Want higher SVCD bitrates ? Don't use bbMPEG ...

[marannmarann]

Ok,
Here's the scoop.

This all started when I baught a
Norcent DP-300 DVD palyer and saw
reports on vcdhelp.com of people
claiming the player was capable of
playing SVCDs at a 5 Mb/s bitrate.
I had been having trouble playing
SVCDs at anything over about 2.9 MB/s
so I decided to find out why.

At first I thaught it was a SVCD
burnt vs. raw mpeg burnt CD issue.
This turned out to be partly true.

If I burnt a CD as a raw mpeg2 file,
the player would manage up to about
a 4 MB/s bitrate, but if I burnt the
same material in a SVCD format (Always
using NERO) I couldn't go above 2.9 MB/s
without the playback pausing/skipping.
Again, this turned out to be partly true.

Everything below was burnt as a non
standard SVCD using Nero.
(Am still continuing with the RAW mpeg2
tests as I suspect raw mpeg2 files will
play at a faster bitrate than SVCD burnt CDs)


After some testing, I started to notice
that the material encoded using DVD2SVCD
was to blame. If I encoded the same stuff
(DVD rip of 1 chapter from an NTSC DVD)
manualy using tmpgenc, it would play fine.
I finally tracked it down to a problem
with bbMPEG. The material I had been
encoding manualy using tmpgenc was not
being muxed using bbMPEG, I was encoding
both the video and audio using tmpgenc by
choosing the "System(Video+Audio)" option
in the main screen. Again, the material
done this way would ALWAYS be able to be
played at a higher bitrate on my Norcent
DP-300 than the material done using DVD2SVCD
(besweet + tmpgenc + pulldown + bbmpeg)

FYI : When I used tmpgenc manualy, all
settings were the same as when I used
dvd2svcd. I loaded the same
"AviSynth_Script_file.avs" file as the
video source, used the the same "Encoded_audio_1.mp2"
as the audio source, and via "File -> open project"
I loaded the same "TMPGEnc_Project_file.tpr" project
file, all of which dvd2svcd had created during
the dvd2svcd encode part of the test, so from my
limited understanding, all settings should have
been the same for the tmpgenc encode and dvd2svcd
encode. (Maybe someone can confirm this)


Here's what I found ...

Using dvd2svcd :

Max bitrate (Tried 720x480 AND 480x480)
that can be played back without skipping is 2900 KB/s

If I take the exact same "Pulldown_Encoded_Video_NTSC.mpv"
OR "Encoded_Video_TMPGEnc_NTSC.mpv" which dvd2svcd
produces and then mux it with the "Encoded_audio_1.mp2"
file manualy using tmpgenc mpeg tools -> Multiplex,
then I can go to 4500 KB/s.

---------------------------------

Using tmpgenc directly :

Max bitrate (Tried 720x480 AND 480x480)
that can be played back without skipping is
4500 KB/s using the "System(Video+Audio)" option.
Again, same exact settings as was used for the
dvd2svcd part of the test.

I then did the same test, except I chose
"ES (Video Only)" in tmpgenc, thus encoding a
video only file at 4 MB/s total bitrate (Video + Audio)
I then muxed the video stream with the same old
"Encoded_audio_1.mp2" audio stream using bbmpeg
and it skipped during playback. Next, I muxed the EXACT
same two files using tmpgenc's mpeg tools -> Multiplex
and guess what, it plays back flawlessly EVERY time.

Let me say that this is not a fluke. I performed the
above tests over and over and over during the past 3 days.
the results are always the same.

As I said at the beginning, I think when the files are
burnt as raw mpeg2 files to CD and played that way, I can
play back at an even higher bitrate, but I'm not done
with those tests yet so don't quote me.

[marannmarann]

OK, done with testing raw mpg2 files and it would seem that (The material being encoded probably makes a difference too,but I stuck with the same high action
material for all the tests)

1- When using bbmpeg to cut and multiplex mpeg2 video streams and mpeg1 audio steams, AND authoring the CDs as non standard SVCD using NERO, the max
bitrate that would play back on my Norcent DP-300 is about 2900 kb/s MAX combuned audio & video.

2- When burning the CDs in the same way as #1 but the material was muxed using the TMPGENC MPEG TOOLS, or if the material was encoded using TMPGENC
for video as well as audio to begin with "System(Video+Audio)" option in the front screen, max playback bitrate on the Norcent goes up to 4500 kb/s without a glich EVER.

3- Again, when using bbmpeg to cut and multiplex mpeg2 video streams and mpeg1 audio steams, but this time burning the mpeg2 files directly in NERO
(Choosing "New Data CD" in the Nero Wizard) and playing them as raw mpg2 files on the Norcent, the MAX playback bitrate increases from 2900 kb/s to 4500 kb/s.

4- When burning the CDs in the same way as #3 but the material was muxed using the TMPGENC MPEG TOOLS, or if the material was encoded using TMPGENC
for video as well as audio to begin with "System(Video+Audio)" option in the front screen, max playback bitrate on the Norcent is 4500 kb/s without a glich EVER.

So, if your have been backing up your DVDs using DVD2SVCD and then burning them as VCD, SVCD, etc ... which I suppose most people are since not every
DVD player supports playback of raw mpg2 files, then you are probably not getting the maximum bitrates from your encodes.

The way to go seems to be using DVD2SVCD but skipping bbmpeg and using tmpgenc to mux instead, unless you are burning raw mpeg2 files directly to CD as
bbmpeg doesn't seem to effect these.

OR

use dvd2svcd to just create the AviSynth_Script_file.avs and
TMPGEnc_Project_file.tpr files then stop dvd2svcd, open tmpgenc manualy, load the TMPGEnc_Project_file.tpr project, choose the AviSynth_Script_file.avs files
as the video source, the Encoded_audio_1.mp2 as the audio source, and then use the "source range" option to encode exactly 800MB chunks.

Although it's not always practical to encode at 4500 kb/s, it's nice to have some play in what speed your player will be able to handle.

For example, those situations where using 3 cds for a given movie will give you video quality you will not be satisfied with, but going to 4 cds will require a bitrate
too high for your player to handle.


Pls note:
Your milage may vary depending on the material you are encoding, type of media, etc ...

I'm wondering if anyone has ever noticed this ...
I think I'm just picky, but there you have it ...

Marann