DVD-RB can't reencode LPCM audio to AC3?

[Yobbo]

I'm just wondering why this hasn't been implemented in DVD Rebuilder? It seems like a logical feature to have?

[jdobbs]

I'm just wondering why this hasn't been implemented in DVD Rebuilder? It seems like a logical feature to have? All audio in DVD-RB is kept intact, including LPCM.

[Ghitulescu]

Dolby Labs require a licence for it ...

[xterminater]

I wonder if LPCM audio really makes a difference when compared to DTS or even dolby digital 5.1?

[Ghitulescu]

I wonder if LPCM audio really makes a difference when compared to DTS or even dolby digital 5.1?

The very same way a DivX footage compared to the uncompressed original.

[setarip_old]

@xterminater I wonder if LPCM audio really makes a difference when compared to DTS or even dolby digital 5.1?It's in the ear of the beholder ;>}

Audiophiles will state that, yes, LPCM is better, while the majority of disc viewers/listeners would say they can't discern any meaningful difference...

[jdobbs]

@xterminater It's in the ear of the beholder ;>}

Audiophiles will state that, yes, LPCM is better, while the majority of disc viewers/listeners would say they can't discern any meaningful difference... Proven by many scientific double-blind tests (when the compressed audio's bitrate is sufficiently high) . Machines can detect it, but not humans because of psycho-acoustical audio limitations.

In fact, machines will also see a significant difference between the original analog signal and an LPCM source -- because the LPCM is made up of only samples of the analog signal (typically at 44.1Khz or 48Khz) that are used to create a facsimile upon playback. Lots of people say they can hear that difference too -- but, oddly enough, they can never seem to spot it when challenged to identify the digital signal in a double-blind test.

[Ghitulescu]

While most of the time is simply a placebo, there is a difference. However, since the lossy compression algorithms usually employ the weaknesses/limitations of the human senses, it's sometimes difficult to discern X from Y, even in a controlled environment. One needs trained eyes and/or ears.

There are some issues to be set/solved/taken into consideration before actually compare or judge the facts/tests:
1. the higher the bitrate and the more performant the algorithm, the narrower the differences
2. the quality of the reproduction device plays a decisive role
3. the surrounding (noise, reflections, absorbtions etc.) is also important
4. the initial quality, including the "sound/optical" resolution is crucial.

To 1. I don't think it requires any explanation.
To 2. I can only say three things: it's much easier to recognize the lower quality sound/video when you're used to high quality sources and A/V-chains than vice-versa (conversely, one gets more easily accommodated in a 7* hotel from a 2* than from a 7* down to 2*, provided someone else pays for you). The second issue is the argument I have often heard during the initial days of MP3: the sound of any 128kbps audio is indistinguishable from the CD it came. Well, that was true indeed, using the PC and the PC-speakers, no difference at all. People became more "selective" only after hardware MP3 players appeared and they could listen the "indistinguishables" on a real audiochain, and they notice the differences. The third is that all senses can be educated, while they are generally genetic conditioned (some hear better, some have an absolute hearing (very rare)), one can be trained to spot issues never thought possible, because while the senses feel, it's the brain that interprets the signals.
To 3. I can repeat the second argument of #2 above. And that most people hear the music in "improper" conditions (MP3 players with in-ear headphones in a noisy environment, or in a car stereo, or on a PC through 10$ speakers and so on).
To 4. there are several issues. The audio resolution can be decisive in narrowing the differences. Generally speaking, using DTS MA of 192/24 8chn and extremely expensive A/D-gear to capture a telephone conversation is overkill, one can obtain quite similar acoustic results using maybe 8/12 mono, the PC mic interface and a noise gate. This was recognized long time ago (Nyquist). There is also the possibility that an MP3 encoding can actually clean the residual noise eg of a live recording, making a high bitrate encoding sound superior to the original uncompressed. Not least important is the mastering, considering that most people hear the music either in car (home-job-home) or in portables (again home-school-home) and/or in noisy environments, the late music was generally more audio compressed to make it louder - this subject has been discussed a while ago also here in doom9.

Sorry for this long slightly off-topic issue.

[ArthurIhde]

While most of the time is simply a placebo, there is a difference. However, since the lossy compression algorithms usually employ the weaknesses/limitations of the human senses, it's sometimes difficult to discern X from Y, even in a controlled environment. One needs trained eyes and/or ears.

There are some issues to be set/solved/taken into consideration before actually compare or judge the facts/tests:
1. the higher the bitrate and the more performant the algorithm, the narrower the differences
2. the quality of the reproduction device plays a decisive role
3. the surrounding (noise, reflections, absorbtions etc.) is also important
4. the initial quality, including the "sound/optical" resolution is crucial.

To 1. I don't think it requires any explanation.
To 2. I can only say three things: it's much easier to recognize the lower quality sound/video when you're used to high quality sources and A/V-chains than vice-versa (conversely, one gets more easily accommodated in a 7* hotel from a 2* than from a 7* down to 2*, provided someone else pays for you). The second issue is the argument I have often heard during the initial days of MP3: the sound of any 128kbps audio is indistinguishable from the CD it came. Well, that was true indeed, using the PC and the PC-speakers, no difference at all. People became more "selective" only after hardware MP3 players appeared and they could listen the "indistinguishables" on a real audiochain, and they notice the differences. The third is that all senses can be educated, while they are generally genetic conditioned (some hear better, some have an absolute hearing (very rare)), one can be trained to spot issues never thought possible, because while the senses feel, it's the brain that interprets the signals.
To 3. I can repeat the second argument of #2 above. And that most people hear the music in "improper" conditions (MP3 players with in-ear headphones in a noisy environment, or in a car stereo, or on a PC through 10$ speakers and so on).
To 4. there are several issues. The audio resolution can be decisive in narrowing the differences. Generally speaking, using DTS MA of 192/24 8chn and extremely expensive A/D-gear to capture a telephone conversation is overkill, one can obtain quite similar acoustic results using maybe 8/12 mono, the PC mic interface and a noise gate. This was recognized long time ago (Nyquist). There is also the possibility that an MP3 encoding can actually clean the residual noise eg of a live recording, making a high bitrate encoding sound superior to the original uncompressed. Not least important is the mastering, considering that most people hear the music either in car (home-job-home) or in portables (again home-school-home) and/or in noisy environments, the late music was generally more audio compressed to make it louder - this subject has been discussed a while ago also here in doom9.

Sorry for this long slightly off-topic issue.

wow,thanks for your nice reply!http://www.free123.net/sig/38/smile.gif