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View Full Version : Bug in Nero's MPEG-4 ASP encoder with Custom Matrices


bond
24th April 2005, 21:03
as some people reported that some nero certified standalones play custom matrices encoded with nero, but not with xvid i played around with the latest nerodigital encoder a little bit and found a bug in nero:
normally when encoding with custom matrices it has to be signalled in the VOL (video object layer) that a custom matrix has been used and the used matrix itself

but when encoding with nero and a custom matrix this doesnt happen, eg the VOL looks like this:
Video Object Layer
random_accessible_vol - 0
video object type - 17
is_object_layer_identifier - 1
verid - 1
vol_priority - 1
aspect_ratio_info 1
vol_control_parameters - 1
chroma format - 1
low delay - 1
vbv_parameters - 1
bit rate 494
vbv buffer size 121
vbv occupancy 10222
video object layer shape - 0
vop_time_increment_resolution - 25000
fixed_vop_rate - 1
fixed_vop_time_increment - bits 15 1000
vol width - 640
vol height - 256
interlaced - 0
obmc_disable - 1
sprite - 0
not_8_bit - 0
quant_type - 1
load_intra_quant_mat - 0
load_nonintra_quant_mat - 0
complexity estimation - 1
resync_marker_disable - 1
data partitioned - 0
scalability - 0 when encoding in xvid with a custom matrix it looks like this:
Video Object Layer
random_accessible_vol - 0
video object type - 1
is_object_layer_identifier - 0
aspect_ratio_info 1
vol_control_parameters - 1
chroma format - 1
low delay - 1
vbv_parameters - 0
video object layer shape - 0
vop_time_increment_resolution - 25
fixed_vop_rate - 1
fixed_vop_time_increment - bits 5 1
vol width - 720
vol height - 288
interlaced - 0
obmc_disable - 1
sprite - 0
not_8_bit - 0
quant_type - 1
load_intra_quant_mat - 1
8 16 16 16 16 16 16 16 16 16 17 16 17 16 17 18
17 18 18 17 18 21 19 20 21 20 19 21 24 22 22 24
24 22 22 24 25 25 27 30 27 25 25 29 31 35 35 31
29 36 41 44 41 36 47 54 54 47 65 70 65 88 88 115

load_nonintra_quant_mat - 1
18 18 18 18 18 18 18 18 18 18 19 18 19 18 19 21
19 20 20 19 21 23 21 22 24 22 21 23 27 24 24 27
27 24 24 27 29 28 30 33 30 28 29 32 35 39 39 35
32 40 46 50 46 40 53 61 61 53 73 79 73 98 98 129

complexity estimation - 1
resync_marker_disable - 1
data partitioned - 0
scalability - 0now i see two possible explanations for this:
1) nero simply doesnt signal the used matrices in the VOL when encoding with custom matrices, which is borked
2) nero simply doesnt encode with a custom matrix, but with normal mpeg quantisation, even if a custom matrix is specified in the gui. this would propably be more likely as:
- the way nero writes the VOL is the standard way for signalling MPEG quantisation
- mpeg-4 decoders can decode the nero streams which should use a custom matrix, which i assume wouldnt be possible when the matrix is not signalled in the VOL

either way, its a bug in nero recode2...

JohnV
24th April 2005, 21:24
Acknowledged, but low prio.

bond
24th April 2005, 21:39
Originally posted by JohnV
Acknowledged, but low prio. fixing fake features is low priority?

well if so than i have a suggestion: nero could finally release the avc high profile encoder, but make it output only main profile streams... :p

SeeMoreDigital
24th April 2005, 22:13
Hmmm!

I'm curious JohnV, Recode2 has offered custom MPEG encoding for well over a year now. Has it always been broken, or is this just a recent thing?


Cheers

JohnV
24th April 2005, 23:58
Originally posted by bond
fixing fake features is low priority?

well if so than i have a suggestion: nero could finally release the avc high profile encoder, but make it output only main profile streams... :p Well you are funny today.. :) Yes, it's low prio because it doesn't cause any problems really because CMX are ignored, and the feature is not much used even at Doom9. But maybe it's fixed soon anyway.

video
25th April 2005, 09:17
Originally posted by JohnV
Well you are funny today.. :) Yes, it's low prio because it doesn't cause any problems really because CMX are ignored, and the feature is not much used even at Doom9. But maybe it's fixed soon anyway.

JohnV but bond has reported, that xvid movies using CMX having playback problems on nero digital certified standalones. and that's a serious problem...

stephanV
25th April 2005, 10:02
i dont think Nero Devices support CMX...

calinb
25th April 2005, 10:04
Originally posted by SeeMoreDigital
Hmmm!

I'm curious JohnV, Recode2 has offered custom MPEG encoding for well over a year now. Has it always been broken, or is this just a recent thing?


Cheers I tried some CQMs with Recode2 over a year ago and the results looked terrible so I gave up. Guess it's been broken for awhile. Bond had the smarts to investigate the reasons why!:sly:

JohnV
25th April 2005, 16:28
CMX is fixed now in Recode2, available in a future update (maybe doesn't make it to the next one). You can't use CMX with ND standard profile.
But I agree that it would be good if standalone players would still use CMX correctly if present, so lets see..