substantial. For a typical movie length, .wmv files can exceed 4GB, while .tp and .ts files of the same length can exceed 8GB, sometimes even over 20GB. Therefore, besides file suffixes, file size can also be used to determine if a file is an HDTV file.
FLV is short for Flash Video. FLV streaming media format is a new video format, fully named Flash Video. Due to its extremely small file size and fast loading speed, it makes online video viewing possible. Its emergence effectively solves the problem of large SWF file sizes when importing video files into Flash, which previously hindered good network usage.
Currently, all major online video websites use this video format, such as Sina Blog, 56, Youku, Tudou, Ku6, YouTube, and others, without exception. FLV has become the mainstream format for current video files.
