Info and forum posts by 'Kevin Bryant'
Joined on: Tuesday, 30th January 2001, 08:59, Last used: Tuesday, 30th January 2001, 08:59
Access Level: Mostly Harmless
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This user has posted a total of 46 messages. On average, since joining, this user has posted 0.01 messages a day, or 0.04 messages a week. In the last 30 days, this user has posted 0 messages, which is on average 0 messages a day.
Recent Messages Posted:
No need to bow! All the info is available on the Dolby web-site (lots of long PDF files) which is where I got it from.
I work for HP in computer support, but part time in TV as `sound engineer` (whatever that means) hence an `awareness` of digital sound techniques and an interest in how DD & DTS work and Surround vs Stereo vs Mono compatibility.
As an addition to my previous post, I`d also like to point out that the `bedroom telly` scenario is also likely to be listening in mono, so those seperate L & R get combined to `M`. The net effect of this, whether listening to a DD5.1 downmix (in Lt/Rt mode) or a true Dolby Surround mix is that ALL the surround channel gets removed....and think of all those films broadcast on TV where people are still listening in mono. The film sound balancer has a tremendous challenge in making his mix sound as good as possible in a variety of listening conditions!
Not quite so...
If your DVD player did not have a Dolby Digital (DD) decoder then you would hear no sound from your DVDs at all. Dolby Digital refers to the combined digital bitstream that represents a number of (possibly) seperate audio channels within, these channels are compressed (lossy) and combined in a DD encoder and it is the job of the DD decoder to uncompress & split them out again. How this output is presented is dependant on the facilities the decoder has available...eg If it has the full 6 analogue outputs then it can present each of the six encoded audio channels (L,C,R,LS,RS,LFE) on it`s respective output. If (as per Scan) you only have 2 analogue outputs then you have to combine a 5.1 (6 channel) mix down to 2. This is done in 2 ways, the difference being what is done with LS&RS...
1) LO/RO where L output = L + C*0.707 + LS, Routput = R + C*0.707 + RS
2) Lt/Rt where L output = L + C*0.707 + LS, Routput = R + C*0.707 - RS
LO/RO just adds everything together (with a 3db loss on the centre channel because your reproducing this from two loudspeakers)
Lt/Rt puts the two surround channels out of phase and hence emulates the action of a Dolby Surround encoder ready to be decoded by a Dolby Surround (or better Dolby Surround Pro-Logic) decoder. HOWEVER this emulated surround mix is NOT as the director intended which is why you should really use the `Dolby Surround` soundtrack on the DVD rather than the Dolby 5.1 `downmix` (The Dolby Surround mix is actually a matrixed L + C + R + S down to 2 channels..there`s a bit of Dolby B type noise reduction in there as well...for fun! But it`s still stored in a Dolby Digital format...confused? Now you know why they have so much fun labelling your DVD case!)
Both methods lose the LFE (Low Frequency Effects) channel.
The DD data stream also includes data about the audio such as it`s level, this `meta-data` is used to implement the `dynamic range compression` (or late night mode) such that loudness peaks can be controlled. There are 2 modes for this also, RF mode & Line mode. RF mode compresses quite a bit harder than Line mode but is suitable if you plan to feed the audio through an RF modulated link (eg via your video modulator around the house)...your bedroom telly is unlikely to be able to cope too well with the extremes of `near silence` & then `spaceship crash lands in New York` but your Hi-Fi (Line mode) probably can!
So to sum up....there is no advantage to having a 2 channel output rather than 6 channel. Now that was the long way round huh :-)
Hope that helps
This item was edited on Wednesday, 21st March 2001, 19:55
Right let`s sort this out....
First, there are two types of the `firmware`, one designed to work with the ADV7172 video DAC, the other version with the CS4955 video DAC. If you load the wrong type of firmware compared to the actual DAC installed in your machine, you will kill your machine. I did not know about this video DAC difference until a few weeks ago.
Next we have a little note found in the Scan firmware revision history document...
(1) Support to update program code on Multiple Vendor`s Flash ROMs.
The implication of this is that versions PRIOR to v1.95 (ie 1.80) do NOT understand how to program certain flash rom types - quite what types v1.80 DOES understand isn`t exactly clear, but I know in my case that it can cope with AMIC 29040 chips. The type of Flash rom chip is reported by the firmware (but only later versions!) in the SSW screen, just after the Ram DAC type eg. ADV7172 00000003 - you can decode the flash rom type according to the following list (not that it`ll help you much!)
00000000 : ROM only - not flashable.
00000001 : SYNCMOS 29c51004
00000002 : SST 29c51004
00000003 : AMIC 29040
00000004 : EON 29F040
00000005 : AMD 29F040
00000006 : HYUNDAI 29F040
My guess is that newer machines are being shipped with some different flash rom types such that the old firmware can`t burn them. So your currently running 2.08 say, and you then burn v1.80 - this works great, until the v1.80 code is running and you try to burn v2.23 or whatever. I think the lesson is, don`t downgrade before v1.95!
Nivz - I think your FAQ needs updating a little :-)
This item was edited on Thursday, 8th March 2001, 19:03
You CAN find out without opening up - take a look at the Software Status Window (SSW) and note the number after `ADV7172`, compare this with the list on hdubois site (which I can`t find the bookmark for at the moment) All I can remember is that 00000003 is AMIC.
I use CDRWIN 3.8c on CD-RW - file & backup tools, `retain full paths` set false. Finalise/Close Session & write leadout track enabled. CDROM Mode 1.
Before you downgraded to v1.80, did you look at the software status screen? If so, did you note down/remember the number after the `ADV7172` line (the first line), this is normally 00000003 but I`m wondering if yours was/is different.
The subwoofer will make no difference. This is a problem with the amp being unable to lock/decode the DTS digital output from your DVD player. Check that you have any audio `dither` options disabled on your player, also check the digital output settings of the player...there may be a special option for DTS, but failing that a `bitstream` output should be sufficient.
Excuse ignorance but is the DV3100 `certified` as producing DTS output? There should be no reason why it cannot, but internal dither algorithms destroy the DTS data and some players cannot turn it off.
I`ve always used CD-RW media burned with CDRWIN 3.8c in CDROM Mode1 @ 2x (my rewriter will only burn on CDRW @ 2x!) ALWAYS Close/Finalize & Write Postgap.
Something I noticed in the firmware changes txt file...
(1) Support to update program code on Multiple Vendor`s Flash ROMs.
This implies that the flash update code in earlier versions of firmware is not as `manufacturer` aware and MAY be the reason why some updates fail. Those who downgrade to v1.80 from v1.95 or above take a risk that the v1.80 EEPROM update code will not be able `burn` a newer version of firmware into the EEPROM. The only thing I can say is that v1.92 understands how to burn `AMIC` EEPROMs and I`ve a sneaky suspicion that the code was designed for this manufacturer from the outset as most of the ancilliary support chips are also made by AMIC.
If mummy takes away Bears `praystation` he`ll really start throwing his toys out of his pram and mummy won`t be able to cope with that, mind you, she`s being a bit irresponsible letting him on this forum anyway :-)
A Word of Warning!
The version of 2.14 from the hdubois site & the version of 2.14 provided by Scan (with help from NiVZ) are NOT the same! The files do not checksum the same and I wouldn`t like to say what the differences are!
I would trust the Scan/NiVZ one more as the provision path is better known.
You sure it wasn`t the amp hissing rather than all 3 players - sounds a bit odd to me!
Reaper I think you`re on somewhat dodgy ground - Why are you playing a R1 DVD in a R2 DVD Player? How have you managed to get it to play? ("I`ve hacked it") I may be wrong, but there are at least 2 very big get out clauses for Debenhams/Lecson.
The Scan has a built in Dolby Digital decoder BUT only two analogue outs (left & right). When decoding 5.1 soundtracks, the machine downmixes (combines) 5.1 into just 2 channels. You have some control over how this downmixing is performed but at best you get a pseudo Dolby Surround Pro-logic mix - it would be better to use the Dolby Surround (ie 2 channel) mix if the disc provides it rather than the downmix. If you want to get at the full 5.1 channels you need to use the digital output (co-ax or optical) into a Dolby Digital capable decoder/amp.
Such amps include (but not limited to) Denon AVR1601 and Yamaha DSP-A5. Both are also capable of decoding DTS soundtracks. You are looking at around £250-300 - Shop around!
This item was edited on Saturday, 10th February 2001, 18:56
No, TaeYoung Telstar`s product they know as the DVD 3000, is the same as Daewoo DHC 2200, Daewoo DVD 2000, Scan SC 2000, Divido, Manhattan DVD 2000, Emerson EMD 2100, Grundig GDV130 & last but not least, the Logix 3000. They are all the same product (but some with cosmetic changes) The pre-occupation with `2000` in Europe is probably related to our recent millenium change.
It has not been superceded as yet but, like any product, including those made by Sony and Hitachi, it will be at some point. It`s called marketing and the replacement products are not necessarily better...and that includes the big brands.
This item was edited on Saturday, 10th February 2001, 10:57
Hmm, interesting! All I can say is you`re right, there is most definitely a time difference between the digital out & analogue outs when playing MP3, every other format appears `in-sync`. This may be fixed in v2.08 firmware (I seem to remember there being an MP3 related fix in that version) but I would wait until the `latest & greatest` firmware is released in the near future.
If I get time I`ll test v2.11 & v2.08 over the weekend....unless anyone else wants to volunteer !
The short answer is "yes" - the longer answer....
Assuming your DVD player has a digital audio output (I`d be surprised if it didn`t) then all you need is a Dolby Digital decoding amplifer, which takes the compressed Dolby Digital signal, uncompresses and then `splits` it to seperate 5.1 outputs. Amplifiers you could consider looking at include the Denon AVR1601 and Yamaha DSP-A5, there ARE others available of course.
>The music at -60dB was about the same volume as the noise from the
>DVD player on both 2 channel and 6 channel outputs.
oh dear, my guess was right!
>The S/N ratio of the LG3350 is specified to be more than 100dB. As the
>noise seems to be as loud as a -60dB audio signal can one say that the
>S/N ratio is 60dB? If so, the unit is well off the design specification.
Yes & No, it depends how you want to conduct the test as you yourself have discovered! Playing a source with `digital black` will activate the mute circuits so the noise floor drops to -100dBFS or so. Playing a source with digital noise at -87dBFS should deactivate the mute, so the noise floor should be at -87dBFS. From your own test with very quiet music, it would appear that this -87dBFS noise would in fact be swamped by the player generated noise up at around -60dBFS. If the noise floor is at say -60dBFS, then the loudest signal that can be produced must be 0dBFS, therefore, the Signal to Noise ratio can only be 60dB at most. For comparison, a good cassette deck with Dolby B noise reduction will get you a S/N ratio of about 65dB.
I analysed the mp3 file you put up earlier and the major noise components are at 15.625KHz (TV line timebase & doesn`t surprise me at all, this stuff gets everywhere!), 5.4KHz & 10.8KHz The last two have no obvious source to me but are harmonically related. The most likely cause is poor supply filtering to the D/A converters as all converters are affected, the next most likely is crosstalk between PCB tracks. This is not likely to be a problem with the digital input to the converters.
Also minor spikes at 8KHz & 9KHz can be seen, along with a general 10dB increase in `mush` starting at around 14.5KHz. This is not something that can be fixed by software but is rather a hardware problem. It may be a design fault, or maybe there is a faulty batch of players out there as more than one of you has noticed an issue.
Sorry to say this, but I would start talking to LG!
I don`t own/know the Lecson, but does it have any `3D virtual surround` type modes on it, if so, turn them off...they always cause `fun` to delicate ears!
Yep sounds like a design fault to me. Could be something simple like insufficient -+V supply rail filtering or poor routing of the D/A output traces on the PCB (high cross-talk) Either way, the `hardware mute` is a very nasty workaround (basically a brutal noise gate!) and should not be required...useful for producing spec sheets though (look at the signal to noise ratio on this!)
Makes me wonder if the main output is similarly affected...what you need is a test cd with noise recorded at about -87dB to `toggle` the bottom 2 bits, this should disable the `brutal mute` and allow you to hear if there is any other noise at higher levels (bet it`s at around -60dB!)
I could burn you a test audio CD if you want.
Ooops, I forgot about changing the digital out mode on my DVD player as suggested, so I tried it. It`s a case of so close but so far (for me at least) My player when set to output PCM only, will indeed provide the decoded DD soundtrack including the 5 to 2 channel `Pro Logic` downmixing. The digital output appears to be in essence that provided to the on-board DVD D/A converters. However, it appears that the SCMS bits are set such that you cannot record the output, my MD recording spitting the words "SCMS prohibit` at me. If you have a SCMS stripper available then you ARE on to a winner, but if not then you`ll have to go analogue as I originally suggested. To be fair, the data compression algorithms of decompressing DD, downmixing and then compressing/decompressing with ATRAC are likely to hide the analogue artifacts, just watch those peak levels.
You may also want to try listening with the 5 to 2 channel downmix mode switched from `LtRt` (sort of pro-logic) to `LoRo` (which just adds all 5 channels together), the effects channels MAY `sit` a little better in the mix. You may even find that DD 2 channel soundtrack (ie the real pro-logic mix) if available will replay better still, depends on the movie. Try it!
PS. Make sure you disable `RF mode` and set `Line Mode` and set dynamic range compression to 0 otherwise you`ll throw all that movie dynamic range away!
This item was edited on Wednesday, 7th February 2001, 21:44
I thought it was "Big feet...Big shoes" !
My point EXACTLY as long as you don`t put SCAN owners down either!
#DEFINE SARCASM_MODE TRUE
ha ha ha ha ha - you BOUGHT a TOSHIBA!!!!!!!
They must have seen you coming. I don`t know how ANYONE could buy a TOSHIBA - how useless can you get?!
Just felt like saying that. No offence.
#DEFINE SARCASM_MODE FALSE
This item was edited on Monday, 5th February 2001, 22:15
ha ha ha ha ha - you BOUGHT a SONY!!!!!!!
They must have seen you coming. I don`t know how ANYONE could buy a SONY - how useless can you get?!
Just felt like saying that. No offence.
This item was edited on Monday, 5th February 2001, 20:58
But it affects both DVD & Video..I very much doubt his VCR is capable of producing an RGB output. But a VERY common problem when using RGB as you say!
Whilst you should certainly be able to record MP3 & CD output digitally, you will not be able to record the DVD soundtrack as it is output as a Dolby Digital datastream not 44.1/48KHz 16bit PCM, you`ll have to go via analogue.
Remember? I`ve still got the screwdriver :-)
The ONLY thing a `widescreen` VCR MAY do is assert a control signal (pin 16 I think) on the scart output to force your TV into widescreen mode...you`ll probably have to press a button on the VCR remote though as it`s got no other way of auto switching for you!
So yes it`s a marketing ploy! Anyone else remember the great `Computer compatible` marketing ploy on cassette machines for Sinclair ZX81 & Spectrums - oh dear showing my age!
Probably wondering what to do when you run out of toes :-)