TMPGEnc VBR & SVCD Bitrate: sparkles over 2500 !! :-((

[Giuliano]

Hi.
I wanted to check the file product by TMPGEnc, using the template it gives (an average fo 1950 2-pass VBR, 2520 max.)

I checked the MPG2 with Bitrateviwer, and I found the bitrate to rise somtimes up to 3000 Kbit/s (!!) althought the maximum bitrate was setted to 2520. It is strange, but it happened with 2 cd (The others part 1 & 2)

The second strange thing is that the template show
MPEG.Video.MaxBitRate = 2520000
but the guide on vcdhelp shows the maximun bitrate for the SVCD to be only 2500, so it seems thata the maximum bitrate given with the template is incorrect !

Whath we have to think: is the bitrateviwer to misunderstand the MPG2 file or is the encoder to overcome the specifications ?

Giuliano

P.S.
whatching the SVCD on the standalone player, the player's bitrate indicator has a range for the SVCD of 0 to 5 Mbits/s (?!)
Isn't it strange ?

[Triffid]

Just some comments:

I find VBR to generally stay well below the maximum bitrate - it hovers around the average. So to get a high bit rate I need to put the avaerage up near the maximum (or just use CBR)! What I do find is that bitrate veiwer ALWAYS gets bitrate for the last GOP wrong (well maybe only if it is a short GOP??) so you see this big leap at the end, but the rest of it is OK. Is it the same for you, or does it go up to 3000 in the middle somewhere?

If your player can handle 5000 kbits/s then you are a very luck person!! My Pioneer 444 gives up at about 2600 and starts chopping the audio and running the video in slowmotion...(and I love the look of SVCD at >4000)

[adam]

I have read that bitrate viewers can never be totally accurate but its true that mpeg encoders often don't respect yoru max bitrate setting. I think its just the nature of vbr encoding that its hard to allocate the bitrate exactly as specified. The bitrate spikes that you are experiencing are common, even in cbr encoding, and they rarely cause any playback problems.

The maximum video bitrate for svcd is actually 2600kbits per sec though I think realisitically 2500kbits is a more reasonable limit to use for most people and I assume thats why its listed that way on this site. The total maximum bitrate (video + audio + some overhead) for svcd is 2,788,800 bps. So taking a reasonable audio bitrate into account, your video should only peak around 2500kbits.

There is nothing wrong with the template but remember its just a suggested setting and not the only available option.