User Manual

Multichannel Monitoring Tutorial Booklet (M2TB) rev. 3.5.2

Masataka Nakahara : SONA Corporation

22 / 74

2-3. Recording response

By “recording response” we mean the response allowed when the master tape produced by the studio is

recorded onto the production target media.

The response of each channel recorded on the media will depend on the encoding method and

compression method as described above.

In the case of analog recording, the response will depend on the specifications of the recording media.

However for lossy compression (irreversible compression), it is important to note that “fs” and “Qb” do

not directly determine the recording response (in particular, the dynamic range).

Currently for most media, full-range recording is possible for all channels.

However in the case of LFE and surround channels, there will be differences depending on the media.

2-3-1. LFE channel

For media that is recorded in Dolby DIGITAL, such as film and DVD-Video, the bandwidth is restricted

to 120 Hz at the time of encoding*.

This also applies to DTS. However in film, the range to 80 Hz is the recording band for the LFE channel

of DTS.

Similarly for the MPEG-2 used in digital broadcast (Europe), the upper limit of the LFE storage

bandwidth is restricted to 125 Hz.

In MPEG-2 AAC (digital broadcast, Japan), full-range recording is possible for encoding, but due to

considerations of the propagation spectrum, there may be a bandwidth limitation on the LFE channel.

Thus, it is necessary to be aware of the recording bandwidth of the LFE channel when the propagation

system is taken into account (see ISO/IEC and ARIB).

For music media (DVD-Audio, Super Audio CD), the LFE channel allows full-range recording in the

same way as the main channels.

* To be precise, Dolby Digital can record signals of up to about 600 Hz on the LFE channel of DVD-

Video, but since the LFE channel LPF (fc=120 Hz) is applied by default as an option during encoding, it

is best to consider 120 Hz as the upper frequency limit for recording and playback on the LFE channel

except for special cases.

2-3-2. Surround channels (S, LS, RS, BS)

For 3-1 matrix (Dolby stereo, Dolby surround, DTS stereo), the recording bandwidth of the S channel is

restricted to 100 Hz–7 kHz. For 5.0 matrix (Dolby Pro Logic II), the LS and RS recording channels are

restricted to 100 Hz–20 kHz.

In DTS for film (5.1, 6.1), the recording bandwidth of the surround channels (LS, RS, BS) is restricted to

80 Hz and above, but since sound recorded on the master tape that is lower than this point is collectively

recorded on the LFE channel, the resulting playback is full-range. This is known as “bass management”

(described in section 4).