bugGNU Octave - Bugs: bug #35191, aviread does not obey video time...

 
 

bug #35191: aviread does not obey video time scale

Submitted by:  None
Submitted on:  Thu 29 Dec 2011 04:59:05 PM UTC  
 
Category: LibrariesSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Inaccurate Result
Status: Octave ForgeAssigned to: None
Originator Name: GrieviantOriginator Email: -unavailable-
Open/Closed: ClosedRelease: 3.2.4
Operating System: Microsoft Windows

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Thu 29 Dec 2011 05:07:06 PM UTC, comment #3:

To the Octave-Forge project: while we handle the merging of the two projects, please consider this bug report.

Jordi Gutiérrez Hermoso <jordigh>
Project Administrator
Thu 29 Dec 2011 05:04:38 PM UTC, comment #2:

By the way, someone was recently working on the video package: http://octave.1599824.n4.nabble.com/Video-Package-Installation-for-x86-64-OS-X-td4233266.html

Jordi Gutiérrez Hermoso <jordigh>
Project Administrator
Thu 29 Dec 2011 05:03:29 PM UTC, comment #1:

This looks like a problem with an Octave Forge package, not a bug
in Octave. The correct place to report this problem is the
Octave Forge mailing list, octave-dev@lists.sourceforge.net.

A copy of this update to the bug report is being sent to that
list so that they are aware of it. Please follow up there.

Jordi Gutiérrez Hermoso <jordigh>
Project Administrator
Thu 29 Dec 2011 04:59:05 PM UTC, original submission:

I'm encountering a problem using aviread() to extract video frames from an h264 encoded .mp4 file. aviinfo() gives

Filename = C:\Temp\GH1.MP4
FileSize = 11853799
FileModDate = 19-Dec-2011 11:14:06
NumFrames = 32
FramesPerSecond = 59.940
Width = 1280
Height = 720
ImageType = truecolor
VideoCompression = h264
Quality = 100
NumColormapEntries = 0
AudioFormat = aac
AudioRate = 48000
NumAudioChannels = 2

This all looks correct except for the NumFrames parameter. The video is 18 seconds in length and therefore has about 18*60 = 1080 frames (file size = 11.3 MB). Is aviinfo() maybe returning the number of key frames rather than the total number of frames?

Anyway, on to the problem. When I read and display the first 5 frames with aviread(), what I see is the 1st frame repeated 4 times, followed by the 5th frame. It's as if aviread() is doing a coarse decimation rather than interpolating at the correct points in time. This happens regardless of what frame offset into the video stream I choose, not just at the start.

I should also mention that both QuickTime and VLC yield the correct results when scrolling this video frame by frame. I've heard that VLC also uses ffmpeg, so it would seem that the bug is unique to aviread() rather than a problem with ffmpeg.

If it's really necessary I could post the images which show the results I'm getting, but hopefully this description is good enough.

Octave 3.2.4 on Win7 64
video-1.0.2 package

Anonymous

 

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  • -unavailable- added by jordigh
  • -unavailable- added by jordigh (Posted a comment)
  • -unavailable- added by None (Submitted the item)
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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 29 Dec 2011 05:05:51 PM UTCjordighCarbon-Copy-=>Added -unavailable-
    Thu 29 Dec 2011 05:03:29 PM UTCjordighStatusNone=>Octave Forge
      Open/ClosedOpen=>Closed

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