In the impression of the average person, I always feel that the Dolby Digital should be multi-channel, or that it should be included in the main channel, the central channel, the latter and the ultra-low channel 5.1 channel surround sound. , But the fact is not the case. Record the Dolby Digital sound effect in the DVD movie, there are many possibilities. It can be the most simplified mono, or it is well known 5.1 channel, of course, there is also an internal Dolby between the two. Digital Stereo, Dolby Digital 4.0Bdolby Digital 5.0 ... etc. This must be added, which is the sound storage mode in the DVD. In addition to Dolby Digital, you can also be the DTS digital surround sound, Europe's MPEG 2,? Sony The development of SDDS, or PCM digital format, high-quality stereo as an account, but current DVD mainly uses Dolby Digital to record sound, create a rich surround effect.
Below is a few Dolby Digital format that may appear on the DVD, let us know one by one:
1. Dolby Digital Mono: Dolby Digital mono sound effect only mono effect is not enough to form a standing sound, mostly in the old movie. When the film is made, the mono sound will be stored as an AC. -3 format, therefore when playing with Dolby Digital System, only intermediate channel voices. Such sound quality performance is undoubtedly a comparative monoculation, because even basic three-dimensional feelings are very lacking, more surround effects.
2. Dolby Digital Stereo: Dolby Digital Double Sound Effects store the stereo signal of the two-channel as AC-3 format, so when you decode the Dolby Digital System, you can send the left and right channel speaker from the main channel. This is actually with our common two-channel systems (which are all in the general sound), which is a considerable approach, can construct a sense of stereo sound, but Dolby Digital's sound is compressed, how much affects the sound quality And the CD record has not been compressed and has a high-quality potential.
3. DOBLY DIGITAL SURROUND: Dolby Digital Surrounded by a matrix coding, the main channel, the central channel is squeezed into two channels, and stored in AC-3 format. Dolby Digital System Decoding, you can listen to the complete five-channel, but the surround channel is mono sound, not stereo. Not only four speakers, how can it be five channels? That is because the surround channels in the rear of the general family theater system are double channels, which is a single voice in a double channel, which is to make two speakers.
4. Dolby Digital 4.0: Dolby Digital Sound Friendly 4.0 The independent four channels, including the primary channel, the central channel and the surround channel encoded into the AC-3 format stored in the DVD movie, so through the Dolby Digital When the system is decoded, the complete five channels can be heard. At this time, the surround channel is a separate mono recording. At first glance, Dolby Digital Surround appears to be the same, in fact, otherwise. Strictly said strictly Come, Dolby Digital Surround is the use of two channels to store data, and the intermediate channels and surround channels are dressed from these two channels, calculated; but Dolby Digital 4.0 is a solid use of four sounds. Dao is stored in the primary channel, the central channel and the surround channel, or some different.
5. Dolby Digital 5.0: Dolby Digital Surround Sound Effect 5.0 Putting a separate five channels, including the primary channel, the central channel and the rear channel encoded into the AC-3 format stored in the DVD movie, when Dolby Digital When the system is decoded, the complete five channels can be restored. At this time, the surround channel begins to walk independently double-channel route, providing more accurate positioning and sound field enclosure.
6. Dolby Digital 5.1: Dolby Digital Sound Sound Effect 5.1 In addition to the main channel, the central channel is outside the latter channel, plus an ultra-low sound channel, and then this six channels are encoded into AC-3 format storage. Therefore, when you decode the Dolby Digital System, you can listen to the five channels and add an ultra-low sound channel. Since this bass channel only covers the low frequency range, it is not a complete frequency range, so it is considered 0.1. Remind the reader, not all DVD movies provide bass sound sound effects, so if your primary speaker is sufficient to sink, it can also play the effect of extending low frequencies, do not have to add this ultra-low sound Although Dolby Digital has a variety of possibilities, it also contains a variety of different output channels, but in general, we are simply in Dolby Digital 5.1, which is 5.1 channel Dolby Digital or AC-3. As for the two channels of Dolby Digital 2.0, most of them will call 2 Channel Dolby Digital. 7. PCM Tone Quality Digital Sound Effect: DVD can also be utilized compared to the aforementioned several AC-3 encoding techniques The PCM format stores uncompressed two-channel signals. Since there is no handler that has no compression loss, the best sound quality performance can be obtained. In fact, this PCM recording format is the same as the CD record, but because the DVD has huge Spatial and speed advantages, can boldly use higher sampling rates and resolution, so it can provide far more than conventional CD performance.
8. DTS digital surround sound: Surround effects of 5.1 channels, DTS uses different compression techniques with AC-3 to store surround sound to DVD. When playback, you must use a system with DTS decoding capability to hide in DVD. The 5.1 channels in the middle are released. The same is the difference between DTS with Dolby Digital 5.1? The biggest difference is that both use different 'algorithms', that is, use different ways to compress 5.1 sounds of sounds.
Dolby Digital 5.1 can press the same data less, occupying the smallest space. In turn, since DTS does not deliberately pursue the most powerful compressive ability, there is also a chance to save more information, if processing is proper, it can be provided very Superior performance.
Encoding Dolby Digital (Dolby AC-3) Dolby Pro Logic DTS
Treatment method Each channel independent digital encoding analog matrix calculation each channel independent digital encoding
Number of recorded channels * 5.1 channel 2 channel 5.1 channel
Play the number of 5.1 channels in the channel 5.1 channel
Surrounding channels stereo stereo mono stereo
Surround channel bandwidth 20Hz ~ 20kHz 100Hz ~ 7kHz 20Hz ~ 20kHz
Independent ultra-low sound channels
Transmission rate 448kbps ** n / a 1536kbps
Note: * When the recording is recorded, the number of channels (CHANNEL) is required. For example, although Dolby ProLogic is a surround system, but in fact, the central channel and surrounded by the matrix. The channel is hidden in both channels, so only two channels are used to store. ** This is the average value on the general DVD, but the actual transmission rate is possible.
Today's hegemonic A-C3
The AC-3 development was originally applied to the cinema. The AC-3 sound effect is limited because the space of the film is limited, so the data of the AC-3 sound effect is stored on the film, the intermediate of the tooth hole and the tooth hole, this part of the space is real Too little, so Dolby's engineers have to delete them to be deleted, so that there is room for space, this destructive compression will still be distorted, but in order to move on the original equipment, this It is also forced to practice
The AC-3 uses 6 speaker mode, except for overweight bass, the rest is the full-band STEREO channel, 48kHz, 16bit, and each channel is recorded in the field, and the AC-3 is surrounded. The channel has a complete positioning ability
The traffic of the AC-3 data is 192kbps. It is about 8 of the uncompressed data. The 5.1 channel traffic is 384kbps ~ 448kbps, and the maximum can be increased to 640kbps, the smaller the data traffic representative. The compression ratio, the sound is relatively better, and the details can be heard, but the Dolby AC-3 is very good to control, so the focus of the impact is to hear. The details are more widowed. DTS
Say that Dolby Digital is the middle of the tubular hole of the film, because the space limit must adopt a large amount of compressed mode, so the part of the sound quality is sacrificed, but this limit is used by the original silent small company DTS. The simple method is solved, the method is to put these sound data on another CD-ROM, which makes it synchronized with the image, not only the space increases, but the data traffic can also be relatively large, more Replace the CD card of the loud sound data, you can discharge other language versions, which is quite convenient to the cinema, and because of this DTS winning Dolby AC-3 in the professional theater.
In the LD era, because the LD of the congenial specifications, it is impossible to compatibility with the 5.1 channel Dolby AC-3 and DTS. It is a fish and bear's pauses that cannot be obtained. This also caused the failure of DTS in the family theater market, to the current DVD A times, because the large capacity of DVD can be compatible with AC-3 and DTS on a DVD, but DTS must adopt PES forms that are incompatible with past PCM formats because of some non-technical levels, although the joints of the digital output are The same, but the old DVDPlayer can't identify the PES format, so the user who wants to use the DTS sound must replace the new generation of models to use DTS, which undoubtedly hinders the DTS route.
The difference between DTS and AC-3 is the size of data traffic. DTS has 1536kbps data traffic on the DVD, compared with 384kbps ~ 448kbps, there are more than 3 times more data traffic, even if the AC-3 pulls the limit 640kbps, DTS is still 2 times more, which makes DTS to hear more details compared to AC-3, and the whole space sensation and mobile life will be more excellent, clearer.
High TX
THX is invented by the Oscar Sound Award winner, which is in Dolby Digital and DTS is a different concept of different concepts. Although it is also 5.1 channels, the horn can also be said to be the same, but it has accurate positioning There is only three channels in front, and then surrounded by two MONO channels.
The spirit of THX is to improve the sound quality of the original cinema and the home theater. The sound effect of the original movie wants to express correctly is given to the cinema or home to watch the video of the film, so THX is for each link, such as a disc, expander, The speakers, even the specifications of audiovisual spaces have strict requirements, and it is not good because each device needs to be certified. Therefore, the certification cost added is quite high, and the full and correct THX sound is really expected. Wonderful.
THX has a considerable consideration of the Wongye, because the central channel of the cinema is located behind the screen, which will inevitably cause the high-frequency portion attenuation, so the gain treble part effect will be deliberated when the film is recorded. Attenuation at the screen, if it is directly sleeved in the hidden channel in the home theater, because the hidden channel of the family theater does not need to penetrate the screen, it will cause the high frequency part to become too abutment. , Lost the effect of the film originally expressed.
THX is also a specification of 5.1 channels, and the horn is roughly the same, but its real positioning effect is limited to the three channels in front, and the surround channel is only Mono sound.
Note: The new version of the THX specification, and then has a complete positioning, which can be matched with the AC-3 / DTS
THX compares with the top two?
Since THX is different from the concept of AC-3 and DTS, the characteristics are different, the positioning effect is less than the back of the two, so the foothold is different, why compare? THX basically A requirement for the equipment and the environment, is also a post-level treatment. It has been certified by THX, which represents a certain level of sound performance. Of course, THX is complementary to AC-3 and DTS, with AC-3 or DTS The system, plus THX authentication is more like Tiger to add, and of course, the equipment of the AC-3 and DTS is sufficient to standardize THX for "sound quality performance", of course, can take THX to do certification.
SDDS sound
The full name of SDDS is SONY DYNAMIC DIGITAL SOUND, of course, is developed by Sony, which uses the sensory encoding technology of the same source of MD, due to the Colombia / Tri Star, the United States, Samsukia, USA SONY company, it will now launch a copy of this sound effect, but in shadows with higher Dolby Digital and DTS share, SDDS is relatively low. Different from Dolby Digital and DTS 5.1, SDDS The two channels belonging to the 7.1 channel, the two channels are the middle left and the middle and right channels, that is, the SDDS has five channels in front. DTS follows the footsteps of Dolby Digital officially entered the home surround system Market, do SDDS have a chance to participate in the market? At present, Sony has no action in this area. It should be no possible in the short term. DTS ES Discrete 6.1
Most AVs have not had a 6.1 or 7.1 channel system, and DTS officially announced the launch of new 6.1 channel systems on June 15, 2000 this year. This new system is called DTS ES Discrete 6.1. Discrete ? It is separated, independent.
That is to say, DTS ES Discrete 6.1 is put the rear surrounded by a separate track (actually an independent extension area outside the 5.1 channel core area of the master), and does not require matrix coding. The procedure around the channel around the channel.
Since there is no matrix code, of course, it is not necessary to decode from the left and right surround channels. In fact, we are currently using the 5.1 channels per channel independent, and there is no mutual mixing. Just but for "right After surround the channel, it has been used for the old method of the previous matrix mixed to surround the channel. According to the DTS LORR Kramer (Director of Spacial Technical Projects, they believe that the matrix method will surround the channel The practice in the left and right surround channels is not appropriate, so I have long wanted to process the rear surround channel to deal with independent channels, which is not difficult to technology.
In addition, the electronic movie played in the film E-Cinema (or digital movie Digital Cinema) has determined that the rear surround channel is used, and the share of the DTS system in the cinema is not subjected to the Dolby system, so it will definitely In the cinema, you can use the independent wrapping system. In this case, DTS simply decides to launch an independent lavback channel system in the home market, which is the DTS ES Discrete 6.1 system.
