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Old 20th February 2003, 14:46   #1  |  Link
Platin
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Multiangle Bitrate calculation

Hello,

Is the total bitrate calculated differently when you deal with multiangle encodings? I have a PGC that has 2 angles. Both are encoded having max bitrate 9300 kbps and average 4200 kbps. I have checked the relevant settings for multiangle encoding in CCE, i.e. "Close all GOPs", "Restrict auto I fram insertion" and "Equalize each GOP's bit length". Also, this might not be relevant, but my packet size is 128 (defaulted). Should I up it for better compression?

In Scenarist I drop angle1 as the main stream in the track, and then angle2 is added. Angle type is Seamless (default). After that I add the two 224kbps audiostreams and three subtitlestreams. Then I simply drop the track into my Title_1 folder in the Scenario editor tab and start compiling the project. This is what I get after it has encoded the subtitles and are starting to compile the video:
Code:
Info	Multiplexing
Info	Multiplexing VOB Main Stream
Warning	Total bitrate too HIGH. Video buffer underflow (DTS=89616142 SCR=89622324 (around 00:16:34:24).

Info	picture_type: IPBPBBPBBPBB

Info	picture_size: 74180 45168 28920 53556 27532 28008 57888 37740 33924 49188 30448 27704 

Info	gop bitrate: 7908096

Error	dvd_mux : DoMux Multiplexing Error
Error	Terminated Multiplexing (kk2-1.scn-P1A1-t_t.vob.0).
Error	 Total bitrate is too HIGH. Please reduce the stream bitrate or the number of stream.
Error	 Multiplex is failed.
Info	Multiplexing failed, Track<P1A1-t> 

Error	MuxFromDB:MuxVTS failed
Error	Multiplex failed
Error	DVD files could not be created
Not knowing much of what that means, I follow the instructions to lower bitrate on my videostreams. I first tried with max=8000 and avg=4200 but that gave me almost the same error but at a different location in multiplexing the stream.

Then I tried with max=9300 and avg=3900 but that also failed in a similar error. So then I tried with max=8000 and avg=3900 and finally the project compiled. My question is, how can i pre-calculate the bitrate so I don't have to do this trial-and-error encoding? Also I want to maximize my average bitrate of course. It seems that multiangles take up more space on the DVD...

Thank you for reading.
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Old 20th February 2003, 14:52   #2  |  Link
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when dealing with Multi Angle, the COMBINED bitrate of the streams (all angles + audio + subs) must not exceed 9.8mbps, which means you are going to have to specify 4500 peak for each stream (for example).

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Old 21st February 2003, 00:50   #3  |  Link
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Hello, thank you for your reply. I have re-encoded my video assets. This time I added them all to the project. Before I only tested with the first PGC. Now I got a new problem And it's even before the compilation of the project.

My problem is after I exported the project to script and edited it with ScenChap v1.27, copied the chapters from the original .IFO, imported the new script into Scenarist v2.6, and wants to start authoring my VTS and Titles. If I drop any of the "smaller" tracks, into a new Title then no prob. But when I drop one of the bigger ones (containing the main movie) Scenarist crashes with error message about memory read failure or something.

I'm using XP.
Any suggestions are welcome.
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Old 21st February 2003, 01:56   #4  |  Link
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Doh! I'm such an idiot. I went back and restarted the whole project, but this time I remembered that none of the guides said anything about adding multiangles and then running ScenChap on it. So I exported the tracks before I added multiangles to them.

But now I'm wondering how the end results will be... what if the chapters are not the same for the different angles? Any thoughts on that anyone?

Well, I'm compiling it right now...

Yup, it failed Something about it wrong ILVU. Well, I guess I'll do it without ScenChap...

Last edited by Platin; 21st February 2003 at 02:05.
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Old 25th February 2003, 10:01   #5  |  Link
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In the multi-angle sections of the PGC, the video bit rate is the maximum across all angles.

The bit rate constraint varies with the number of angles: from 2 to 5 angles, the total bit rate (max video plus audio plus sub-picture) must be less than 7.8Mbits per second.

From 6 to 8 angles, the limit is 7.3Mbits per second.

9 angles the limit is 6.8Mbits per second.
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Old 25th February 2003, 10:32   #6  |  Link
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Thanks, that sounds interesting. Have you learned that from experience or is there any 'whitebook' thingie on multi-angles?

I eventually managed to solve it just by following auenf's advice. But since the PGCs were multi-angle through out the most of the disk (even though it wasn't necessary for the original authors to do that), I had to use a very low average bitrate to fit both angles on the disk.

The first angle is the Japanese version of the series, while the second angle is the English. But they only differ at the beginning and end credits where producers and voice actors are listed for the Japanese or the English team. An interesting project would be to re-author it entirely, to only keep those part of the video that needs to be multi-angle like that, but the rest of the video being only 1 angle. Would IFOUpdate manage to correct it's pointers?

If I would rip it all over again (probably will someday soon ) I would only keep the first angle with the Japanese version. The quality wouldn't suffer that much then. But it is nice to have an almost exact replica of the original. Btw, in case anyone were wondering, the main angle (Japanese) I reencoded at 1900 kbps average and the English angle at 1500 kbps, 3-pass VBR. The original video+audio+subs after demuxing were a whopping 11.4 GB in size, and I had even skipped 3 of the 6 subtitle tracks or otherwise it would add 1.2 GB more.
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Old 25th February 2003, 11:33   #7  |  Link
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I quoted it from the DVD Fusion encoding manual.

It should be in Scenarist's manual also. They should conform to the same specs. Although Scenarist is made by Dalkin (now bought by Sonic), they might be slightly different, just check the documentation it came with.


DVD Fusion supports different "blocks" of multi angle. In my typical 1 hour video I'll have angle 1 60 min, and 1 or 2 additional angles at 5 minutes each, placed at different times through out the movie.

Only the blocks during multi angle need these settings.


11111111111M11111M11111M1111M111111111
..................2222222..........222222.............
..................3333333..........333333............
..................4444444..........444444............


Only between the M's does the video encoding need to be "special". During the rest of the time code angle one is encoded at 9.2mbps with different gop lengths (scene change detection).

You can use CCE to edit the encoded bit stream to only close all GOPs at the needed points, and keep max quality at all others.

TMPG can do this too in GOP structure tab, force picture type setting. You can also set the bitrate per frame, and it has an auto complet function.

So, with 4 angles, one 192 ac3 stream, 0 substream, each video can have a max bitrate of 1902kbps. It's actually less than (9800 - 192)/4 wich is 2402. With 2 angles the limit would be 3804, instead of 4804.
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Old 27th February 2003, 12:44   #8  |  Link
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I'm not agree with you, if you look in sonic support base :

BITRATE CONSTRAINTS IN MULTI-ANGLE BLOCKS.

The usual bit rate constraints for a PGC (that the peak video rate plus the audio and sub-picture rates must be less than 9.8Mbits/second) is modified somewhat in a multi-angle PGC. In the multi-angle sections of the PGC, the video bit rate is the maximum across all angles (rather than the sum as one might expect). The bit rate constraint varies with the number of angles: from 2 to 5 angles, the total bit rate (max video plus audio plus sub-picture) must be less than 7.8Mbits per second. From 6 to 8 angles, the limit is 7.3Mbits per second, and for 9 angles (the maximum legal number) the limit is 6.8Mbits per second. That bit rate constraint applies within the angle block and for the 2.5 seconds preceding each angle block.

To successfully lay out a mains & ends PGC with two mains, two ends, and three audio tracks the video must be encoded with two separate maximum bit rates, one for the mains & ends, and the other for the rest of the movie.

Mains and ends video bit rate = 7.8Mbits/sec. (max, 2 angles) - 3*0.448Mbits/sec. (audio) = 6.456Mbits/sec. Movie video bit rate = 9.8Mbits/sec. - 3*0.448Mbits/sec (audio) = 8.456Mbits/sec.

In the PGC editor, the movie is laid out like so:

main movie end
2.5sec.
|
V
V1 #####========================#########
V2 ##### ######
A1 ......................................
A2 ......................................
A3 ......................................

he sections of video marked with "#" marks are encoded at 6.456Mbits/sec. The sections of video marked with "=" marks are encoded at 8.456Mbits/sec.

BITRATE CONSTRAINTS

Angles Max bitrate
-----------------------
2-5 7.8Mbits/sec.
6-8 7.3Mbits/sec.
9 6.8Mbits/sec.

You will need to reduce the total max bitrate by up to 1.5 mbps when dealing with multiple high bitrate (>224Kbps) audio. Sometimes you will also have to reduce the vbv buffersize in encodes.

Note: These are intended to be conservative estimates.


IT's say for one angle !!!! for exemple for two angle you can have each video at 6.5 Mbits (it's working, is use it).
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Old 18th June 2003, 13:02   #9  |  Link
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sorry to revive this thread, but i guess it fits here best!

i just want to recapitulate what i read above, please somebody confirm that i'm right with my conclusions!

first the movie i'm dealing with: Amelie Region 2 special edition disk 1
i'm currently trying to reencode the main movie that has two angles. one for the french version and one for the german. it appears to me that only the opening part (maybe the first 5 to 10 minutes) and the closing credits are different.

What i've done: encode both angles seperately @ min 0 avg 3000 max 9000, which was obviously wrong, as i got the same problem than Platin had.

anyway, now i'm wondering if i just have to lower the bitrate in the parts that are acutally different. or do i habe to go for a total max bitrate of 4500? - which would rather suck...

i have to sub streams and two dd 5.1 audio streams @ 384 kbit

thanks for any confirmation, any additions etc are greatly appreciated,

steVe
PS: i think it's obvious that this is my first multi angle dvd backup
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Old 18th June 2003, 17:43   #10  |  Link
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You do have to lower the bitrate, but it is not divided up by the angles. These are the max's for interleaved:
2-5 7800
6-8 7300
9 6800
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Old 18th June 2003, 17:53   #11  |  Link
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thanks a lot...
unfortunately i'm still not sure about one thing: does this mean 7800 for 2 angles + audio + subs... or does it mean 7800 for each angle audio and subs?

please excuse my ignorance... (:
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Old 18th June 2003, 17:59   #12  |  Link
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I was just going to edit and clarify that. The maximums I listed are for each angle's total bitrate, i.e. in place of the 10080 value used for a single angle. It includes all video, audio, subpicture and PCI packets for one angle only. Each angle may use this maximum value, there is no interaction.
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Old 18th June 2003, 18:05   #13  |  Link
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ok thanks... so i guess i'm going to do another cce pass limiting the max bitrate to 7800 minus 2x ac3 minus subs... so i guess i might be going for around 7000 kbit for max... well that should be acceptable (:

thanks for your help
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Old 18th June 2003, 18:57   #14  |  Link
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ok... back again

i have to admit i cheated a bit i reencoded the movie while waiting for an answer to this thread, with a max bitrate of 4500... unfortunately even with this, almost too low setting, i cannot suceed in scenarist.
here's what i have
angle 1.mpv approx 2 gig @ min 0 avg 2500 max 4500
angle 2.mpv approx 2 gig @ - "-
audio 1.ac3 @ 384 kbit (5.1 ac3)
audio 2.ac3 @ 384 kbit (5.1 ac3)
subtitle 1 \
subtitle 2 - no idea what bitrate they have, but it can't be that high, can it?

anyway, when i'm building the DVD i get the same error, just at another point. while i got it right at the beginning first (where there's real multi angle present) i now get it pretty much in the middle of the movie (where the two movies are exactly the same)

another thing that kind of confuses me: when building the dvd files it says: video file size: 880 MB ??
how can that be, when one angle alone has 2 gig+ ?

thanks again for any advice/ help

steVe
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Old 23rd June 2003, 11:06   #15  |  Link
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Hi, maybe you solved it by now but this is what you did wrong I think: You can't have 4500 as max. The sum of both angles (including audio and subtitles) cannot exceed 7800 at any point in the stream. So you have to lower your max.

I forgot how to estimate the bitrate of the subtitles, but you can probably find the answer in another thread.

A bit of advice: only do multiangles on the start and end of movie if that's where there's difference because otherwise your bitrate would be too low to get good quality.
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Old 23rd June 2003, 11:13   #16  |  Link
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hi,
thanks for the hints, but as you assumed i did the backup already. for a bit further detail you might want to see this thread.
i of course only did those parts multiangle that were truly multiangle allthoug those persisted throughout the whole movie.
to the bitrate: i actually encoded the movie (that is now playing fine) with those settings for all vobids: min 1000 avg 3000 max 7000 and it worked. now of course i can't say if it was just luck and all the multiangle scenes, which were mostly quiet, almost still scenes, accidentially were below 4500 kbit.

subs: well the bitrate cannot be really significant anyway as one sub stream got around 15 megs uncompressed and is then compressed by scenarist to 2-3 megs iirc!

steVe
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Old 23rd June 2003, 13:10   #17  |  Link
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The bitrates for each angle are seperate, you do not divide it up. DVD players skip the agles that are not playing, without ever putting anything from them into the buffer. See my post above for the maximums.
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