How does Dxtory capture audio?

[Malix]

anyhoo, I'll be making another test overnight and see if anything changes.

Also,

Hmm, very weird.
What does it say if you open the video, and check the wave file (tell me the duration of the video file, and the wave file).

Can't. I was a bit too fast to delete the recording 

[De-M-oN]

The streams themselfs are perfectly synchron. At least for me.

It is normal that the lengths differ.

For 30fps video a frame has a length of 33ms. Audio can be closed anytime.

DXTory closes the file as soon as possible. No computer does close 3 files at .xxx ms exact same time.

But if the streams arent synchron for you within the track - then thats an else problem with - how said - I cant in any way share with you. All perfect for me.

[zerowalker]

As i said before, record over night, and see if it is in perfect sync.
Probably the aren´t.

You probably are lucky with the Clock being fairly close, making it, maybe 30ms desync per hour, which isn´t noticable until 3hours+.

And as you say, audio and video shouldn´t be precise the same duration, which is what i mean that stretching them would make a sync, but it wouldn´t be perfect, as if they are the same duration, something isn´t right as they never are exactly the same.

The thing is, it´s better to have desync with streams that are in length according to the desync, then to have them close to length with each other (video,audio) as that will make the desynced information going away If the audio plays to slow, if it plays to fast, then it it´s possible to sync without loss of any "real" information.

anyhoo, I'll be making another test overnight and see if anything changes.

Please do, i am eager to see what the results are.

[De-M-oN]

I dont mean stretching, I just meant that you cut off the too long audio. This doesnt change the rest of the remaining audio of course.

But you say you have it also within the track, and thats strange..

I can remember a 3,5 hour doom 3 LP Together session, but that was with Fraps though.. But it was synchron 'til the end.
How said: It would wonder me if it would be with DXTory else. I had never synch problems with my pc ..

[zerowalker]

I think fraps have done something to get sync, i think they resample the audio or something.
Dxtory is pure, it gives you the Audio and Video without doing anything, which ends in higher quality.

I may be wrong though about the fraps resampling, but i do think it does something.

However, when i think about it, when i used fraps, i got desync as well, not sure if it was the same, but it probably was.
Hmm, well nto sure anymore.


But as said, desync with audio/video will never really give you any problem in normal use, it only affects recording.
The only way to solve it is by either letting the video and audio run on the same clock (best solution), or fixing the problem afterwards by slowin/speeding the audio, or video.

[De-M-oN]

Fraps records without filtering as well.

but you have synchronous surface lock enabled? sry if I asked already.

[zerowalker]

Well that explains the desync there aswell, however, i wonder how it does when you record a mic, as it adds it into the same stream.

And yes, have tried that, usually have that and Wait for available buffer on.

Doesn´t change the sync at all though.

Do you get desync if you have it off?

[Malix]

Aand back after recording 6 hours of looping nes footage, I used UT codec & 30fps capture this time around.

The results are pretty much the same than the first time, my video goes more and more desync the further the video gets. At 1 hour mark, the sync is very slight, 2h mark it's noticeable and at the 6 hour mark it's roughly a full second off.
Also the audiotrack is roughly 1 second too long. For "lulz", I tried stretching the audio to same length as the video and then it seems to sync up perfectly... wow.


My errorlog contained thousands of lines of this

Code Select Expand

========== 2013/06/21 22:42:14 ==========
PID:1784     C:\Program Files (x86)\Dxtory Software\Dxtory2.0\Dxtory.exe
PID:1784     TID:3540     TickCount:115129109 Logical Error eIndex=250000 m_DebugIndex=249999
PID:1784     TID:3540     TickCount:115129125 Logical Error eIndex=250001 m_DebugIndex=250000
PID:1784     TID:3540     TickCount:115129140 Logical Error eIndex=250002 m_DebugIndex=250001
PID:1784     TID:3540     TickCount:115129156 Logical Error eIndex=250003 m_DebugIndex=250002
PID:1784     TID:3540     TickCount:115129171 Logical Error eIndex=250004 m_DebugIndex=250003
PID:1784     TID:3540     TickCount:115129187 Logical Error eIndex=250005 m_DebugIndex=250004
PID:1784     TID:3540     TickCount:115129203 Logical Error eIndex=250006 m_DebugIndex=250005


but judging by the timestamp, that was for the first test I did


edit: did a test with another game, Gunpoint, ~1.5h of footage and towards the end the audiosync starts to drift off. Though video and audio tracks are the same length.

edit 2: some bit more specific data if needed
Timed the difference between jumping animation and accompanying sound in the Gunpoint recording
00:00:26,29 ~2 frames. https://dl.dropboxusercontent.com/u/7484348/gunpoint_1.avi ~2MB
01:23:53,20 ~9 frames https://dl.dropboxusercontent.com/u/7484348/gunpoint_2.avi ~10MB

so roughly 230ms of delay in audio in 1h23min of recording, that starts to get quite noticeable.

[zerowalker]

Interesting.

Though i´t´s very weird that your audio length is longer, i have a clip that is 16 hours long, and they are the same.

Hmm, may be game dependent though as it seems to differ for you.

But this proves that the problem exists.

[Malix]

could probably try the NES-emulator recording tonight with Fraps to rule out my system derping.

[zerowalker]

Please do.

Here is information from my 16 hour clip:

Code Select Expand



Video
ID                                       : 0
Format                                   : Lagarith
Codec ID                                 : LAGS
Duration                                 : 16h 11mn
Bit rate                                 : 20.0 Mbps
Width                                    : 897 pixels
Height                                   : 672 pixels
Display aspect ratio                     : 4:3
Frame rate                               : 60.000 fps
Color space                              : RGB
Bit depth                                : 8 bits
Bits/(Pixel*Frame)                       : 0.552
Stream size                              : 136 GiB (93%)

Audio
ID                                       : 1
Format                                   : PCM
Format settings, Endianness              : Little
Format settings, Sign                    : Signed
Codec ID                                 : 1
Duration                                 : 16h 11mn
Bit rate mode                            : Constant
Bit rate                                 : 1 536 Kbps
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Stream size                              : 10.4 GiB (7%)
Alignment                                : Aligned on interleaves
Interleave, duration                     : 1000 ms (60.00 video frames)

[Malix]

I might be on to something.

Zerowalker, are you per any chance using Virtual Audio Cables?

I noticed in my preliminary fraps tests that some NES sounds sounded a bit different every so often, it seemed that my VAC was over/underflowing occasionally.
Noticed my clock rates were fluctuating quite a bit, tweaked my settings & elevated priorities to make it more  stable.

It was easier to spot from simpler audio than from normal music or game audio

[zerowalker]

Nope, i am not using VAC at all.

I have been using my sound card output.
But has also tried the soundcard "what you hear" input, which plays what is, played (if you get what i mean;P)

And both give the exact same results.

[Malix]

Testing done.

6 hours of fraps recording and no sound desync.

did a new test of 3 hours with dxtory, ~2/3rd second off & audio track longer than video. the sync can be fixed with stretching the audio track to same length as video, but I'd rather not. Wish this was fixed in DxTory side :/

[zerowalker]

Great!

Weird that Fraps isn´t wrong though, make me think that it may be resampling and stuff after all.
Though if it isn´t, and it just works, then it´s awesome!

And as you say, you shouldn´t need top fix it, as the problem shouldn´t even be there (at least not if it can be fixed).
Hope Exkoder looks into this.