[MPlayer-users] perfect playback from dvd, jerky from mpg4?

[Andres Meyer]

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Problem: jerky playback of encoded movie

configuration:
- - Asus A7N (nforce 415), 512MB, 1.533Ghz Athlon XP

- - Gentoo Linux

- - Radeon 8500, XFree 4.2.2

- - sblive 5.1 (all playback stereo)
  alsa9 and sourceforge emu10k1 tested for hwac3. not satisfactory -> tests in
  stereo with emu10k1 (works perfectly for dvd playback)

- - yahama hifi ac3 decoder available, not used here

- - mplayer 0.90rc5, compiled for AthlonXP

- - silicon image ide controller, DMA on, Maxtor 160GB HD

setup:
dvd image mounted on loopback interface:
losetup /dev/loop/0 shes_all_that.iso


testruns:
mplayer -vo x11 -zoom -ao oss -dvd 1 -dvd-device /dev/loop/0
- -> perfect playback. cpu on ca. 20%

coding:
Trying to get a perfect movie to the harddisk, including the ac3-track:

nice -18 mencoder -dvd 1 -dvd-device /dev/loop/1 -ovc lavc -vop 
crop=708:362:6:58 -alang en,de,fr -oac copy -lavcopts 
vcodec=mpeg4:aspect=1.81:vhq:v4mv:vbitrate=2000:vpass=1 -o /dev/null; nice 
- -18 mencoder -dvd 1 -dvd-device /dev/loop/1 -ovc lavc -vop crop=708:362:6:58 
- -alang en,de,fr -oac copy -lavcopts 
vcodec=mpeg4:aspect=1.81:vhq:v4mv:vbitrate=2000:vpass=2 -o 
"shes_all_that.avi"

mplayer -vo x11 -zoom -ao oss shes_all_that.avi
- -> good sync, goody audio, but somewhat jerky image playback, cpu on ca. 30%

Anybody got an idea why this is? As a perfect dvd playback seems to be 
possible, I believe mplayer can detect the correct parameters, so mencoder 
should also. It also rules out software timing detection problems, hardware 
display problems and hw hard-disk problems. Is it an encoder problem?

Its just that jerkyness that makes the movie worse than the original, 
everything else is perfect.

I also tested with -vop detc but it did not change anything

Any ideas would be appreciated,
Andres

PS: my encoding script

#!/usr/bin/python
#
# mencoder dvd backup script
#
# Andres Meyer, 2003

import os
import re
import sys
import getopt

losetup = "/sbin/losetup"
loopdev = "/dev/loop/1"

usage = "enc.py {{-i | --iso} movie.iso | {-d | --dvd} /dev/dvd} [{-o | 
- --output} movie.avi] [{-l | --language} en] [-p | --pretend]\nhint: chmod u+s 
/sbin/losetup; modprobe loop; chmod 666 /dev/loop/*\n"

try:
	opts, tmp = getopt.getopt(sys.argv[1:], "i:o:l:d:p", ["iso=", "output=", 
"language=","dvd=", "pretend"])
except getopt.GetoptError:
    	print usage
	sys.exit(2)


source = None
target = None
lang = "en,de,fr"
pretend = None

for o, a in opts:
	if o in ("-i", "--iso"):
		cmd = "%s -d %s" % (losetup, loopdev)
		os.popen(cmd)
		cmd = "%s %s \"%s\"" % (losetup, loopdev, a)
		os.popen(cmd)

		if target == None:
			path, ext = os.path.splitext( a)
			target = "%s.avi" % path
			
		source = loopdev
	if o in ("-d", "--dvd"):
		source = a
	if o in ("-o", "--output"):
		target = a
	if o in ("-l", "--lang"):
		lang = a
	if o in ("-p", "--pretend"):
		pretend = 1

if source == None:
    	print usage
	sys.exit(2)	

print "source: %s, target: %s, lang: %s\n" % (source, target, lang)


cx = 10000
cy = 10000
cw = 0
ch = 0

trackNum = 1

cropNum = None
dvdInfo = ""
while cropNum == None:
	for minute in range( 20, 30):
		cmd = "mplayer -vo null -dvd %s -dvd-device %s -vop cropdetect -ss 00:%s:00 
- -frames 12" % (trackNum, source, minute)
		print "cmd :%s" % cmd
		dvdInfo = os.popen( cmd).read()
		cropNum = re.compile( r".*\(-vop crop=(.*):(.*):(.*):(.*)\).*").search( 
dvdInfo)

		print "*************************************************\n"
		print dvdInfo

		if cropNum == None:
			trackNum = trackNum + 1
			if trackNum > 9:
				sys.exit("************ error  *************\n")
			break

		x = int( cropNum.group(3))
		y = int( cropNum.group(4))
		w = int( cropNum.group(1))
		h = int( cropNum.group(2))

		cx = min( cx, x)
		cy = min( cy, y)
		cw = max( cw, w)
		ch = max( ch, h)

print "**********"
print "Crop=(%s:%s:%s:%s)" % (cw, ch, cx, cy)

resMatch = re.compile( r".*Movie-Aspect is (.*):1.*").search( dvdInfo)
aspect = float( resMatch.group(1))
print "Aspect=%s" % aspect

resMatch = re.compile( r".*VIDEO:  MPEG2  (.*)x(.*)  \(aspect.*\) (.*) fps 
.*").search( dvdInfo)
resX = int( resMatch.group(1))
resY = int( resMatch.group(2))
fps = float( resMatch.group(3))

newAspect = (float(cw) / float(resX))/(float(ch) / float(resY)) * aspect

cmd = "nice -18 mencoder -dvd %s -dvd-device %s -ovc lavc -vop 
crop=%s:%s:%s:%s -alang %s -oac copy -lavcopts 
vcodec=mpeg4:aspect=%s:vhq:v4mv:vbitrate=2000" % (trackNum, source, cw, ch, 
cx, cy, lang, newAspect)

cmd1 = "%s:vpass=1 -o /dev/null" % cmd
cmd2 = "%s:vpass=2 -o \"%s\"" % (cmd, target)


print
print
print "%s; %s" % (cmd1, cmd2)

if pretend == None:
	os.popen( cmd1).read()
	os.popen( cmd2).read()

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