To measure bitrate, what do we use ??

[apfraats]

My question is about HOW TO CORRECTLY DETERMINE BITRATE ?

I used bitrateviewer, and already JDOBBS and others stated BITRATEVIEWER is giving too high values (JDOBBS, if padding was an issue, it could maybe happen), or too LOW values....


JDOBBS talked IIRC about bitrate determination at GOP LEVEL.
BITRATEVIEWER reports bitrate at a SECOND(time-unit) LEVEL.

Now I'm lost and I finally wanted a tool that correctly reports bitrate of M2V,MPV and VOB files.

Anyone ?

The problem is that DVD-RB was setting a max-bitrate for a 5500 kbps/CBR !! marked movie to 7127, which seems somewhat high.
The highest value reported by BITRATE VIEWER was just 6290 kbps.

When I demuxed in DVD-LAB-PRO 1.53 the MAX BITRATE was: 6552 kbps.

AAAARGGGGGGGHHHHHhhhhhh !!!!! (shall I throw dices next time ? :) )

Then I used BITRATE VIEWER on the demultiplexed MPV: 6288 kbps.
(this is much like using the VOB's directly, luckely).


It's all R2 PAL stuff.


So now the main question:

How should bitrate be calculated in the CORRECT WAY ???
Are there any tools to do so ? Yes, which ones ??

Thanx a lot if somebody knows something about this in depth.

Do not respond by claiming this post is wrong here, because it's in DVD-RB's context.

[Vurbal]

It's been a while since I used it, but IIRC MPEG Stream Eye (from Elecard) can show you bitrates at the GOP level, or even the size of a specific frame. I do remember it showing me a different bitrate than (the free version of) Bitrate Viewer.

[laserfan]

Another tool to try is MPEG-2 Validator.

[Boulder]

I think someone once said that Bitrate Viewer's result must be multiplied by 1,024 (that's one point zero twenty four ;)) for the correct result.

[jptheripper]

not for pal material i dont think

[apfraats]

Well we can sure that bitrate viewer is not to trust.

Some say it gives a too high bitrate, some say it's to low.


Thanks so far, keep reacting on this topic and I'll try the tools used.

Bitrate viewer AGAIN reported a peak of >9000 kbps on DVD-RB output that had DTS and 5.1 audio, so it would be out of spec.

I just used to output as input again and used RB-OPT to see the reported bitrates (maximum) as DVD-RB limits then to source or methematical MAX restrictions, and there were IN SPEC at about 8560 Kbp/s max.

But let's find out if JDOBBS can confirm a way to correctly caclutates bitrates in a user friendly way, and how he does it. As far as I know he is calculating at GOP-level.

[feedback]

DGIndex shows the bitrate approx. every 64 frames although it does not appear to give an 'Average' bitrate of the VOB. Maybe someone could add that feature in the future.:D

There is a tool in the Berkeley Mpeg Tools http://bmrc.berkeley.edu/frame/research/mpeg/
that thoroughly analyzes MPEG streams by analyzing or printing out most of the information in the stream called Mpeg Stat.
The source code from Berkeley is available for those that want it.

Another tool 'Mpeginfo' is based on the MPEG-decoder by the Berkeley Multimedia Research Center.

[Prodater64]

DVD Lab Pro has an internal bitrate viewer tool.

[jdobbs]

The problem is that DVD-RB was setting a max-bitrate for a 5500 kbps/CBR !! marked movie to 7127, which seems somewhat high.What does this mean? DVD-RB doesn't mark anything as CBR??? Then it says "marked movie to 7127" -- I'm not sure what you're talking about here...

[neuron2]

DGIndex shows the bitrate approx. every 64 frames although it does not appear to give an 'Average' bitrate of the VOB. Maybe someone could add that feature in the future. That's a good idea. Thank you.

DGIndex counts the number of bytes passed to the MPEG2 video parser and then uses the frame rate to calculate a running bitrate over a 64-frame window.

[apfraats]

What does this mean? DVD-RB doesn't mark anything as CBR??? Then it says "marked movie to 7127" -- I'm not sure what you're talking about here...

No JDOBBS sorry, it was the SOURCE I was referring to. That was marked CBR @ 5500 Kbps.........at least that was bitrateviewer telling me.

Not the output of course....

[apfraats]

DVD Lab Pro has an internal bitrate viewer tool.


Yep, also not to trust, because it reports bitrate maxs different from DVD-RB.

And I suppose DVD-RB does it the correct way, at GOP level IIRC. (At least I remember JDOBBS stating that)

[kumi]

Is bitrate determined on a GOP-level an accurate indicator of stand-alone player performance? i.e. if a program shows the bitrate at the GOP-level spiking above the maximum DVD-Video specs, will that be a usable indicator of SAP playback problems?

About bitrateviewer, you can set the multiplier to 1024 instead of 1000 in the program settings.

What about Elecard StreamEye? That claims to give the video stream bitrate... is it calculated on a GOP level?

[jdobbs]

No JDOBBS sorry, it was the SOURCE I was referring to. That was marked CBR @ 5500 Kbps.........at least that was bitrateviewer telling me.

Not the output of course....A CBR source has a number of challenges... The maximum and minimum source bitrates would be the same as the average. I would never recommend encoding anything at CBR that is going to be run through DVD-RB. In fact I can't think of a good reason to use CBR for anything other than maybe a broadcast stream. I've never seen a commercial disc that used CBR -- but of course there are probably some out there somewhere.

[jdobbs]

Is bitrate determined on a GOP-level an accurate indicator of stand-alone player performance? i.e. if a program shows the bitrate at the GOP-level spiking above the maximum DVD-Video specs, will that be a usable indicator of SAP playback problems?

About bitrateviewer, you can set the multiplier to 1024 instead of 1000 in the program settings.

What about Elecard StreamEye? That claims to give the video stream bitrate... is it calculated on a GOP level? Using GOP gives a "smoothing effect" that lowers the impact of single frame spikes. That method is only used for determining the peak input bitrate (from a source DVD that is to be backed up) and at no point is meant to measure problems with SAPs. The output maximum bitrate is calculated based upon DVD specs and also have to consider the combined video/audio/subpicture/overhead requirements.

[kumi]

That method [GOP] ... at no point is meant to measure problems with SAPs. The output maximum bitrate is calculated based upon DVD specs and also have to consider the combined video/audio/subpicture/overhead requirements.I see. From reading other threads (http://forum.doom9.org/showthread.php?t=102922&highlight=bitrate+overall) it's apparent that problems arise due to many factors such as buffer overflows. Also, CBR streams might cause bitrate viewers to choke, according to Mug Funky.

[feedback]

Originally Posted by feedback
DGIndex shows the bitrate approx. every 64 frames although it does not appear to give an 'Average' bitrate of the VOB. Maybe someone could add that feature in the future.
That's a good idea. Thank you.

DGIndex counts the number of bytes passed to the MPEG2 video parser and then uses the frame rate to calculate a running bitrate over a 64-frame window.
So, is DGIndex going to be having the 'Average Bitrate' feature soon?:)

Regards,

[Rippraff]

This has already been implemented with version 1.4.6b3 (http://forum.doom9.org/showthread.php?p=764522#post764522). :)
As the first RC is out now it will not take very long to the final version.

Cu Rippraff

[feedback]

This has already been implemented with version 1.4.6b3 (http://forum.doom9.org/showthread.php?p=764522#post764522). :)
As the first RC is out now it will not take very long to the final version.

Cu Rippraff
Thanks for info. Rippraff. I have been waiting for the upgrade from neuron2 but I sure missed that one...he added the new function at warp speed.http://users.pandora.be/eforum/emoticons4u/happy/1055.gifThanks neuron2!

I have since down loaded the newest version of DGIndex with the new average bitrate feature. One thing though, I ran a VOB of about 1 gig though DGIndex and got an average bitrate of 6.096Mbps. I then ran the same VOB through Bitrate Viewer and got an average bitrate of 7.197Mbps. That is a big difference in bitrate.

However, I am much more inclined to trust neuron2 and DGIndex's average bitrate over Bitrate Viewers average bitrate. What do you guys think?

Regards,

[kumi]

Anyone know what software they're using over at dvdbeaver (http://www.dvdbeaver.com/film/DVDReview6/2046.htm) to measure video bitrate? They compare a lot of DVDs...

[manono]

That one's called DVD Bit Rate Viewer. It gets the bitrate from the DVD in the DVD-ROM and shows the total bitrate, video, audio, subs, and overhead. You can get it here:

http://www.visualdomain.net/bitrate.htm

[hallway]

I was just referred to bitrate14 yesterday. What's the opinion on this one ?

By the way, how in the world does it "read" the DVD so quickly. It's instant.

[nwg]

Bitrate14 also includes all the audio in the title.

[RIPRECOBACK]

A CBR source has a number of challenges... The maximum and minimum source bitrates would be the same as the average. I would never recommend encoding anything at CBR that is going to be run through DVD-RB. In fact I can't think of a good reason to use CBR for anything other than maybe a broadcast stream. I've never seen a commercial disc that used CBR -- but of course there are probably some out there somewhere.


Ok, let's say that about 5% of my collection (over 1500 in total) has CBR as encoding method. That you can clearly see with bitrate viewer. (although not to trust reported bitrate in a numeral way).

So once every twenty dvd's or so I have one encoded with CBR.

What I do is manually setting max_bitrate to a higher value, that's within dvd-specs concerning other bitrate demanding things (audio, subtitling, room for error e.g.)

But seeing all these post, it isn't clear to me how and with what tool to determine the correct bitrate of video vob, m2v files e.d.

So I always use DVD-RB running the prepare fase and rb-obt to determine the max_bitrate in a stream.

Al least dvd-rb behaves consistently in reposrting max_birate....

But I really would like a simple way to do this correctly....

Every tool tried in this thread reports different birates (max_bitrate) , so i'm also lost here........


How should bitrate and max_bitrate be considered in a way it's compliant to dvd-specs ???

[hallway]

Anyone else who's tried bitrate14 notice that it hardly shows any "dips" below a given bitrate ? That seems unusual to me. It shows almost a flat line on the low side that the bitrate (almost) never goes below.

[jdobbs]

Ok, let's say that about 5% of my collection...has CBR
That's really unusual. In 900 commercial discs tested I have yet to have seen one. I would also have serious reservations in believing it if it were reported by any software on a commercial disc. Then if I did find it on a commercial disc I'd be tempted to send a letter to the authoring house telling them that they shouldn't quit their daytime job.

But that's just me.

[jptheripper]

wait, if an authoring house made a cbr disk, shouldnt you tell them that they SHOULD quit their day job?

[manono]

Hi-

In 900 commercial discs tested I have yet to have seen one.

You really have to get out more; out into the mean streets where not every DVD is a beauty put out by Warner, Sony, Disney, Paramount, or New Line. I see them periodically and if RIPRECOBACK says maybe 5% of his collection uses CBR encoding, then I, for one, am prepared to believe him. Depending on where he lives, I believe it's perfectly possible that the DVD production houses aren't as advanced as in the US. But even in the US such DVDs are far from rare. Here's a DVD comparison between 2 R1 releases of a fairly well known Film Noir. One uses CBR and the other (I think) uses 1-pass VBR encoding:

http://www.dvdbeaver.com/film/DVDCompare10/impact_.htm

Here's another one:

http://www.dvdbeaver.com/film/DVDReviews16/an_autumn_afternoon_dvd_review.htm

It may be using 1-pass VBR encoding, but it's pretty much the same thing. I own that DVD. It's an official R3 Hong Kong release of Yasujiro Ozu's final film, the only DVD release of that film with English subtitles anywhere. Here's a part of the BitRate Viewer graph of the same DVD:

http://img76.imageshack.us/img76/3166/bitrateviewer8hc.th.jpg (http://img76.imageshack.us/my.php?image=bitrateviewer8hc.jpg)

Ozu's films are pretty static, but the bitrate graph is pretty much like that all the way through. But when you see the Q-Scale fluctuate around a static bitrate line like that, then that's proof of something funny going on, as far as I'm concerned.

I would also have serious reservations in believing it if it were reported by any software on a commercial disc.

Believe it. DVD Bit Rate Viewer as used on the DVDBeaver web site is accurate.

[manono]

Hi-

Anyone else who's tried bitrate14 notice that it hardly shows any "dips" below a given bitrate ? That seems unusual to me. It shows almost a flat line on the low side that the bitrate (almost) never goes below.

He's zooming out 3x in those pics, and the bitrate curve tends to flatten out as you zoom out. For example, here's a pic, also zoomed out 3x, of a reencoded DVD5 I made with the minimum set for 500, and a 192 bitrate for the audio. It has a set of subs, so, the minimum if used, should be somewhere around 700:
http://img76.imageshack.us/img76/1633/zoomout4pg.th.jpg (http://img76.imageshack.us/my.php?image=zoomout4pg.jpg)
Just to look at it, you'd think the minimum was 2000 or so. But unzoomed it looks like this:
http://img62.imageshack.us/img62/2826/dvdnozoom1kf.th.jpg (http://img62.imageshack.us/my.php?image=dvdnozoom1kf.jpg)
And there you get a better idea of the true curve, and that it does go down to 700 near the beginning. Also, you have to remember that the studios aren't setting their minimum bitrates at 250, 300, or 500 as we often do for our DVD5 backups, but to 2,000, 3,000, or 4,000. So that's why you often see that flattening of the curve at the bottom.

[kumi]

That one's called DVD Bit Rate Viewer. It gets the bitrate from the DVD in the DVD-ROM and shows the total bitrate, video, audio, subs, and overhead.[...]There's remarkable little information on the site... is the calculated average bitrate is also for video+audio+subs+overhead? If that's the case, someone should inform dvdbeaver, they're displaying DBRV's calculated average under "Video" :o

Believe it. DVD Bit Rate Viewer as used on the DVDBeaver web site is accurate.Great! As a bonus, it's lightning fast... it literally takes less than a second, reading from a mounted image. In fact, I initially wrote it off as a fake because of this.

[laserfan]

...As a bonus, it's lightning fast... it literally takes less than a second, reading from a mounted image. In fact, I initially wrote it off as a fake because of this.Can someone please explain this? How can it possibly give an accurate graphical representation without scanning the entire DVD? Which even at 16x will take a few minutes???

I'm vaguely aware that MPEG2 files contain "headers" with bitrate information in them--if BR Viewer is reading these headers that might explain this partially. Do headers exist for every cell?

[jdobbs]

If you just read the NAVPACKs, they include a sector pointer to the next NAVPACK. So you could jump through the stream reading only the NAVPACK sectors and calculate the bitrate as it is stored (audio/video/subpictures) by using the length of all the sectors in-between. The System Clock Reference is also in the NAVPACK, so you could use that as the time reference. All you need is time and size to calculate bitrate.