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| DIV |
| Posted: Aug 22 2011, 06:26 AM |
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Newbie
Group: Members
Posts: 2
Member No.: 32729
Joined: 22-August 11
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Hello.
First of all I should acknowledge that I am using VirtualDub software because it has many great features ...and is free. So thanks for that.
At the moment I am experiencing a bit of frustration with erratic playback speed after pausing/rewinding. While I sometimes use the software for 'dubbing', I also use it for playback. I display only the 'input' pane, maximised to fill the window. This is to identify at what frame of a video sequence particular events occur. E.g. for a bouncing ball, the frames when it is at the peak of its bounce. To do this, I find I need to repeatedly pause/step/rewind/play. Unfortunately, when I recommence the playback from the middle of the video sequence, the playing speed seems to be accelerated (50% faster?) for roughly 2 seconds / 60 frames, and then it settles down to a (practically) constant speed*.
The videos are encoded in Xvid**, using the 'quality' setting, are about 5500 frames long, and are supposed to play back at 20fps.
I have the latest stable release: v1.9.11, Build 32842.
My computer runs Windows 7, 64bit, has 8GB of RAM and a decent HDD. According to Windows 7 benchmarking, the graphics card is not quite as good, but not too bad. More details below.
I would appreciate any advice.
Yours sincerely,
DIV
* It would be nice to be able to monitor the true playback speed — in the status bar, say.
** I have installed both the Xvid codec from xvid.org, and also the one the comes with ffdshow tryouts (http://ffdshow-tryout.sourceforge.net/). I use the latter for encoding.
More details about my computer
PERFORMANCE INFORMATION
Base score 3.4
Determined by lowest subscore
Subscores
Component Details
Processor Intel® Core™2 Duo CPU P8600 @ 2.40GHz 6.0
Memory (RAM) 8.00 GB 6.0
Graphics NVIDIA Quadro NVS 160M 3.4
Gaming graphics 3838 MB Total available graphics memory 5.3
Primary hard disk 249GB Free (466GB Total) 5.9
Windows 7 Enterprise
System
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Manufacturer Dell Inc.
Model Latitude E6400
Total amount of system memory 8.00 GB RAM
System type 64-bit operating system
Number of processor cores 2
Storage
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Total size of hard disk(s) 466 GB
Disk partition (C:) 249 GB Free (466 GB Total)
Media drive (D:) CD/DVD
Media drive (E:) CD/DVD
Graphics
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Display adapter type NVIDIA Quadro NVS 160M
Total available graphics memory 3838 MB
Dedicated graphics memory 256 MB
Dedicated system memory 0 MB
Shared system memory 3582 MB
Display adapter driver version 8.16.11.8992
Primary monitor resolution 1280x1024
DirectX version DirectX 10
Network
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Network Adapter Intel® 82567LM Gigabit Network Connection
Network Adapter Deterministic Network Enhancer Miniport
Network Adapter Intel® WiFi Link 5100 AGN
Network Adapter Deterministic Network Enhancer Miniport
Network Adapter Deterministic Network Enhancer Miniport
Network Adapter Deterministic Network Enhancer Miniport
Notes
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The gaming graphics score is based on the primary graphics adapter. If this system has linked or multiple graphics adapters, some software applications may see additional performance benefits. |
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| phaeron |
| Posted: Aug 23 2011, 05:51 AM |
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Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
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This may be caused by audio buffering with compressed audio sources. If this is the case, changing the audio processing mode to full processing mode will give smoother preview.
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| DIV |
| Posted: Aug 23 2011, 06:20 AM |
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Newbie
Group: Members
Posts: 2
Member No.: 32729
Joined: 22-August 11
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| QUOTE (phaeron @ Aug 23 2011, 05:51 AM) | | This may be caused by audio buffering with compressed audio sources. If this is the case, changing the audio processing mode to full processing mode will give smoother preview. |
Hello. Thank-you for your suggestion.
Actually these videos are generated from a camera that has no microphone. As far as I can see, the AVI's contain no audio at all.
My 'default' settings were that Video is set to Full processing mode, while Audio was set to Direct stream copy.
I have just tried switching Audio to Full processing mode, but it didn't seem to make a difference.
After looking through the options available, I was guessing that maybe my buffering wasn't big enough, so after making the initial post on this forum, I tried increasing the buffering to 32MB for AVI output buffering and 1MB for Wave input buffering*.
I didn't write down what they were before, but something like 2MB and 128kB, respectively. Did I change these in the wrong direction? Should I make them smaller???
I have not changed the Render pipelining (32 video buffers, 2s audio buffer).
As a refinement of my original report, today I notice that actually it also happens if I only _pause_, and then resume playing. (I.e. it is not necessary to manually move to a different frame.)
Now when I look at the artefact again, it is almost as if after pressing play, there is a delay, and then the video rushes to try to 'catch up' with where it should have been, and when it has caught up it slows down to the nominal playing speed.
I don't seem to have the problem when viewing uncompressed AVI's.
Similarly, with the compressed Xvid AVI's, it struggles to go backward smoothly & quickly (when holding down left arrow), rather there are delays, and jumps (not every frame shown); whereas with the uncompressed AVI's it is smoother and quicker, with every frame shown.
Maybe it is related to the number of key frames or something like that? Maybe too much overhead of decoding? Although my CPU does not seem to max out. I have all CPU-specific optimisations enabled.
I would rather if it would go backwards (or forwards) smoothly and slowly, rather than quickly and jerkily.
Kind regards,
DIV
P.S. I do not have Drop frames when behind enabled. I tried it, but didn't like the results.
* By the way, there might be a small glitch in the dialogue box here, which says "output buffering" under both sliders. |
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