July 5th, 2007
So ogg is well known as the open format for audio and people seem to love it, it has broad support. To be precise, ogg is just a container format, so just the fact that a file is an ogg file doesn't tell you much more about it than a zip file tells you about its content.
On the video side of things, noone seems to use ogg. Even though it is an open and by all accounts free format, I very rarely come across ogg videos. And sadly when I do, often they are broken. Since Theora seems to be the most used codec for ogg video, I'm assuming they're all encoded in that format (I know I've never seen an ogg video not in theora, although I don't make a point of checking).
Common symptoms:
- Timer is completely bonkers, saying a 20 minute video is several hours long and whatnot.
- Video stream has lots of bugs, frame freezes.
- Audio/video sync can be way off.
Case in point, download this video from Akademy. In mplayer and vlc alike the timer is confused, and the video stream freezes as well. This is the kind of problem I've seen a lot of times with ogg videos.
Now it may be a production mishap for this particular video. But I've seen these bugs with ogg a lot more than with other formats. In mplayer, even if you reindex the stream the timer still doesn't get it right. It tells me the video is 412:29:15 long.
So what is it? Is ogg/theora busted or is the implementation busted? Is the encoder so bad that it's impossible to produce a video without bugs? Or is the decoder buggy?
Just use Matroska instead. It has much more features, and its support is catching on in video players (thank goodness).
It's not actually about what I want to use, I don't produce videos at all. I'm currently watching some more of the talks from KDE's Akademy and all of them have these bugs where the video freezes half the time, then works again, then stops again, meanwhile the audio runs unencumbered. mplayer, vlc and xine all brings this out.
I see confused timers more in Mpeg and WMV files, actually.
Theora is the open-source poster-boy but in open-source software it doesn't seem to be supported properly. Encoding to Theora and Vorbis in certain open-source programs tends to give very low quality audio in the Vorbis track.
Who wants to encode to Theora? Not a lot of people; it's a reasonable codec but the proprietary software and hardware world doesn't interoperate with it. So not many people test out Theora support in their favourite video authoring and playback programs, and we get bugs creeping in.
I mean, it has just occurred to me that I never tested my own video transcoding program's support for Ogg Theora - how daft is that? So to answer your question, Theora doesn't suck, just the support for it.
I don't see any problems with Vorbis as it's a bit more popular overall.