Bizarre: each segment 2191 avg vbr

[raddygast]

Ok this is really weird, and it can't have anything to do with QMatOp. I tried Prepare on another TV episode disc, this one has four episodes.
To my surprise every VTS (episode) came out to be 2191 for the bitrate. They are all of similar size, but not exactly the same size.

What's more I checked the ECL file and each SEGMENT is exactly 2191 as well. This is just beyond weird. What could be causing this problem?

rebuilder.log and a snippet from the ECL file reproduced:

-----------------
[06:14:30] Phase I, PREPARATION started.
- CCE SP 2.70.1.5 encoder selected.
- VTS_01: 917,858 sectors.
-- Scanning and writing .D2V file
-- Processed 85,606 frames.
-- Building .AVS and .ECL files
- VTS_02: 909,632 sectors.
-- Scanning and writing .D2V file
-- Processed 84,842 frames.
-- Building .AVS and .ECL files
- VTS_03: 925,076 sectors.
-- Scanning and writing .D2V file
-- Processed 86,281 frames.
-- Building .AVS and .ECL files
- VTS_04: 910,396 sectors.
-- Scanning and writing .D2V file
-- Processed 84,925 frames.
-- Building .AVS and .ECL files
- Reduction Level for DVD-5: 57.4%
- Overall Bitrate : 2,191Kbs
- Space for Video : 3,811,636KB
- HIGH/LOW/TYPICAL Bitrates: 2,192/500/2,191 Kbs
[06:18:33] Phase I, PREPARATION completed in 4 minutes.


ECL (every segment has the same vbr avg/min/max like this):

[item]
title=V01000000001001
aud_out=0
vaf_file=D:\DVD\RB-WORK\MY_SO_CALLED_LIFE_DISC2\D2VAVS\V01000000001001.vaf
aud_file=D:\DVD\RB-WORK\MY_SO_CALLED_LIFE_DISC2\D2VAVS\V01000000001001.mpa
file_focused=0
packet_size=2048
width=720
height=480
frame_rate_idx=1
cbr_brate=6000
vbr_brate_avg=2191
vbr_brate_min=500
vbr_brate_max=7800
seq_endcode=0
dvd=0
half_width=0
half_height=0
lum_level=0
adjust_q_matrix=0
aspect_ratio=2
gop_m=3
gop_nm=5
gop_hdr=15
seq_hdr=1
all_closed_gop=0
fix_gop_length=0
samples_per_sec=44100
stereo=2
brate_idx=7
crc=1
progressive=0
alternate_scan=1
intra_dc_prec=2
intra_dc_precision_9_max=113
intra_dc_precision_10_max=113
aud_mode=0
tc_ref_frm=0
drop_frame=0
fix_vbv_delay=0
letter_box=0
pulldown_detect=0
offset_line=0
create_new_vaf=1
credits_tweak=0
credits_start=0x00000
credits_brate=1000
h_filter=0
h_filter_idx=8
dither=0
dither_max=8
quality_prec=25
timecode=0x0000000
q_char_f=25
tc_offset=0
v_filter=0
v_filter_val=6
pict_name=
pict_type=3
pict_level=255
video_type=16
vid_file0=D:\DVD\RB-WORK\MY_SO_CALLED_LIFE_DISC2\D2VAVS\V01000000001001.m2v
vid_file1=D:\DVD\RB-WORK\MY_SO_CALLED_LIFE_DISC2\D2VAVS\V01000000001001.m2v
vid_out=1
vaf_out=1
opv_q_factor=20
opv_brate_min=0
opv_brate_max=7800
vbr_bias=25
vbr_pass=3
use_filter=0
filter_val=6
non_linear=1
top_first=0
mpeg1=0
mpeg1_cps=1
qmat_idx=0

[mrslacker]

What about it is weird? Only jdobbs could expand on what the analysis does to allocate bitrates... But the content is very similar from one episode to the next, so it makes sense. That's obviously a really low bitrate, but it makes sense.

[raddygast]

The low bitrate is understandable -- but it's totally weird that not only would each VTS have an overall vbr bitrate avg that is identical, but also each specific segment within each VTS would have that same vbr bitrate.

It's like the prepare routine is not actually properly scanning the source and allocating bitrate based on the demands of the content. It's almost like CBR or something.

I hope jdobbs can tell me what's going on. It's spooky.

[mrslacker]

Originally posted by raddygast
It's like the prepare routine is not actually properly scanning the source and allocating bitrate based on the demands of the content. It's almost like CBR or something.
Of course, within each cell, it is still variable. If the source were CBR, that might explain it. Is that what you mean? If DVD-RB bases it's bitrate assignments (in part) on the overall bitrate for each cell, I guess it would come out this way. Or if the average quantizer is the same between cells maybe. :confused: I've wondered exactly what is done to do the allocation. Maybe motion vectors are counted to predict which frames and cells need extra bits.

I'm sure all these questions have been answered before, but I haven't looked.

[raddygast]

Source isn't CBR, because in PowerDVD ShowInfo mode I see the bitrate moving up and down as is normal with VBR. I just can't for the life of me figure out why it'd behave this way, esp. when disc 1 of the same show worked as normal in DVD-RB's prepare stage.