On Tue, 25 May 2004, Anne Wilson wrote:
> I tried the -N switch which came up with:
>
> [EMAIL PROTECTED] Data]$ lav2mpeg -N -m mpeg2 -o newbyhall.mpg newbyhall3.eli
> 11:43:14 - being noisy - mode=mpeg2 - outfile=newbyhall.mpg -
> 11:43:14 - using mode=mpeg2, stereo=2 audio bpr=224
> 11:43:14 - beginning conversion of newbyhall3.eli to newbyhall.mpg
> 11:43:14 - had 3296 to encode
> 11:43:14 - beginning video encoding
> COMMAND=nice -n 19 lav2yuv newbyhall3.eli | nice -n 19 yuvdenoise -F
> | nice -n 19 mpeg2enc -f 3 -b 1152 -q 12 -4 1 -2 1 -o newbyhall.m2v
> ++ WARN: [lav2yuv] unspecified sample-aspect-ratio --- taking a guess...
> INFO: [yuvdenoise]
...
> INFO: [yuvdenoise] Y frame size : w:768 h:576
> INFO: [yuvdenoise] CbCr frame size : w:384 h:288
> INFO: [yuvdenoise] Frame border : x: 0 y: 0 w:768 h:576
> INFO: [yuvdenoise] Search radius : 8
...
> INFO: [yuvdenoise] Pass 2 threshold : 4
> INFO: [yuvdenoise] Y - contrast : 100 %
> INFO: [yuvdenoise] Cr/Cb - contrast : 100 %
> INFO: [yuvdenoise] Sharpen : 125 %
...
> INFO: [mpeg2enc] Progressive input - selecting progressive encoding.
> INFO: [mpeg2enc] Encoding MPEG-2 video to newbyhall.m2v
> INFO: [mpeg2enc] Horizontal size: 768 pel
> INFO: [mpeg2enc] Vertical size: 576 pel
> INFO: [mpeg2enc] Aspect ratio code: 1 = 1:1 pixels
> INFO: [mpeg2enc] Frame rate code: 3 = 25.0 (PAL/SECAM VIDEO /
> converted FILM)
> INFO: [mpeg2enc] Bitrate: 1152 KBit/s
> INFO: [mpeg2enc] Quality factor: 12 (Quantisation = 17) (1=best, 31=worst)
That video is going to look very poor - 1152Kb/s for full frame
(7XXx576) is an extremely low bitrate. Usually one needs around
3500Kb/s
> INFO: [mpeg2enc] Field order for input: none/progressive
> INFO: [mpeg2enc] Sequence unlimited length
> INFO: [mpeg2enc] Search radius: 16
> INFO: [mpeg2enc] GOP SIZE RANGE 9 TO 15
> INFO: [mpeg2enc] Setting colour/gamma parameters to "PAL B/G"
> INFO: [mpeg2enc] Progressive format frames = 1
> **ERROR: [mpeg2enc] Horizontal size is greater than permitted in
> specified Level
> 11:43:14 - ugh! video encoding failed, bailing. used command:
> 11:43:14 - nice -n 19 lav2yuv newbyhall3.eli | nice -n 19 yuvdenoise
> - -F | nice -n 19 mpeg2enc -f 3 -b 1152 -q 12 -4 1 -2 1 -o newbyhall.m2v
>
> I presume that the clue is in the line
> ++ WARN: [lav2yuv] unspecified sample-aspect-ratio --- taking a guess... ?
>
Not really - that's a "**WARN" error, not a fatal one and the
processing continued on.
> What do I need to do about this?
Use ITU-R BT.601 (Rec.601) instead of square pixels? :)
The problem is actually the last **ERROR line from the encoder mpeg2enc:
**ERROR: [mpeg2enc] Horizontal size is greater than permitted in specified level
Why did mpeg2enc give that (fatal) error? Because 768x576 is
outside the 720x576 frame size permitted at MPEG-2 [EMAIL PROTECTED] (Main
Profile @
Main Level).
You can't put a frame size of 768x576 with 1:1 pixels on a DVD anyhow so
it is necessary to resample/scale the data to a valid DVD framesize.
MJPEG cards generate square pixels - great for graphics works but
a pain for video (DVD, etc) since video pixels are not square. Thus
rescaling is almost always needed when dealing with MJPEG (DV on the
other hand generates Rec.601 pixels so the scaling step isn't needed).
First, get a copy of 'y4mscaler' installed on the system - it's not
part of mjpegtools and is found at
http://www.mir.com/DMG/Software/y4mscaler.html
While you're downloading/building it you may want to read:
http://www.mir.com/DMG/aspect.html
where you'll see that 768x576 1:1 pixels is equivalent to 702+54/59
59:54 pixels. Can't have fractional pixels (or odd numbers for that
matter) so that is rounded up to 704x576. Guess what? 704x576
_IS_ one of the permitted DVD frame sizes for PAL!
So, what you need to do is scale the data taking into account
square pixel input, PAL (59:54) pixels output. y4mscaler will
do all the necessary calculations for you with something like:
y4mscaler -I sar=1:1 -O sar=PAL -O size=704x576
or perhaps:
y4mscaler -I sar=1:1 -O sar=PAL -O preset=DVD
but I suspect the latter will pad to a 720x576 frame size - no need
for that since 704x576 is a valid DVD frame size and will save ~2%
on the encoding time, etc.
Good Luck!
Cheers,
Steven Schultz
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