[FFmpeg-devel] [PATCH] Fix distortion problem in MPEG1/2 video

[Heesuk Jung]

Hi,

I checked excuting times at 50 samples and please refer the test result as
below.

*P value and statistical significance:*
  The two-tailed P value is less than 0.0001
  By conventional criteria, this difference is considered to be extremely
statistically significant.

*Confidence interval:*
  The mean of Full Parsing minus Header Parsing equals 0.00416
  95% confidence interval of this difference: From 0.00280 to 0.00552

*Intermediate values used in calculations:*
  t = 6.0730
  df = 98
  standard error of difference = 0.001

  Group  Full Parsing    Header Parsing  Mean0.053320.04916SD0.003780.00303
SEM0.000530.00043N50       50


Thanks



2013/5/14 Michael Niedermayer <michaelni at gmx.at>

> On Tue, May 14, 2013 at 03:49:08PM +0900, Heesuk Jung wrote:
> > Hi,
> >
> > I'm sorry for late response and update my feedback for this issue.
> >
> > * Background of my suggestion
> >  - I believe that many files by pod encoder don't need full parsing
> option
> > and
> >    low possibility need full parsing.
> >    : As you know and so I concerned performance loss for many normal
> files.
> >  - And I tried to generalize this issue to slove problem ans I realized
> > that
> >   root cause is wrong frame size information of header.
> >    Ans so I suggest that we decide full parsing after checking frame
> length
> > within 7 frames.
> >
> > * Full Parsing Enable/Disable speed test
> >  1) Test file
> >    - I selected high bitrate file to clarify this issue.
> >    - Input #0, avi, from
> > '/home/hsjung/download/ProblemMedia/AVI/[3]_tp_MPEG2_MP3.avi':
> >   Metadata:
> >     encoder         : PotEncoder
> >   Duration: 00:00:59.23, start: 0.000000, bitrate: 25067 kb/s
> >     Stream #0:0: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, stereo,
> s16p,
> > 96 kb/s
> >     Stream #0:1: Video: mpeg2video (Main) (MPG2 / 0x3247504D), yuv420p,
> > 1280x720 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 29.97 tbn, 59.94 tbc
> >  2) Test Environment
> >   - Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz
> >   - 8GB RAM, 256GB SSD
> >  3) Test Method
> >   - I evaluated the below excuting time at 5 times.
> >   - time ./ffprobe ~/download/ProblemMedia/AVI/\[3\]_tp_MPEG2_MP3.avi
> >  4) Evaluate time result
> >   - Full Parsing
> >             1               2              3              4
>  5
> >            Avg
> > real 0m0.051s 0m0.054s 0m0.053s 0m0.056s 0m0.054s 0m0.0536s
> > user 0m0.040s 0m0.032s 0m0.036s 0m0.036s 0m0.032s 0m0.0352s
> > sys 0m0.008s 0m0.020s 0m0.016s 0m0.016s 0m0.020s 0m0.016s
> >   - Header Parsing
> >             1               2              3              4
>  5
> >            Avg
> > real 0m0.046s 0m0.049s 0m0.047s 0m0.050s 0m0.048s 0m0.048s
> > user 0m0.044s 0m0.020s 0m0.024s 0m0.032s 0m0.028s 0m0.0296s
> > sys 0m0.004s 0m0.028s 0m0.020s 0m0.016s 0m0.020s 0m0.0176s
> >  5) Summary
> >   - Test result is about 6ms(Total video duration is 59s) difference
> > between Full parsing and header parsing.
> >
> > I hope your feedback and thanks
>
> This does not look statistically significant
> try yourself: http://www.graphpad.com/quickcalcs/ttest1/
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Democracy is the form of government in which you can choose your dictator
>
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