How does a VHS player know to play a tape back at SP, LP or EP?

When recording VHS tapes, one can set the recording quality to SP, LP or EP. I am curious how upon playback the VHS player is able to play at the appropriate speed. Additionally, could two different recording speeds be used on the same VHS tape? (For example: The first half of the tape being recorded at SP and the second half at EP).

How does a VHS player know to play a tape back at SP, LP or EP?
In addition to audio and video tracks there is a control track on the VHS tape that tells the machine whether a program is in SP, LP, or EP. When you record a program you tell the machine which mode to use and it changes the control track to comply as often as you wish.
Reply:What the hell is this EP sheepie? Report It

Reply:The scan lines that appear on the screen are encoded as stripes on the tape. The distance between stripes on the tape is determined by the recording speed. The player just tries different speeds until it finds the one that is correct. If the speed changes, the player can tell that the signal is not right and it tries different speeds again until it finds the correct one.
Reply:It reads a signature placed on the tape. Therefore you could use any number of modes it would just look fuzzy during the transition.
Reply:Magnetically encoded while recording

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