MOD and TOD

Key takeaways

MOD and TOD belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MOD and TOD to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MOD and TOD from memory before moving on to harder problems.

Reference excerpt

MOD and TOD are recording formats for use in digital tapeless camcorders. The formats are comparable to XDCAM EX, HDV and AVCHD.

Overview MOD and TOD are informal names of tapeless video formats used by JVC (MOD and TOD), Panasonic (MOD only) and Canon (MOD only) in some models of digital camcorders. Format names correspond to extensions of video files. Neither JVC nor Panasonic, who pioneered the format, explained the meaning of the file extensions, and the formats were never given an official name. Some think that TOD stands for "Transport stream on disk". MOD is used exclusively for standard definition video files, while TOD is used for high definition files. The first camcorders that used MOD format appeared in 2003. JVC introduced the Everio GZ-MG30, which recorded directly to an internal hard disk drive. Panasonic unveiled the SDR-S100, which recorded to SD cards. The encoding scheme, data rate, frame rate and frame size closely matched parameters of DVD-video. In January 2007 JVC announced its first high definition tapeless consumer camcorder, the Everio GZ-HD7, which recorded 1080i MPEG-2 video to either a built-in hard disk drive or an SD memory card. Data rates, frame sizes and frame rate were comparable to 1080-line XDCAM and HDV video. Panasonic has never released a consumer high definition camcorder that used TOD recording format. Instead, Panasonic joined Sony to develop AVCHD. In January 2008 Canon unveiled a family of tapeless standard definition consumer camcorders: the FS100, FS10 and FS11. All these camcorders record in MOD format. Both MOD and TOD are file-based formats that are stored on a random-access media. Directory structure and naming convention are identical except for extensions of media files. Each file has a sequential name with last three characters comprising a hexadecimal number, which allows for 4096 unique file names. Standard definition video is stored in MPEG program stream container files with MOD extension; in most other systems these files have extension MPG or MPEG. High definition video is stored in MPEG transport stream container files with TOD extension; in most other systems these files have M2T extension. Despite the file structure being unique to this video recording format, the location for still images follows the standard agreed upon by many still camera manufacturers. Standard definition video can be recorded in 4:3 and 16:9 formats. Some video decoders do not interpret the aspect ratio information in the media file header correctly, so 16:9 video may appear squeezed horizontally when viewed. Software that is shipped with camcorders is capable of processing the aspect ratio information correctly, aided perhaps by the metadata stored in MOI files. There are also third-party tools for modifying the wide-screen aspect ratio information in the media file header so that it satisfies decoders which would otherwise fail to interpret this information correctly in an unmodified MOD file. Some tools such as MediaInfo can correctly report the aspect ratio of widescreen MOD files, but media players may or may not display them correctly depending on the capabilities of the video decoder that they are utilizing at the time.

Conversion to widely accepted formats MOD video can be viewed on a computer with a player that is capable of reproducing MPEG-2 video. This video can be easily authored for watching on a DVD player without recompression, because it is fully compliant with DVD-video standard. TOD format is comparable with AVCHD, but cannot be directly played on consumer video equipment. Media files must be packaged into distribution formats like HD DVD or Blu-ray Disc, using authoring software. One of TOD recording modes, "1440CBR", has the same frame size, aspect ratio and frame rate as 1080i HDV, and can be loosely called "HDV on disk". While many camcorders that produce the MOD and TOD formats also include Windows and/or Mac conversion software to run on your computer, there are other tools available for free to do the same work. Transport stream files can be converted into program stream files without recompressing the video itself. For example, FFmpeg, a free program, performs the conversion on Windows, Mac and Linux systems with the following command

$ ffmpeg -i myClip.TOD -vcodec copy -acodec copy myClip.mpg A similar command is used for MOD files:

$ ffmpeg -f mpeg -i myClip.MOD -vcodec copy -acodec mp2 -ab 192k myClip.mpg This is no longer necessary if the free and open source VLC media player is used, and, at least on Linux, the process is usually automated, such that connecting the camera to the PC via USB invokes the file manager and then the intuitive action of selecting a TOD file invokes VLC to play the file, or allows a simple copy and paste to transfer the file to the PC. VLC is also available for Windows.

Specifications

See also H.262/MPEG-2 Part 2: digital video compression scheme HDV: tape-based high definition format that uses MPEG-2 Part 2 video compression XDCAM: a family of tapeless high definition formats that use MPEG-2 Part 2 video compression

References

External links

Worked examples

Example 1 — a first encounter with MOD and TOD

Start with the simplest possible case. Write down what MOD and TOD claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MOD and TOD before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MOD and TOD ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MOD and TOD

In research: MOD and TOD appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MOD and TOD in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MOD and TOD is common in secondary-school and first-year university syllabi. It links to neighbouring topics Filename extensions, High-definition television, Video storage, so understanding it makes those chapters shorter.
In everyday life: Look for MOD and TOD outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study MOD and TOD in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MOD and TOD means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MOD and TOD out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MOD and TOD in simple terms?

MOD and TOD are recording formats for use in digital tapeless camcorders. The formats are comparable to XDCAM EX, HDV and AVCHD.

Why does MOD and TOD matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MOD and TOD?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MOD and TOD.