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

[Heesuk Jung]

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



2013/5/13 Michael Niedermayer <michaelni at gmx.at>

> On Mon, May 13, 2013 at 09:56:38AM +0900, Heesuk Jung wrote:
> > Hi Michael,
> >
> > Can you check the uploaded media file which works well without full
> parsing
> > ?
>
> how much speed gain do you have from disabling full parsing ?
> do you think its worth the extra complexity to not just enable it
> for all pot encoder generated files ?
> (extra complexity also likely means more bugs)
>
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Old school: Use the lowest level language in which you can solve the
> problem
>             conveniently.
> New school: Use the highest level language in which the latest
> supercomputer
>             can solve the problem without the user falling asleep waiting.
>
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