- This chapter provides a short primer on video files, formats and - codecs â because it is often cause for confusion: + This chapter provides a short primer on video files, formats and + codecs – 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 + A video file is a container. It usually contains one + video track, one or more audio tracks, and possibly + subtitle tracks, chapters… + The way 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 + title="Coder-Decoder">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 + 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 + 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 + 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 + 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 + href="http://ffmpeg.org/">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 + 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. + The export dialog includes presets for common format and codec + combinations (such as DVD, web-video,..). If in doubt, one of the + presets should be used.
- 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. + As a last note: every time a video is transcoded, the quality can only get + worse. Hence for the final mastering/muxing process, one should + always go back and use the original source of the video.
-