Texas Instruments MSP50C614 manual ROM Usage With Respect to Various Synthesis Algorithms

ROM Usage With Respect to Various Synthesis Algorithms

6.4 ROM Usage With Respect to Various Synthesis Algorithms

The following table lists some possible synthesis options and their ROM requirements. The models assume that just enough program space, as necessary for storage of the synthesis algorithm, is used. The remainder of the ROM is dedicated entirely to the speech data, with the goal of maximizing the synthesis playback time.

If any two synthesis algorithms are to be used in combination, e.g., MELP and LPC together, then a separate allocation must be made for each algorithm within the same fixed pool of ROM. (The program space must hold two algorithms, and the speech data is allocated in proportion to how much speech duration is used for each algorithm.)

The bit-rates and program sizes given in this table are only approximations. The estimates are applicable at the time of this printing, but they are subject (and likely) to change. Also, the data-rate is sometimes dependent on the properties of the speech.

←	C614 Total ROM Storage	→
	32,768 words

BIST

2048 words

MELP program

4.2 k words

MELP speech data	rate ≅ 2.4 k bits±per±second
26 k words ⇒	∼ 170 seconds of speech

BIST

2048 words

CELP program

6 k words

CELP speech data	rate ≅ 5.0 k bits-per-second
∼ 25 k words ⇒	∼ 79 seconds of speech

BIST

2048 words

LPC program

1.5 k words

D6 LPC speech data	rate ≅ 2.0 k bits-per-second
29 k words ⇒	∼ 230 seconds of speech

BIST

2048 words

ADPCM program

0.3 k words

ADPCM speech data rate ≅ 32.0 k bits±per±second (@ 8 kHz S.R.)

30 k words ⇒ ∼ 15 seconds of speech

BIST

2048 words

8±bit PCM speech data	rate	≅ 64.0 k bits±per±second (@ 8 kHz S.R.)
30 k words ⇒		∼ 7.5 seconds of speech

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