gaps

[dj-27]

A lot of effort has been expended by all the good developers of this project
to address gapless playback of the authored DVDAs.  And rightly so, as gapless
playback is crucial for enjoyment of many music programs.

If I recall correctly, Discwelder Chrome deals with this problem (for MLPs, at
least) by requiring the music program to be one continuous file and then
adding track points for that file during the authoring step.  This is like
burning a CD-audio using one wave file and a cue sheet, except with Chrome I
recall that the assignment of track points is a tedious, manual, process.  But
it works.

I assume the DVDA-Author developers have considered this approach (i.e.,
authoring with a single file in a Group and using something like a cue sheet)--
but found it too difficult or problematic?



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[fabrni]

Yes, this is an obvious way out, though a last resort. Lee has done work on it, I offered him to make this version public through a dev testing branch.
Fab

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[Udo-12]

--- On Mon, 5/18/09, dj <deedj@...> wrote:
> A lot of effort has been expended by
> all the good developers of this project
> to address gapless playback of the authored DVDAs. 
> And rightly so, as gapless
> playback is crucial for enjoyment of many music programs.

Indeed. See my 'discussions' with NAD...

> If I recall correctly, Discwelder Chrome deals with this
> problem (for MLPs, at
> least) by requiring the music program to be one continuous
> file and then
(...)
> I assume the DVDA-Author developers have considered this
> approach (i.e.,
> authoring with a single file in a Group and using something
> like a cue sheet)--
> but found it too difficult or problematic?

I don't know, but I think it does not matter if it is one file or not since dvda-author can make multiple files appear as one stream. The core issue, I guess, is what the disc should look like at the AMG/SAMG level.(see http://dvd-audio.sourceforge.net/spec/audio_ts.shtml)
Did anybody compare a discwelder DVD-A with same-audio dvda-author?

Gapless test-ISO's remain welcome, to test on the NAD T524.

Udo


     

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[nnguru]

In this forum, there has been a lot of discussion around the issue of gapless behavior.  Some of this discussion has been extremely confusing, at least with respect to my empirical observations.  Let me state a few assertions that I believe to be correct.

 

 1.  To avoid confusion, let me use the word "blip" to describe the observation of an interruption in sound playback at the transition from one track to another.  So defined, a blip may be synonymous with what is called a gap, but I use a different word because on certain players (including two different computer players and my Oppo 981) a blip is heard even when there is no real gap in the stream of information embedded in the corresponding AOB file.

 

 2.  It is possible that different players produce blips at track transitions for different reasons, that is, by different mechanisms.  Some players may produce a blip because the hardware cannot find the new portion of the sound stream quickly enough. I have never observed this mechanism.  What I have observed are blips produced by a player merely because of the presence of a track transition.  By this I mean that the player, having recognized a track transition, inserts a gap in the sound stream regardless of whether the data in the wave file or the MLP file was continuous.  DJ is correct in his recollection that the Chrome authoring program inserts markers at track transitions, at least when dealing with MLP files.  This method is needed in the case of MLP, because of the very nature of an MLP stream: dependencies extend over many more samples than in the case of wave files.  If gapless performance is expected with MLP encoding, it is probably not a good idea merely to generate independent MLP files for a series of successive tracks, because the MLP coding for each new track will start afresh and not join properly with the previous track.  (Even so, some players still have no problem.)  Examination of the MLP files for cases in which gapless behavior is needed suggests that the producers paid attention to this issue.  Each successive track respects the state of the previous track.  This strongly suggests that a large wave file was initially converted and then either split into a file for each track, or used as a whole with track information appropriately computed and placed in the IFO files (cue sheet approach).

 

 3.  If you are skeptical about my assertion that blips have little to do with navigating the sound files and everything to do with how player chooses to respond to a track transition, I strongly encourage testing the assertion yourself with the aid of an easily produced test disc.  I provided a recipe for producing these discs in a previous note to this forum.  Rather than repeat the contents of that note, let me merely comment on what you can demonstrate.  Disc two provides track transitions (as seen by the player) at points where the sound stream, by construction, is necessarily continuous, as well as the absence of track transition (again, as seen by the player) at points where there is an actual transition from one file to another.  for clarity, let us consider a hypothetical example.  As in my previous note, suppose the wave files are called a, b, c, and d and have durations ta, tb, tc, and td.  Then in the first disc, track transitions would occur at the following times (measured from the beginning): ta, ta+tb, ta+tb+tc.  In the second disc, the tracks have been rotated such that the order is b, c, d, a.  and transitions would occur at the following times: tb, tb+tc, tb+tc+td.   However, by the manipulation of the IFO files as described in the note, the test disc (that produced in the folder DVD) has files as in the second disc but the player thinks that transitions occur at the same times as for disc one, namely,  ta, ta+tb, ta+tb+tc.  Assuming that the track times themselves were not unluckily chosen, the latter three transition times should be sufficiently different from  tb, tb+tc, tb+tc+td.  When this disc is played on a gapless-noncompliant player, sound blips should be heard at times ta, ta+tb, ta+tb+tc.   Similarly, the absence of a sound blip may well be observed at the original transition times, i.e.,  tb, tb+tc, tb+tc+td.   This is what I have observed on three different players.    If a blip is indeed observed at these original transition times, it may indicate the other blip mechanism mentioned above.

 

 4.  If a player produces blips at track transitions where the underlying sound stream is continuous, it would seem that nothing can be done, even in principle, at the authoring level to mitigate the blip while at the same time retaining the convenience of a track mark at that point.  If one is willing to do without the track mark, it may be eliminated by manipulation of the IFO files.  Similarly, it may be possible to move the track mark a small amount, such that the blip is less objectionable.  At the level of manipulating the IFO files, it is possible to arrange that more than one program within a single group access the same AOB files.  For example, one program could have all track marks present and the other no track marks at all.  Therefore the second program would play continuously, while the first program would offer random-access.  Unfortunately, in the absence of menus, I have not found any simple way of stopping play after the first of these programs completes.   It is possible to assign the programs to different titles, but most players do not assign any particular significance to titles; in fact all players with which I am familiar ignore them completely.

  To answer one of dj's questions: It does not look to be too difficult to arrange a minimalistic cue sheet approach to authoring.  The real question is whether it offers any particular advantages.  Such an approach, however, appears not to offer any particular advantages with respect to the gapless issue.

Lee

On Tue, May 19, 2009 at 12:55 AM, udo <udovdh@...> wrote:

--- On Mon, 5/18/09, dj <deedj@...> wrote:
> A lot of effort has been expended by
> all the good developers of this project
> to address gapless playback of the authored DVDAs. 
> And rightly so, as gapless
> playback is crucial for enjoyment of many music programs.

Indeed. See my 'discussions' with NAD...

> If I recall correctly, Discwelder Chrome deals with this
> problem (for MLPs, at
> least) by requiring the music program to be one continuous
> file and then

(...)

> I assume the DVDA-Author developers have considered this
> approach (i.e.,
> authoring with a single file in a Group and using something
> like a cue sheet)--
> but found it too difficult or problematic?

I don't know, but I think it does not matter if it is one file or not since dvda-author can make multiple files appear as one stream. The core issue, I guess, is what the disc should look like at the AMG/SAMG level.(see http://dvd-audio.sourceforge.net/spec/audio_ts.shtml)
Did anybody compare a discwelder DVD-A with same-audio dvda-author?

Gapless test-ISO's remain welcome, to test on the NAD T524.

Udo

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[nnguru]

Udo,

You requested an image file for a test disc.

Here is a link to image.iso.

http://rapidshare.de/files/47229991/image.iso.html

I used 4 very short files, a.wav , b.wav, c.wav, d.wav whose playing times were approx. 9 s, 14 s, 20 s, 14 s, respectively.

These files were produced by splitting up a little less than 1 minute of music.  The solo cello featured here makes it easy to hear blips.

Disk 1 was authored with the command  dvda-author -o udo1 -pp 278 -g  a.wav b.wav c.wav d.wav 

Disk 2 was produced with \dvdh\dvda-author -o udo2 -pp 278 -g   b.wav c.wav d.wav a.wav

Disk 3 was derived from the AOB from disk 1 and the IFOs of disc 2, and therefore had the track order of disc one and the track transition positions of disc two.  I tested these discs and found that disc one changed tracks at nine seconds, 23 seconds, and 43 seconds.  Disc two changed tracks at 14 seconds, 33 seconds, and 47 seconds.  Disc three, as expected, changed tracks at 14, 33, and 47 seconds, just like disc two.  It sounded, again as expected, just like disc one, except for different placement of the track transitions and therefore the blips on my Oppo 981.

For convenience, I combined these three discs into one by a technique that I mentioned in an earlier note.  Hence the disc whose image is image.iso has three groups that correspond respectively to discs 1, 2, and 3.

To summarize, group 3 demonstrates that if there is no track change indicated to the player at the point of a track transition, a blip does not occur.  This is the case at nine seconds for group 3.  Though there is an actual track change at nine seconds, the ifo information for group 3 says there is a transition at 14 seconds.  And thus a gapless-noncompliant player blips at 14 seconds and not at nine seconds.  A player that handles gaps properly will play groups one and three identically.

Lee

On Tue, May 19, 2009 at 2:28 PM, Lee Feldkamp <lfeldkam@...> wrote:

In this forum, there has been a lot of discussion around the issue of gapless behavior.  Some of this discussion has been extremely confusing, at least with respect to my empirical observations.  Let me state a few assertions that I believe to be correct.

 

 1.  To avoid confusion, let me use the word "blip" to describe the observation of an interruption in sound playback at the transition from one track to another.  So defined, a blip may be synonymous with what is called a gap, but I use a different word because on certain players (including two different computer players and my Oppo 981) a blip is heard even when there is no real gap in the stream of information embedded in the corresponding AOB file.

 

 2.  It is possible that different players produce blips at track transitions for different reasons, that is, by different mechanisms.  Some players may produce a blip because the hardware cannot find the new portion of the sound stream quickly enough. I have never observed this mechanism.  What I have observed are blips produced by a player merely because of the presence of a track transition.  By this I mean that the player, having recognized a track transition, inserts a gap in the sound stream regardless of whether the data in the wave file or the MLP file was continuous.  DJ is correct in his recollection that the Chrome authoring program inserts markers at track transitions, at least when dealing with MLP files.  This method is needed in the case of MLP, because of the very nature of an MLP stream: dependencies extend over many more samples than in the case of wave files.  If gapless performance is expected with MLP encoding, it is probably not a good idea merely to generate independent MLP files for a series of successive tracks, because the MLP coding for each new track will start afresh and not join properly with the previous track.  (Even so, some players still have no problem.)  Examination of the MLP files for cases in which gapless behavior is needed suggests that the producers paid attention to this issue.  Each successive track respects the state of the previous track.  This strongly suggests that a large wave file was initially converted and then either split into a file for each track, or used as a whole with track information appropriately computed and placed in the IFO files (cue sheet approach).

 

 3.  If you are skeptical about my assertion that blips have little to do with navigating the sound files and everything to do with how player chooses to respond to a track transition, I strongly encourage testing the assertion yourself with the aid of an easily produced test disc.  I provided a recipe for producing these discs in a previous note to this forum.  Rather than repeat the contents of that note, let me merely comment on what you can demonstrate.  Disc two provides track transitions (as seen by the player) at points where the sound stream, by construction, is necessarily continuous, as well as the absence of track transition (again, as seen by the player) at points where there is an actual transition from one file to another.  for clarity, let us consider a hypothetical example.  As in my previous note, suppose the wave files are called a, b, c, and d and have durations ta, tb, tc, and td.  Then in the first disc, track transitions would occur at the following times (measured from the beginning): ta, ta+tb, ta+tb+tc.  In the second disc, the tracks have been rotated such that the order is b, c, d, a.  and transitions would occur at the following times: tb, tb+tc, tb+tc+td.   However, by the manipulation of the IFO files as described in the note, the test disc (that produced in the folder DVD) has files as in the second disc but the player thinks that transitions occur at the same times as for disc one, namely,  ta, ta+tb, ta+tb+tc.  Assuming that the track times themselves were not unluckily chosen, the latter three transition times should be sufficiently different from  tb, tb+tc, tb+tc+td.  When this disc is played on a gapless-noncompliant player, sound blips should be heard at times ta, ta+tb, ta+tb+tc.   Similarly, the absence of a sound blip may well be observed at the original transition times, i.e.,  tb, tb+tc, tb+tc+td.   This is what I have observed on three different players.    If a blip is indeed observed at these original transition times, it may indicate the other blip mechanism mentioned above.

 

 4.  If a player produces blips at track transitions where the underlying sound stream is continuous, it would seem that nothing can be done, even in principle, at the authoring level to mitigate the blip while at the same time retaining the convenience of a track mark at that point.  If one is willing to do without the track mark, it may be eliminated by manipulation of the IFO files.  Similarly, it may be possible to move the track mark a small amount, such that the blip is less objectionable.  At the level of manipulating the IFO files, it is possible to arrange that more than one program within a single group access the same AOB files.  For example, one program could have all track marks present and the other no track marks at all.  Therefore the second program would play continuously, while the first program would offer random-access.  Unfortunately, in the absence of menus, I have not found any simple way of stopping play after the first of these programs completes.   It is possible to assign the programs to different titles, but most players do not assign any particular significance to titles; in fact all players with which I am familiar ignore them completely.

  To answer one of dj's questions: It does not look to be too difficult to arrange a minimalistic cue sheet approach to authoring.  The real question is whether it offers any particular advantages.  Such an approach, however, appears not to offer any particular advantages with respect to the gapless issue.

Lee

On Tue, May 19, 2009 at 12:55 AM, udo <udovdh@...> wrote:

--- On Mon, 5/18/09, dj <deedj@...> wrote:
> A lot of effort has been expended by
> all the good developers of this project
> to address gapless playback of the authored DVDAs. 
> And rightly so, as gapless
> playback is crucial for enjoyment of many music programs.

Indeed. See my 'discussions' with NAD...

> If I recall correctly, Discwelder Chrome deals with this
> problem (for MLPs, at
> least) by requiring the music program to be one continuous
> file and then

(...)

> I assume the DVDA-Author developers have considered this
> approach (i.e.,
> authoring with a single file in a Group and using something
> like a cue sheet)--
> but found it too difficult or problematic?

I don't know, but I think it does not matter if it is one file or not since dvda-author can make multiple files appear as one stream. The core issue, I guess, is what the disc should look like at the AMG/SAMG level.(see http://dvd-audio.sourceforge.net/spec/audio_ts.shtml)
Did anybody compare a discwelder DVD-A with same-audio dvda-author?

Gapless test-ISO's remain welcome, to test on the NAD T524.

Udo

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[Udo-12]

Hello Lee,

--- On Tue, 5/19/09, Lee Feldkamp <lfeldkam@...> wrote:
> You requested an image file for a test disc.
>
> Here is a link to
> image.iso.
> http://rapidshare.de/files/47229991/image.iso.html

Thanks! I'll burn and test on the T524. Maybe next week on the T535.

> I used 4 very short files, a.wav , b.wav, c.wav,
> d.wav whose playing times were approx. 9 s, 14 s, 20 s, 14
> s, respectively.
(....)
> To summarize, group 3 demonstrates that if there
> is no track change indicated to the player at the point of a
> track transition, a blip does not occur.  This is the case
> at nine seconds for group 3.  Though there is an actual
> track change at nine seconds, the ifo information for group
> 3 says there is a transition at 14 seconds.  And thus a
> gapless-noncompliant player blips at 14 seconds and not at
> nine seconds.  A player that handles gaps properly will
> play groups one and three identically.

I'll burn and play the disc and write down where the blips are.
Then we can draw conclusions...

Udo


     

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[Udo-12]

Hello Lee,

--- On Tue, 5/19/09, udo <udovdh@...> wrote:

> --- On Tue, 5/19/09, Lee Feldkamp <lfeldkam@...>
> wrote:
> > You requested an image file for a test disc.
> >
> > Here is a link to
> > image.iso.
> > http://rapidshare.de/files/47229991/image.iso.html
>
> Thanks! I'll burn and test on the T524. Maybe next week on
> the T535.

Here's the results.
I hear a cello-piece of around 56 seconds that was played 3 times before the player would stop.
Below are my notes. A gap is  a short pause, a tick is a short tick-like sound, like a dropout or non-zero cut in a wav.

1
2 begin 9 seconds -> gap
3 begin 23 seconds -> gap
  35 seconds tick
4 begin 42 seconds -> gap

1
2 begin 14 seconds -> gap
 25 tick
3 begin 33 seconds -> gap
4 begin 47 seconds -> 51 seconds silence, music until 56 seconds

1
2 begin 14 seconds -> gap
3 begin 33 seconds -> gap
 35 tick
4 begin 47 seconds -> gap

Kind regards,
Udo


     

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[dj-27]

Lee Feldkamp <lfeldkam@...> writes:
>  
>  1.  To avoid confusion, let me use the word "blip" to describe the
observation of an interruption in sound playback at the transition from one
track to another.  So defined, a blip may be synonymous with what is called a
gap, but I use a different word because on certain players (including two
different computer players and my Oppo 981) a blip is heard even when there is
no real gap in the stream of information embedded in the corresponding AOB
file.
>  
>  4.  ....At the level of manipulating the IFO files, it is possible to
arrange that more than one program within a single group access the same AOB
files.  For example, one program could have all track marks present and the
other no track marks at all.  Therefore the second program would play
continuously, while the first program would offer random-access.  
Unfortunately, in the absence of menus, I have not found any simple way of
stopping play after the first of these programs completes.   It is possible to
assign the programs to different titles, but most players do not assign any
particular significance to titles; in fact all players with which I am
familiar ignore them completely.
>
>   To answer one of dj's questions: It does not look to be too difficult to
arrange a minimalistic cue sheet approach to authoring.  The real question is
whether it offers any particular advantages.  Such an approach, however,
appears not to offer any particular advantages with respect to the gapless
issue.
> Lee
>

Lee:

I like your suggestion about nomenclature (blip versus gap).  Almost all discs
I've made with DVDA-Author play without any blips in my standalone players--I
guess I'm lucky (but sad to hear that at least one Oppo model makes blips).  
But the same discs always play with a blip at every track change when played
with the Audigy software DVDA player (mine is Audigy 2 ZS vintage; I don't
know if newer ones are better).  Anyway, I would assume the discs are
adequately authored to not have gaps and it is a shortcoming of the Audigy
player to produce blips.  Hence I never use the Audigy player except for
checks during authoring.  (I may switch to the ShaPlay player, especially if
Shadson can make it blipless.)

Your comments on manipulating the IFO files are interesting.  How hard is it
to make a "surrogate program" that refers to another program's AOBs?  It would
be nice to have that capability so one could author a different setlist from
the same AOBs (e.g., all tracks versus selected tracks).

You say that your players largely ignore Titles.  Can the different programs
you speak of be in different Groups, or must they be in the same Group?  All
of my players can be set to stop at the end of a Group.  I think WaveLab can
do this sort of thing (author a "surrogate program"), but I've never done it
because I've only fiddled with a demo that can't save anything.  Maybe someone
who owns the full program could do some small trials to determine
if "surrogate programs" can be in different Groups.  Or maybe people already
know the answer.

Regarding the cue sheet business, it seems like a low priority unless it could
resolve some shortcoming like the blips some people experience.  It's main
value would just be convenience when you happen to have a single large wave,
not any new functionality.


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[Udo-12]

Hello,

--- On Wed, 5/20/09, dj <deedj@...> wrote:
> Regarding the cue sheet business, it seems like a low
> priority unless it could
> resolve some shortcoming like the blips some people
> experience.  It's main
> value would just be convenience when you happen to have a
> single large wave,
> not any new functionality.

I also think we don't need to attach high priority to cuesheets.
We can do the splitting in other software.
Most important is understanding what possibilities we have to make the audio as gapless as possible with whatever tricks. Next of course is overall program quality and bugfixing.
Then there's the other features that are on the list.

Udo


     

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[fabrni]

I do agree with Lee on the idea that many gaps/blips may be unreleated to either audio or the way dvda-author encodes AOBs or system files.

If we take a user-oriented approach to the gapless issue there are three different causes for gaps:

- holes in the original audio: sometimes a small number of zeros are added either by editing software or by the recording hardware, and they go unnoticed until a hex editor is used. I'd be curious to hexedit some of Udo's original audio files for a check;
- possible shortcomings of dvda-author itself -- there's still no clear evidence there;
- player hardware, whether occurring in track-to-track, title-to-title, or group-to-group transition (not continuous in current dvda-author releases).

Lee wrote in a previous post that he had not observed hardware shortcomings related to the player taking time to get from one title to another. Although I did not notice this with my basic Pioneer DVD-A player, I do have this issue with my old DVD-V player. As the principles governing system files and virtual machine commands are pretty close (remember the DVD-A standard has common ground with the DVD-V standard) I do think there may be occasional issues with title-to-title/group-to-group transitions caused by other factors than blips while reading AOBs.

This is what I referred to in the some notes on hybrid (2) page: "A common feature of both audio zone and video zone is the ban on direct jumps from a title in the title domain to another title. To get from one title to another, the player must go through a part of system space, accessible with special virtual machine commands."

And there might be differences there between title-to-title nav and group-to-group nav. In an experimental version of dvda-author that is not ready for release, I experienced "continuous" group-to-group transition, using conjectural virtual machine commands, and even the DJ approach of a user-defined set list (burned as a special group of VM commands linking to other groups, a trick I considered a year ago when I did basically the same for video-linking and never had time to cleanly implement).
Although I had no issue with continuous title-to-title transitions, I did have some with VM-coded group-to-group transitions, which elicits the above point.

Having said that, with Lee's latest posts in mind, I now think that this possible cause has nothing to do with Udo's troubles, which now seem to be related to AOB playback.

Fab

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[Udo-12]

Hello,

--- On Wed, 5/20/09, fabrni@... <fabrni@...> wrote:
> - holes in the original audio: sometimes a small number of
> zeros are added either by editing software or by the
> recording hardware, and they go unnoticed until a hex editor
> is used. I'd be curious to hexedit some of Udo's
> original audio files for a check;

My original audio files are gapless. I store them as flacs and they play without issue in xmms.
Then I load them in either wavbreaker or audacity to split.
When I have the T535 I can of course split the same audio in both programs to compare. wavbreaker does not work well for 24-bit audio, though.

> - possible shortcomings of dvda-author itself --
> there's still no clear evidence there;

And there is no padding, and certainly not with zeroes, except when indicated, right?

> - player hardware, whether occurring
> in track-to-track, title-to-title, or group-to-group
> transition (not continuous in current dvda-author
> releases).

NAD admitted that the T524 is not capable of gapless because of hardware restrictions. (?!? the same hardware does play DVD-V without issue, even with LPCM audio...)

> Lee wrote in a previous post that he had not observed
> hardware shortcomings related to the player taking time to
> get from one title to another. Although I did not notice
> this with my basic Pioneer DVD-A player, I do have this
> issue with my old DVD-V player. As the principles governing
> system files and virtual machine commands are pretty close
> (remember the DVD-A standard has common ground with the
> DVD-V standard) I do think there may be occasional issues
> with title-to-title/group-to-group transitions caused by
> other factors than blips while reading AOBs.

You mean timing related issues in the player that may be reproducible or not at all?

> Having said that, with Lee's latest posts in mind, I
> now think that this possible cause has nothing to do with
> Udo's troubles, which now seem to be related to AOB
> playback.

I.e.: the player and not the disc nor the audio?

Kind regards,
Udo


     

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[nnguru]

dj,

Putting different versions of the same program in different groups was in fact my first approach to a gapless workaround.  I am pretty sure I mentioned it in early postings to this forum.   roughly speaking, the method can be made to work, but I had some difficulty with certain players.  It is possible that they pay attention to how the AOB material is referenced.  I observed some very strange navigation issues the last time I tried it.  Having said that, I intend to revisit the issue now that I know how to generate the PP and TS files from the ATS files.  This should resolve any inconsistencies that might have led to the navigational issues that I observed.

Most, possibly all, commercial discs that I have examined make use of a single group, usually with multiple titles in that group.  Because they have menus at their disposal, they are not subject to  the navigational limitation.

Lee

On Wed, May 20, 2009 at 4:57 AM, dj <deedj@...> wrote:

Lee Feldkamp <lfeldkam@...> writes:
>  
>  1.  To avoid confusion, let me use the word "blip" to describe the
observation of an interruption in sound playback at the transition from one
track to another.  So defined, a blip may be synonymous with what is called a
gap, but I use a different word because on certain players (including two
different computer players and my Oppo 981) a blip is heard even when there is
no real gap in the stream of information embedded in the corresponding AOB
file.
>

>  4.  ....At the level of manipulating the IFO files, it is possible to

arrange that more than one program within a single group access the same AOB
files.  For example, one program could have all track marks present and the
other no track marks at all.  Therefore the second program would play
continuously, while the first program would offer random-access.
Unfortunately, in the absence of menus, I have not found any simple way of
stopping play after the first of these programs completes.   It is possible to
assign the programs to different titles, but most players do not assign any
particular significance to titles; in fact all players with which I am
familiar ignore them completely.
>
>   To answer one of dj's questions: It does not look to be too difficult to
arrange a minimalistic cue sheet approach to authoring.  The real question is
whether it offers any particular advantages.  Such an approach, however,
appears not to offer any particular advantages with respect to the gapless
issue.
> Lee
>

Lee:

I like your suggestion about nomenclature (blip versus gap).  Almost all discs
I've made with DVDA-Author play without any blips in my standalone players--I
guess I'm lucky (but sad to hear that at least one Oppo model makes blips).
But the same discs always play with a blip at every track change when played
with the Audigy software DVDA player (mine is Audigy 2 ZS vintage; I don't
know if newer ones are better).  Anyway, I would assume the discs are
adequately authored to not have gaps and it is a shortcoming of the Audigy
player to produce blips.  Hence I never use the Audigy player except for
checks during authoring.  (I may switch to the ShaPlay player, especially if
Shadson can make it blipless.)

Your comments on manipulating the IFO files are interesting.  How hard is it
to make a "surrogate program" that refers to another program's AOBs?  It would
be nice to have that capability so one could author a different setlist from
the same AOBs (e.g., all tracks versus selected tracks).

You say that your players largely ignore Titles.  Can the different programs
you speak of be in different Groups, or must they be in the same Group?  All
of my players can be set to stop at the end of a Group.  I think WaveLab can
do this sort of thing (author a "surrogate program"), but I've never done it
because I've only fiddled with a demo that can't save anything.  Maybe someone
who owns the full program could do some small trials to determine
if "surrogate programs" can be in different Groups.  Or maybe people already
know the answer.

Regarding the cue sheet business, it seems like a low priority unless it could
resolve some shortcoming like the blips some people experience.  It's main
value would just be convenience when you happen to have a single large wave,
not any new functionality.

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[nnguru]

Udo,

It looks like your player by default plays all groups without stopping.  The three passes through the same material correspond of course to the three groups that I mentioned in the posting that accompanied the link.

Your observations are almost exactly what is expected, apart from the ticks you observed (I'll come back to this later.)  In group 1 (the first pass through the 56 second program) you are observing the result of player induced gaps at the track transition points.  These are not due to any discontinuity in the underlying sound files, but merely due to the presence of track change information in the IFO files.  This is demonstrated in group 3, which is based on the same succession of the original wave files but with the track change information in the IFO files placed at different points, namely at about 14, 33, and 47 seconds, essentially where you observed gaps for group 3.(at the risk of being repetitious, let me note that these gaps occur at points in the wave files that are not close to either end, and hence not attributable except by accident to anything going on in the wave files).

If we wished in this case to be able to listen to the entire 56 seconds with no gaps at all, even with your current player, all we need to do is to eliminate the track change information from the IFO files.  This was a feature of version S that has not yet made it into the mainstream program.  For example, the version S syntax

dvda-author -o DVD -gst a.wav b.wav c.wav d.wav

produces a single-track version of the program.  Moreover, it works properly even if the splitting that produced 4 wave files from the original file was not done with proper attention to the splitting point, i.e., it borrows as required from the next file so as to satisfy the interleaving requirements, for all combinations of sampling rate and number of channels.

I'm a bit puzzled about the ticks you heard for groups one and three, because the time of 35 seconds for group 1 does not correspond to any special time and is in fact about halfway between track transitions.  In the case of group 3, the tick is about two seconds after the track transition and the gap that it causes. In the case of group 2, the tick occurs about two seconds after the transition from the first file to the second file.  Given that the source in this case was a radio broadcast of uncertain provenance, it might be well to repeat the experiment with an ultraclean source.  I should mention however that I do not hear ticks in any of these three places, while I hear blips due to gaps in the same place as you do when I listen with my Oppo; on my Pioneer player everything is perfectly continuous.

Here is a PC script to produce files from which the 3 disks can be generated; group 3 of the disk we have been discussing corresponds to directory DVD in this script.

rmdir /S /Q dvd

rmdir /S /Q disk1

rmdir /S /Q disk2

dvda-author -o disk1 -g a.wav b.wav c.wav d.wav

dvda-author -o disk2 -g b.wav c.wav d.wav a.wav

dvda-author -o dvd   -g a.wav b.wav c.wav d.wav

del dvd\audio_ts\ats*.ifo

del dvd\audio_ts\ats*.bup

copy disk2\audio_ts\ats*.ifo dvd\audio_ts\

copy disk2\audio_ts\ats*.bup dvd\audio_ts\

dir dvd\audio_ts\

Any working version of dvda-author should work here.  Fab's capability to extract wav files can be used to recover files a.wav etc. from a disk burned from image.iso.

Lee

On Wed, May 20, 2009 at 3:58 AM, udo <udovdh@...> wrote:

Hello Lee,

--- On Tue, 5/19/09, udo <udovdh@...> wrote:
> --- On Tue, 5/19/09, Lee Feldkamp <lfeldkam@...>
> wrote:
> > You requested an image file for a test disc.
> >
> > Here is a link to
> > image.iso.
> > http://rapidshare.de/files/47229991/image.iso.html
>
> Thanks! I'll burn and test on the T524. Maybe next week on
> the T535.

Here's the results.
I hear a cello-piece of around 56 seconds that was played 3 times before the player would stop.
Below are my notes. A gap is  a short pause, a tick is a short tick-like sound, like a dropout or non-zero cut in a wav.

1
2 begin 9 seconds -> gap
3 begin 23 seconds -> gap
 35 seconds tick
4 begin 42 seconds -> gap

1
2 begin 14 seconds -> gap
 25 tick
3 begin 33 seconds -> gap
4 begin 47 seconds -> 51 seconds silence, music until 56 seconds

1
2 begin 14 seconds -> gap
3 begin 33 seconds -> gap
 35 tick
4 begin 47 seconds -> gap

Kind regards,
Udo

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[Udo-12]

Hello Lee,

--- On Wed, 5/20/09, Lee Feldkamp <lfeldkam@...> wrote:

> Your observations are almost exactly what is
> expected, apart from the ticks you observed (I'll come
> back to this later.)  In group 1 (the first pass through
> the 56 second program) you are observing the result of
> player induced gaps at the track transition points.  These
> are not due to any discontinuity in the underlying sound
> files, but merely due to the presence of track change
> information in the IFO files.  This is demonstrated in
> group 3, which is based on the same succession of the
> original wave files but with the track change information in
> the IFO files placed at different points, namely at about
> 14, 33, and 47 seconds, essentially where you observed gaps
> for group 3.(at the risk of being repetitious, let me note
> that these gaps occur at points in the wave files that are
> not close to either end, and hence not attributable except
> by accident to anything going on in the wave files).

Thanks for you analysis.

> If we wished in this case to be able to listen
> to the entire 56 seconds with no gaps at all, even with your
> current player, all we need to do is to eliminate the track
> change information from the IFO files.  This was a feature
> of version S that has not yet made it into the mainstream
> program.  For example, the version S syntax
>
> dvda-author -o DVD -gst a.wav b.wav c.wav
> d.wav
> produces a single-track version of the program.

That would be the same as recording the 'long' WAV (before cutting it into sub-tracks) as one track/group onto DVD-A?
But how could I jump to a certain spot *and* enjoy gaplessness?

>  Moreover, it works properly even if the splitting that
> produced 4 wave files from the original file was not done
> with proper attention to the splitting point, i.e., it
> borrows as required from the next file so as to satisfy the
> interleaving requirements, for all combinations of sampling
> rate and number of channels.

Interesting. This feature would be a welcome addition to dvd-author. (although I understand that splitting at CDDA-sectors should also work for 24-bit audio).

> I'm a bit puzzled about the ticks you heard
> for groups one and three, because the time of 35 seconds for
(...)
> provenance, it might be well to repeat the experiment with
> an ultraclean source.  

Maybe I should just generate some suitable sounds?

> Here is a PC script to produce files from which
> the 3 disks can be generated; group 3 of the disk we have
> been discussing corresponds to directory DVD in this
> script.
> rmdir /S /Q dvd
> rmdir /S /Q disk1rmdir /S /Q
> disk2
> dvda-author -o disk1 -g a.wav b.wav c.wav
> d.wav
> dvda-author -o disk2 -g b.wav c.wav d.wav
> a.wav
> dvda-author -o dvd   -g a.wav b.wav c.wav
> d.wav
> del dvd\audio_ts\ats*.ifodel
> dvd\audio_ts\ats*.bupcopy
> disk2\audio_ts\ats*.ifo
> dvd\audio_ts\copy
> disk2\audio_ts\ats*.bup
> dvd\audio_ts\dir
> dvd\audio_ts\

What about the disk1 directory?
And how do I get the three groups?

Kind regards,
Udo


     

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[nnguru]

Udo,

The easy answer is that you cannot have both random-access and gapless play, if your player does not support it.  However, just as in the days of matrix quadraphonic one could have more than two channels you some loss of separation was tolerable, when can trade off a loss of random-access for an increase in gaplessness.  Furthermore, if your desires for both random-access in gaplessness do not need to be satisfied at the very same time, it is possible to improve the situation.  For example, if anyone sitting you need just one of the other of these qualities, by authoring two versions of the program, based on only one expenditure of space for the AOB file, one can choose at any given sitting the program version that best meets his needs.  Clearly, this approach can be elaborated to more than two versions so that an almost complete workaround is achieved.  In particular, let us consider a program with 10 tracks and therefore nine transition points.  We could accomplish almost the effect of random-access by creating 10 programs.  The first would have no track marks and would play from beginning to end without gaps.  The second would have a track market first transition point but none thereafter.  Therefore if one felt the need to go to the second track one would simply access the second program and let it play from there.  The third program would have a track mark at the beginning of track three, and none thereafter.  And so on.  In this way, any given track would be randomly accessible, and having been accessed play would continue to the end without gaps.  Obviously, if fewer random-access points are required, fewer programs would be needed.

To provide a concrete idea of how this might work, I produced a two program disk image, making use of two groups to allow selection between them.  As the first group contains the entire 56 second program with all track marks present, while the second group contains the entire program with no track marks.  Both groups work off the same data, contained in the first AOB file.  (The second AOB file is there simply to maintain the formal structure.)  Note that this is what DJ was inquiring about.  

An obvious limitation of this approach, at least as implemented here, is that we have only nine groups at our disposal.  It is just as easy, actually easier, to use titles instead of groups, but as I have mentioned before most players do not recognize titles as entities to jump to based on button pushes.  What we need is the ability to jump to the specified title,, and the only way I can see this happening is by use of menus.  Of course it is possible that with a deeper understanding one could change the repertoire of actions controlled by the buttons.

Note to Fabrice: how do I learn about the virtual machine?

I hope you will try this disc and give me some feedback.  I have found that eliminating the track marks is the only way to listen comfortably to certain discs, such as "the dark side of the Moon."

The link is

http://rapidshare.de/files/47236806/image.iso.html

Caution: not every player will be happy with the disc made from this image.  The second group would not play on either of my computer players, but did play properly on both Pioneer and Oppo players.

The three group disk image that I uploaded earlier was produced from three individual disk file sets using an early version of what I think will turn out to be a very useful program.  (I have mentioned it before in this forum.)  Basically, it allows a DVD audio disc to be created from the ATS files of previously authored discs.  (DJ points out that this is a bit like the ability of DVD shrink to create a disk from previously authored parts.)  This means that one need not always begin at the level of sound files to create a DVD audio disc.  There are a few other implications, which will occur to you upon suitable reflection.  At the moment, this program exists only for PC.  

Combining the three discs, as produced by the script given earlier, was mainly for convenience in the sense of uploading only one file and requiring the burning of only one disc.

Lee

On Wed, May 20, 2009 at 10:54 AM, udo <udovdh@...> wrote:

Hello Lee,

--- On Wed, 5/20/09, Lee Feldkamp <lfeldkam@...> wrote:
> Your observations are almost exactly what is
> expected, apart from the ticks you observed (I'll come
> back to this later.)  In group 1 (the first pass through
> the 56 second program) you are observing the result of
> player induced gaps at the track transition points.  These
> are not due to any discontinuity in the underlying sound
> files, but merely due to the presence of track change
> information in the IFO files.  This is demonstrated in
> group 3, which is based on the same succession of the
> original wave files but with the track change information in
> the IFO files placed at different points, namely at about
> 14, 33, and 47 seconds, essentially where you observed gaps
> for group 3.(at the risk of being repetitious, let me note
> that these gaps occur at points in the wave files that are
> not close to either end, and hence not attributable except
> by accident to anything going on in the wave files).

Thanks for you analysis.

> If we wished in this case to be able to listen
> to the entire 56 seconds with no gaps at all, even with your
> current player, all we need to do is to eliminate the track
> change information from the IFO files.  This was a feature
> of version S that has not yet made it into the mainstream
> program.  For example, the version S syntax
>
> dvda-author -o DVD -gst a.wav b.wav c.wav
> d.wav
> produces a single-track version of the program.

That would be the same as recording the 'long' WAV (before cutting it into sub-tracks) as one track/group onto DVD-A?
But how could I jump to a certain spot *and* enjoy gaplessness?

>  Moreover, it works properly even if the splitting that
> produced 4 wave files from the original file was not done
> with proper attention to the splitting point, i.e., it
> borrows as required from the next file so as to satisfy the
> interleaving requirements, for all combinations of sampling
> rate and number of channels.

Interesting. This feature would be a welcome addition to dvd-author. (although I understand that splitting at CDDA-sectors should also work for 24-bit audio).

> I'm a bit puzzled about the ticks you heard
> for groups one and three, because the time of 35 seconds for

(...)

> provenance, it might be well to repeat the experiment with
> an ultraclean source.  

Maybe I should just generate some suitable sounds?

> Here is a PC script to produce files from which
> the 3 disks can be generated; group 3 of the disk we have
> been discussing corresponds to directory DVD in this
> script.
> rmdir /S /Q dvd

> rmdir /S /Q disk1rmdir /S /Q

> disk2
> dvda-author -o disk1 -g a.wav b.wav c.wav
> d.wav
> dvda-author -o disk2 -g b.wav c.wav d.wav
> a.wav
> dvda-author -o dvd   -g a.wav b.wav c.wav
> d.wav
> del dvd\audio_ts\ats*.ifodel
> dvd\audio_ts\ats*.bupcopy
> disk2\audio_ts\ats*.ifo
> dvd\audio_ts\copy
> disk2\audio_ts\ats*.bup
> dvd\audio_ts\dir
> dvd\audio_ts\

What about the disk1 directory?
And how do I get the three groups?

Kind regards,
Udo

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[dj-27]

Lee:

I tested your 2-Group image file (where the second Group is like a surrogate
referencing the first Group's AOBs).  Results are:

Software players:

ShaPLAY: Played the first Group with 4 tracks in it fine.  Recognized that
there were two Titles, but would not go to the second Group.  This player will
go to second Titles or Groups on regular discs that don't have a "surrogate
Group" as I'm calling it.

Audigy DVD player:  Played the first Group normally.  Recognized the second
Group, but when you play the track, it seems to give a split second of
silence.  It acts like it sees a track with no data in it and quickly skips to
the end.

PowerDVD6:  Played the first Group normally and stopped.  Recognized the
second Group but when played, it seemed to play the full 56 seconds of track 1
but without producing sound.  But it continued the same behavior past 56
seconds, counting forever (I guess) unless I stopped it manually.

Standalone players:

Pioneer 563a:  Played the first Group normally and stopped.  Recognized Group
02 but would not play it.  Seemed to get stuck at the start of the track of
Group 02.  Tried various navigation methods/buttons to play it but it would
not.  This player has problems playing certain DVDAs like Neil Young's Harvest.

Panasonic F85:  Played the first Group normally and stopped.  Told it to play
Group 02 and it played it normally and stopped.

Denon 1930ci:  same as Panasonic.

I also noted that DVDA Explorer says "Unknown stream type" for Group 02 Track
01, and had no channel or bitrate data listed.  I wonder what it would say for
a surrogate Group authored by WaveLab.


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