ffdshow tryouts project: Discussion & Development

[STaRGaZeR]

There's a problem in the filter, ffmpeg produces correct output while ffdshow doesn't. I'll look into it.

[TheShadowRunner]

Build 3713 crashes badly when feeding it the attached XVID file (crash in ntdll.dll).
No issues with build 3703 !
(XP SP3 32bit)

[nightfly]

How hard would it be to implement the following rule for "Swap Channel" feature:

If LPCM == 6 Channel then enable the swap channel setting/feature.

The reason is that Nvidia's HDMI driver has had this nastly bug for some time where if you have a 7.1 speaker setup and playback a 5.1 LPCM track, it'll output the surround channels to the rear channel instead of the side.

I've hacked on MPC-HC before so I am willing to take a look, just need to know where to start or solicit alternate ideas.

[cyberbeing]

That isn't really a bug. It's not strange for the rear left and rear right surrounds of a 5.1 track to playback on the rear left and rear right surrounds in a 7.1 speaker setup. The side channel speakers you speak of, don't exist in a 5.1 setup.


Does setting a Preset solve your problem?

on decoder match: raw LPCM
AND
on number of channels: 6

[STaRGaZeR]

Deband is fixed in r3718. Report any issues as always.

ICL12: http://www.mediafire.com/?168mvl4d0vpc786
MSVC x64: http://www.mediafire.com/?qyxbeb0jpjtzyjq

Despite the name, the builds are r3718.

[clsid]

Originally Posted by TheShadowRunner

Build 3713 crashes badly when feeding it the attached XVID file (crash in ntdll.dll).
No issues with build 3703 !
(XP SP3 32bit)

Please upload the file somewhere else.

[clsid]

I have noticed a weird bug with decoding Techsmith video (TSCC). It decodes with correct colors during DirectShow playback (using r3719). It then converts from BGR24 to RGB32.
When decoding in VirtualDub using VFW mode, the colors are wrong. Red and blue seem swapped. However, when I force a different colorspace like RGB32 or YV12 (VDub menu > Video > Color Depth), it decodes with correct colors. Colors are also wrong when using the Old Renderer in MPC, in which case it outputs RGB24.
Does anyone have an idea what might be wrong?

Here is a sample file:
http://www.mediafire.com/?7llbdqshl33s620

[nightfly]

Originally Posted by cyberbeing

That isn't really a bug. It's not strange for the rear left and rear right surrounds of a 5.1 track to playback on the rear left and rear right surrounds in a 7.1 speaker setup. The side channel speakers you speak of, don't exist in a 5.1 setup.


Does setting a Preset solve your problem?

on decoder match: raw LPCM
AND
on number of channels: 6

Well, a 7.1 differs from a 5.1 setup by adding rear speakers and thus the rears should only be used in 7.1 audio formats.

I am not familiar with "Presets" but will look around ffdshow and see if I can find what you're referencing as that does sound like it could work.

So I'd define a preset and that preset would contain the channel swap?

[Snowknight26]

Originally Posted by clsid

Does anyone have an idea what might be wrong?

Conversion from BGR is broken. I think I've mentioned it (when it came up with Fraps) a few too many times.

[cyberbeing]

Originally Posted by STaRGaZeR

Deband is fixed in r3718. Report any issues as always.

ICL12: http://www.mediafire.com/?168mvl4d0vpc786
MSVC x64: http://www.mediafire.com/?qyxbeb0jpjtzyjq

Despite the name, the builds are r3718.

No wonder it looked so bad before, the initial commit was borked.

I haven't compared against the old ffdshow gradfun2db yet, but the r3718 fixed ffmpeg deband filter does seem to be working properly now. The major problems I had with r3717 seem to be gone.

Originally Posted by nightfly

Well, a 7.1 differs from a 5.1 setup by adding rear speakers and thus the rears should only be used in 7.1 audio formats.

This is incorrect. A 7.1 setup adds side speakers to a 5.1 setup.

5.1 (Front L, Center, Front R, Rear L, Rear R)
7.1 (Front L, Center, Front R, Rear L, Rear R, Side L, Side R)

Originally Posted by nightfly

I am not familiar with "Presets" but will look around ffdshow and see if I can find what you're referencing as that does sound like it could work.

So I'd define a preset and that preset would contain the channel swap?

Yes, you create a preset which auto-loads with 6 channel LPCM and does your channel swap. Your default preset will load in all other cases.

[madshi]

Originally Posted by cyberbeing

A 7.1 setup adds side speakers to a 5.1 setup.

5.1 (Front L, Center, Front R, Rear L, Rear R)
7.1 (Front L, Center, Front R, Rear L, Rear R, Side L, Side R)

No, that's not true. The surround channels in a 5.1 setup are considered "side/surround", not "rear/back". There was a long discussion about this in the eac3to thread, and after studying Dolby and DTS papers and even an email reply from Microsoft the general consensus was that 5.1 has side/surround channels and not rear/back channels.

[cyberbeing]

Interesting, but I think it really just comes down to how someone has their 7.1 system set up.

If the 7.1 system is setup like this, the sides wouldn't represet a 5.1 surround channels very well, since they are suppose to represent sound from the rear surrounds of the viewer (not direct sides):

In a setup like that, using the 7.1 Rear Left and Right would be closer to the 5.1 Left and Right Surrounds.

[madshi]

Originally Posted by cyberbeing

Interesting, but I think it really just comes down to how someone has their 7.1 system set up.

If the 7.1 system is setup like this, the sides wouldn't represet a 5.1 surround channels very well, since they are suppose to represent sound from the rear sides of the viewer (not direct sides)

[...]

In a setup like that, using the 7.1 Rear Left and Right would be closer to the 5.1 Left and Right Surrounds.

Check out the Dolby speaker placement guide:

http://www.dolby.com/consumer/setup/...ide/index.html

If you click on "5.1", the guide says:

"Left and Right Surround Speakers: These speakers should be placed to the sides of your seating position".

The recommended angle is 90-110°. Now compare that to the Dolby recommended setup for 7.1, and you'll find that the position of the surround speakers is *exactly* the same. 7.1 just adds back speakers to 5.1. The placement of the 5.1 speakers doesn't change at all.

And if you think about it, it makes sense, at least if you want to watch 5.1 movies in their original form and not artificially upconverted to 7.1 (by some phony algorithm by the receiver). If the surround speaker placement would differ between 5.1 and 7.1, you'd have to move the surround speakers around all the time, if you switch between 5.1 and 7.1 movies.

So the final word is:

A 7.1 setup adds back speakers to a 5.1 setup.

[cyberbeing]

Even though they list the same numbers, they must be calculating them differently, as Dolby Digital's diagrams show significantly different placement. And as before, ignoring numbers, with speaker placement as those diagrams show, the 7.1 rears would be closer to what the 5.1 rear surrounds are supposed to represent.

[madshi]

I would rather trust the numbers than the diagrams. In the 7.1 diagram it looks like 90°, while in the 5.1 diagram it looks like 110°. So both diagrams are "within spec".

There are more indications for what I said, all already discussed in the eac3to thread. Let me list a couple:

(1) according to MS docus the MS mixer drops the *back* channels if you play 7.1 content with a 5.1 speaker system
(2) the header files for XPSP2 and newer OSs define the 5.1 speaker mask in such a way that surround/side channels are included, but rear/back channels are not
(3) 5.1 DTS-HD files have speaker information stored in the header, they list: "C L R Ls Rs LFE" (you can check with "eac3to some.dts -logdts")
(4) the official Dolby AC3 spec names the speakers of the 5.1 AC3 format "L,C,R,Ls,Rs, LFE"

[cyberbeing]

Originally Posted by madshi

I would rather trust the numbers than the diagrams. In the 7.1 diagram it looks like 90°, while in the 5.1 diagram it looks like 110°. So both diagrams are "within spec".

As I mentioned, the 5.1 seems the be calculated from the center (rear?) of the viewers head, while the 7.1 seems calculated from the front (center?) of the viewers lap. The intention seems clear. The 5.1 rear surrounds are designed to act as both side and rear speakers (which is why the 5.1 surrounds are angled exactly between where the 7.1 side and rear are in the diagram). With 7.1 it split the rear surrounds of 5.1 into distinct side and rear speakers.

Using the dot on the diagram, the 5.1 in that diagram shows 120° with a range of 115°-125°. Using the center of where the viewer's head would be as the reference, the 5.1 in that diagram shows 100° with a range of 90°-110°.

The 7.1 in that diagram shows 100° with a range of 90°-110° from the dot.

There is no right or wrong, it only comes down to where you have your 7.1 side and rear speakers placed in your setup. In some cases the sides would be sufficient, in others the rears would be preferable. If your 7.1 side speakers are arranged like the surround in the 5.1 diagram, then they are best used on 5.1 tracks. If your 7.1 side speakers are arranged like the 7.1 diagram, the rears would be best used on 7.1 tracks.


So the final word is:

A 7.1 setup splits 5.1 rear surrounds into distinct side and rear speakers

[nevcairiel]

Wow, you're seriously arguing with the dot-position now? The dot is the head. No matter what gfx of a sofa is under there. Also, trust numbers, don't trust graphics.

Anyhow, if you setup your 5.1 surround speakers as rear speakers, thats just how it is.
If you setup 7.1, you will have side speakers, which should be directly to the side, or a bit behind you.

If your personal preference is to have the 5.1 go to the rear speakers, thats your personal opinion, of course. Having an option to output it there might be useful for you, i guess. But its not the "right" way, nor the "wrong" way. Just not the "standard" way. Maybe someone will some day write it for you :d

With profiles you should be able to do it anyway, unless you're bitstreaming to your receiver.

[STaRGaZeR]

Originally Posted by cyberbeing

No wonder it looked so bad before, the initial commit was borked.

I haven't compared against the old ffdshow gradfun2db yet, but the r3718 fixed ffmpeg deband filter does seem to be working properly now. The major problems I had with r3717 seem to be gone.

Yeah, sorry about that. The filter system in ffdshow is... strange.

[BatKnight]

The main question is simple:
Is ffdshow audio mixer correctly playing 5.1 and 7.1 files, sending the audio to the correct speaker, considering the Dolby setup?

Nuno

[clsid]

Originally Posted by Snowknight26

Conversion from BGR is broken. I think I've mentioned it (when it came up with Fraps) a few too many times.

Isn't that a different problem, related to tv/pc range?
BGR24 to RGB32 is done properly for TSCC. But it seems that BGR24 is outputted as RGB24 without conversion.