#g711

[voipswitch-blog]

VoIP

Mira la nota http://www.servervoip.com/blog/codecs-y-formatos-de-audio-en-telefonia-ip/

Codecs y Formatos de audio en Telefonia IP

Como es común en toda comunicación de múltiples medios (multimedia), es necesario utilizar un “lenguaje” común durante la trasmisión, y en caso de querer almacenarla en nuestro sistema algun tipo de formato. Para ello Asterisk utiliza toda una serie de Codecs y Formatos, tanto de video, como d...

[voipswitch-blog]

VoIP

Mira la nota http://www.servervoip.com/blog/que-codecs-usa-tu-equipo/

¿Qué codecs usa tu equipo?

Que Codecs usa tu equipo? Ayer hablando con Sergio en Pergamino, nos dimos cuenta que nuestra comunicación funcionaba en un sólo sentido. El estaba usando un teléfono IP Grandstream BT101, y yo usaba el softphone Xlite. Cuando yo lo llamaba, la comunicación se establecía con Codec G711u (tam...

[dhobits]

[kratel-blog]

Mean Opinion Score (MOS)

Mean Opinion Score (MOS)

Mean Opinion Score (MOS) is a test used in telephony networks to obtain a human user's perspective of call quality in a particular network. Customers can obtain MOS scores for their networks by visiting: Will my internet connection and network support high quality VoIP calls?

MOS Score Summary Reference:

1 - Unsatisfactory - Very annoying distortion which is objectionable

2 - Poor - Annoying distortion but not objectionable

3 - Fair - Perceptible distortion that is slightly annoying

4 - Good - Slight perceptible level of distortion but not annoying

5 - Excellent - Imperceptible level of distortion

What Customers should expect:

A MOS score of 4 is very optimal for a G711 codec call, which is a standard codec, and is comparable to Toll quality. A score of 5 is a rare occurrence and not receiving scores in the range of 5 is not a disqualifier for a high quality voice experience, as well as VoIP in general.

Most customers using BYOB (Bring Your Own Broadband) can expect a rating of 3.3 - 4.2 in non-congested converged networks. Customers with heavily congested networks will see ratings of 1 - 3.1; in those scenarios we highly recommend considering a dedicated internet connection for the phone service, or the implementation of Quality of Service (QoS) on customer networks.

[letits-blog-blog]

g711 implemetation in erlang

I implemeted g711 for audio companding in erlang programming language.

Quote from wiki:

G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation (PCM) of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also be used for fax communication over IP networks (as defined in T.38 specification). G.711, also known as Pulse Code Modulation (PCM), is a very commonly used waveform codec. G.711 uses a sampling rate of 8,000 samples per second, with the tolerance on that rate 50 parts per million (ppm). Non-uniform (logarithmic) quantization with 8 bits is used to represent each sample, resulting in a 64 kbit/s bit rate. There are two slightly different versions; μ-law, which is used primarily in North America, and A-law, which is in use in most other countries outside North America.

If you're interesting, welcome - g711 in Erlang.