disabling gain in ipod video line out? please help.

[reyrios]

I have been using rockbox for more than 3 years now, and I just realized that I can actually turn up and down the volume of the ipod while connected with a LOD in the line out (bottom fo the player), when did this happen? I dont want this? I need a fixed line out, I always use my ipod with an amp o connected to a dock, it is not my player because in apple mode, the line out is still fix and there is no volume control, any help will be great.

[saratoga]

I have been using rockbox for more than 3 years now, and I just realized that I can actually turn up and down the volume of the ipod while connected with a LOD in the line out (bottom fo the player), when did this happen?

Apparently it came along with the recent change allowing wider volume control range on the video.  In order to get to the lowest volumes the DAC has to adjust a setting that reduces the voltage out of the entire DAC.  As I understand it, you can either:

1)  Keep volume above -58dB (IIRC) in which case the line out stays at line level
2)  Revert r24318 in your local build : http://svn.rockbox.org/viewvc.cgi?view=rev&revision=24318

Presumably #1 is your best bet, since if you listen at the same volume you did before you'll still get line out level.

[Buschel]

I have submitted a change (r24318) to allow volume control down to -90 dB for the iPod Video. If you lower the volume below -56 dB the lineout will be affected as well. Above -56 dB there is no effect at all.
Can you please check whether this is the effect you are talking about? If not, can you please check whether the effect you are talking about came in with r24318?

[reyrios]

How can I revert r24318?

[saratoga]

How can I revert r24318?

Remove the changes to the source code I linked and then compile your own build from the modified source.  If you're not used to SVN, doing it by hand is probably quickest. 

[reyrios]

I did not understand a single word of that Saratoga, thanks anyway! Can't I just use and older build? maybe I have one from last year in one of my back ups in one of my external hard drives. I don't see why would anybody want to have gain in their line out, is there an archive with older builds?

[saratoga]

I don't see why would anybody want to have gain in their line out,

Read above.

is there an archive with older builds?

Downloads section the on extreme left hand side of your screen.

[Llorean]

There is no way to avoid having gain in line out while simultaneously offering volume levels below -58. As was said above, as long as you keep volume above -58 your line out should be line level.

This suggests that you too want to use the lower minimum volume, or you wouldn't be seeing this problem, so I'm sure you can understand why it was put in. It only offers a minimal drawback that can be avoided rather easily.

Either that or there's a bug present which needs addressed.

[reyrios]

I think I understand now, so -58=line out, and above  -58 would actually be lower than line out? would this translate in better sound when connected to an external amp? let say in -80, less distortion?

[saratoga]

would this translate in better sound when connected to an external amp? let say in -80, less distortion?

It'll result in quieter sound, probably no other difference.

[Llorean]

Anywhere from -58 to 0 should be "line out", -59 and lower should be quieter.

[Buschel]

It is as simple as that: Main volume (headphone) from 0..-57 dB will not affect the line out level at all. Main volume (headphone) from -58..-89 dB will lower the line out level by some dB (rule is: -58 dB main volume -> -1 dB line out, -59 dB -> -2 dB, and so on).
If the behaviour is different in any way, please report in detail.

I have implemented this documented (see the manual) behaviour as the former headphone volume range was too small in quite environment. Several users waited for the possibility to be able to user lower volumes. The ipod hardware does not allow to lower the headphone below -57 dB without affecting the lineout level.