[MPlayer-users] xv: distorted output as a result of cropping/scaling

[Peter Schuller]

Hello again,

I've discovered what I believe to be a bug in something, possibly m
player.

Given any normal .AVI with an mpeg-4 codec (at least divx and lavc is
affected) that is playable normally, adding -vop scale=x:y distorts the
image *IF*:

(1) x != the size of the original movie. Scaling vertically is not a
problem, only horizontally.

   AND

(2) xv is used as the video output (-vo xv (default)). Fullscreen or not
- doesn't make a difference.

I can see the same effect if I make the same form of scaling using
mencoder, and then trying to playback the results *without* scaling
during playback.

Unfortunately I am unable to make a screenshot of xv output, so I will
describe it. The effect is horisontal displacement of each row of pixels
relative neighboring rows. Imagine a rectangular picture coerced into a
trapezoid. I'm seeing the same effect, except obviously in a rectangular
output window. (So for example, a vertical line in a movie would appear
to be a slanted line with this distortion.)

Additionally, cropping has the same effect as soon as I touch the
horizontal size.

I have put up a file *encoded* with "-vop crop=719:333:0:35". The
original horizontal size is 720. I do not know if the problem is
reproducable for anyone else, but given that I am able to see the effect
without special parameters during playback, I'm hoping it is universally
visible. The file is available at: 

   http://www.scode.org:8080/mplayer/cropped_and_distorted.avi

Is anyone else able to see the effect?

Here's the full output of mplayer with -v when played on my box:

 '2001_A_SPACE_ODYSSEY1-1.vob.avi' '-v'
Font /home/scode/.mplayer/font/font.desc loaded successfully! (206 chars)
======= AVI Header =======
us/frame: 40000  (fps=25.000)
max bytes/sec: 0
padding: 0
MainAVIHeader.dwFlags: (2320) HAS_INDEX IS_INTERLEAVED TRUST_CKTYPE
frames  total: 126   initial: 0
streams: 2
Suggested BufferSize: 0
Size:  719 x 333
======= STREAM Header =======
Type: vids   FCC:  (0)
Flags: 0
Priority: 0   Language: 0
InitialFrames: 0
Rate: 250000/10000 = 25.000
Start: 0   Len: 126
Suggested BufferSize: 11865
Quality 0
Sample size: 0
======= VIDEO Format ======
  biSize 40
  biWidth 719
  biHeight 333
  biPlanes 1
  biBitCount 24
  biCompression 1482049860='DIVX'
  biSizeImage 718281
===========================
======= STREAM Header =======
Type: auds   FCC:  (0)
Flags: 0
Priority: 0   Language: 0
InitialFrames: 0
Rate: 48000/1152 = 41.667
Start: 0   Len: 229
Suggested BufferSize: 480
Quality 0
Sample size: 0
======= WAVE Format =======
Format Tag: 85 (0x55)
Channels: 2
Samplerate: 48000
avg byte/sec: 14148
Block align: 1152
bits/sample: 0
cbSize: 12
mp3.wID=1
mp3.fdwFlags=0x2
mp3.nBlockSize=1152
mp3.nFramesPerBlock=1
mp3.nCodecDelay=0
mp3lib: made decode tables with MMX optimization
init layer2&3 finished, tables done
mp3lib: using 3DNow!Ex optimized decore!

MPEG 1.0, Layer III, 48000 Hz 112 kbit Joint-Stereo, BPF: 336
Channels: 2, copyright: No, original: Yes, CRC: No, emphasis: 0
X11 opening display: :0.0
vo: X11 color mask:  FFFFFF  (R:FF0000 G:FF00 B:FF)
vo: X11 running at 1024x768 with depth 24 and 32 bits/pixel (":0.0" => local display)
libavcodec: CPU flags: mmx mmxext 3dnow
ao2: 48000 Hz  2 chans  Signed 16-bit (Little-Endian)
audio_setup: using '/dev/dsp' dsp device
audio_setup: sample format: Signed 16-bit (Little-Endian) (requested: Signed 16-bit (Little-Endian))
audio_setup: using 2 channels (requested: 2)
audio_setup: using 48000 Hz samplerate (requested: 48000)
audio_setup: frags:  16/16  (4096 bytes/frag)  free:  65536
Disabling DPMS
stat: 1

*** free_stream() called ***
Successfully enabled DPMS
vo: uninit ...

-- 
/ Peter Schuller, InfiDyne Technologies HB

PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller at infidyne.com>'
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E-Mail: peter.schuller at infidyne.com Web: http://www.scode.org