gspot , virtualdubmod give different bitrates for same clip!

[koorosh]

i have recorded several short mpeg2 clips via my dvb card.
i tested them with gspot and virtualdubmod to determine video bitrate.
but the resulting bitrate they show are so much different.
gspot shows average video bitrates about 200 to 2000 kbits/s larger than virtualdubmod for same clips.
whichone of these programs can be reliable then ?

[yoda313]

Hello,

Try powerdvd or windvd. They can tell the bitrate in the configurations menu. If those match either gspot or vdubmod I'd say use the powerdvd/windvd bitrate as the "true" bitrate.

Kevin

EDIT - Bitrate viewer can also read mpeg files.

[koorosh]

Hello,

Try powerdvd or windvd. They can tell the bitrate in the configurations menu. If those match either gspot or vdubmod I'd say use the powerdvd/windvd bitrate as the "true" bitrate.

Kevin

EDIT - Bitrate viewer can also read mpeg files.

here are the results given by three programs for one of clips :

gspot : 7926 kb/s
virtualdubmod : 5166 kb/s
windvd5 : 3917 kb/s

[midnightsun]

math I say!!

(((file size in byte)*8/(file duration in seconds))/1000)-(audio bitrate)=
video bitrate+overhead in kb/s (where it's assumed that k stands for 1000)

[bugster]

For mpeg files, use bitrate viewer.

[babyboo]

math I say!!

(((file size in byte)*8/(file duration in seconds))/1000)-(audio bitrate)=
video bitrate+overhead in kb/s (where it's assumed that k stands for 1000)

He is not trying to determine which bitrate to use as he has already encoded his clips. He is trying to determine which application he can use that will reliably identify the bitrate because he either...

A) Forgot what bitrate he used...or
B) Wants to be able to determine the bitrate used on other clips that he did not encode himself)

[midnightsun]

I did understand that, thank you. If he does what I wrote in my previous post he will know what bitrate was used to encode the file, which is what he's seeking help for.

[babyboo]

I did understand that, thank you. If he does what I wrote in my previous post he will know what bitrate was used to encode the file, which is what he's seeking help for.

True...my oversight. I didn't look close enough at your calculation. I just assumed your post was telling him how to calculate what bitrate to use instead of the reverse.

[koorosh]

math I say!!

(((file size in byte)*8/(file duration in seconds))/1000)-(audio bitrate)=
video bitrate+overhead in kb/s (where it's assumed that k stands for 1000)

thanks for reply

i did the calculation and the result was : 5039 which is near to virtualdubmod given bitrate.
what are the other programs saying then ?
are they pointing to max. and min. bitrate or what ?

[johns0]

The programs will give you different bitrates cause the movie runs with with variable bitrates as its been encoded,

[koorosh]

The programs will give you different bitrates cause the movie runs with with variable bitrates as its been encoded,

they are not pointing to variable bitrates
gspot is saying that it is average video bitrate :



virtualdubmod calls it average too :



well ....

[bugster]

The programs will give you different bitrates cause the movie runs with with variable bitrates as its been encoded,

they are not pointing to variable bitrates
gspot is saying that it is average video bitrate :



virtualdubmod calls it average too :



well ....

Gspot is simply reading the mpeg header info. Vdub is reading the whole file and calculating the real average.