HTML5: Up and Running

Batch Encoding Ogg Video with ffmpeg2theora

(As in the previous section, in this section I’m going to use “Ogg video” as a shorthand for “Theora video and Vorbis audio in an Ogg container.” This is the combination of codecs+container that works natively in Mozilla Firefox and Google Chrome.)

There are a number of offline encoders for Ogg video. If you’re looking at batch encoding a lot of video files and you want to automate the process, you should definitely check out ffmpeg2theora.

ffmpeg2theora is an open source, GPL-licensed application for encoding Ogg video. Prebuilt binaries are available for Mac OS X, Windows, and modern Linux distributions. It can take virtually any video file as input, including the DV video produced by many consumer-level camcorders.

To use ffmpeg2theora, you need to call it from the command line. (On Windows, go to Start Menu→Programs→Accessories→Command Prompt. On Mac OS X, open Applications→Utilities→Terminal.)

Figure 5-12. Encoding in progress

ffmpeg2theora can take a large number of command-line flags. (Type ffmpeg2theora --help to read about them all.) I’ll focus on just three of them:

• --video-quality Q, where Q is a number from 0–10.

• --audio-quality Q, where Q is a number from –2–10.

• --max_size=WxH, where W and H are the maximum width and height you want for the video. (The x in between is really just the letter “x”.) ...