Today I’ll talk about media formats and the phenomenon that many people do not know much about them. They don’t know how to distinguish a container format from a codec. Some others are ignorant about it and therefore show their unfair bias towards some media formats and even use some fake information to attack those forms on forums and newsgroups. In order to not behaving like those people, I hope you’ll learn some knowledge about them.
.MOV, .AVI and .WMV are media files and actually they are container files. The ‘format’ you are talking about is actually the container format. A container file tells us the organization of its inside data streams is without say anything about the representation of it. In this way, the codecs are responsible for representing the actual data. They make descriptions of the compression and decompression of video and audio data. Although it is right for you to use any codec inside any container format in theory, certain codecs are actually only allowed to be used in certain formats. Take the Sorenson codec WMV video for example, they are only used in QuickTime files and Windows Media files respectively, check more about how to convert WMV to MOV by using professional wmv converter on Windows and Mac OS X.
Because of the lack of the basic knowledge to distinguish formats from codecs, many people take for granted that all QuickTime files use the notorious Sorenson codec and they are eyesore for playing. Or, in their opinions, since AVI use the DIVX codec, they will always be in good quality.
However, none is ‘ideal’ format for all. It is easier to use some formats on certain platforms, while it’s nearly impossible for some others to use. The best way for you to deal with the insertion into website problem is to make the users be able to make a choice among different formats.
Making container formats confused by codecs is the most common mistake people often make. Although many people are in hatred of QuickTime, the fact is that they’re in hatred of the Sorenson codec, for which they don’t even know what it is. Since AVI is in good quality, some other people consider it as a great format, but I can show you an AVI which will make you throw up. While others want to know the reason for AVI or MOV plays well on their computers while other formats show no image or sound.
A container file is downloaded when you download a movie. As you can see from the name, as a file, it contains some other things. You can find nothing from the instruction book for MOV or AVI files about the way to store, compress and decompress real videos and audio data (MOV to AVI for Mac). What they do is only to provide data streams with a wrapper. Talking about a ‘format’ is actually talking about a container file’s structure. There it is nonsense for one to say that “the AVI format has a good video compression”, since it has nothing to do with the process of compression.
Internal structure of container file
A container file is often structured by one or more data streams. For the most common files, they have both a video and an audio stream. However, there can be random kinds of streams in more advanced formats, such as in QuickTime. Any designed container for streaming, no matter it is from a sequential medium like DVD or from the internet, is able to interleave the streams massively, which guarantees the data which is supposed to be together temporally. Take audio chunks for example, they, for which can as well as be read from nearly the same position inside the file, belong with certain video frames. As mentioned before, the format instruction book says nothing about what’s in the streams themselves where the codecs effect, but how they are contained in the file.