Different bitrate depending on video?

LoKoRg · 18th July 2003, 17:46

Well...first sorry for my bad english, but i will try to explain my problem (maybe not a real problem)

When i encode the video (I use NSV Batch Encoder) to NSV files...
i use the next configuration...

NSV format options
audio send: 0
min/max syn = 10/50
File Header (check)
TOC (default) = 1024
Some metadata...

Audio - Samplerate 22050 (lowpass filter) - Mono - Lame CBR-Mono-16 - Quality Normal

Video - VP3
bitrate 8 - keyframe bitrate 4
allow drop
quality 63
Auto keyframe (check)
and the rest by default...

I encode 2 videos...
one with regular action change (not much, just con color cachange...gradients, something like the winamp VIS plugin)
and the other with more action, scene change, more like a real musical video...

Well...the thing is...
the files are very similar in time...
(the first is 4:00 minutes, the other 4:06)

but the output filesize are very different....
The first is 958 KB (4:00)
And the second 1293 KB (4:06)

i calculate the KB/sec based on size and time duration...

first:
3.99 (4) KB/sec = 31.9 (32) kbps

second:
5.2 KB/sec = 41.6 kbps

well, some people say that 1 KB is not much on this days, but in this case for my is a kind of a problem, not serious but a little problem...

And other thing...
How can a predict the video file size and the used kbps, based ond the configuration of NSENC ?

for example, I use 16 kbps for audio... and 8 kbps for video...
16+8 = 24 kbps (plus maybe some metadata information, keyframe, etc)

but the real thing is I use
first case:
8 kbps more than expected (1 KB/sec)

second case:
17.6 kbps more... (2.2 KB/sec)

Well...can someone explain my why this happen?

Is the video encode variable?
if is somthing like this
the idea of put the biterate of video is for the maximun bitrate used...if the video is with poor action, i improve the quality, but maintein the video bitrate..
and if the vidoe is high action, i only use the maximum bitrate, i dont use more than that...

i hope someone knows...

By the way...
I love Shoutcast, NSV, ...cool tools, thx to nullsoft for this tools...

Jeeper One · 19th July 2003, 08:07

Hi everyone:

First off, encoding ANYTHING at 16/22 isn't a very good idea. If you're going to use 16 Kbps., it MUST be a sampling rate 16000 Khz. or LOWER (not higher).

Secondly, I've noticed the same thing about the differing bitrate wwhen it comes to the video bitrate reading. Now that I have Winamp 3 and it seems to have NO PROBLEM WHATSOEVER playing NSV videos, I've started encoding at 64/44 stereo, but I've seen the bitrate in the final product shoot in upwards of 300 Kbps and (sometimes) EVEN HIGHER!!

Is this reading of the bitrate from the video itself (i.e. WITHOUT the audio) or is this something to be expected with NSV??

Or is this just yet another bug??

Cheers for now :-)

Patrick Cook
Proud Member - Electronic Frontier Foundation - http://www.eff.org/
Program Director
Jeeper One Radio Network
KPDC Internet TV - REAL Web TV
kpdcnetradio@msn.com
kpdcnettv@attbi.com
pchamster@msn.com
Denver, Colorado
http://kpdcnetradio.***********/
http://kpdcnettv.***********/
NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.***********/webcam.html KPDC Internet TV - http://kpdcnettv.***********/webcam.html

Jeeper One · 19th July 2003, 08:10

Hi everyone:

First off, encoding ANYTHING at 16/22 isn't a very good idea. If you're going to use 16 Kbps., it MUST be a sampling rate 16000 Khz. or LOWER (not higher).

Secondly, I've noticed the same thing about the differing bitrate. Now that I have Winamp 3 and it seems to have NO PROBLEM WHATSOEVER playing NSV videos, I've started encoding at 64/44 stereo, but I've seen the bitrate in the final product shoot in upwards of 300 Kbps and (sometimes) EVEN HIGHER!!

Is this reading of the bitrate from the video itself (i.e. WITHOUT the audio) or is this something to be expected with NSV??

Or is this just yet another bug??

Cheers for now :-)

Patrick Cook
Proud Member - Electronic Frontier Foundation - http://www.eff.org/
Program Director
Jeeper One Radio Network
KPDC Internet TV - REAL Web TV
kpdcnetradio@msn.com
kpdcnettv@attbi.com
pchamster@msn.com
Denver, Colorado
http://kpdcnetradio.***********/
http://kpdcnettv.***********/
NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.***********/webcam.html KPDC Internet TV - http://kpdcnettv.***********/webcam.html

LoKoRg · 19th July 2003, 19:19

Well, I know is not a good idea to compress with this configuration, but for now i doing some test, and even this low configuration cause my some trouble in bandwidt, well for now this is only part of my problem...

back to the original question...
i have a little problem with the audio, I smplerate to 22050 Hz because when try to samplerate to 11025 and a get this error
"openOutput: error creating audio compressor"

i try to use 11025 or 22050 because this are kind of standard...

Well, to jump this problem i compress the video only...and the results are...

First video (low action, color changes)
final size: 490 KB
duration: 240 sec
490/240 = 2.04 KB/sec = 16.33 kbps

Second Video (more action)
final size: 814 KB
Duration: 246 sec
814/246 = 3.3 KB/sec = 26.47 kbps

I use the same configuration metioned in the first message

now i am doing some changes...wait a minute...
change the frames to 8 fps (and preserve the same configuration above)
the audio in 16000 Hz, 16 kbps, mono

More results...
First video
final size: 863 KB
duration: 240 sec
863/240 = 3.59 KB/sec = 28.76 kbps

Second Video
final size: 1072 KB
duration: 246 sec
1072/246 = 4.35 KB/sec = 34.86 kbps

I find this very rare, because when someone compress and Mp3 with certain bitrate, the final result is not depending on the audio type, even if is only silence, the file size of 2 different Mp3 with the same bitrate is the same file size...

I dont know the VP3 video compression, but as i mention before, if i set certain bitrate the file size is not bigger than expected...

Is this bug or is the way tha VP3 works?

Jeeper One · 19th July 2003, 20:31

Hi everyone:

You can't compress at 16/22 and expect it to sound very good. If you're going to use 22050, you WILL need to up the bitrate to AT LEAST 24 Kbps.

If you have the bandwidth to do this, then you should stick with either 16/16 or 16/11 mono and leave it at that.

THAT is what I'm trying to say....

Cheers for now :-)

Patrick

LoKoRg · 19th July 2003, 21:41

the problem is not with the audio or video quality, this don´t matter for me right now....

i just find very weird that if i compress 2 video files with the same video duration (4:00 minutes), and use the same NSV configuration configuration the 2 files are different in size...

Jay · 19th July 2003, 23:43

that is because VP3 is variable bitrate.

LoKoRg · 20th July 2003, 02:24

mmm... i think about that, but even so, the file size is espected to be some kind of constant or lower certain range of size...

if is set the audio bitrate to 16...and the video bitrate to 8, the "result" must be sometime like 24 kbps total...plus some "metadata" (maybe not metadata like that whe enter in the video, maybe more information, scene change, etc)...

24 kbps = 3 KB/sec
so
3*time = expected_filesize KB
(If VP3 is varible bitrate, this shoul be the maximum filesize)
and if whe add the "metadata" variable
3*time + "metadata" = real_filesize KB

but even with the low motion video the filesize is very weird...

First Video (low motion)
Expected filesize:
3*240 = 720 KB
3*240 + "metadata" = real_filesize KB
720 + "metadata" = 863 KB
So, the "metadata" must be
"metadata" = 143 KB
Let say this is a good metadata

Second Video (high motion)
Expected filesize:
3*246 = 738 KB (just a little higher than abvove for the extra 6 seconds
3*240 + "metadata" = real_filesize KB
738 + "metadata" = 1072 KB
"metadata" = 334 KB
Is more than two times bigger than the low action video...

I even try to do with good video quality, but the filesize are really different..
for example the low action video get to 7-8 MB, and the high action to 9-10 MB

Well...i really love NSV, is a great idea, great solution...i just love it
and sorry for have too many questions, but he avaible information, reame, forum topics are in some ways too vague....
(and sorry for the "too mathematical" expresion, but in this way i can explain better the question)

And other little question...
In the NSENC configuration, is the
"[checkbox] Allow dropped frames (Enables CBR)"

This really works or is the cause of all my problems in the earth? (well, just the problems i have with NSV

)

Jeeper One · 20th July 2003, 08:51

Hi everyone:

Quote:

Originally posted by KXRM
that is because VP3 is variable bitrate.

So even though the bitrate of the video itself varies, the overall video (including the audio) will still remain pretty much at or around 64K (the bitrate I'm encoding at). Right??

Cheers for now :-)

Patrick

Jay · 20th July 2003, 11:31

no the way nullsoft has the encoder setup is that the variables you set in the configuration screen for bitrate are targets, if the encoder feels that it's an unacceptable target it will just get as close as possible. So if you choose 64kbps as your VP3 video stream, it will do it's best but generally will be dependent on other variables such as frame rate, keyframe settings and whatever action is on the screen, if you are looking a basically a wall on the video and there is no motion then it will get very close to target expectations if they are set low, but if there is alot of action and your frame rate is 29.97 then you can fully expect that it will not be able to reach your settings.

I am not sure if this behavior will change, that would be up to where the format goes and if and when nullsoft implements it (if they are able to)

Quote:

In the NSENC configuration, is the
"[checkbox] Allow dropped frames -->(Enables CBR)<--"

this has already been proven false, and has been reported to be innacurate.

LoKoRg · 20th July 2003, 13:24

so thats why....
thx for the explain

I hoe in the near future (like 2013) the CBR works...

Jeeper One · 21st July 2003, 02:33

Hi everyone:

Yeah thanks! :-)

In the meantime, I think I'll do CD backups and then start toying with the frame rate a little to see if I can get the NSV bitrate down to where it should be.

Either that or I'll just simply set the frame rate in the NSV encoder a little lower and go from there. :-)

Cheers for now :-)

Patrick Cook
Proud Member - Electronic Frontier Foundation - http://www.eff.org/
Program Director
Jeeper One Radio Network
KPDC Internet TV - REAL Web TV
kpdcnetradio@msn.com
kpdcnettv@attbi.com
pchamster@msn.com
Denver, Colorado
http://kpdcnetradio.***********/
http://kpdcnettv.***********/
NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.***********/webcam.html KPDC Internet TV - http://kpdcnettv.***********/webcam.html

18th July 2003, 17:46	#1
LoKoRg Junior Member Join Date: Feb 2001 Location: Third planet around the Sun Posts: 32	Different bitrate depending on video? Well...first sorry for my bad english, but i will try to explain my problem (maybe not a real problem) When i encode the video (I use NSV Batch Encoder) to NSV files... i use the next configuration... NSV format options audio send: 0 min/max syn = 10/50 File Header (check) TOC (default) = 1024 Some metadata... Audio - Samplerate 22050 (lowpass filter) - Mono - Lame CBR-Mono-16 - Quality Normal Video - VP3 bitrate 8 - keyframe bitrate 4 allow drop quality 63 Auto keyframe (check) and the rest by default... I encode 2 videos... one with regular action change (not much, just con color cachange...gradients, something like the winamp VIS plugin) and the other with more action, scene change, more like a real musical video... Well...the thing is... the files are very similar in time... (the first is 4:00 minutes, the other 4:06) but the output filesize are very different.... The first is 958 KB (4:00) And the second 1293 KB (4:06) i calculate the KB/sec based on size and time duration... first: 3.99 (4) KB/sec = 31.9 (32) kbps second: 5.2 KB/sec = 41.6 kbps well, some people say that 1 KB is not much on this days, but in this case for my is a kind of a problem, not serious but a little problem... And other thing... How can a predict the video file size and the used kbps, based ond the configuration of NSENC ? for example, I use 16 kbps for audio... and 8 kbps for video... 16+8 = 24 kbps (plus maybe some metadata information, keyframe, etc) but the real thing is I use first case: 8 kbps more than expected (1 KB/sec) second case: 17.6 kbps more... (2.2 KB/sec) Well...can someone explain my why this happen? Is the video encode variable? if is somthing like this the idea of put the biterate of video is for the maximun bitrate used...if the video is with poor action, i improve the quality, but maintein the video bitrate.. and if the vidoe is high action, i only use the maximum bitrate, i dont use more than that... i hope someone knows... By the way... I love Shoutcast, NSV, ...cool tools, thx to nullsoft for this tools...

19th July 2003, 20:31	#5
Jeeper One Major Dude Join Date: May 2003 Location: Denver, Colorado Posts: 1,054	Hi everyone: You can't compress at 16/22 and expect it to sound very good. If you're going to use 22050, you WILL need to up the bitrate to AT LEAST 24 Kbps. If you have the bandwidth to do this, then you should stick with either 16/16 or 16/11 mono and leave it at that. THAT is what I'm trying to say.... Cheers for now :-) Patrick Pat Cook WSO-AM Soap Opera Radio (Currently On The SHOUTcast YP But Website Coming Soon) Englewood, CO

19th July 2003, 23:43	#7
Jay Moderator Alumni Join Date: May 2000 Location: Next Door Posts: 8,888	that is because VP3 is variable bitrate. -Jay \| Radio Toolbox.com

21st July 2003, 02:33	#12
Jeeper One Major Dude Join Date: May 2003 Location: Denver, Colorado Posts: 1,054	Hi everyone: Yeah thanks! :-) In the meantime, I think I'll do CD backups and then start toying with the frame rate a little to see if I can get the NSV bitrate down to where it should be. Either that or I'll just simply set the frame rate in the NSV encoder a little lower and go from there. :-) Cheers for now :-) Patrick Cook Proud Member - Electronic Frontier Foundation - http://www.eff.org/ Program Director Jeeper One Radio Network KPDC Internet TV - REAL Web TV kpdcnetradio@msn.com kpdcnettv@attbi.com pchamster@msn.com Denver, Colorado http://kpdcnetradio.*********/ http://kpdcnettv.*******/ NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.*******/webcam.html KPDC Internet TV - http://kpdcnettv.*******/webcam.html Pat Cook WSO-AM Soap Opera Radio** (Currently On The SHOUTcast YP But Website Coming Soon) Englewood, CO

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19th July 2003, 08:07	#2
Jeeper One Major Dude Join Date: May 2003 Location: Denver, Colorado Posts: 1,054	Hi everyone: First off, encoding ANYTHING at 16/22 isn't a very good idea. If you're going to use 16 Kbps., it MUST be a sampling rate 16000 Khz. or LOWER (not higher). Secondly, I've noticed the same thing about the differing bitrate wwhen it comes to the video bitrate reading. Now that I have Winamp 3 and it seems to have NO PROBLEM WHATSOEVER playing NSV videos, I've started encoding at 64/44 stereo, but I've seen the bitrate in the final product shoot in upwards of 300 Kbps and (sometimes) EVEN HIGHER!! Is this reading of the bitrate from the video itself (i.e. WITHOUT the audio) or is this something to be expected with NSV?? Or is this just yet another bug?? Cheers for now :-) Patrick Cook Proud Member - Electronic Frontier Foundation - http://www.eff.org/ Program Director Jeeper One Radio Network KPDC Internet TV - REAL Web TV kpdcnetradio@msn.com kpdcnettv@attbi.com pchamster@msn.com Denver, Colorado http://kpdcnetradio.*********/ http://kpdcnettv.*******/ NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.*******/webcam.html KPDC Internet TV - http://kpdcnettv.*********/webcam.html

19th July 2003, 08:10	#3
Jeeper One Major Dude Join Date: May 2003 Location: Denver, Colorado Posts: 1,054	Hi everyone: First off, encoding ANYTHING at 16/22 isn't a very good idea. If you're going to use 16 Kbps., it MUST be a sampling rate 16000 Khz. or LOWER (not higher). Secondly, I've noticed the same thing about the differing bitrate. Now that I have Winamp 3 and it seems to have NO PROBLEM WHATSOEVER playing NSV videos, I've started encoding at 64/44 stereo, but I've seen the bitrate in the final product shoot in upwards of 300 Kbps and (sometimes) EVEN HIGHER!! Is this reading of the bitrate from the video itself (i.e. WITHOUT the audio) or is this something to be expected with NSV?? Or is this just yet another bug?? Cheers for now :-) Patrick Cook Proud Member - Electronic Frontier Foundation - http://www.eff.org/ Program Director Jeeper One Radio Network KPDC Internet TV - REAL Web TV kpdcnetradio@msn.com kpdcnettv@attbi.com pchamster@msn.com Denver, Colorado http://kpdcnetradio.*********/ http://kpdcnettv.*******/ NEW WEBCAM PAGES - KPDC Internet Radio - http://kpdcnetradio.*******/webcam.html KPDC Internet TV - http://kpdcnettv.*********/webcam.html

19th July 2003, 19:19	#4
LoKoRg Junior Member Join Date: Feb 2001 Location: Third planet around the Sun Posts: 32	Well, I know is not a good idea to compress with this configuration, but for now i doing some test, and even this low configuration cause my some trouble in bandwidt, well for now this is only part of my problem... back to the original question... i have a little problem with the audio, I smplerate to 22050 Hz because when try to samplerate to 11025 and a get this error "openOutput: error creating audio compressor" i try to use 11025 or 22050 because this are kind of standard... Well, to jump this problem i compress the video only...and the results are... First video (low action, color changes) final size: 490 KB duration: 240 sec 490/240 = 2.04 KB/sec = 16.33 kbps Second Video (more action) final size: 814 KB Duration: 246 sec 814/246 = 3.3 KB/sec = 26.47 kbps I use the same configuration metioned in the first message now i am doing some changes...wait a minute... change the frames to 8 fps (and preserve the same configuration above) the audio in 16000 Hz, 16 kbps, mono More results... First video final size: 863 KB duration: 240 sec 863/240 = 3.59 KB/sec = 28.76 kbps Second Video final size: 1072 KB duration: 246 sec 1072/246 = 4.35 KB/sec = 34.86 kbps I find this very rare, because when someone compress and Mp3 with certain bitrate, the final result is not depending on the audio type, even if is only silence, the file size of 2 different Mp3 with the same bitrate is the same file size... I dont know the VP3 video compression, but as i mention before, if i set certain bitrate the file size is not bigger than expected... Is this bug or is the way tha VP3 works?

19th July 2003, 21:41	#6
LoKoRg Junior Member Join Date: Feb 2001 Location: Third planet around the Sun Posts: 32	the problem is not with the audio or video quality, this don´t matter for me right now.... i just find very weird that if i compress 2 video files with the same video duration (4:00 minutes), and use the same NSV configuration configuration the 2 files are different in size...

20th July 2003, 02:24	#8
LoKoRg Junior Member Join Date: Feb 2001 Location: Third planet around the Sun Posts: 32	mmm... i think about that, but even so, the file size is espected to be some kind of constant or lower certain range of size... if is set the audio bitrate to 16...and the video bitrate to 8, the "result" must be sometime like 24 kbps total...plus some "metadata" (maybe not metadata like that whe enter in the video, maybe more information, scene change, etc)... 24 kbps = 3 KB/sec so 3time = expected_filesize KB (If VP3 is varible bitrate, this shoul be the maximum filesize) and if whe add the "metadata" variable 3time + "metadata" = real_filesize KB but even with the low motion video the filesize is very weird... First Video (low motion) Expected filesize: 3240 = 720 KB 3240 + "metadata" = real_filesize KB 720 + "metadata" = 863 KB So, the "metadata" must be "metadata" = 143 KB Let say this is a good metadata Second Video (high motion) Expected filesize: 3246 = 738 KB (just a little higher than abvove for the extra 6 seconds 3240 + "metadata" = real_filesize KB 738 + "metadata" = 1072 KB "metadata" = 334 KB Is more than two times bigger than the low action video... I even try to do with good video quality, but the filesize are really different.. for example the low action video get to 7-8 MB, and the high action to 9-10 MB Well...i really love NSV, is a great idea, great solution...i just love it and sorry for have too many questions, but he avaible information, reame, forum topics are in some ways too vague.... (and sorry for the "too mathematical" expresion, but in this way i can explain better the question) And other little question... In the NSENC configuration, is the "[checkbox] Allow dropped frames (Enables CBR)" This really works or is the cause of all my problems in the earth? (well, just the problems i have with NSV )

20th July 2003, 13:24	#11
LoKoRg Junior Member Join Date: Feb 2001 Location: Third planet around the Sun Posts: 32	so thats why.... thx for the explain I hoe in the near future (like 2013) the CBR works...