Quantcast Codecs: Libavcodec Progress Thread - Page 2 - digitalFAQ.com Forums [Archives]
  #21  
03-13-2006, 08:42 AM
Sagittaire Sagittaire is offline
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Mencoder can make compliant stream like I prove in this thread.

My mencoder HPII trailer (in first thread for test codec) is compliant:
- IfoEdit check say "no underflow"
- Mencoder check say "no underflow"
- hank315 (HC developper) say "best of my knowledge no error, stream is compliant"
- All my mencoder stream are good for all the SAP tested
- and now DVD-Video Verifier say "no fatal error for MPEG2 stream"

Anyway subject is close for me. Try to find incompatible SAP with this hard example and speak after about that ...
http://multimediacom.free.fr/Video/MENCODER.rar
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  #22  
03-13-2006, 03:27 PM
rds_correia rds_correia is offline
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Well-well, look at what we have here .
So Philips DVD Verifier needs registration...
Very interesting!
Let me tell you a story.
Once upon a time there was a thread in this forum about bitrates and about how they were measured by BitrateViewer.
Don't ask me where the thread is because I just can't find it anymore.
So, in this thread everybody was using bitrateviewer to draw conclusions on how encoders were better or worse than other encoders.
The interesting part of it was that even using the same sources as some people that posted on that thread, using the same scripts, plugins versions, encoder versions, etc...I could never reach the same results as other people that even posted screenshots of bitrateviewer.
A few weeks past that, I went to visit my cousin and he told me how he found kvcd so useful and that he had done some encoder comparison to choose which one to keep installed.
Guess what tool he used to make the comparison? Yep, bitrateviewer!
Now the funny part of this.
He had found similar results to the ones found by other members of this forum that were completely different from mine .
I spent hours at his place trying to figure out how it was possible, until I decided to reinstall all his tools.
And bang suddenly the results on his computer were very similar to the ones on my home PC.
And that's when he told me bitrateviewer was missing some bits of information.
I told him that bitrateviewer free version doesn't show all possible info and he laughed while he applied a crack he had downloaded days before for bitrateviewer.
And indeed there was the difference .
Bitrateviewer free edition displays different results when compared with a cracked edition!
Which one is the more reliable?
Beats me!, but I'll never know because I don't use warez.
End of story.
Now, I'm not saying that Saggitaire used warez to show us his findings, but if by any chance he did, then his results might be completely different from the reality .
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  #23  
03-13-2006, 03:48 PM
rds_correia rds_correia is offline
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Quote:
Originally Posted by Sagittaire
Try to find incompatible SAP with this hard example and speak after about that ... [/color]
http://multimediacom.free.fr/Video/MENCODER.rar
I don't need to go find one that doesn't work with Mencoder's encodes.
I have one right here with me that doesn't read mencoder's encodes properly.
It's and "el cheapo" AG DVD-336K.
No matter what settings I use with mencoder it can NEVER read it properly.
There! Satisfied?
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  #24  
03-13-2006, 05:24 PM
Dialhot Dialhot is offline
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Quote:
Originally Posted by rds_correia
Bitrateviewer free edition displays different results when compared with a cracked edition!
I already knew that and, guess what, I discovered that... while testing mencoder Perhaps it's a wanted trap put there by the author
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  #25  
03-13-2006, 09:08 PM
Sagittaire Sagittaire is offline
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Quote:
Now, I'm not saying that Saggitaire used warez to show us his findings, but if by any chance he did, then his results might be completely different from the reality .
well it's simple ... gamma can check directly my mencoder file with DVD-Video Verifier v1.5.0 and post result here
http://multimediacom.free.fr/Video/MENCODER.rar

I think that result will be exactly the same ... ???


Quote:
I don't need to go find one that doesn't work with Mencoder's encodes.
I have one right here with me that doesn't read mencoder's encodes properly.
It's and "el cheapo" AG DVD-336K.
No matter what settings I use with mencoder it can NEVER read it properly.
There! Satisfied?
1) You test this file ... ???
http://multimediacom.free.fr/Video/MENCODER.rar
(sorry it's slow ... I know)

problem here is not your mencoder encoding (gamma encoding are not compliant for example) but my mencoder encoding. I use very special multipass CLI for mencoder. Generaly mencoder make compliant stream only for third pass in most case ...

2) I can't find reference for this SAP. Certainely specific clone product. You know the chip used for hardware decoding ... ???
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  #26  
03-14-2006, 05:10 AM
gamma gamma is offline
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Quote:
Originally Posted by Sagittaire
Generaly mencoder make compliant stream only for third pass in most case ...
I quote: "Generally....most case....."

We need an encoder that produces compliant streams, period.

If an encoder "generally" produces an playable stream which in "most case" is compliant, then we don't need this encoder.

IF you found a way to encode a clip using mencoder with a special CLI and so on, which is really compatible, then it's great. For fun. Not for encoding video. Because of the simple reason that it's just not reliable, as you suggested yourself in your previous posts.

I'll try to take your sample to my work and verify it.
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  #27  
03-14-2006, 05:27 AM
Sagittaire Sagittaire is offline
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Well actually mencoder has simply difficult for Rate Control. If you exclude RC problem then MPEG2 structure stream is DVD compliant.

Make always compliant stream with one pass is actually simply impossible:
- vqscale mode is real constant quantizer mode : mencoder don't use vbv specification for make stream
- vbitrate mode use partially vbv specification : priority is not to respect vbv specification but target bitrate

Quote:
I quote: "Generally....most case....."
Mean simply that Multipass to respect vbv is necessary.

- One pass bitrate can make vbv compliant but it's generaly not the case. Quality is crap
- Two pass make generaly vbv compliant stream for source like DVD. Quality is not optimal.
- For hardest source like Quick Time Trailer three pass are necessary. Necessary too if you use high bitrate for DVD source. Quality is optimal

I make always my encoding in three pass for highest possible quality. If you want know if your stream is compliant (at first, second or three pass) then it's very simple : Mencoder check always underflow problem.
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  #28  
03-14-2006, 05:34 AM
gamma gamma is offline
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Quote:
Originally Posted by Sagittaire
Well actually mencoder are simply difficult for Rate Control. If you exclude RC problem MPEG2 struture stream is DVD compliant.
That's what we're saying all along.
Glad you finally agree.
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  #29  
03-14-2006, 06:30 AM
rds_correia rds_correia is offline
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@Sagittaire,
Hey pal, I used to love mencoder and I was a strong supporter, as you all can recall.
But...either you tell us how to produce such a compliant stream with mencoder, or I'm affraid we won't be much supportive of it.
And no, I still haven't tested your clip because I haven't had time.
The DVD player I told you about is surely a clone of some other player out there, but I can't help you much with that.
All I can say is that such SAP used to be very popular here in Portugal due to it's price.
Cheers
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  #30  
03-14-2006, 07:12 AM
Sagittaire Sagittaire is offline
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Quote:
Hey pal, I used to love mencoder and I was a strong supporter, as you all can recall.
But...either you tell us how to produce such a compliant stream with mencoder, or I'm affraid we won't be much supportive of it.
Well I will make faq for my complete and detailled encoding procedure with mencoder (next week I think)

You test that and you say if my procedure work for you. I my procedure don't work for you then discution is closed and I change my signature ...
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  #31  
03-14-2006, 07:16 AM
rds_correia rds_correia is offline
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Quote:
Originally Posted by Sagittaire
If my procedure don't work for you then discution is closed and I change my signature ...
sounds fair
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  #32  
03-14-2006, 04:07 PM
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Quote:
- MPEG2 Q4 is for me high quality encoding. For example CQ 80 in TMPGEnc make encoding at ~ quantizer 4
Lavcodec uses a LINEAR Quantisation where TmpgEnc, CCE and others do use a NONLINEAR Quantisation. So a Quantizer of 4 in lavcodec results in a significant worse output than compared to a Quantizer of 4 when using TmpGenc, CCE etc.!

Do make an encode using Mencoder where at very low lit underwaterscenes when Q gets kept at Q2 (vmin=2) recognisable 4x4 up to 8x8 Blocks do occur when surfaces do fade from dark blue to very dark blue or almost black. I almost solved that by using vmin=1 and tweaking the lmin argument which caused th Q dropping almost to 1.5 -> blocks where off, ... but on the other side this caused other problems in the ratecontrol.
I dont know if that issue has been fixed already or if its not the case when using your CLI arguments.

Quote:
For example CQ 80 in TMPGEnc make encoding at ~ quantizer 4
TmpGenc uses variable Q's when doing a CQ based encoding. Do watch the curve it still bahaves variable. This results in a for human eyes more good looking picture. Same in Case of OPV in CCE.
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  #33  
03-14-2006, 04:30 PM
Dialhot Dialhot is offline
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Quote:
Originally Posted by incredible
Lavcodec uses a LINEAR Quantisation
Really ? I did not notice that. The non-linear quatization is one of the most interresting enhancement of MPEG2 over MPEG1. It's stupid to not use it.
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  #34  
03-14-2006, 05:22 PM
incredible incredible is offline
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Do look in Bitrateviewer (jupp its mentioned in the mpeg header). Lavcodec resulted streams are generaly Nonlinear.

A Q of 2 in Lavcodec matches almost a Q of 4 in TmpgEnc, CCE etc. Keep in mind Im talking about human eyes subjective comparison.

Both types of quantisation do got their pros and cons. I think Kika could explain that very deeply. Anyhow I remember that Petercheat sometime offered to switch Lavcodec in Nuenc to nonlinear quantisation. But in his words it wasn't worth it imho. I dont remember correctly.

Do make an encode in TmpgEnc and check the quantisation, it will also be here a nonlinear one. Surprising. Out of Specs? Boooom

Said objectively:
I still dont see the sense of that war in here. The main spirit of KVCD was to NOT follow the specs, enlarging GOPs, switching, tweaking etc.
Thats also the reason why a SAP compatibility chart is given in the portal.
If the bitrate spiking of libavcodec is solved by some tricky arguments in the command line, ok. The rest, well ..... same in case of KVCD: If the SAP doesnt support it. Switch over or get a new SAP which is proofed playing back even DVDs of Oil where fries have been boiled in

I do expect from commercal DVDs that they are FULL specs compilant, the backups should be played back in my own SAP. If I have to handle a Job I dont make any experiencies and choose CCE or TmpgEnc.



Quote:
If my procedure don't work for you then discution is closed ----> and I change my signature ...
Think about it anyway. That could be a pleasure in general, not only depending on all this lavcodec hadaik!
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  #35  
03-14-2006, 06:29 PM
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Quote:
Originally Posted by incredible
Lavcodec resulted streams are generaly Nonlinear.
Linear

Note: I don't think that any spec specifies if the quantization has to be linear or not, but I may be wrong.
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  #36  
03-15-2006, 02:58 AM
Boulder Boulder is offline
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Quote:
Originally Posted by Sagittaire
For good security with RC you must target more than average q4 encoding with mencoder. Make "high bitrate (low average quantizer)" with mencoder is in practice useless and very difficult
I don't see a point in using an encoder that you constantly have to tweak in order to keep things compliant. Keeping compliancy should be the encoder's problem, not mine.

I'm not allowed to use high bitrates and am supposed to take care that the avg quantizer is over 4? Yeah right..

IMHO, the main thing about compliancy is simply the bitrate spikes because of the physical boundaries. Long GOPs are not a (big) problem.
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  #37  
03-15-2006, 05:33 AM
rds_correia rds_correia is offline
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Hmmm, I'm affraid there's more than that (bitrate spikes) to it.
I once ran a couple of tests between Tmpgenc vs Mencoder.
I still have those KDVDs with me.
Yesterday I ran those mpegs through bitrate viewer and on one of the clips the bitrate never went above 4000 but still it doesn't play on my old SAP.
So I believe that bitrate spikes are not the only problem here.
BTW, I muxed those mpegs with Tmpgenc DVD author with audio 48Khz and I don't recall if it reported any errors during the authoring.
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  #38  
03-15-2006, 06:00 AM
Boulder Boulder is offline
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What comes to error reporting, I wouldn't trust TMPGEnc DVD Author a bit

Demux the VOBs and try muxing in MuxMan. It produces a very good analyser log if anything goes wrong.
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  #39  
03-15-2006, 11:07 AM
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Today I tested Sagittaire's sample. The VOB produced this:

Quote:
************************************************** **********
*
* ERROR SUMMARY :
*
* 95 Informations
* No Recommendation violations
* No Oddities
* No Warnings
* No Syntax errors
* 470 Errors
* 2 System errors
*
************************************************** **********

After demuxing the m2v produced this:

Quote:
************************************************** **********
*
* ERROR SUMMARY :
*
* 2 Informations
* No Recommendation violations
* No Oddities
* No Warnings
* 61 Syntax errors
* No Errors
* 2 System errors
*
************************************************** **********
Certainly looks alot better than my encoding with lavcodec

That brings us back to the point that I (and Boulder) stated earlier: an encoder should produce compliant stream without constantly tweaking it.
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  #40  
03-15-2006, 04:47 PM
rds_correia rds_correia is offline
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Ooops, wait a minute Gamma.
If Sagittaire's MPEG file reads a lot of errors on DVD Verifier but the demuxed M2V doesn't, then I would say that those errors were introduced by the authoring tool which doesn't make much sense...

@Sagittaire,
What authoring tool did you use on this sample?
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