madshi bug tracker - madVR
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0000109madVRbugpublic2013-07-14 12:422014-04-01 19:42
nakomaru 
madshi 
normalminoralways
acknowledgedopen 
x64Windows 7 Ultimate6.1 (Build 7601)
v0.86.8
MPC-HC v1.6.8.7417 Jun 15 2013
Haali Media Splitter 1.13.138.14 or MPC Internal MP4 Splitter (shown)
MPC Internal Decoder (Worse) or ffdshow tryouts rev4515 (shown)
Software
<select>
no
Off
all modes
NVidia
GeForce GTX 460
320.49
0000109: Irregular frame rates when playing back at non-default speed in MPC-HC
When using MPC-HC/madVR to play back video/audio at a faster than normal rate, for example, at 2.0x speed, the video stream appears to drop frames or stutter.

While using EVR or EVR-CP, the video playback appears to be very smooth and drops few/no frames.

This occurred for me with all of the filter chain combinations indicated, as well both with the ffdshow audio decoder and the built in MPC AAC decoder.

Just after finishing putting together some example files, I noticed that this does not occur in madVR when there is no audio stream. So smooth playback during fast forward is definitely possible in MPC-HC/madVR.
1. Begin playing a video file with audio in MPC-HC with madVR.
2. Increase the playback speed by some amount. (even 1.25x is noticeable)
3. Video appears to drop frames or has an irregular frame rate cadence.
When playing back at higher speeds such as 2.0x, the video appears to drop frames. This is demonstrated in dustforce_fastforward_evrcp_vs_madvr.mkv with evr on the left at 2.0x and madVR on the right at 2.0x. The source video dustforce_panning_60fps.mp4 provided is 60fps footage with a good amount of panning which shows this effect well. Although the comparison video is also captured at 60fps and necessarily drops half the frames, evrcp still appears smooth. I have included a 30fps capture as well to make sure this was not a high framerate issue.

When playing back at moderately increased speeds such as 1.25x, the frame rate cadence appears to be irregular. What seems to be happening is it will play ~0.5 seconds at 0000001:0000001.3x, then ~0.1 seconds at ~0.5x speed, and so on, or something to that effect. This should be obvious when the character jumps in the 30fps footage.

In addition to the 30fps audio/video mp4 capture, there is also an mkv version to show this happens with both containers, and a no audio version to show this doesn't happen with video only streams.

http://home.comcast.net/~nakospace/dustforce_panning_60fps.mp4 [^]
http://home.comcast.net/~nakospace/dustforce_fastforward_evrcp_vs_madvr.mkv [^]
http://home.comcast.net/~nakospace/dustforce_panning_30fps.mp4 [^]
http://home.comcast.net/~nakospace/dustforce_panning_30fps.mkv [^]
http://home.comcast.net/~nakospace/dustforce_panning_30fps_noaudio.mkv [^]
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Issue History
2013-07-14 12:42nakomaruNew Issue
2014-04-01 19:42madshiNote Added: 0000550
2014-04-01 19:42madshiAssigned To => madshi
2014-04-01 19:42madshiStatusnew => acknowledged

Notes
(0000550)
madshi   
2014-04-01 19:42   
Which display refresh rate did you test this on? FWIW, I see no problems here at all, as long as the sped up framerate does not exceed the display refresh rate. However, if you e.g. speed up the 60fps video by 2.0x, with 60Hz, then madVR has to drop a lot of frames, and currently it does not do this very well, resulting in stuttering. I consider this a bug, but I also don't consider it very important because you should always use a refresh rate which is higher than the (sped up) movie framerate. Or if you can't, then enable SmoothMotion FRC, and playback gets smooth again. Actually with SmoothMotion FRC is should be smoother than with EVR/VMR, if the sped up framerate exceeds the display refresh rate.

Can you confirm my test results?

I'll set the problem with non-smooth playback if the framerate exceeds the refresh rate with smooth motion FRC turned off to "acknowledged", which means that I'll fix that at some point, but it might take a while until I get to that.