Default mappings from payload type numbers to encodings

Μ-law (or Mu-law) is a standard multimedia digital signal codec (compression/decompression) algorithm for pulse code modulation issued by the International Telephone and Telegraph Advisory Committee. As a method of compression extension, Μ-law can improve the signal-to-noise ratio without adding more data. Mu-law because the letter μ in Greek is pronounced as myoo, the term mu-law is derived from Μ-law, and in addition, the term is sometimes written as u-law due to pronounced consistency. Currently, Mu-law is used by the United States and Japan, while Europe and other places use another multimedia digital signal codec, decoder (compression/decompression) algorithm, A-law.

Payload Type De nitions:

Payload type indicates PCMU encoding, 8,000 Hz sampling rate, 2 channels.

Payload type values in the range 96-127 is de Ned dynamically through a conference control protocol

Entries in Tables 4 and 5 with payload type \dyn "has no static payload type assigned and is only used

With a dynamic payload type. Payload Type 2 is assigned to G721 in RFC 1890 and to it equivalent successor G726-32 in draft versions of this speci CA tion,
But it use was now deprecated and that static payload type was marked reserved due to conflicting use
For the payload formats g726-32 and AAL2-G726-32 (see section 4.5.4). Payload type indicates
The Comfort Noise (CN) payload Format speci ed in RFC 3389 [9]. Payload type is marked
\reserved "Because some draft versions of this speci cation assigned
Version of the Comfort Noise payload format. The payload type range 72-76 is marked \reserved "
So, RTCP and RTP packets can be reliably distinguished (see section \summary of Protocol
Constants "of the RTP protocol speci cation).

PT, encoding media type clock rate channels
Name (HZ)
0 PCMU A 8,000 1
1 reserved A
2 Reserved A
3 GSM A 8,000 1
4 G723 A 8,000 1
5 DVI4 A 8,000 1
6 DVI4 A 16,000 1
7 LPC A 8,000 1
8 PCMA A 8,000 1
9 G722 A 8,000 1
Ten L16 A 44,100 2
L16 A 44,100 1
QCELP A 8,000 1
8,000 CN A 1
MPA A 90,000 (see text)
G728 A 8,000 1
DVI4 A 11,025 1
DVI4 A 22,050 1
G729 A 8,000 1
Reserved A
Unassigned A
Unassigned A
Unassigned A
Unassigned A
Dyn g726-40 A 8,000 1
Dyn g726-32 A 8,000 1
Dyn g726-24 A 8,000 1
Dyn g726-16 A 8,000 1
Dyn g729d A 8,000 1
Dyn g729e A 8,000 1
Dyn Gsm-efr A 8,000 1
Dyn L8 A var. var.
Dyn RED A (see text)
Dyn Vdvi A var. 1
#Table 4:payload Types (PT) for audio encodings

PT encoding media type clock rate
    name (Hz)
Unassigned v
CelB v 90,000
26 JPEG v 90,000
Unassigned v
(NV v 90,000
Unassigned v
) Unassigned v
to H261 v 90,000
+ M PV V 90,000
mp2t AV 90,000
H263 V 90,000
35-71 unassigned?
72-76 reserved N/a N/a
77-95 Unassig Ned?
96-127 dynamic?
Dyn h263-1998 V 90,000
#Table 5:payload types (PT) for video and combined encodings