Audio Ease - BarbaBatch - Supported Filetypes - CCITT
CCITT G.711 (8 bits A-law)
CCITT G.711 (8 bits μ-law)
CCITT G.721 40 Kbps (4 bits ADPCM, 8 kHz)
CCITT G.723 16 Kbps (2 bits ADPCM, 8 kHz)
CCITT G.723 24 Kbps (3 bits ADPCM, 8 kHz)
CCITT G.723 40 Kbps (5 bits ADPCM, 8 kHz)
CCITT G.726 24 Kbps (3 bits ADPCM, 8 kHz)
CCITT G.726 32 Kbps (4 bits ADPCM, 8 kHz)
CCITT G.726 40 Kbps (5 bits ADPCM, 8 kHz)
CCITT G.729 40 Kbps (5 bits ADPCM, 8 kHz)
All these files are standards in telephony audio.
All these files are headerless
G.729 can be input and output to Barbabatch, and it can be played back, but Barbabatch requires the filename extension .729 in order to recognize it at the input.
All other CCITT types can be output from BarbaBatch, not used as input. .
Generally a high perceived level is needed from these files as well as a dramatically low dynamic range. We suggest you use the BarbaBatch look ahead peak limiter in conjunction for this conversion with a setting like this:
G.711 is specified in ITU recommendation G.711.
Audio data is encoded as eight bits per sample, after logarithmic scaling.
These files are identical to Dialogic A-law and μ-law files.
G.721 is specified in ITU recommendation G.721. Reference
implementations for G.721 are available as part of the CCITT/ITU-T
Software Tool Library (STL) from the ITU General Secretariat, Sales
Service, Place du Nations, CH-1211 Geneve 20, Switzerland. The
library is covered by a license.
G.723 is specified in ITU recommendation G.723.1, "Dual-rate speech
coder for multimedia communications transmitting at 5.3 and 6.3
kbit/s". Audio is encoded in 30 ms frames, with an additional delay.
ITU-T Recommendation G.726 describes, among others, the algorithm
recommended for conversion of a single 64 kbit/s A-law or μ-law PCM
channel encoded at 8000 samples/sec to and from a 32 kbit/s channel.
The conversion is applied to the PCM stream using an Adaptive
Differential Pulse Code Modulation (ADPCM) transcoding technique.
G.726 is a backwards-compatible superset of G.721, a recommendation
which is no longer in force. G.726 also describes codecs operating at
40 (5 bits/sample), 24 (3 bits/sample) and 16 kb/s (2 bits/sample).
These are labeled G726-40, G726-24 and G726-16, respectively.
G.729 and G.729A are defined in ITU-T Recommendation G.729, "Coding
of Speech at 8 kbit/s using Conjugate Structure-Algebraic Code
Excited Linear Predictive (CS-ACELP) Coding" and its Annex A,
respectively. These two audio codecs are compatible with each other
on the wire so there is no need to distinguish further between them.
The codecs were optimized to represent speech with a high quality;
G.729A achieves this with very low complexity.