science

G.723.1

G.723.1 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand G.723.1 rather than just read about it. In short: G.723.1 is an audio codec for voice that compresses voice audio in 30 ms frames. An algorithmic look-ahead of 7.5 ms duration means that total algorithmic delay is 37.5 ms.

Key takeaways

G.723.1 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect G.723.1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of G.723.1 from memory before moving on to harder problems.

Reference excerpt

G.723.1 is an audio codec for voice that compresses voice audio in 30 ms frames. An algorithmic look-ahead of 7.5 ms duration means that total algorithmic delay is 37.5 ms. Its official name is Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s. It is sometimes associated with a Truespeech trademark in coprocessors produced by DSP Group. This is a completely different codec from G.723. There are two bit rates at which G.723.1 can operate:

6.3 kbit/s (using 24-byte frames) using a MPC-MLQ algorithm (MOS 3.9) 5.3 kbit/s (using 20-byte frames) using an ACELP algorithm (MOS 3.62)

Use G.723.1 is mostly used in Voice over IP (VoIP) applications due to its low bandwidth requirement. Music or tones such as DTMF or fax tones cannot be transported reliably with this codec, and thus some other method such as G.711 or out-of-band methods should be used to transport these signals. The complexity of the algorithm is below 16 MIPS. 2.2 kilobytes of RAM is needed for codebooks. G.723.1 is a required audio codec in the H.324 ITU-T recommendation for H.324 terminals offering audio communication. In 3GPP 3G-324M specification support for G.723.1 is not mandatory, but recommended.

Features Sampling frequency 8 kHz/16-bit (240 samples for 30 ms frames) Fixed bit rate (5.3 kbit/s with 20 byte 30 ms frames, 6.3 kbit/s with 24 byte 30 ms frames) Fixed frame size for each rate (5.3 kbit/s with 20 byte 30 ms frames, 6.3 kbit/s with 24 byte 30 ms frames) Algorithmic delay is 37.5 ms per frame, with 7.5 ms look-ahead delay G.723.1 is a hybrid speech coder, with high bit rate using multi-pulse maximum likelihood quantization (MP-MLQ) and low bit rate using algebraic code-excited linear prediction (ACELP) The complexity of the algorithm is rated at 25, using a relative scale where G.711 is 1 and G.729a is 15. G.723.1 Annex A defines 4 byte silence insertion descriptor (SID) frame for Comfort Noise Generation PSQM testing under ideal conditions yields mean opinion scores of 4.08 for G.723.1 (6.3 kbit/s), compared to 4.45 for G.711 (μ-law) PSQM testing under network stress yields mean opinion scores of 3.57 for G.723.1 (6.3 kbit/s), compared to 4.13 for G.711 (μ-law)

Licensing As of January 1, 2017, the patent terms of most patents applying to G.723.1 have expired. With regard to the unexpired licensed patents of their G.723.1 patent license agreement, the licensors of G.723.1 patents, namely AudioCodes, Orange SA, and Université de Sherbrooke have agreed to license their patents under the existing terms on a royalty-free basis starting January 1, 2017. The authorized intellectual property rights licensing administrator for G.723.1 technology is Sipro Lab Telecom. Members of the G.723.1 patent pool are AudioCodes, France Telecom, Université de Sherbrooke, Nippon Telegraph and Telephone Corporation and Nokia.

See also List of codecs Comparison of audio coding formats RTP audio video profile

References

External links ITU-T Recommendation G.723.1 - technical specification Intellectual Property Rights page on ITU website (with link to patent declaration database)

Illustrations

Worked examples

Example 1 — a first encounter with G.723.1

Start with the simplest possible case. Write down what G.723.1 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 G.723.1 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 G.723.1 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 G.723.1

In research: G.723.1 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 G.723.1 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: G.723.1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio codecs, ITU-T G Series Recommendations, ITU-T recommendations, so understanding it makes those chapters shorter.
In everyday life: Look for G.723.1 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “G.723.1” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study G.723.1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what G.723.1 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 G.723.1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is G.723.1 in simple terms?

G.723.1 is an audio codec for voice that compresses voice audio in 30 ms frames. An algorithmic look-ahead of 7.5 ms duration means that total algorithmic delay is 37.5 ms.

Why does G.723.1 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 G.723.1?

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 G.723.1.