+ This chapter provides a short primer on video files, formats and + codecs â because it is often cause for confusion: +
+ ++ A video file is a container. It usually contains one + video track and one or more audio tracks. + How these tracks are stored in the file is defined by the + file format. Common formats are + avi, mov, ogg, mkv, mpeg, mpeg-ts, mp4, flv, or vob. +
++ Each of the tracks by itself is encoded using a Codec. Common video codecs + are h264, mpeg2, mpeg4, theora, mjpeg, wmv3. Common audio codecs are + mp2, mp3, dts, aac, wav/pcm. +
++ Not all codecs can be packed into a given format. For example the + mpeg format is limited to mpeg2, mpeg4 and mp3 codecs (not entirely true). + DVDs do have stringent limitations as well. The opposite would be .avi; + pretty much every audio/video codec combination can be contained in an avi + file-format. +
++ To make things worse, naming conventions for video codecs and formats are + often identical (especially MPEG ones) which leads to confusion. + All in all it is a very wide and deep field. Suffice there are different + uses for different codecs and formats. +
+ ++ Ardour supports a wide variety of video file formats codecs. More + specifically, Ardour itself actually does not support any video at all + but delegates handling of video files to ffmpeg, which supports over 350 different + video codecs and more than 250 file formats. +
++ When importing a video into Ardour, it will be transcoded + (changed from one format and codec to another) to avi/mjpeg for internal + use (this allows reliable seeking to frames at low CPU cost — the + file size will increase, but hard disks are large and fast). +
++ The export dialog includes presets for common format and codec + combinations (such as DVD, web-video,..). If in doubt use one of the + presets. +
++ As last note: every time a video is transcoded, the quality can only get + worse. Hence for the final mastering/muxing process, one should + always to back and use the original source of the video. +
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