DVD2SVCD BitRate Fine Tuning Problem

[jerryzak]

Here’s my problem:

1) Recently I have been experimenting with conversion of “The Man Who Knew Too Little” (with Bill Murry) from DVD NTSC to SVCD. Movie is under 100 min., not that many explosions to worry about. On the software side I am using DVD2SVCD front-end software (ver 1.1.0 Built 1c) with TMPGEnc Plus (ver. 2.510.49.157) ‘retail’ MPEG engine.

The problem I am experiencing involves setting up DVD2SVCD software => tweaking Bit Rate.

For starters I did not touch most of the options. The only ones I changed included Audio 1 Bitrate => that I moved down to 128; and in Encoder tab I changed Rate Control Mode to => 2 Pass VBR, and Motion Search Precision to => Highest Quality. I the Bitrate tab (this movie fits into ‘Between 76 and 100 mins’. category) on the First Trial I picked => 800MB SVCD disks and on the Second Trial I picked => 740MB disks (qty. 2 in both cases, resulting in 2730~2041 and 2513~1876 bitrate range, respectively)

Now the problem part… The resulting .mpv (video only) files have Nominal Bitrate of 2530000 bit/sec with Average of 2585 kbit and 2376 kbit respectively (so well within the specs). The problem starts when I analyze the bitrate with Teco BitRate Viewer (ver 1.5.054) which reports the datastream to peak at 3443 kbit and 3446 kbit. Visual inspection of the bitrate graph shows that the resulting mpeg file goes over the limit quite often (actually it hovers closely at the border values throughout the movie).

I did play both resulting disk-sets on my CyberHome CH-DVD 500 player – and I must say that I am dropping frames left and right making the movie really choppy. Yet, at the same time the visual quality of compression is great (per frame).

2) I decided to dedicate a whole new computer for the task of DVD to SVCD conversion. We are talking brand spanking new setup. Loaded that with newest version of DVD2SVCD (ver 1.1.1 Built 2) and did a trial using “Just Cause” – that movie is over 100 minutes so the default bitrates for 2-pass VBR went DOWN.

After burning the CDs and visually checking them on my CyberHome I was somewhat encouraged – this time resulting material was way more smooth. Yet there were still some dropped frames here and there.

Verifying file with BitRate Viewer showed again some jumps in bitrate above 3000 kbit.

3) So my real question is: How Do I Manually Adjust The Upper Threshold For Default Bitrate Values Used By DVD2SVCD Software ??? Even when DVD2SVCD Level is set to Advanced, the Bitrate tab displays bitrate ranges grayed, and I cannot retype them from keyboard.

Any Feedback Will Be Appreciated

Thanx

[manono]

Hi-

I'm not sure I understood your whole post (it was a long one), but did you mention what you had for the max bitrate? In your case, it would be 2756-128=2628. And your max average should be 300 or so below that.

However, your problem could lie with your audio bitrate. Many players have problems with audio bitrate that low and can produce the symptoms you describe. I'd suggest changing the audio bitrate to 192, and then hitting "Use Default" in the Bitrate Tab. Then adjust CD Size and number of CDs if necessary.

markrb says this in this Thread (http://forum.doom9.org/showthread.php?s=&threadid=37721&highlight=audio+bitrate+128) (and in many others):
Trust me raise that audio bitrate to at least 160 if not 192. Many DVD players have issues with 128 Kbit audio and your ears will thank me for it.

[jerryzak]

In my tests I used the Default settings for bitrate: Max. 2530; Min. 300; Max. avg 2230. All I changed was audio bitrate (that was moved down from 198 to 128 kbps to provide more 'padding' for video bitrate).

Again my problems were not with audio (which was crystal clear and smooth) but with jerky video quality.

Also, there are known issues with SVCD playback on CH-DVD 500 but in my case I do believe that my problems were caused by going over spec bitrate and not by player unrefined firmware.

[manono]

Yeah, I agree. You're not supposed to get those kinds of bitrate spikes with those settings. You might post the problem in the SVCD Basics Forum. That's where the experts live. Don't tell them you used 128 audio, though, or they'll jump all over you. And they'll want to see the log file. Good Luck.