E0262 MIS - Multimedia Playback Systems Prof Pallapa. Venkataram, Electrical Communication...

E0262 MIS - Multimedia Playback Systems

Prof Pallapa. Venkataram,Electrical Communication Engineering,

Indian Institute of Science, Bangalore – 560012, India

Multimedia Playback Systems


Playback System Model


Playback System Model A multimedia playback consists of a disk-read which

feeds samples into a (D/A) converter at the same rate at which they were sampled and a display which consumes data the rate at which it has recorded.

The D/A converter creates a signal that closely approximates the original to the display (or playout) unit.

If the samples are not delivered to the D/A converter at precisely the rate at which the sampling occurred, the reproduced sound (or video) will not match the sampled sound (or video).


General Playback Framework The data is not compressed.

Digitization of video done by using analog frames of video data at fixed intervals and storing them in binary form.

Digitization of audio data is most commonly achieved by sampling an analog signal at fixed intervals and by storing the amplitude of each sample in binary form.

Reading the digitized multimedia data (either video or audio or text or images, etc.) is used to refer to retrieving data from the storage device(s), while the term “consume” is used refer to data being consumed by the D/A converter for playout.

Delays exist in storage devices and playback units.


Principles of Multimedia data storage and

retrievalData include Audio, Video and animations. Retrieval of these date types from Secondary storage has to satisfy certain time constraints in order to be acceptable to the user.

Analyze minimal Buffer requirementMinimum start time for sucessful playback


Read Function


Time is chosen so that no samples are Read.

If reading is complete at tr then

t <0, R(t) = O.

t > tr, R(t) = R(t

r)

R(t) is non decreasing function 0


Consumption Function

Let t0 be the start time for playback.

Samples Consumed at time t is:


Buffer Function

Number of Samples that must be buffered at any time


Playout Calculation


Minimal Start Time


Continuous Playback

Theorems for three cases:(1) The transfer rate of the device is equal to the

consumption rate.(2) The transfer rate is less than the consumption rate.(3) The transfer rate is greater than the consumption rate.


Buffer function


Buffer Requirements


Playback with Unavoidable delays


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Properties of Multichannel Playback

E0262 MIS - Multimedia Playback Systems Prof Pallapa. Venkataram, Electrical Communication...

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