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Technical Objections To the Ogg Container Format
E1ven writes "The Ogg container format is being promoted by the Xiph Foundation for use with its Vorbis and Theora codecs. Unfortunately, a number of technical shortcomings in the format render it ill-suited to most, if not all, use cases. This article examines the most severe of these flaws."
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Because, in general, you don't only want a video stream. You want to be able to bundle multiple streams together (usually of different types, eg an audio stream and a video stream). Vorbis, for example, is audio. Theora would be video. Ogg (the container) exists to bundle them together into a single file, so you can have a movie and sound with it.
I'm not an expert in video or audio production, I just dabble in it as a hobby. but one thing I often wonder is, what is the point of these container formats?
The point of containers is to make the contained media modular. This way, you can assemble a multimedia ("many media"... whodathunkit) file from several individual pieces of media, each with codecs that may or may not be on speaking terms, into a cohesive file that i played as a unit.
If you define a format that has a video track and two channels of audio, you might think, hey, that's great, and play stuff on your computer. But what if you want a 5.1 audio track? Make another format, one for stereo and one for 5.1. Second audio program, like an alternate language? More formats: one for stereo + stereo SAP, one for 5.1 main + stereo SAP, one for 5.1 both; up to 5 formats now. Subtitles or closed captioning? More formats: up to 20 now. A different audio codec? Even assuming the SAP tracks and main use the same codec (they might not; depends on where you got the SAP track from), add 20 formats per audio codec. Multiple video codecs? The number of formats can grow exponentially. And we haven't even gotten to things like multiple camera angles and sideband info like text commentary, HTML links to things discussed in the show, or TV listings.
Or you can define a container and then, in each of those cases, only need to define a new component to be put into the container, and you're done. Containers make things much simpler and easier to implement.
However, it's not unique to OGG. AFAIK, MKV is also patent-free, and it's the standard container for torrents^Wprivate-encoded HD video. And it's a much better container anyway.